Calidad de Los Implantes Dentales

International Dental Journal (2003) 53, 000-000

© 2003 FDI/World Dental Press0020-6539/03/06000-35

Quality of dental implants*Asbjørn Jokstad, Oslo, NorwayUrs Braegger, Bern, SwitzerlandJohn B. Brunski, Troy, USAAlan B. Carr, Rochester, USAIgnace Naert, Leuven, BelgiumAnn Wennerberg, Gothenburg, Sweden

Background: Clinicians need quality research data to decide which dentalimplant should be selected for patient treatment. Aim(s)/objective(s): Topresent the scientific evidence for claims of relationship between charac-teristics of root formed dental implants and clinical performance.Study design: Systematic search of promotional material and Internetsites to find claims of implant superiority related to specific characteristicsof the implant, and of the dental research literature to find scientific supportfor the claims. Main outcome measures: Critical appraisal of the researchdocumentation to establish the scientific external and internal validity as abasis for the likelihood of reported treatment outcomes as a function ofimplant characteristics. Results: More than 220 implant brands have beenidentified, produced by about 80 manufacturers. The implants are madefrom different materials, undergo different surface treatments and come indifferent shapes, lengths, widths and forms. The dentist can in theorychoose among more than 2,000 implants in a given patient treatmentsituation. Implants made from titanium and titanium alloys appear toperform well clinically in properly surgically prepared bone, regardless ofsmall variations of shapes and forms. Various surface treatments arecurrently being developed to improve the capacity of a more rapid anchor-age of the implant into bone. A substantial number of claims made bydifferent manufacturers on alleged superiority due to design characteristicsare not based on sound and long- term clinical scientific research. Implantsare, in some parts of the world, manufactured and sold with no demonstra-tion of adherence to any international standards. Conclusions: The scien-tific literature does not provide any clear directives to claims of allegedbenefits of specific morphological characteristics of root-formed dentalimplants.

Key words: Implantology, systematic review, dental industry, evidence-based dentistry

*Report initiated by and document approved by FDI Science Commission.

Correspondence to: Professor Asbjørn Jokstad, Institute of Clinical Dentistry, Universityof Oslo, PO Box 1109 Blindern, N-0317 Oslo, Norway. E-mail: [email protected]

Clinicians have for many decadesattempted to replicate teeth byimplanting alloplasts into bone.Scientifically based implant therapy,however, emerged at the end ofthe 1970s following groundbreakingstudies with 10-years clinical resultspresented by a research group inSweden directed by Dr Per-IngeBrånemark1,2. Their studies demon-strated conclusively that pure titaniumintegrates with bone tissue if it iscarefully prepared surgically, andthat a transmucosal element (abut-ment) joined to the implant canretain an intraoral prosthesis with apredictable clinical outcome. Duringthe years since these discoveries,there has been a proliferation ofmanufacturers who produce implantsusing various biomaterials andsurface treatments. These are termedoral- or dental implants, but thetwo terms are in practice regardedas synonyms. Dental implants varyin material, dimensions, geometries,surface properties and interfacegeometry3,4, so today the dentistneeds to select from more than2,000 different dental implants andabutments in a specific treatmentsituation. Certain manufacturersalone offer more than 100 differ-ent implants in varying shapes andmaterials. Other manufacturersfocus in their promotional materialon seemingly significant advantagesin implant characteristics, but with-out relevant clinical support of theclaims. The bewildered clinician isleft with the question of which

000

International Dental Journal (2003) Vol. 53/No.6 (Supplement)

criteria one should employ to differ-entiate between good and badquality.

Dental implants, characteristics

A careful surgical technique isstrongly associated with a success-ful treatment outcome, at least forthe early post-insertion period, butimplant-specific features should beconsidered important as well. Inaddition to the actual materialcomposition, at least two morpholo-gical characteristics may be relevant,namely the implant’s geometry andthe surface topography2.

Implant material

The majority of dental implantstoday are made from commerciallypure (c.p.) titanium or titaniumalloys. A smaller group of implantsare made entirely out of, or surface-coated with, a complex of calciumphosphate, of which the mostcommon is hydroxyapatite (HA).Other implants that have beencommercially available previouslycomposed of materials such asaluminium oxide, ‘bioglass’, ‘crystal’and ‘vitreous carbon’ have nowmore-or-less disappeared. C.p. tita-nium is produced with variousdegrees of purity, which is impor-tant for, for example, airplanemanufacturers.

Basically, the maximum oxygenpercentage defines the commerciallypure grade of titanium accordingto an American standard (ASTMF67). C.p. titanium grade 1 has thehighest purity because of its lowoxygen and iron content versus c.p.titanium grade 4, which has thehighest maximum oxygen and ironpercentage. Implants are madefrom the full range of differentc.p. titanium grades. For example,Brånemark system® implants (NobelBiocare, Sweden) are made fromgrade 1 c.p. titanium, while ITI®

implants (Straumann, Switzerland)are made from grade 4 c.p. tita-nium. Titanium alloys are designedwith ASTM grades from 5 to 29,and several manufacturers use the

grade 5 titanium alloy, oftendesigned Ti-6Al-4V, for dentalimplants (e.g. Sargon®, SargonEnterprises, USA). In general, c.p.grade 1 titanium demonstrates thehighest corrosion resistance andlowest strength, while grade 4(titanium) and grade 5 (titaniumalloy) demonstrate greater yieldstrengths. As the corrosion resist-ance is almost entirely dependentupon the iron content, severaldental implant manufacturers (e.g.Astra Tech, Sweden) use grade 4titanium where the iron content islimited to below the maximumallowed in grade 1. The directimplications of the relatively smalldifferences in mechanical and physi-cal properties on the clinicalperformance intraorally are uncer-tain, e.g. the relationship betweentensile or fatigue strength and theincidence of mechanical complica-tions over time5.

Implant geometry

Root formed dental implants havebeen designed in a wide variety ofbody geometries. The implantswere previously categorised asscrew, cylinder and hollow baskettypes. Today, the last group isregarded as obsolete and thedistinction between the screw type,i.e. having threads, and the cylindertype is becoming blurred. Theterms threaded and non-threadedimplants are often used as syno-nyms for screw and cylinderimplants. Both screws and cylin-ders are manufactured with straight,tapered, conical, ovoid or trape-zoidal walls. Variations in the formof the threads, supplementing vents,grooves and steps increase thecomplexity of characterising implantsby geometries. There even existimplants designed to expand theapical part after placement into theprepared bone tissues. A trendseems to exist towards producingimplants with three-dimensionalmorphology that alters along thevertical axis. Figure 1 illustrates thewide variation in geometries of rootformed implants. In addition, some

dentists place trans-mandibular,blade, or frame implants, but invery small numbers and these willnot be described further in thisreport. Sub-periosteal and sub-mucosal implants are todayregarded as obsolete.

Implant surface topography

Different methods are being usedto alter the surface topography ofdental implants. One or several ofthese methods are used to produceeither an isotropic surface (i.e. withsurface asperities that are randomlydistributed so the surface is identicalin all directions) or an anisotropicsurface (i.e. surface with a direc-tional pattern) (Table 1). The surfacetreatments are suggested to improvethe capacity of anchorage into bone.It has been postulated, mostly onbasis of animal and histologicalstudies, that this advantage can beseen in an early healing phase incomparison with a turned surface6,7.

The predictability for an accept-able treatment outcome has beenshown to be very good for implantsmachined with a turning process8,9.The clinical outcome of other vari-ous surface modifications has alsobeen published to different extent.Most studies suggest a predictableand more rapid osseointegrationof implants with different surfacetreatments, e.g. blasted10,11, acidetched12,13, blasted plus acidetched14–16, porous17, oxidised18 andtitanium plasma sprayed19,20. Arecent study has also questionedwhether different surface treat-ments, besides changing the surfacetopography, perhaps even alter thesurface chemistry, and thus alsoneed to be considered as a variablein clinical studies21.

Can the quality of dentalimplants be measured?

According to the InternationalOrganisation for Standardisation(ISO) a dental implant is: “A devicedesigned to be placed surgically within oron the mandibular or maxillary bone toprovide resistance to displacement of a

000

Jokstad et al.: Quality of dental implants

Figure 1. Variations in dental implant design features in general (top) and from top to bottom the implant/abutment interface, the implantflange, the coronal, the midbody and the apical thirds (bottom).

dental prosthesis” (ISO 1942-5). Thecorresponding definition for adental implant system is: “Dentalimplant components that are designed tomate together. It consists of the necessary

parts and instruments to complete theimplant body placement and abutmentcomponents” (ISO 10451).

The definitions encompass twoelements that may in theory be

associated with aspects of quality.If the process that allows ‘a devicedesigned to be placed surgically’ for someimplant systems is straightforwardand not associated with high risk

000

International Dental Journal (2003) Vol. 53/No.6 (Supplement)

Table 1 Methods used to alter surface topography of dental implants (sorted alphabetically).

Machining process Resulting surface topography Example

Acid etched surface (The surface Isotropic surface with high frequency HCl/ H2SO4 (Osseotite®, 3i Implant innovations,is usually etched in a two-step irregularities Palm Beach Gardens, USA)procedure)

Blasted surface (The surface is Creates an isotropic surface TiO2 particles (Tioblast®, Astra Tech AB, Mölndal,blasted with hard particles) Sweden)

Blasted + acid etched surface An isotropic surface 1. Large size Al2O3 particles & HCl & H2SO4 (SLA®,(The surface is first blasted and Institute Straumann AG, Waldenburg, Switzerland);then acid etched) 2. Tricalcium phosphate & HF & NO3 (MTX®,

Centerpulse Dental, Carlsbad, USA)

Hydroxyapatite coated surface In general, a rather rough and isotropic Sustain® (Lifecore Biomedical Inc, Chaska, USA)surface

Oxidized surface (Increased Isotropic surface with the presence of TiUnite® (Nobel Biocare AB, Göteborg, Sweden)thickness of the oxidized layer) craterous structures

Titanium Plasma Sprayed (TPS) A relatively rough isotropic surface ITI® TPS (Institute Straumann AG, Waldenburg,surface Switzerland)

Turned surface Cutting marks produce an oriented, Brånemark System® MKIII (Nobel Biocare,anisotropic surface Göteborg, Sweden)

of complications but not for othersystems, this may be an indicatorof quality. Evidently, simplicity ofplacement is in itself not anadequate criterion for implant qual-ity, but must be regarded incontext with material propertiesand other reported outcome crite-ria. The second element is ‘providingresistance to displacement’. Conse-quently, reliable documentation thatthis in fact is the case for a specificdental implant or implant system isa characteristic of high quality.

The ISO definition does notallude to any temporal require-ments, but most people wouldprobably agree that the ‘resistance todisplacement’ should remain for aminimum period, and preferablyas long as possible. Thus, onedirect estimate of the quality of adental implant is the reportedresults observed in clinical trials thathave lasted for an extended period,e.g. for more than five years. Itshould be required that the docu-mentation of acceptable clinicalperformance are data obtained in aclinical trial with an appropriateresearch design and adequate levelof external and internal validity.

The quality of a dental implantor implant system may also bedefined by another dimension,which is the requirement that eitherthe implant per se or the manufac-

turing process should conform toa national or an international stand-ard. Although several countriesdemand that products need tocomply with such standards inorder to be marketed, this doesnot apply to all parts of the world.Moreover, the ethical conduct ofthe manufacturer is important,which is reflected by a sincere andexact format of the product docu-mentation, as well as the form ofthe presentation of products, forthe users, i.e. the dentist.

Scientific evidence andrequired study designs

Whether one wishes to addressadequate clinical performance ofan implant or whether the aim is tocompare the performance ofdifferent products the choice ofadequate scientific documentationwill differ. The validity of any clini-cal trial, however, depends on anappropriate choice of outcomevariables and reliable measurementof these, regardless of the studydesign. It is the authors’ task todescribe such details in theirreports to enable the reader bothto comprehend the paper but also,if wishing to do so, to repeat thetrial without doubting how this wascarried out.

Adequate clinical performance

of an implant can best be demon-strated in a longitudinal trial, eitherprospective or retrospective. Theexternal validity of such trials areto a large extent related to patientdropout and – representativity aswell as other variables such asoperator experience and clinicalsettings. One may also obtain animpression of clinical performancefrom reports of case series.However, there is an increased riskof selective recording of treatmentdata, as well as risk for spuriousstatistical associations. Moreover,potentially confounding variablesare more or less difficult toaccount for and this may skew thetreatment outcome without anychance of knowing by how much.The final type of clinical study type,case reports, often lack manydetails, which makes it difficult tointerpret the implant performancein general.

Scientific documentation ofsuperiority of one product versusanother requires a more stringentstudy design. This is best appraisedusing a randomised controlled trialdesign (RCT). In a RCT the parti-cipants are allocated at random toreceive different interventions. Anappropriate random allocationmeans that all trial participants havethe same chance of being assignedto either an experimental or to a

Table 2 Design characteristics of the dental implant that may be associated with clinical success. (Factors associated withinadequate quality control of the production process are excluded in this table, e.g. inferior materials, contamination and poorprecision. These elements should be assured by the manufacturer’s adherence to a production quality control standard, e.g.

ISO9001)

Clinical outcome Design characteristic

1. Ease of placement • Implant body geometry

2. Osseointegration • Implant body geometry• Implant material• Implant surface topography

3. Aesthetics • Implant and abutment interface geometry • Abutment material and geometry

4. Peri-implant mucositis • Implant body geometry • Implant material • Implant surface topography• Implant and abutment interface geometry• Abutment material, geometry and surface topography

5. Marginal bone loss • Implant body geometry • Implant material • Implant surface topography• Implant and abutment interface geometry • Abutment material, geometry and surface topography

6. Mechanical problems of the implant/ • Implant body geometryabutment/ superstructure connections • Implant and abutment interface geometry (Joint geometry strength, precision fit of

components, torque reliability, i.e. clamping force)• Abutment material, geometry and surface topography

7. Mechanical failure of the dental implant • Implant body geometry • Implant material• Implant dimensions

control group. Properly accom-plished randomisation minimisessystematic patient selection bias andsince the groups thereby in theorybecome identical, apart from theintervention, any difference inoutcome is attributable solely tothe intervention. The larger thegroups under study, the moreconfidence can be placed that it isthe effect of the intervention that isreflected by the treatment outcomesand not some confounding under-lying patient variables. It must beemphasised that a report based ona RCT does not automatically trans-late as a high quality paper. Criticalappraisals of the literature in pros-thodontics suggest that numerousRCTs are poorly reported22,23.

If no RCTs can be identifiedfor comparing products or specificimplant characteristics, prospectivecontrolled clinical trials, and to alesser degree clinical trials usingother study designs, provide someindications of product differences.However, the possibility of incor-rect conclusions increases withthese less stringent study designs

due to risk of bias and influence ofconfounding variables. Studies thatreport the treatment outcome of asingle patient cohort, prospectivelyor retrospectively, without anycomparison group must not beused as the basis for comparisonsof product performance. Thereason is that variations betweenstudy variables such as clinicalsetting, clinician experience, treat-ment indication, patient selectionand socio-demographics, etc.impede any meaningful compari-sons because these significantvariations can strongly influence theoutcome.

Extrapolating laboratory studydata to promulgate hardwareclaims and product superiority isinvalid for generalising to the clini-cal setting since laboratory data,even if statistically significant, maybe irrelevant or even directlymisleading in the clinical environ-ment. Only well-designed clinicaltrials can supply evidence of prod-uct differences that are clinicallyrelevant.

The aim of this paper is to

present and discuss the availablescientific evidence of clinical perfor-mance of different dental implantsystems. The objective is to helpcustomers to recognise high qualitydental implants on the basis of thisevidence.

Materials and methodsInformation presented bymanufacturers

We first recorded as many manu-facturers of dental implants andbrands as possible by browsingdental journals and programmebooklets for advertisements as wellas lists of exhibitors at majorimplant and prosthodontic meet-ings. Languages were limited toEnglish, German, Scandinavian,Spanish and French. We alsoappraised papers in dental journalsand meeting abstracts for the samepurpose. We identified thereafterthe Internet websites of the manu-factures. Next we appraised thewebsites and printed promotionalmaterial from the manufacturers toidentify claims of product superi-

ority on the basis of one or moreparticular implant characteristics.We also recorded whether themanufacturer announced on theirwebsite or in their promotionalmaterial that either the manufac-turing process or the implantconformed to any internationalstandards, e.g. ISO, or if it is certi-fied according to such standards,e.g. by a CEN notified body inEurope or FDA in USA. Wecontacted the manufacturers inseveral cases where no clinical stud-ies of a specific implant brand couldbe identified, with an invitation toprovide this information.

Claims of clinical superiority dueto specific morphological charac-teristics could be categorised intoseven general groups (Table 2).

Scientific literature

We systematically searched variouselectronic databases (Medline,Embase and the Cochrane OralHealth Group specialist register) toidentify clinical trials on dentalimplants. We also hand-searchedseveral implant journals in anattempt to reduce the likelihood ofmissing relevant articles. We alsochecked the bibliographies of stud-ies and relevant review articles.Medline included, in October 2003,6,353 articles indexed under‘Dental implant’. The Pubmedsearch using a methodology filterfor sensitivity searching identified574 papers on therapy and 1,345on prognosis. The CochraneControlled Trials Register included392 controlled clinical trials. TheFinnish national register for dentalimplants, which includes data onplaced and removed implants inFinland since 1994, was also usedas a source to relate clinical perform-ance to implant brand.

We identified all implants andimplant systems that had beenevaluated in the clinical trials. Onthe basis of the number of clinicaltrials and the scientific methodo-logical quality of the reports wedefined four levels of clinical

documentation:A. Implant or implant system with

extensive clinical documentation,i.e. more than four prospectiveand/or retrospective clinical trials

B. Implant or implant system withlimited clinical documentation,i.e. less than four trials, but ofgood methodological quality, i.e.randomised controlled trial orprospective clinical trial, eithermulticentre or with study sam-ples consisting of more than 50patients or 200 dental implants

C. Implant or implant system withlimited published clinical docu-mentation and not fulfillingdocumentation levels A or B

D. Implant or implant system withno published clinical documen-tation.The next phase was to critically

appraise the clinical trials thatreported an association betweenclinical performance and specificcharacteristics of dental implants.In view of the high number ofclinical studies, relatively few trialswere designed to specifically evalu-ate the influence of specific charac-teristics of the implant (Table 3)24–84

or the abutment (Table 4)85–94 onclinical performance. We sorted theclinical trials according to the meth-odology strength of the studydesign. Four broad categories weredefined:• Category A1, clinically controlled

trial with patient randomisation(RCT)

• Category A2, clinically controlledtrial with split-mouth random-isation, (Split-mouth RCT)

• Category B, (prospective) clini-cally controlled trial withoutrandomisation (CCT)

• Category C, clinical study apply-ing any other study design thanA or B (e.g. retrospective cohort,case-series, case-controls, etc.).

Results

We have, as at October 2003, iden-tified about 80 manufacturers ofdental implants, who market slightlymore than 220 different implant

brands (Table 5). In addition, approxi-mately 60 implant brands/manu-facturers were recorded, but theseappear to have vanished from themarket. However, it should not beruled out that a small number ofthese may still be obtainable in vari-ous parts of the world.

About half of the manufactur-ers inform on their websites to whatextent their company and productscomply with an international stand-ard or are certified (Table 5). Ofthese, it is almost universally a refer-ence to ISO 9001 and/or EN46001. Less common is a referenceto the European Union medicaldevice directive 93/42/EEC, to theCE notified body, to other ISOand EN standards or to a FDAmarket clearance or reference tothe so-called FDA 510K. Most ofthe companies who do not presentsuch information on their websitehave included this information intheir printed promotional material,but some manufacturers still lackany information on this subject(Table 5).

Only a minority of the dentalimplant manufacturers can provideextensive clinical documentation oftheir implant brands for the patient(Code A in Table 5, n=10). Incontrast, 29 manufacturers marketdental implants with no clinicalresearch documentation at all (CodeD in Table 5).

A compilation of the differentstudies according to study designsand documented or appraisedpossible influences on treatmentoutcomes is presented in Table 6.Studies with lower levels of scien-tific evidence strength are onlyincluded in this review where thereis a lack of studies with better studydesigns.

1. Ease of placement

Summary: Differences in ease ofplacement, as a function of theimplant morphology have not beensystematically evaluated in clinicaltrials. Two reported outcomes areoperation time and surgeons’ pref-

Table 3 Clinical studies where one or more implant characteristic has been associated with the clinical performance, identifiedas Geometry -, Material -, Surface topography or combinations of these (Complex). Sorted by study design, characteristic and first

author name.

Study design* Reported or appraised influence Sample (n) Per. (yrs) Authors of implant characteristic on clinical performance

RCT Complex: Brånemark System® vs IMZ® (30x3)x2 1 Batenburg et al. 1998 (The Netherlands)24

vs ITI®

RCT Complex: Astra Tech vs Brånemark 184+187 3 Engquist et al. 200225

System® 1 Åstrand et al. 1999 (Sweden)26

RCT Complex: Astra Tech vs ITI® 56+46 1 Kemppainen et al. 1997 (Finland)27

RCT Complex: Brånemark System® vs IMZ® (32+29)x2 5 Meijer et al. 2000 (The Netherlands)28

RCT Complex: Brånemark System® vs ITI® 102+106 3 Moberg et al. 2001 (Sweden)29

RCT Complex: Southern vs Sterioss 48x224x2 2 Tawse-Smith et al. 200216

1 Tawse-Smith et al. 2001 (New Zealand)30

RCT Geometry: IMZ® 1-stage vs IMZ® 2-stage (20x3)x2 2 Heydenrijk et al. 200331

vs ITI® , TPS coatingsIMZ® vs ITI® , TPS coatings (20x2)x2 1 Heydenrijk et al. 200232

Meijer et al. 2003 (The Netherlands)33

RCT Material: Sterngold-Implamed®, plasma- 176x2 5 Jones et al. 199934

spray Ti vs HA coated <1 Jones et al. 1997 (USA)35

RCT Material: IMZ®, Ti plasma-spray vs 147+145 3-7 Mau et al. 2002 (Germany)36

HA coated

RCT Surface: Brånemark System® 55+66 1 Rocci et al. 2003 (Italy)37

Standard vs TiUnite

Split-RCT Complex: Brånemark System® vs ITI® 77+73 1 Åstrand et al. 2002 (Sweden)38

Split-RCT Complex: Steri-Oss TPS vs HA screw 634 3 Geurs et al. 2002 (USA)39

vs HA cylinder (brand not described)

Split-RCT Complex: Brånemark System®, vs HA 615 5 Jeffcoat et al. 2003 (USA)40 screw vs HA cylinder (brand notdescribed)

Split-RCT Complex: Spectra system, HA groove 2641 <1 Orenstein et al. 199841

vs HA screw vs HA cylinder vs Ti screw 2633 <1 Truhlar et al. 199742

vs Ti-alloy basket vs Ti-alloy screw 1565 <1 Ochi et al. 1994 (USA)43

Split-RCT Complex: Astra Tech vs Brånemark 45+50 2 van Steenberghe et al. 2000 (Belgium)44

System®

Split-RCT Geometry: Brånemark System®,, standard 44x2 1 Friberg et al. 2003 (Sweden)45

vs Mk IV screws

Split-RCT Surface: Astra Tech, turned Ti 64+64 5 Gotfredsen & Karlsson 200146

vs TiO2 –blasted 2 Karlsson et al. 1998 (Scandinavia)47

Split-RCT Surface: 3i, Dual-etch vs turned Ti 247+185 2-5 Khang et al. 2001 (USA)48

Split-RCT Surface: ITI®, SLA vs TPS 68x2 1 Roccuzzo et al. 2001 (Italy)14

CCT Complex: Brånemark System® vs ITI® 160+78 1–3 Becker et al. 2000 (USA)49

CCT Complex: Brånemark Conical® vs 40+40+164+84 3–8 Chiapasco & Gatti 2003 (Italy)50

FriaLoc vs Ha-Ti® vs ITI®

CCT Complex: Brånemark System® 78+80 2–5.5 Pinholt 2003 (Denmark)51

Standard, MKII & MKIII vs ITI® SLA

Split-CCT Complex: 3i, 2 geometries, turned Ti, 15x3 3 Røynesdal et al. 1998 (Norway)52

HA & TPS

Split-CCT Complex: 3i, 2 geometries, turned Ti, 15x3 3 Røynesdal et al. 1999 (Norway)53

HA & TPS

Split-CCT Geometry: Brånemark System®, standard 288+275 5 Friberg et al. 199754

vs self-tapping screws 288+275 3 Olsson et al. 199555

88+91 1 Friberg et al. 1992 (Sweden)56

CS Complex: Core Vent, Screw Vent® vs 85+11+105 >2 De Bruyn et al. 1992 (UK)57

Swede Vent® vs Brånemark System®

CS Complex: IMZ® vs ITI® Bonefit vs ITI® TPS 168+150+ 109 1–10 Gómez-Roman et al. 1998 (Germany)58

CS Complex: Astra Tech Tioblast ® vs ITI® 31+93 1–10 Ellegaard et al. 1997a, 1997b (Denmark)59,60

hollow screw cont'd...

Study design* Reported or appraised influence Sample (n) Per. (yrs) Authors of implant characteristic on clinical performance

CS Complex: ZL-Duraplant, Turned vs 58+369 3–5 Graf et al. 2002a, 2002b (Germany)18,61

electrochemical surface & screw vscylinder

CS Complex: Astra Tech vs Brånemark 15x2 >2 Puchades-Roman et al. 2000 (UK)62

System®

CS Complex: Brånemark System® vs ITI® 90+32 1–8 Krausse et al. 2001 (Germany)63

CS Complex: Brånemark System® vs 1964 1–16 Noack et al. 2001 (Germany)64

Frialit®-2 vs IMZ®

CS Complex: Brånemark System® vs IMZ® 384 1–8 Scurria et al. 1998 (USA)65

CS Complex: IMZ® vs ITI® 3 implant geometries 264+36 0.5–11 Spiekerman et al. 1995 (Germany)66

CS Complex: Brånemark System® screws 54+133 2– Valentini & Abensur 2003 (France)67

vs IMZ® cylinders

CS Geometry: Brånemark System®, 4 screw 252 1–8 Bianco et al. 2000 (Italy)68

geometries & 4 abutment geometries

CS Geometry: ITI®, 4 implant geometries 2359 1–8 Buser et al. 1997 (Switzerland)19

CS Geometry: ITI®, 5 implant geometries 654 1–7 Carr et al. 2003 (USA)69

CS Geometry: Brånemark System®, 4 screw 82 1–5 Engquist et al. 1995 (Sweden)70


CS Geometry: ITI®, 4 implant geometries 1286 1–10 Ferrigno et al. 2002 (Italy)71

CS Geometry: Brånemark System®, multiple 1141 1–10 Lentke et al. 2003 (Germany)72

screw & abutment geometries

CS Geometry: Brånemark System®, 3 screw 84 1–6 Malevez et al. 1996 (Belgium)73


CS Geometry: Brånemark System®, 5 screw 270 1–11 Naert et al. 2000 (Belgium)74

geometries

CS Geometry: Brånemark System®, 3 screw 668 1–15 Naert et al. 2001 (Belgium)75

geometries

CS Geometry: Brånemark System®, 5 screw 1956 1–16 Naert et al. 2002a, 2002b (Belgium)76,77


CS Geometry: Brånemark System®, 3 screw 1279 1–3 Quirynen et al. 1992 (Belgium)78

geometries

CS Geometry: Brånemark System®, standard 84+86 3 Raghoebar et al. 2003 (International)79

& MKII screws

CS Geometry: ITI®, 2 implant geometries 187 1–7 Romeo et al. 2002 (Italy)80

CS Geometry: Frialit®-2, stepped screw 802 1–5 Wheeler 2003 (USA)81

vs stepped cylinder

CS Material: Bicon®, HA vs Ti vs TPS 2349 0–7.5 Chuang et al. 2002 (USA)82

CS Material: not specified, HA vs Ti 2098 1–6 Weyant & Burt 1993 (USA)83

CS Surface: 3i, Dual-etch vs turned vsself-tapping vs ICE® vs Osseotite® 1583 1–5 Davarpanah et al. 2002 (France)84

*RCT: Randomised controlled trial, Split-RCT: Split mouth randomised controlled trial CCT: Controlled clinical trial, CS: Case Series

erence. One split-mouth RCTfocused on influence of geometryand suggested a slight effect onprimary stability, albeit operatorbias cannot be avoided. There areno studies with specific focus oninfluence of implant material or surface topography. Implants withdifferent geometry, material andsurface topography have beenevaluated in two RCTs and onesplit-mouth RCT. These presentslight evidence that implant brand

can be associated with time neededfor surgery. However, as none ofthe studies were in any way blinded,investigator preferences may haveinfluenced both the actual trialprocedures as well as the trialreporting. One clinically controlledtrial with focus on influence ofgeometry has also suggested thatchanges in implant geometry mayimprove the ease of placement asreported by the surgeon. However,the study design does not control

for possible operator bias regard-ing implant preference.

Category A1 studies:Randomised controlled trialsStudies where implant geometry, mate-rial and surface topography influences onthe outcome ‘ease of placement’ areconfounded.

The time for surgical installation ofBrånemark system® implants in themandible has been measured to be65 minutes and 77 minutes for ITI®

Table 4 Clinical studies where one or more implant abutment characteristic has been associated with the clinical performance,identified as Geometry -, Material -, Surface topography or combinations of these (Complex). Sorted by study design, characteris-

tic and first author name.

Study design* Reported or appraised influence Sample (n) Period (yrs) Authors of implant characteristic on clinical performance

RCT Geometry: Brånemark system® Standard 5x4x2 2 Gatti & Chiapasco 2002 (Italy)85

vs transmucosal abutment

Split-RCT Material: Brånemark system® Ti vs 34x2 +10x2 1& 3 Andersson et al. 2001 (Sweden)86 ceramic abutment

Split-RCT Material: IMZ® Ti vs ceramic abutment 14x2 12 wks Barclay et al. 1996 (UK)87

Split-RCT Material: Brånemark system® Ti vs 6x2 1 Bollen et al. 1996 (Belgium)88

ceramic abutment

Split-RCT Surface: Brånemark system® Ti 6x4 3mths Quirynen et al. 1996 (Belgium)89

abutments with 4 different surfaceroughness

CCT Geometry: Omniloc® 2 abutments 429 5–7 McGlumphy et al. 2003 (USA)90

CS Complex: IMZ® & IME/IMC vs ITI® & 138+50 0.5-8 Behr et al. 1998 (Germany)91

Octa abutment

CS Geometry: Spline® vs Threadlock® 44+52 3 Bambini et al. 2001 (Italy)92

abutments

CS Geometry: Brånemark system® 3 1170 1–10 Eckert & Wollan 1998 (USA)93

abutment screws

CS Geometry: Brånemark system® 2 259 1–9 Scholander 1999 (Sweden)94

abutments

*RCT: Randomised controlled trial, Split-RCT: Split mouth randomised controlled trial CCT: Controlled clinical trial, CS: Case Series

cont'd...

Table 5 List of manufacturers and implant brands. Documentation of clinical and laboratory studies can be found in a databasewith links to manufacturers’ websites located on the website of the FDI World Dental Federation (http://www.fdiworldental.org/resources/implants.htm). Validation codes: A: Extensive clinical documentation; B: Some documentation identified of acceptable

quality; C: Some documentation identified, but of poor quality; D: No clinical documentation

Manufacturer, Country Implant brands Document Information Comply to standard,on website as registered elsewhere

1. ‘O’ Company Inc., USA 1. Cylinder D – FDA2. Threaded3. Performance Plus Taper4. RBM Blade

2. 3i Implant Innovations, Inc., 5. ICE Super Self-Tapping A – ISO9001, EN46001,USA 6. Osseotite® TG™ (CE0483), FDA

7. Osseotite®8. Osseotite® XP™9. Osseotite® NT™10. Osseotite® Certain™

3. ACE Surgical Supply Comp, 11. Ace screw (Ace Dental Implant System) C ISO9001, EN46001USA

4. Alpha Bio GmbH, Germany 12. DFI (Dual-Fit-Implant) D (CE0483)

5. Altatec Medizintechnische CAMLOG® implant system B – ISO5832&5833Elemente GmbH & Co. KG, 13. Cylinder Line ISO13484, EN46001,Germany 14. Root Line (CE0124)

15. Screw Line16. Screw-Cylinder Line

6. Altiva Corp., USA 17. NTR Natural Tooth Replacement System™ C FDA market FDAclearance

7. Anthogyr, France 18. Hexagon System B ISO9001, EN4600119. Octagon System20. Temporary

8. AS Technology, Brazil 21. Titanium Fix Auto Rosqueável Hex D – –22. Roscado Hex23. Roscado Hex PS

cont'd...


9. Astra Tech, Sweden 24. AstraTech A ISO9001/ISO14001 EN46001, CE, FDA25. AstraTech ST26. Fixture MicroThread™

10. Basic Dental Implants LLC, 27. Omni-Tight™ D – FDAUSA

11. BEGO Semados, Germany 28. Semados® C – CE 0044, DINISO9001 + 9002, EN46001

12. Bicon Dental Implants, USA 29. Bicon Implant System B – ISO9001, EN46001,CE, FDA

13. BioHorizons Implant 30. Maestro™ System B – ISO9001, EN46001,Systems, Inc, USA CE, FDA

14. Bio-Lok International, Inc. 31. Classic Cylinder D ISO9001, (CE0123) ISO9001, EN46001,(Subsid.: Orthogen Corp.), 32. LaserLok™ FDA 510K CE, FDAUSA 33. Micro-Lok™ Screw

34. Micro-Lok™ Cylinder 35. Silhouette™ 36. Silhouette™ I.C.

15. BioHex Corp. (prev. 37. BioHex™ (prev. BIT™ ) One Piece- C HPB (Canada), FDABiomedical Implant One Stage™ Implant System FDA regulationsTechnology), Canada

16. Biotechnology Institute,S.L., Spain 38. B.T.I. Implant C ISO9001, EN46001,

MDD93/42/EEC(CE0123)

17. Bone System, Italia 39. Bone System 2 D ISO9001, EN46001,MDD93/42/EEC(CE0123)

18. BTLock s.r.l., Italia BTLock System D ISO9001, EN46001,40. Screw: turned, acid-etched, HA coated, MDD93/42/EEC

TPS coated, BTTITE (CE0373)41. Cylinder: Screw: turned, acid-etched,

HA coated, TPS coated, BTTITE

19. Centerpulse Dental Inc. 42. Taper Lock A ISO9001 ISO9001, EN46001,(prev. Sulzer Dental) 43. Swiss-Plus CE, FDA(prev. Calcitek), USA 44. Swiss-Plus +taper

45. Screw-Vent®46. Screw-Vent® +taper47. AdVent48. Spline

20. Cowell Medi , Korea 49. Bioplant External Type D – –50. Bioplant Internal Type

21. Cresco Ti Systems, 51. OI-90 Implant Series (Osseo-Integrator) C ISO9001, EN46001Switzerland

22. Dental Tech, Italy 52. Physioplant dental implant system D – ISO9001, EN46001

23. Dentatus, Sweden 53. MTI-Monorail™ Transitional A –

24. Dentoflex Comércio e 54. Dentoflex de hexágonos externo D – –Indústria de Materiais 55. Dentoflex de hexágonos internoOdontológicos, Brazil

25. Dentsply Friadent, Germany 56. ANKYLOS implant system A (CE0123) ISO9001, EN46001,57. FRIALIT®-2 stepped cylinder, HA FDA58. FRIALIT®-2 -stepped screw, TPS59. FRIALIT®-2 -stepped screw Synchro,

TPS60. FRIALIT®-2 -stepped screw, Tiefstruktur61. FRIALIT®-2 -stepped screw, Synchro

Tiefstruktur62. XiVE®

63. XiVE®TG64. IMZ®-TwinPlus implant system65. Friadent® CELLplus

cont'd...


26. Dr Ihde Dental GmbH, Allfit ® C – (CE0483)Germany 66. ATI

67. ATIE68. Compression69. DiskosEDDDS/EXDDS70. Diskos EDXAAS71. KOS72. SSO73. STC74. STI 75. STO

27. Dyna Dental Engineering 76. Dyna Octalock® C – ISO CEb.v., Netherlands

28. Eckermann Laboratorium, 77. Eckermann Plus! C ISO13485,Spain 78. Eckermann Transicional (CE0318)

79. Eckermann Duplo80. Eckermann All Spiral

29. Elite Medica, Italy 81. Elite Implant System C ISO9001,82. Fastite EN4600183. Mini

30. Euroteknika, France 84. Secure D –

31. Impladent Ltd, USA 85. LaminOss® Osteocompressive C – ISO9001, EN46001,Implant System CE, FDA

32. Impladent S.L, Spain 86. Defcon® D – –

33. Implant Microdent System, Microdent System D – (CE0318)S.L, Spain 87. Microdent Universal

88. Especial Serie MS-Micro89. Especial Serie MT

34. IMTEC Corporation, USA 90. Press-Fit B/C ISO9001, EN46001, FDA91. Press-Fit TPS CE92. Screw-Type93. Sendax MDI

35. Innova LifeSciences 94. Endopore™ A ISO9002, CE, FDA ISO9002,Corp, Canada 95. Entegra™ 510K EN46002, CE, FDA

36. Institut Straumann AG, ITI® Dental Implant system A ISO9001, EN46001, ISO9001,Switzerland 96. Screw (CE0123) EN46001, CE, FDA

97. Screw Esthetic Plus98. Hollow Cylinder99. Hollow Cylinder, Esthetic Plus100.ITI® Narrow Neck (NNI)101.ITI® Wide Neck (WNI) 102.ITI® TE™

37. Interdental S.R.L, Italia Ergo-System C ISO9001, EN46001,103.External Exagon (CE0546)104.Internal Exagon

38. Jmp dental GmbH, Germany 105.jmp Mini-Implantat D – –

39. JOTA AG, Switzerland 106.JOTA D ISO9001, EN46001,(CE0408)

40. Klockner Implants, Spain Klockner system B ISO9001, EN46001,107.K2 (CE0318), FDA108.SK4109.S3110.S4111.S6

41. LASAK Ltd, Czechia 112.Impladent B ISO9002 EN46002

42. Leone S.p.A, Italy 113.Leone Implant System D ISO9001 EN46001ISO13485

cont'd...


43. Lifecore Biomedical, Inc., 114.Restore, Threaded, RBM, regular&wide A ISO9001, EN46001,USA 115.Restore, Threaded, TPS, regular&wide FDA

116.Restore, Threaded, Ti, regular&wide117.Restore, Threaded, HA, regular&wide118.Restore, Cylinder, RBM, regular&wide119.Restore, Cylinder, TPS, regular&wide120.Restore, Cylinder, Ti, regular&wide121.Restore, Cylinder, HA, regular&wide122.Stage-1™, RBM, regular&Wide,

+/-Esthetic Collar123.Stage-1™, TPS, regular&Wide, +/-Esthetic

Collar124.SuperCAT Super Self-Tapping125.Sustain, HA coated (MC) cylinder

44. MIS Implant Technologies MIS Trio Implant System C – EN 46001, ISO9001,Ltd Company (MIS), Israel 126.Internal connection FDA

127.External connectionMIS implants128.Bio-Com Fixture129.Internal hexagon, Screw130.Internal hexagon, Cylinder131.External hexagon, Screw132.External hexagon, Cylinder

45. Mozo-Grau, Spain 133.Mozo-Grau Threaded C – (CE 0044), EN134.Mozo-Grau Cylinder 46001, ISO9001,

FDA

46. Neobiotech Comp. Ltd. 135.Neoplant Fixture Surface treated D – –Korea 136.Neoplant Ficture Turned Surface

47. Neodent, Brazil 137.Titamax Liso I D – –138.Titamax Liso II139.Titamax Poros140.Titamax Dual

48. Nobel Biocare, Sweden 141.Brånemark System® MKIII, A ISO14001 ISO9001, EN46001,142.Brånemark System® MKIII, TiUnite CE, FDA143.Brånemark System® MKIV,144.Brånemark System® MKIV, TiUnite145.Replace® Select, Straight, NP, RP, WP 146.Replace® Select, Tapered, NP, RP, WP147.Replace® Select, Straight, NP, RP, WP,

TiUnite 148.Replace® Select, Tapered, NP, RP, WP,

TiUnite149.Replace® Select, Straight, NP, RP, WP, HA 150.Replace® Select, Tapered, NP, RP, WP,

HA151.NobelPerfect™

49. Odontit S.A. Argentina 152.Implante eFeDeA™ D – FDA153.Implante Osseomate™

50. Oral implant S.R.L, Italy 154.Tramonte Screw D – –

51. Oraltronics, Germany 155.Pitt-Easy®Bio-Oss C ISO9001, EN46001,156.Bicortical® Screw I FDA157.Osteoplate®2000

52. Osfix Intl Ltd, Finland 158.BiOsfix C (CE0537)

53. Osstem Comp. Ltd, Korea 159.Avana System C ISO9001, (CE0434)

54. Osteo-Implant Corp., USA 160.Osteo® Threaded C ISO9001 FDA161.Osteo® HA

55. Osteo-Ti, UK 162.Osteo-Ti implant system C CE

56. PACE™ Dental 163.PACE™ D FDA 510KTechnologies, Inc., USA

57. Paraplant 2000, Germany 164.Paraplant 2000 D – –

cont'd...


58. Park Dental Research 165.Star*Lock™ Screw, RBM, C ISO9001, (CE0459)Corp., USA 166.Star*Lock™ Screw, TPS

167.Star*Lock™ Screw, HA168.Star*Lock™ Cylinder, RBM,169.Star*Lock™ Cylinder, TPS170.Star*Lock™ Cylinder, HA171.Star/vent™ Screw, RBM,172.Star/vent™ Screw, TPS 173.Star/vent™ Screw, HA174.Star/vent™ Cylinder (Press-fit), RBM, 175.Star/vent™ Cylinder, TPS 176.Star/vent™ Cylinder, HA177.Startanius Blade

59. Pedrazzini Dental 178. press quick® D (CE0301)Technologie, Germany

60. RT Medical Research & 179.Inner Hexagon Line, Post-extractive D ISO9001, EN46001,Technologies, Italy 180.Inner Hexagon Line, Standard (CE0476)

181.Outer Hexagon Line, Post-extractive182.Outer Hexagon Line, Standard

61. Sargon Enterprises Inc, 183.Sargon® Immediate Load™ B ISO9001, EN46001, FDAUSA (CE0470)

62. Schrauben-Implantat- 184.K.S.I.-Bauer-Schraube C – (CE0482)Systeme GmbH, Germany

63. Schütz-Dental, Germany 185.IMPLA smart D – ISO9001, CE

64. SERF (Société d’Etudes, 186.EVL C ISO9002, (CE0413)de Recherches et deFabrications), France

65. Simpler Implants Inc., 187.Simpler (HA) C ISO9002, CE, FDA,Canada 188.Simpler Threaded DHW

189.Simpler1 (HA)190.Simpler1 Threaded

66. Southern Implants (Pty) 191.External Hexed B (CE0124)Ltd, South Africa 192.Internal Hexed

67. Star-Group-International 193.Sky-Implant-System D – –GmbH, Germany

68. Sterngold Implamed® Dental 194.Implamed Turned, TPS, Regular, A ISO9001, EN46001, FDAImplant Systems, USA Wide & Narrow (CE 0197), FDA

195.Implamed Turned Partial TPS, Regular,Wide & Narrow

196.Implamed Turned Regular, Wide & Narrow197.Implamed HA, Regular, Wide & Narrow198.ERA Implant System

69. Sudimplant, France T.B.R.® system C ISO9002, EN46002 (CE0459)199.Oct-In200.Hex-out 201.Z-1

70. Sweden & Martina SpA, 202.Pilot® C – (CE0476) ISO9002,Italy 203.Premium® standard EN46002

204.Premium® conical205.Premium® Trisurface206.Premium® Kohno207.Premium® Aurum208.Premium® cylindrical209.PRO-Link® Out-Link®210.PRO-Link® In-Link®

71. Tenax Dental Implant 211.Tenax Dental Implant System C Clearance in CanadaSystems, Canada only

72. TFI System, Italia Easy Grip® C ISO9001, EN46001,212.Short neck (CE 0476)213.Wide214.Bullet, TPS215.Large


73. Thommen Medical, 216.SPI®Element D ISO9001, EN46001,Switzerland 217.SPI®Direct MDD93/42/EEC

218.SPI®Onetime

74. Timplant, Czechia 219.Timplant® D ISO9002, EN46002

75. Tiolox implants GmbH, 220.Tiolox C – (CE0483)Germany 221.Tiolox HA

76. Trinon Titanium GmbH, 222.Q-Implant® C ISO9001, EN46001,Germany 223.jmp Mini-implant no. 1 (CE0483)

77. Victory-med, Germany 224.Disk-implantate B –

78. ZL-Microdent-Attachment 225.ZL-Duraplant B (CE0044) ISO9001 EN46001GmbH, Germany

* FDA: FDA Quality System Regulation (formerly GMP, Good Manufacturing Practice)

Table 6 References of the identified clinical studies where clinical outcomes have been associated with implant or implantabutment characteristics, identified as Geometry -, Material -, Surface topography or combinations of these (Complex). A1: RCT:

Randomised controlled trial, A2: Split-RCT: Split mouth randomised controlled trial, B: Controlled clinical trial, C: clinical studyapplying any other study design than A or B (e.g. retrospective cohort, case-series, case-controls, etc.)

Clinical outcomeStudy design* Study reference Ease of Osseointegration Esthetics Peri-implant Marginal Mechanical Mechanical& focus & placement (early & late) mucositis bone loss problems failing ofnumber of of interface implantstudies

A1Geometry:2 [31-33][85] – [31–33] – [31-33][85] [31-33][85] [31] –Material:2 [34,35][36] – [34,35][36] – – – – [36]Surface:1 [37] – [37] – – [37] – –Complex:6 [24][25,26][27] [26][29] [24][25,26][27] [27] [24][25,26][27] [24][25,26][27] [25,26] –

[28][29][16,30] [28] [29][16,30] [28][29][16,30] [28][29][16,30] [28][29] –

A2Geometry:1 [45] [45] [45] – – – – –Material:3 [86][87][88] – – [86] [86][87][88] [86] [86] –Surface:4 [14][46,47][48][89] – [14][46,47][48] – [14][47][89] [14][46] – [46]Complex:5 [38][39][40] [44] [38][41-43][44] – [39][40][44] [38][40][44] – –

[41–43][44]

BGeometry:2 [54-56][90] [54-56] – – – [54-56] [90] –Material:0 – – – – – – – –Surface:0 – – – – – – – –Complex:5 [49][50][51][52][53] – [49][50][51] – – [49][52][53] – –

CGeometry:17 [19][68][69][70][71] – [19][74][75] – – [70][73] [68][92] [76,77]

[72][73][74][75] [76,77][78][80] [93][94][76,77][78][79][80] [81][81][92][93][94]

Material:2 [82][83] – [82][83] – – – – –Surface:1 [84] – [84] – – – – –Complex:11 [57][58][59,60] – [57][58][59,60] – [18,61][62] – [63][91] –

[18,61][62][63][64] [18,61][64][65][65][66][67][91] [66][67]

hollow screw implants (p <0.05)29.The authors proposed that extratime for the ITI® implants (n=106)was needed to select proper heal-ing caps and careful suturing. Theadditional time needed for theabutment connection in a secondstage surgery on the Brånemark

system® implants (n=102) took onaverage 42 minutes. The authorsreported on the other hand thatthe time needed for the followingprosthodontic procedures andsubsequent controls favoured theBrånemark system®. Thus, it wassuggested that in sum, the total

accumulated time needed for acomplete treatment did not differbetween the two systems.

The time used for surgicallyinserting Astra Tech Tioblast®

implants (n=184) and Brånemarksystem® MKII implants (n=184) in66 patients was reported by

abutment and complication inobtaining perfect alignment.

Category B studies: Clinicallycontrolled trials

Implant geometry influence on the out-come ‘ease of placement’.

Friberg et al.54 compared the simpli-fying of the surgical insertion tech-nique by modifications of the screwgeometry. Brånemark system® self-tapping (MKII) and standardimplants (n=179) were compared.The authors had intended to carryout the study as a prospective split-mouth RCT, but this was abandonedwhile the study progressed. Thenew implant geometry was notentirely successful, in that certainproblems were encountered duringthe surgical insertion. The implantgeometry was therefore modifiedand evaluated in a subsequent trialon 563 implants in 103 patients.After the motor driven equipmentused to install the implants hadbeen modified a slight improve-ment was obtained with the newscrew geometry 55,56.

2.Osseointegration

Summary: Very few comparativestudies exist that report the predict-ability or rate of osseointegrationas a function of isolated geometryinfluence (i.e. material and surfacetreatment being identical), due tomaterial influence (i.e. surface treat-ment and geometry being identical),or due to surface treatment influ-ence (i.e. material and geometrybeing identical). The few studiesthat have been carried out are ofrelatively short observation periods.Geometry influence was addressedin one RCT and one split-mouthRCT, but found no influence onperformance. Material influence hasbeen assessed in two RCTs, whichindicate either minor differences orpresent ambiguous data. Surfacetopography influence has beenaddressed in one RCT and threesplit-mouth RCTs, which suggestslightly better results with someforms of surface treated implants

compared to turned ones. Implantswith different geometry, materialand surface topographies have beenevaluated in six RCTs and threesplit-mouth RCTs. These studies failto demonstrate clear differencesbetween different implant brandsregarding osseointegration. Thiswas also corroborated in three CCTtrials. However, as none of theselatter studies were blinded, investiga-tor preferences may have influencedboth the actual trial process as wellas the trial reporting. Finally, aheterogeneous group of clinicalstudies employing different strate-gies to clarify a relationship betweenimplant morphology and osseointe-gration failure present contrastingconclusions, as expected in view ofthe increased probability of spuri-ous statistical associations found inclinical studies with weak methodo-logical designs. A positive elementof these studies is the often largepatient samples and/or long obser-vation periods, but the risk ofvarious forms of bias introducedin the results should be recognised.

Category A1 studies:Randomised controlled trialsImplant geometry influence on the out-come ‘osseointegration’.

Pairs of cylinder IMZ® with TPScoating or ITI® solid screw implantswith TPS coating were placed inthe mandibles of 40 patients withmoderate jaw resorption and over-dentures retained by bar and clipattachments were made after threemonths. Results after one32 and twoyears31 have been presented. Onlyone IMZ® implant was lost, negatingany meaningful inferences aboutcomparability. The implant coatingsare assumed to be identical, but thecorrectness of this is uncertain.Moreover, the confounding byother clinical variables makes itdifficult to draw any strong infer-ences on the (lack of) influence ofimplant geometry on osseointegration.

Implant material influence on the out-come ‘osseointegration’.

IMZ® implants with hydroxyapa-

Åstrand et al.27. The surgery opera-tion time did not differ, i.e. 89minutes in the mandible and 95(Brånemark) and 102 (Astra Tech)minutes in the maxilla. Attachingthe abutments at the second surgerystage was found to be more timeconsuming for the Brånemarksystem® implants, i.e. 51 minutesand 43 minutes versus 35 minutesand 32 for the Astra implants inthe maxilla and in the mandible(p<0.05).

Category A2 studies: Split-mouthrandomised design, or randominitially with alternate subsequentplacement


Friberg et al.45 compared the earlybehaviour of a Brånemark system®

modified prototype MKIV implantwith that of the standard implantsin regions of mainly type 4 bone in44 patients. The patients weretreated with implants for 39 maxil-las and 5 mandibles and these werefollowed up for 1 year. The MKIVimplants more frequently requireda higher insertion torque andshowed a significantly higher primarystability than the control implant.This difference in stability levelledout over time, at the abutmentoperation and at the 1-year visit thestability was similar.

Studies where implant geometry, mate-rial and surface topography influences onthe outcome ‘ease of placement’ are con-founded.

The average time used for surgi-cally placing Astra Tech Tioblast®

implants (n=50) and Brånemarksystem® MKII implants (n=45) in18 patients did not differ betweenthe two systems regarding implantsurgery, i.e. 42 minutes44. Theabutment connection was reportedto be faster on the Astra Techimplants (15 min vs. 20 min). Theauthors experienced difficulties inobtaining a clinically acceptable fitbetween the Astra Tech abutmentand the superstructure and attrib-uted this to the conical shape of the

tite (HA) or titanium plasma-flame(TPF) were compared over 3–7years by Mau et al.36. TPF can beconsidered as synonymous to tita-nium plasma spray, TPS. The studysample consisted initially of 313patients with partially edentulousmandibles treated in five Germanclinical centres. Due to early drop-outs, implant failures, protocolviolations or patient non-compli-ance the study reported the outcomesof 89 patients assigned to receiveHA and 100 patient receiving TPFimplants. One implant was placedin each patient that supported acombined tooth-implant fixedbridge. The employed outcomecriteria were implant loss, signifi-cant bone loss, periotest values andmanual mobility of the tooth orimplant. The investigators usedmultivariate log-rank test on thesurvival data. Moreover, separateanalyses were conducted for theparticipants who switched from theassigned treatment according to theintention-to-treat principle, as wellas sensitivity analyses using best andworst case scenarios for thesepatients. No differences were notedbetween the two surfaces regard-ing osseointegration, nor any of theother outcome criteria addressedin this trial.

Titanium plasma-sprayed cylinderimplants (Sterngold-Implamed®)with and without additionalhydroxyapatite coatings werecompared by Jones et al.34. Thestudy involved 65 patients whoreceived 352 implants in differentintra-oral sites to retain a variety ofsingle crowns, overdentures andfixed bridges. The authors suggestedthat the HA coated implantsallowed a better initial osseointe-gration, but a subsequent paperreported no differences betweenthe two implant systems followingfive years of observation35. Thisreport was difficult to criticallyappraise as there seemed to beseveral confounding variablesinfluencing the result, lack of studydetail descriptions and no otheroutcomes besides ‘loss of implant’

were reported. Both the internaland external validity of this studycan therefore be questioned.

Implant surface topography influence onthe outcome ‘osseointegration’.

TiUnite (n=66) and turnedBrånemark system® (n=55) implantsin the posterior mandibles in 44patients following applying imme-diate loading of partial fixedbridges were compared for oneyear by Rocci et al.37. All fixedtwo- to four-unit bridges wereconnected on the day of implantinsertion. The cumulative successrates were 85 per cent for theturned (8 failed) and 97 per centfor theTiUnite (3 failed) after oneyear of prosthetic load in theposterior mandible. The authorsattributed the relatively high failurerates to smoking and poor bone(quality 4) sites.

Studies where implant geometry, materialand surface topography influences on theoutcome ‘osseointegration’ are confounded.

Meijer et al.28 presented five-year dataof edentulous patients fitted with amandibular overdenture eitherretained by two IMZ® (29 patients)or two Brånemark system® (n=32)implants. Four implants were lostin the IMZ® group (93 per centsurvival), while for the Brånemarksystem® implants the survival ratewas 86 per cent (9 implants lost).The difference was reported to benot statistically significant.

Southern and Sterioss implantswere compared by Tawse-Smith etal.16,30. The implants were loadedafter 12 weeks16, or after 6 and 12weeks30 when a mandibular over-denture was provided for thepatient. No differences were notedin the first study that included 24patients16. In the second study 48patients were allocated to fourgroups of 12 patients, each receiv-ing the two implants after 6 weeksor 12 weeks. The Sterioss implantswere on average shorter than theSouthern. Better performanceregarding osseointegration wasdemonstrated for the Southerncompared to the Sterioss implants,

of which eight failed to osseointe-grate. Seven of these had beenloaded after six weeks, they werein average shorter than the otherimplants in this study and they hadall been inserted by one of the threesurgeons involved in the study.Thus, it is unclear whether the lackof osseointegration of these Steriossimplants could be coincidental,whether it depended on differencesin roughness, length or implantgeometry or on the fact that thesame surgeon had placed them all.

Brånemark system® implants(n=102) and ITI® hollow screwimplants (n=106) placed in themandible were compared in 40edentulous patients by Moberg etal.29. Each patient received four,five or six implants to retain a fixedbridge. Only one implant failed toosseointegrate (Brånemark system®),thus no statistical difference wasdemonstrated.

Brånemark system® MKII (n=187) and Astra Tech Tioblast®

(n=184) implants placed in differ-ent intra-oral regions in 66 patientswere evaluated over one year byÅstrand et al.26. Eight Brånemarksystem® and one Astra Tech implantfailed to osseointegrate, which is astatistically significant difference onimplant level (p<0.05). Five of theBrånemark system® implants thatfailed to osseointegrate occurredin one patient, so no difference wasnoted when using the patient as theunit for statistical comparison.

Pairs of hollow screw ITI®,Brånemark system® and IMZ®

implants were evaluated in threegroups of 30 patients with exten-sive bone loss in the mandible24.During the post-surgery healingperiod, 1/60 Brånemark system®

and 1/60 IMZ® implants failed toosseointegrate. The high clinicalsuccess rates in relation to a relativesmall study sample negate anymeaningful inference of statisticalsignificance.

Single tooth implants made fromAstra Tech (n=46) or ITI® hollowscrew and hollow cylinder (n=56)implants in different intra-oral

regions of 82 patients were evalu-ated by Kemppainen et al.27. Onlyone implant failed to osseointegrate(Astra Tech), so no statistical differ-ence was demonstrated.

Category A2 studies: Split-mouthrandomised design

Implant geometry influence on the out-come ‘osseointegration’.

Friberg et al.45 compared the earlybehaviour of a modified prototypeBrånemark system® MKIV implantwith that of the standard implantin regions of mainly type 4 bonein 44 patients. The patients werefollowed up for one year and theone-year cumulative success ratewas 93 per cent for the MKIVversus 88 per cent for the conven-tional implants (no statisticallysignificant difference).


Turned (n=185) and acid-etched(n=247) implants of the samegeometry manufactured by 3iplaced in 97 completely or partiallyedentulous patients by severaloperators at two clinics was reportedby Khang et al.48. Criteria for successwere the absence of peri-implantradiolucency, mobility, and persist-ent signs or symptoms of pain orinfection. The implant lengths anddiameters varied, as did the propor-tion of implants in anterior andposterior maxilla and mandible.The survival statistics were thereforeanalysed with general modellingestimations, i.e. multivariate analyses.The implant surface was identifiedas a significant factor for thedevelopment of osseointegration.Of the initially 432 implants a higherproportion of the etched implantsosseointegrated versus the turnedones (95 per cent vs 87 per cent).The difference was maintainedthroughout the observation periodfollowing the loading of theimplants. Several perplexing detailsare reported. One is that the timebetween surgical placement andloading was in average 12.7months. Moreover, the temporaldescriptors of the various phases

of the trial do not add up correctly.Finally, in spite of a reportedrandom allocation of the implant,marked asymmetries of intraorallocation were noted. No detailswere provided regarding how thegeneral estimation equations andKaplan-Meier analyses were carriedout and nor patient drop-out orproportion of censored data werepresented. Thus, the inadequatereporting cast doubt about thegeneral validity of this study.

Sandblasted and acid-etched(SLA) (n=68) and titanium-plasmaspray (TPS) (n=68) ITI® implantsof the same geometry were evalu-ated in a double blind study byRoccuzzo et al.14. The implants wereplaced in posterior regions of themandible. No implant losses werereported during the healing stageand at one-year follow-up. Thus,the two surfaces seemed to becomparable when addressing theinitial osseointegration, at least forthis implant geometry over a short-term period. It should be notedthat in this trial the SLA implantswere loaded at 43 days postsurgi-cally, while the TPS implants wereloaded after 86 days.

Turned versus TiO2-blasted

Astra Tech implants were evalu-ated in a multicentre clinical studyby Karlsson et al.47. Fifty patientsreceived at least one turned andone TiO

2 -blasted implant to

support fixed bridges in variouslocations in both jaws. Only twoimplants, both turned, out ofinitially 129 failed to osseointegrate.Thus, no difference with respect toinitial osseointegration could bedemonstrated. However, relatingthe very high clinical success ratesin context with the relatively smallstudy sample precludes meaningfulgeneralised conclusions.

Studies where implant geometry, materialand surface topography influences on theoutcome ‘osseointegration’ are confounded.

Åstrand et al.38 compared the outcomeof fitting fixed partial bridges inthe maxilla of 28 patients supportedone side by ITI® and on the otherside by Brånemark system® implants.

The healing period was six monthsfor both systems to allow for a sin-gle- versus two-stage surgery tech-nique and the observation time wasone year after loading. No signifi-cant difference in survival rate wasnoted with two Brånemark system®

implants (in one patient) and oneITI® implant lost.

Astra Tech Tioblast® (n=50) andBrånemark system® MKII (n=45)implants placed in 18 patients werecompared by van Steenberghe etal.44. One implant was reported lost(Brånemark system®), presumablydue to lack of osseointegration. Thevery high clinical success rates inrelation to a relative small studysample negate any meaningfulinference of statistical significance.

One group of investigatorsincluded in their study nearly 3,000screws, straight and grooved cylin-der and hollow cylinder implantsmade from pure titanium and tita-nium alloys with and without HA-coating. The sponsor of the studyhad manufactured all the implants(Spectra-Vent). Pairs of differentimplants were allocated on a split-mouth basis and stratified bydifferent intra-oral locations.Added to the complexity of thestudy design are difficulties ininterpreting the long-term findingsas the results are not presentedaccording to the original stratifica-tion and implant allocation plan.Finally, the reported numbers ofplaced implants vary in the differ-ent study reports, e.g. n=1,56541,n=2,91042 and n=2,64143. In spiteof the many methodological issuesthat can be raised, however, acommon denominator in the manyreports from this study material isthat for the Spectra system implants,the HA-coated implants and thetitanium implants were compara-ble regarding osseointegration.

Category B studies: Clinicallycontrolled trialsStudies where implant geometry, materialand surface topography influences on theoutcome ‘osseointegration’ are confounded.

Chiapasco & Gatti50 evaluated 328

implants placed in the interforamenarea of edentulous mandibles andimmediately loaded with an implant-supported overdenture. Four implantsystems were used, Ha-Ti® (n=164), ITI® (n=84), and 40 each ofBrånemark Conical® and Frialocimplants. Four implants were placedper patient. Failure criteria wereabsence of clinical mobility, peri-implant radiolucency, pain andperi-implant bone resorption lessthan 0.2mm after the first year ofprosthetic load. The success ratesafter three years were 98 per centfor Ha-Ti®, and 95 per cent for thethree other systems. Eight yearsurvival estimates were only avail-able for Ha-Ti® (89 per cent) andITI® (90 per cent), i.e. no differ-ences between the systems werenoted.

Pinholt51 compared ITI® andBrånemark system® implants placedin augmented extremely atrophicmaxilla in 25 patients; 78 Brånemark®

and 80 ITI® SLA implants wereinserted in the augmented bone andthe patients were followed between20 and 67 months post implanta-tion. The survival rates were 81 percent for the Brånemark® (15 losses)and 98 per cent for the ITI®

fixtures (2 losses) but the authorfailed to describe at what time thissurvival estimate is calculated. Theresults of this evaluation show thatsandblasted large grit acid etchedsurface-treated ITI® implants has asignificant higher survival rate thanturned Brånemark® implants inautogenous grafted maxillary bone.

ITI® titanium-plasma spray (TPS)and Brånemark system® implantswere compared in a multicentretrial by Becker et al.49. Three differ-ent surgeries each treated 29patients using their own surgicaltechniques, i.e. one stage surgeryfor ITI® implants (n=78), and onestage (n=80) and two-stage (n=78)protocols for Brånemark system®

implants. Failed osseointegrationoccurred for two ITI®, three two-stage Brånemark system®, and twoone-stage Brånemark system®

implants. The study design with

three separate patient samples andthe low incidence of osseointegra-tion failure in relation to a relativesmall study sample negates anymeaningful inference of statisticalsignificance.

Category C studies: Clinicalstudies with other study designsMany of the studies in this categorydo not present enough details toestablish whether the numbersrepresent failure to develop osseo-integration (i.e. early failure) orestablished osseointegration thatsubsequently failed (i.e. late failure).The last category includes reportsthat use criteria such as ‘exfoliatedimplants’, ‘implant mobility’, ‘implantloss’, ‘implant removal’ etc, whichcan only be presumed to indicateprogressive loss of osseointegration.

Implant geometry influence on the out-come ‘osseointegration’.

Wheeler81 reported the results ofthe use of the 802 Frialit®-2 Systemimplants in a private practice setting.Both threaded and press-fit formshad been used with comparablesurvival rates (95 per cent vs 97 percent). The author reported that hisexperience was that the use ofstepped cylindrical Frialit®-2 implantsshould not be used in immediateextraction situations.

Hollow screw and solid screwimplants manufactured by ITI®

(n=178) placed in 109 partiallyedentulous patients were comparedby Romeo et al.80. A retrospectivestudy based on observation timesbetween one and seven years indi-cated that the hollow screw andsolid screw demonstrated fairlysimilar success rates (95 per cent vs93 per cent after five years). Thiscorroborates earlier findings reportedby Buser et al.19. These latter authorsalso reported significantly betterperformance for screw (n=1780)versus (hollow) cylinder (n=336)implants (96 per cent vs 91 per centat 7 years). This conclusion wasbased on a multicentre study withobservation times between one andeight years of 2,359 implants placed

in 1,003 patients. The manufacturerdiscontinued the production ofITI® hollow screws in 1997, notbecause of any clinically dramaticresults but rather due to risk esti-mation taking into account theinability of access for therapy incase of infection in the bone inter-nal to the implant.

Brånemark system® implantshave since their introduction hadslightly different geometries. Inves-tigators in Leuven, Belgium havepublished several papers thatdescribe their clinical experiencesusing the different implants andassociations to different clinicaloutcomes74–78. Early studies indi-cated better outcomes when usingself-tapping implants versus earliertypes. Inferior results were obtainedwith a conical type implant intro-duced by Nobelpharma in 1987,which was withdrawn a few yearslater because of poor clinical perfor-mance. Recent papers, including thepatient sample pools of the earlierreports, report no differences inperformance as an influence ofthe different geometries of theBrånemark system® implants74–77.

Implant material influence on the out-come ‘osseointegration’.

Chuang et al.82 carried out a retro-spective analysis of 2,349 implantsin 677 patients to identify riskfactors associated with failures ofBicon implants. An adjustedmultivariate regression model wasused that took into account clus-tering effect of implant failureswithin the same subject. Implantfailures were not associated withcoating (HA, TPS or turned).

Weyant and Burt83 presentedsurvival probabilities of 2,098implants placed in 598 patients inmultiple US Veterans dental clinics.Statistical modelling analyses iden-tified no differences regardingosseointegration between HA coatedand titanium implants. The studyfails to mention which implantbrands had been used, making itdifficult to generalise the results tocommercial products.


The complexity of the relationshipbetween surface treatment of tita-nium implants and long-term clinicalperformance is noticeable in a case-series report presented byDavarpanah et al.84. Patients at 13European centres had over a 1–5years period received turned self-tapping (n=419), ICE (n=619) andOsseotite® (n=545) implants. Theimplants are all manufactured by 3iand represent three ‘generations’ ofimplant products, i.e. as a functionof different geometries and surfacetreatments. The paper describes thatin several instances, the implanttypes were mixed in the samepatient, which suggest an intentionto compare performance on asplit-mouth basis. In the resultssection of the paper success rateswere reported according to maxillaand mandible, anterior and poste-rior, implant diameters and implantlengths. The conspicuous detail isthat success rates as a function ofdifferent implant surface treatmentwere not presented and not evenaddressed in the discussion part ofthe paper. Moreover, the samegroup of authors had published aprevious paper that was referredto in the text, in which the first andsecond generation implants werecompared (92 per cent vs 94 percent survival after three years)95.Although it is not clear whether thesecond paper encompasses thethree-year study sample, one maydeduce that a significant improve-ment of treatment success was notachieved with the newest ‘genera-tion’ of implant design.

Studies where implant geometry, mate-rial and surface topography influences onthe outcome ‘osseointegration’ are con-founded.

In Finland a national register fordental implants was initiated in 1994and administrated by the NationalAgency for Medicines. Systemati-cally collected data on the numbersof placed and removed implants inthe period between 1994 and 2000

have been recorded96. The agencyclaims a fairly high reportingcompliance verified by compari-sons with the sales figures reportedby the manufacturers and import-ers of dental implants in Finland.During the period, 43,533 implantplacements and 808 removals hasbeen registered (1.9 per cent fail-ure). Three existing implant brandshad a higher proportion of remov-als than this average (Brånemarksystem® 324/8,075 = 4.0 per cent,IMZ® 63/1,812 = 3.5 per cent andFrialit® 2 39/1,533 = 2.5 per cent.Implant brands with a lower thanthe mean removal rate were e.g.ITI® (199/17,270 = 1.2 per cent),Astra Tech (77/7,289 = 1.1 percent), and 3i (11/1,229 = 0.9 percent). The validity of employingthese data as indicators of estima-tions of clinical performance ofdifferent implants can be debated.If the dentists in Finlandunderreport implant failures thesedata may overestimate success. Itcan also be argued that the datamay be underestimates of implanttreatment success if primarily retro-spective updating of negative eventstake place, i.e. the dentists do notbother to report treatment successbut report only when some failuremay occur.

Valentini and Abensur67 comparedIMZ® titanium plasma spray-coatedcylindrical (n=133) and Brånemarksystem® (n=54) implants placed insinuses grafted with anorganicbovine bone mixed with demineral-ised freeze-dried bone allograft(DFDBA) or with anorganicbovine bone alone. The survivalrates were similar for the twoimplant types in sinuses grafted withanorganic bovine bone alone afterapproximately seven years.

Two different surface treatmentsof ZL-Duraplant implants in 137patients were evaluated in a trialover 2–6 years18,61. Two implantgeometries were used, thus creat-ing study groups consisting ofsurface treated cylinders (n=30),and screws with (n=339) and with-out (n=58) surface treatments. The

surface treatment is electrochemicaland recognised by the trademark‘Ticer®’. ‘Failure’ was defined asexplanted implant. Similar perform-ance was first noted to begin with,but the cylinders demonstratedpoorer results than the screws afterapproximately one year. Moreover,the surface-treated screws perfor-med better than the untreatedscrews according to the survivalstatistics (p<0.05). Lack of detailprevents calculations of exact esti-mates of initial osseointegrationrates as well as more long-termtreatment outcome success.

Noack et al.64 reported on thesuccess of osseointegrated implantsof the Brånemark system®, Frialit®-1 (Tubinger Implant), Frialit®-2,IMZ® systems and Linkow bladeimplants. The lowest loss rates wereseen with implants in intermediateand distal extension spaces and withsingle-tooth replacements usingIMZ®, Frialit®-2, and Brånemarksystem® implants. In edentulousarches, implants of the IMZ® andBrånemark system® implants hadthe lowest failure rates.

Scurria et al.65 presented retro-spective data from a multicentrepatient pool, consisting of 384implants in 99 patients. Most of theimplants were Brånemark system®

(80 per cent), while the remainingwere IMZ® implants. Uni- andmultivariate log-rank and Wilcoxon’stests of the survival data indicatedno difference between the implanttypes. However, the heterogeneityof the study material and small sizeof one of the samples suggests thatthis would be difficult to detectunless large variable effects werepresent.

Gómez-Roman et al.58 reportedresults after treating 159 patientswith a mandibular overdentureretained by implants placed betweenthe mental foramina. Three implantsystems (IMZ® (n=168), ITI®

Bonefit (n=150) and ITI® TPS(n=109) had been in use over a 10year period. The loss of implantswas in general very low, (n=8 in 5patients) with a slightly poorer

outcome of the TPS implantscompared to the two other systemsobserved over 10 years.

Astra Tech Tioblast® screw (n=31) and ITI® hollow screw (n=93)implants placed in 19 and 56 patientsrespectively were evaluated byEllegaard et al.59,60. The aim of thestudy was to evaluate the implantsplaced following a sinus membranelift versus the ones without addi-tional surgery in periodontallycompromised patients. Althoughthe authors write that it was not theintention to compare the twosystems, most of the results sectionas well as the statistics in the reportactually focus on this aspect. Univari-ate survival statistics indicate nodifferences between the systemsfor most of the evaluated variables,i.e. implant loss, bone loss, pocketdepth, bleeding on probing andplaque deposits. This is hardly surpri-sing in view of the small sample sizes.The additional confounding bydifferences in patient selection,treatment learning curves, differencesin implant lengths and intra-orallocation etc. invalidates both theuse of the statistics as well as anyconclusions forwarded by this studyregarding comparisons of implantsystems.

Titanium plasma sprayed ITI®

(n=36) and IMZ® (n=264) implantswith three different geometriesfollowed up between six monthsand 11 years was reported bySpiekerman et al.66. Due to the retro-spective study design, changes ofoperators and variable learningcurves, patient drop-out and selec-tive placements of implants accord-ing to the initial treatment situationone may question the reliability ofmaking any comparisons. Moreover,the implant geometries havechanged since this study was carriedout, and only one of these (IMZ®,

3.3 mm) is still available today.De Bruyn et al.57 described the

performance of implants placed bythe main author in a private prac-tice. The author first employedScrew Vent® and Swede Vent®

implants (Core Vent Company), of

which he placed 85 and 11 implantsin 31 patients before changing toBrånemark system® implants(n=107) in 25 patients. This reportactually describes two separate caseseries and although the authorscompare the outcomes of the twosystems, factors such as patientselection, treatment learning curve,differences in implant lengths andintra-oral location etc. exclude anymeaningful conclusions. Moreover,incomplete reporting of patientcompliance and drop-outs, differentlength of the observation periods,small sample sizes and lack ofstatistical analyses invalidate manyof the authors’ conclusions aboutimplant comparability. Finally, theScrew Vent® implant that today ismanufactured by Centerpulse andhas another geometry to the oneused in this clinical study.

A paper by d’Hoedt and Schulte97

presented follow-up results from fiveimplant systems, but the report isof limited value today. Most of theimplants evaluated are no longer inproduction (Frialit Tübingen® andITI® E, K & H-types) and the otherimplants are early generations ofmodern type implants (IMZ®, ITI®

TPS and Brånemark system®

implants), with relatively shortfollow-up time. Moreover, thereport lacks details about the obser-ved failure patterns and does notpresent comprehensive documenta-tion of the clinical performance forall five implant systems, but ratherfocuses on highlighting the perform-ance of one of the implant systems.

3. AestheticsSummary: Only one RCT and onesplit-mouth RCT have included thisoutcome as part of the reporting.Both studies concluded that theaesthetic outcome is associatedneither with implant system norabutment material.

Category A1 studies: Randomisedcontrolled trialsStudies where implant geometry, materialand surface topography influences on theoutcome ‘aesthetics’ are confounded.Astra abutments were used for the

Astra Tech implants (n=46) andstandard ITI® solid abutments aswell as ITI® Octa abutments wereused on ITI® implants (n=56) toretain single crowns in 82 patients27.No differences were noted regard-ing patient satisfaction with theaesthetics after one-year of obser-vation.

Category A2 studies: Split-mouth randomised design

Implant material influence on the out-come ‘aesthetics’.

Ceramic (n=44) versus titanium(n=44) abutments placed on singletooth Brånemark system® implantswere compared in a trial using acombined parallel and split mouthRCT study design86. No differenceswere observed regarding aestheticsat one and three year follow-upobservations.

4. Peri-implant mucositis

Summary: The influence of implant/abutment geometry on peri-implantmucositis could not be establishedin two RCTs. The influence ofimplant/abutment material is incon-clusive based on three small split-mouth RCTs. The same conclusionapplies to influence of implant/abutment surface topography,evaluated in on three split-mouthRCTs. Implants with differentgeometry, material and surfacetopographies were evaluated in sixRCTs and three split-mouth RCTs.Minor differences regarding preva-lence of peri-implant mucositis as afunction of these variables werenoted with up to three yearsobservation.

Category A1 studies:Randomised controlled trialsImplant geometry influence on the out-come ‘peri-implant mucositis’.

Cylinder IMZ® with TPS coatingand ITI® solid screw implants withTPS coating were placed in themandibles of 40 patients withmoderate jaw resorption andoverdentures retained by bar andclip attachments were made after

three months32. Signs of peri-implant mucositis were similar inthe two groups, which was alsocorroborated by microbiologicalfindings in the three-month report32,and over one year33 and two years31.

Gatti and Chiapasco85 comparedtwo-piece and one-piece transmu-cosal Brånemark system® implantsthat had been immediately loadedwith an overdenture. Five patients ineach group received four implantseach. No differences were notedregarding periodontal indices afterone and two years, but the samplesize was so small that this studyshould be regarded as a pilot studyonly.

Studies where implant geometry, materialand surface topography influences on theoutcome ‘peri-implant mucositis’ are con-founded.

Brånemark system® MKII (n=187)and Astra Tech Tioblast® (n=184)implants in 66 patients demon-strated no significant differences withregard to peri-implant mucositisafter one year and three years26,and five years25.

Southern and Sterioss implantsdemonstrated similar prevalencesof peri-implant mucositis aroundpairs of implants retaining mandibu-lar overdentures after one16 and twoyears30.

Fixed partial dentures were fabri-cated on Brånemark system® andITI® hollow screw implants placedin the mandible of 40 completelyedentulous patients. The degree ofperi-implant mucositis over threeyears was similar29.

Meijer et al.28 presented five-yeardata of edentulous patients fittedwith a mandibular overdentureeither retained by two IMZ® (29patients) or two Brånemark system®

implants (n=32). No differenceswere noted with regard to differ-ent periodontal indices, i.e. plaque,gingival, bleeding and calculusindices and probing depth. Hollowscrew ITI®, Brånemark system® andIMZ® implants in three groups of30 patients provided with a mandib-ular overdenture retained by abar-clip on pairs of implant abut-

ments presented no differences withregard to peri-implant mucositis atone year24. Astra Tech (n=46) andITI® hollow screw and hollowcylinder (n=56) single tooth implantsin different intra-oral regions of 82patients showed same degree ofperi-implant mucositis after one-year of observation27.

Category A2 studies: Split-mouthrandomised designImplant material influence on the out-come ‘peri-implant mucositis’.

Ceramic (n=44) versus titanium(n=44) abutments placed on singletooth Brånemark system® implantsdemonstrated no differences regard-ing measurements of various indicesof peri-implant tissue health afterone year and three years86.

Barclay et al.87 selected 14 patientswho had been provided with amandibular denture retained by aDolder-bar on two IMZ® implantsfor at least 12 months. Each pairof abutments was replaced with aceramic-coated abutment or a newconventional one and soft tissueparameters were recorded over thenext 12 weeks. No differences werenoted with regard to peri-implantmucositis, although the authorsconcluded that the soft tissue response‘may vary in features that are notapparent when assessed by conven-tional clinical parameters’.

A group of investigators inLeuven, Belgium, has carried outextensive studies on abutments withdifferent surface topographies andchemistry and possible influenceson soft tissues by applying a rangeof different outcome criteria. Clini-cal criteria were reported by Bollenet al.88 who followed six patientsprovided with a mandibular over-denture retained by pairs of aceramic and a titanium abutmentfor one year and noted no clinicallysignificant differences regardingsoft-tissue response.

Implant surface topography influence onthe outcome ‘peri-implant mucositis’.

The soft-tissue response was similarfor four different titanium implantswith different degrees of surface

roughness when observed overthree months89. The author empha-sises that the findings applies onlyfor titanium abutments with a lowsurface roughness, i.e. less thanRa=0,20. The conclusions werecorroborated by other studieswhere microbiological outcomecriteria have been used.

Sandblasted and acid-etched(SLA) (n=68) and titanium plasmasprayed (TPS) (n=68) ITI® implantsof the same geometry placed in theposterior edentulous regions in themandible and provided with fixedbridges showed identical presenceof peri-implant mucositis over oneyear14.

Turned and TiO2-blasted Astra

Tech implants retaining fixed partialdentures demonstrated no significantdifference regarding peri-implantmucositis over five years. At base-line 5 per cent of the TiO

2-blasted

implants and none of the turnedimplants showed signs of peri-implant mucositis. After one yearthe respective figures were 12 percent and 9 per cent, after 3 years 12per cent and 4 per cent and after 5years 6 per cent in both groups46.

Studies where implant geometry, materialand surface topography influences on theoutcome ‘peri-implant mucositis’ are con-founded.

Jeffcoat et al.40 compared 615implants placed in 120 edentulouspatients. Each patient received fiveor six Brånemark system® or ahydroxyapatite-coated threaded orcylindric implant of an unknownbrand. No differences were notedwith regard to periodontal indicesover one to five years.

Geurs et al.39 followed 120healthy edentulous patients thateach had received five or siximplants in the anterior mandiblefor three years. At least one implantwas either a threaded titaniumplasma-sprayed (Steri-Oss), or athreaded or cylindric HA-coatedimplant of unknown brand. Afterthree years, periodontal indices of470 of the originally 634 placedimplants were reported and nodifferences were noted.

Astra Tech Tioblast® (n=50) andBrånemark system® MKII (n=45)implants were reported to becomparable with regard to prob-ing pocket depth, plaque andbleeding on probing over two yearsobservation44.

Category C studies: Clinicalstudies with other study designs

Studies where implant geometry, mate-rial and surface topography influences onthe outcome ‘peri-implant mucositis’ areconfounded.

Two different surface treatmentsof 497 ZL-Duraplant screw andcylinder implants placed in 137patients could not be associatedwith different criteria used to describeperi-implant mucositis, i.e. papillableeding, probing depth and sulcusfluid flow rates over a follow upperiod of two to six years61.

Astra Tech and Brånemarksystem® single tooth implants thathad been in function for a mini-mum of two years in 30 patientswere examined by Puchades-Roman et al.62. Bleeding on prob-ing was similar for both implantbrands. A difference in probingdepth was observed (Brånemark3.3mm vs Astra Tech 2.7mm, p=0.03). The authors attributed thisto probable disparity in biologicwidth relative to the implantgeometries.

5. Marginal bone loss

Summary: Implant geometry influ-ence on marginal bone loss has beenappraised in two RCTs, but withshort observation periods and nodifference between geometries.Influence of abutment/implantmaterial has only been examined inone split-mouth RCT, with a nega-tive conclusion. Surface topographyinfluence studied in one RCT andtwo split-mouth RCTs give incon-clusive evidence of specific surfacesuperiority. Finally, several studieswhere implants with differentgeometry, material and surfacetopographies have been evaluatedusing a RCT design (n=6) and split-RCT design (n=3) failed either to

detect significant differences in boneloss or the observation period wastoo short for making generalconclusions about clinical signifi-cance. A few non-randomisedcontrolled clinical trials (n=4), onthe other hand, suggest that theremay be significant differencesbetween different implant brands.This is also corroborated by twocase series reports that focus on apossible influence of implant-abut-ment geometry on bone loss.However, the possibilities of biasintroduced by utilising less rigorousstudy designs should be recognised.

Category A1 studies:Randomised controlled trialsImplant geometry influence on the out-come ‘marginal bone loss’.

IMZ® cylinder implants with a TPScoating or ITI® solid screw implantswith TPS coating placed in themandible to retain overdentures bybar and clip attachments demon-strated similar mean bone loss(0.6mm) after one year32. The lossafter two years was 1.1mm for theIMZ® 1-stage, 0.8mm for IMZ®

2-stage and 1.2mm for ITI® (onestage)31. The relatively short observa-tion period restricts any generalisa-tion about the influence of geometryon marginal bone loss.

Gatti and Chiapasco85 compared,over two years, two-piece andone-piece transmucosal Brånemarksystem® implants in two groups offive patients each. Four implantswere placed in each mandible andimmediately loaded with anoverdenture. The bone resorptiondid not differ statistically betweenthe two groups, which is hardlysurprising considering the smallsample sizes.

Implant surface topography influence onthe outcome ‘marginal bone loss’.

TiUnite (n=66) and turnedBrånemark system® (n=55) implantswere placed in the posteriormandibles in 44 patients andimmediate loading was appliedwith partial fixed bridges37. Themarginal bone resorption after oneyear of loading was on average

0.9mm with the TiUnite implantsand 1.0mm with the turnedimplants.

Studies where implant geometry, mate-rial and surface topography influences onthe outcome ‘marginal bone loss’ are con-founded.Astra Tech and Brånemark system®

implants used for maxillary and/ormandibular reconstruction revealedno significant differences in boneloss either in the maxilla or themandible at one year (Astra Tech1.6mm, Brånemark 1.9mm)25, threeyears (Astra Tech 1.5mm,Brånemark 1.8mm)25 and fiveyears26. The greater bone lossfollowing abutment connection forthe Brånemark system® was likelydue to more flap reflection.

Southern and Sterioss implantsdemonstrated similar bone lossafter one and two years aroundpairs of implants retaining mandibu-lar overdentures16,30. It is unclear asto whether differences in implantsurface topography or implantgeometry between the two testedimplants or different types ofretaining abutments on the implantsconfound the observed clinicaloutcome.

Astra Tech (n=46) and ITI®

hollow screw and hollow cylinder(n=56) implants were restored withsingle crowns following a six-monthperiod of healing. The baselineradiographs taken one week aftercrown placement were comparedto radiographs taken at one year27.The marginal bone loss was similarfor both implant brands (0.1mm).

Brånemark system® implants andITI® hollow screw implants placedin the mandible were compared in40 edentulous patients29. Recon-structions were full arch prosthesesand radiographs were obtained atprosthesis insertion, one, and threeyears. The results revealed no signifi-cant difference between the implantsystems at three years. Four implantsexhibited progressive bone loss(three ITI® and one Brånemark) and13 implants had measurable margi-nal bone loss at three years (threeITI® and eight Brånemark). The

remaining implants either exhibitedno marginal bone changes or bonegain.

Meijer et al.28 presented five-yeardata of edentulous patients fittedwith a mandibular overdentureeither retained by two IMZ®

implants (29 patients) or twoBrånemark system® implants (n=32).The bone loss was not presentedas mean values in the paper, butthe authors reported that it did notdiffer between the two groupsafter five years.

ITI®, Brånemark system® andIMZ® screw implants were placedin pairs in 30 patients with an eden-tulous mandible to support anoverdenture. Based on a standard-ised technique, significantly lessbone loss was recorded at 12months with the ITI® implant(0.2mm) compared with either theBrånemark system® implant (0.3mm)or the IMZ® implant (0.5mm)24.


Implant material influence on the out-come ‘marginal bone loss’.

Ceramic (n=44) versus titanium(n=44) abutments placed on singletooth Brånemark system® implantswere compared in a trial using acombined parallel and split mouthRCT study design86. No differenceswere observed regarding bone lossmeasurements, which amounted toabout 0.1mm on average, but witha wide variance of bone loss amongpatients (SD up to 0.6mm).

Implant surface topography influence onthe outcome ‘marginal bone loss’.

Turned and TiO2-blasted (Tioblast®)

Astra Tech implants supportingfixed partial dentures were comparedannually for five years46. Radiographswere made using a standardisedtechnique. One observer blindedto the implant surface measuredthe marginal bone loss. The observedbone loss exhibited no significantdifferent between the systems atfive years. The turned implant boneloss was 0.2mm both in the maxillaand the mandible, while thecomparable loss for the TiO

2-

blasted implants was 0.5mm.Sandblasted and acid-etched

(SLA) (n=68) and plasma sprayed(TPS) (n=68) implants of the samegeometry (ITI®) were placed in theposterior edentulous regions in themandible. At the one-year follow-up the accumulated bone heightlevels showed a mean marginalbone loss of 0.6mm (SLA) and0.8mm (TPS) implants14. The shortobservation period restrict furthergeneralisation about the influenceof surface topography on boneloss.

Studies where implant geometry, mate-rial and surface topography influences onthe outcome ‘marginal bone loss’ are con-founded.

Jeffcoat et al.40 compared hydroxya-patite-coated threaded and HA-coated cylindric implants of anunknown brand with Brånemarksystem® implants in 120 edentulouspatients. Each patient received fiveor six implants, of which at leastone was of each implant. All threeimplant types had success ratesabove 95 per cent after five years,when ‘failure’ was defined as morethan 2mm bone loss.

Twenty-eight patients with fixedpartial bridges in the maxillasupported by ITI® and Brånemarksystem® implants on each sides wereobserved over one year38. Therewas no significant change of themarginal bone (0.2mm, Brånemarksystem® and 0.1mm, ITI® implants).The author noted that a crater-formbone loss was observed aroundsome of the ITI® implants (18 percent).

Astra Tech Tioblast® (n=50) andBrånemark system® MKII (n=45)implants placed in 18 patientsdemonstrated minor differences inthe change of the marginal bonelevels over two years (0.2mm forAstra Tech versus 0.0mm forBrånemark system® implants)44.


Implant geometry influence on the out-come ‘marginal bone loss’.

Self-tapping Brånemark system®

MKII implants (n=88) demon-strated similar bone loss comparedto the standard Brånemark system®

implants (n=91) over 0–3 years(0.6mm)54,55 and over 0–5 years(0.8mm)56.

Studies where implant geometry, mate-rial and surface topography influences onthe outcome ‘marginal bone loss’ are con-founded.

Titanium-plasma spray (TPS) ITI®

implants and Brånemark system®

implants were compared in 3 x 29patients in a multicentre trial byBecker et al.49. The patients weretreated at three different surgeriesthat each used their specific surgi-cal technique, i.e. one stage protocolfor ITI® implants (n=78), and a onestage (n=80) and a two-stage(n=78) protocol for the Brånemarksystem® implants. The respectivechanges in bone crest measurementsafter approximately 15 monthsobservation were 1.3mm (maxilla)and 1.0mm (mandible) for the ITI®

implants. The corresponding figuresfor the Brånemark system® implantswere for the one stage and twostage placement respectively 0.1mmand 0.1mm, and 0.2mm and 0.4mmfor the maxilla and the mandible.The authors did not carry out anystatistical comparisons between thetwo implant brands at any stages.

A threaded titanium, a cylinder-shaped titanium with hydroxyapa-tite plasma-sprayed coating (HA),and a cylinder-shaped titaniumplasma-sprayed coating (TPS)implant, all manufactured by 3i,were placed in the anterior mandi-ble of 15 edentulous patients52. TheTPS implants demonstrated signifi-cantly more marginal bone loss atthree years than the other implants.Mean marginal bone loss was0.7mm (range 1-4mm) for the tita-nium implants, 1.2mm (range 1-4mm) for the HA implants, and2.5mm (range 1-6mm) for the TPSimplants. Images were used, whichdo not allow precise assessments(especially less than 0.5mm). Thus,the rank order of bone loss is likelyto be the more appropriate findingthan the actual amount of marginal

bone loss. The three differentimplants were also applied in anon-submerged application in theedentulous mandible. The baselinetime for determination of marginalbone loss was at prosthesis connec-tion. In this study five implants werelost and did not provide data forbone loss. The remaining implantsrevealed marginal bone loss rang-ing from 0-3mm after three years.The mean marginal bone loss was0.3mm (range 0-2mm) for the tita-nium implants, 0.5mm (range 0–1mm) for the HA implants and1.5mm (range 0-3mm) for the TPSimplants53. The findings of thisstudy reinforce the rank order ofmarginal bone loss seen in theprevious study, however directcomparisons of data are compli-cated by the fact that differentbaseline times were used.

Category C studies: Clinicalstudies with other study designsImplant geometry influence on the out-come ‘marginal bone loss’.

Four different geometries ofBrånemark system® implants andfour different abutments were usedto retain 82 single crowns in 58patients in a retrospective study70.Greater bone loss was seen arounda conical type implant comparedto the implants with other geometriesover two years, i.e. 1.2mm versus0.6mm the first year and +0.2mmand +0.1mm the second years.

A similar study design wascarried out in Belgium73 reportingthe results of 84 single crowns onBrånemark system® implants withfour different geometries placed in75 patients and followed over threeyears. More bone loss was recordedaround the conical implants(1.9mm) versus the other self-tapping designed implants (0.6mm).

6. Mechanical problems of theimplant - abutment -superstructure connections

Summary: The low incidence ofmechanical problems reported infour RCTs precludes any general

conclusions. The single split-mouthRCT suggest that ceramic abut-ments may be more prone tomechanical problems than metallicones during placement, but oncethis is overcome, the clinical perform-ance is comparable. A limitednumber of studies using less rigor-ous and occasionally also retrospec-tively study designs suggest that theabutment geometry may affect theincidence of mechanical problemsover time. However, the possibilitiesof bias associated with non-pro-spective study designs should berecognised.

Category A1 studies: Randomisedcontrolled trialsImplant geometry influence on the out-come ‘mechanical problems’.

Cylinder IMZ® with TPS coatingand ITI® solid screw implants withTPS coating were placed in themandibles of 40 patients withmoderate jaw resorption andoverdentures retained by bar andclip attachments were made afterthree months31. During the one yearobservation period, significantlymore mechanical problems wereencountered with the IMZ® system,mainly related to the healing caps.

Studies where implant geometry, mate-rial and surface topography influences onthe outcome ‘mechanical problems’ areconfounded.

Brånemark system® MKII and AstraTech implants (n=184+187) placedin 66 edentulous patients to receivefixed prostheses demonstratedcomparable and low levels ofmechanical complications over fiveyears25,26.

Brånemark system® and ITI®

hollow screw (n=102+106) implantsplaced in the mandible of 40 eden-tulous patients to receive fixedprostheses showed similar very lowincidence of mechanical complica-tions over three years29.

Meijer et al.28 reported thatmultiple prosthetic revisions werenecessary over five years in a groupof edentulous patients fitted with amandibular overdenture eitherretained by two IMZ® implants (29

patients) or two Brånemark system®

implants (n=32). Broken abutmentswere more frequent for the IMZ®

implants.

Category A2 studies: Split-mouth randomised designImplant material influence on the out-come ‘mechanical problems’.

Andersson et al.86 compared in atrial using a combined parallel anda split mouth RCT study design 44ceramic versus 44 titanium abut-ments placed on Brånemark system®

implants. Several fractures of theceramic abutments were experiencedduring the abutment placement (5/34), but comparable performancewas noted over the next three years.



In a 5–7 year follow-up of 429HA-coated cylindric implants(Omniloc) placed into 121 patientsthe mechanical failure rate wassignificantly higher for implants withangled abutments (21 per cent)versus straight abutments (3 percent)90.

Category C studies: Clinicalstudies with other study designsImplant geometry influence on the out-come ‘mechanical problems’.

Bambini et al.92 compared twosystems for interfacing the abutmentdescribed as being ‘antirotational’,i.e. ‘Spline®’ and ‘Threadloc®’systems. Implants were placed onlyin mandibular sites in edentulousareas originally occupied by firstbicuspid to second molar teeth.Twenty-seven patients had 44Threadloc® implants and 32 patientshad 52 Spline® implants. After threeyears, three single Threadloc®

implants (20 per cent) and five pairsof joint Threadloc® implants (6 percent) showed problems and apossible prosthetic screw loosen-ing. With the Spline® series, no screwloosening was encountered. Thestudy concluded that the Spline®

system was more ‘stable’ than the

Threadloc® system. However, thestudy made the interesting remarkthat: “problem cases were solvedby increasing the torque from 30to 35ncm, and in accordance withother studies, clinical screw jointstability was improved withoutchanging the geometry of theimplant/abutment interface.” Thus,the relevance of the initial findingscan be debated.

Retrospective case series evalu-ations of single tooth and partiallyedentulous jaws report that oldertypes of abutments demonstratedmore loose screws than thenewer abutments with othergeometries68,93,94. Although studieswith a retrospective design intro-duce the risk of several varieties ofstudy bias, it is a fact that manufac-turers have continuously modifiedthe geometric designs of the abut-ments and screws, one may presumeas a response to feedback fromclinicians experiencing specificmechanical problems with implantsystems.

Studies where implant geometry, mate-rial and surface topography influences onthe outcome ‘mechanical problems’ areconfounded.

Krausse et al.63 compared the require-ment for maintenance, modification,repair or remake of the implant-supported overdentures made for46 edentulous patients over eightyears. Implants were eitherBrånemark system® (n=90) or ITI®

(n=32). Less maintenance wasrequired for the Brånemark system®

implants (67 per cent remainedunrepaired) compared to the ITI®

implants (55 per cent).Behr et al.91 demonstrated the

importance of having precise fitting,non-resilient abutment componentsleading to rigid connections ofsuprastructures instead of a resil-ient design. In a retrospective studywith up to eight years follow-upthe rate of mechanical complica-tions of 138 ITI® implants wassignificantly lower (13 per cent) thanfor 50 IMZ® implants with resil-ient anchoring components (71 percent).

7. Mechanical failing of dentalimplants

Summary: One RCT and one split-mouth RCT and a few trials basedon other study designs provideinformation on fracture incidence.The findings provide little infor-mation on the possible relationshipbetween implant characteristics andmechanical failing of the implant.

Category A1 studies: Randomisedcontrolled trials

Implant material influence on the out-come ‘mechanical failing of implant’.

IMZ® implants with hydroxyapatite(n=89) or titanium plasma-flamecoating (n=100) supporting three-unit premolar-implant bridges inpartially edentulous mandibles werecompared over more than threeyears by Mau et al.36. The fracturerates were reported to be compa-rable, i.e. 0.3 per cent and 0.1 percent respectively. (Percentagescalculated from the total numberof implant inspections over 3–7years). It is slightly unclear fromthe text whether the rates representonly bulk, i.e. horizontal, or alsopartial fractures.


Implant surface topography influence on theoutcome ‘mechanical failing of implant’.

Gotfredsen and Karlsson46 reportedin their study on fixed partialdentures retained by 133 turned andTiO

2 -blasted Astra Tech implants

that two of the turned implantsfractured within the first two yearsof function. No further fracturesoccurred during the five yearobservation period.

Category C studies: Clinicalstudies with other study designs

Studies where implant geometry, mate-rial and surface topography influences onthe outcome ‘mechanical failing ofimplant’ are confounded.

The Finnish implant register indi-cates that approximately 35 implantshas been removed due to fracturebetween 1996 and 2000. This

constitutes 0.4 per cent of theremoved implants during theperiod (n=808). This is a remark-ably low number in view of thefact that 43,553 implants has beenplaced during the same period. Theregister does not report whether aspecific implant brand is over-represented in this figure96.

Other long-term clinical retro-spective studies corroborate thatimplant fracture is a rare incidence.Naert et al.76,77 report 0.9 per centover 16 years (mean 5.5 years) forBrånemark system® implants inpartial edentulous situations. Eckertet al.98 reported a 0.6 per centfracture rate of 4,937 Brånemarksystem® implants in the maxilla andthe mandible and with the highestfracture rate in partially edentulouspatients (1.5 per cent) versus 0.2per cent in full edentulous jaws.Bahat99 reported 0.2 per cent frac-tures over 5-12 years of Brånemarksystem® implants in the posteriorjaw. Balshi100 reported a similarincidence, also for Brånemarksystem® implants. A higher inci-dence of fractures is associated withlocation in the posterior region,fixed partial dentures supported byone or two implants with canti-lever load magnification andbruxism or heavy occlusal forces5.

Discussion

Promotional material

Only a few manufacturers producebrochures that contain referencesto scientific studies documentingthe performance of their productsand/or present objective informa-tion supported by research reports,or present this on their website.Moreover, rather surprisingly, rela-tively few websites inform to whatextent the manufacturers and/orproducts comply with internationalstandards (Table 5). Many countriesrequire proof of product orproducer adherence to a standardin order to be marketed. Onereason is perhaps that most wellestablished manufacturers mayconsider such information in their

promotional material as redundantbecause the CE mark is mandatoryfor marketing a product in Europeand a FDA approval for USArespectively.

Standardisation

Standards relevant to the manufac-turing of dental implants fall intotwo categories, either quality assur-ance of the manufacturing processor directly applicable to the actualimplant or components of theimplant system. The first categoryof standards centres on the manu-facturing process with focus on forexample, development, production,installation, servicing and documen-tation (e.g. ISO9001, ISO9002,EN46001, EN46002, ISO13485).The majority of manufacturerscomply with these standards (Table5). Accredited certification bodies(synonymous to ‘notified bodies’)verify and control that the manu-facturers adhere to such standards.The equivalent concept in the USAis an adherence to the Good Manu-facturing Practice (GMP), which isregulated by the Food and DrugAdministration (FDA). Both stand-ards involve possible on-the-spotinspections of the product facili-ties. It is important to note thatthese standards contain no require-ments to the end product i.e. theactual dental implant.

Marketing a product in theUSA requires the submission of apre-market notification (510(K)statement) to FDA. This consists inessence of documentation that thesubmitted product has substantialequivalence to a product that isalready on the market with specificinformation about safety and clinicaleffectiveness. General requirementsfor submissions of endosseousimplants are indications for use,device description and sterilisationinformation. Upon request themanufacturer must also providedata on mechanical, corrosion andbiocompatibility testing, as well ascharacterisation of any coatingsused. Further requests may also

include documentation of testreports as well as data from animaland five-year clinical studies. Addi-tional requirements need to befulfilled if the implant coatingincludes calcium phosphate. TheFDA are currently revising therequirements and one proposal isthat the current prerequisite for five-year clinical data can be reduced tothree years with the implant underloaded conditions (www.fda.gov/cdrh/ode/guidance/1389.html).

In Europe, a common systemfor all member countries of theEuropean Union (EU) replaced in1998 all national certificationprogrammes for dental productsthat were in existence. This systemis based on an EC council directive(ED93/42/EEC) pertaining tomedical devices. The directiveincludes dental products and is inessence a demand that all medicaldevices need to be accredited by acertified body before marketingand sale within the EU. All medicaldevices are categorised into class 1,2a, 2b and 3 depending on the riskof potential adverse biologicaleffects, and the required documen-tation of safety and effectiveness islowest for class 1 products andincreases with higher classification.Dental implants are placed incategory 2b. The proof of anaccreditation is the CE label, andonce obtained, the product can besold without any trade barrierswithin EU. The producer can choseone of two alternatives to obtainthe CE-label. Alternative one is tohave their quality assurance systemfor the production inspected andappraised by a controlling body.In practice, the assessment is donerelative to the quality system stand-ards ISO 9001 or the Europeanequivalent EN46001. Alternativetwo is to have the actual productcertified. The problem with thisapproach is that there are fewrequirements and the implants areonly tested to see whether theyreflect the product descriptionssupplied by the manufacturer.

The European standard EN1642

– Dental implants includes require-ments for (1) intended performance,(2) design and properties, includingadd-on components, (3) sterilisa-tion and packaging, (4) marking,labelling and information suppliedby the manufacturer that include:1. Documentation that a risk assess-ment has been carried out e.g.according to a specific ISO proce-dure (EN-ISO14971), 2. Materialsneed to comply with propertyrequirements needed for implants,described in two ISO technical files(EN-ISO10451 and EN-ISO14727)and must be assessed for biocom-patibility according to specificusage tests described in other ISOdocuments (EN-ISO7405 andEN-ISO10993). The prefabricatedparts intended to connect a supra-structure to dental implants needto comply with property require-ments described in more detail inan ISO technical file (EN-ISO14727),3. Dental implants need not bemanufactured under sterile condi-tions or supplied sterile, but thecondition in which they are suppliedrequires clear description on thepackage. Guidance for sterilisationmethods is described in ISO docu-ments (EN550, EN552, EN556)and 4. The information requiredneeds to comply with detailsregarding use of symbols and mini-mum information on labelling andinstructions for use.

In practice, an overwhelmingmajority of all certification processesare focused on the production proc-ess and not on the end products.None of the manufacturers adver-tised on their websites or in theirpromotional printed materials thattheir products complied withEN1642. This signifies that thetraditional independent testing ofproducts according to variousstandards often are not carried outsince the EU directive does notexplicitly instruct that this needs tobe done. European authorities donot implement additional require-ments beyond the CE-label. It canbe speculated whether the presentregulatory systems in USA and

Europe can account for the factthat the large majority of the dentalimplant brands lack solid clinicaldocumentation of beneficial effectsfor the patient (Code A in Table 5).It is even apparent that implantsystems can be marketed in EUwith the current legislation systemwithout any documentation ofclinical performance at all in well-known peer-reviewed scientificjournals (Code D in Table 5).

Clinical documentation

Only approximately ten implantsystems were clinically documentedin accordance with that which wedescribed as extensive. Moreover,it can even be argued that the crite-ria applied in this paper to define‘extensive clinical documentation’ isnot rigorous enough, i.e. more thanfour prospective and/or retrospec-tive clinical trials (Code A in Table5).

Some venture that more thanfour studies are needed to verifythe results of implant systems usedin a variety of indications combinedwith surgical techniques appropri-ate today101. Moreover, althoughthe identified systems received thisclassification code, it does not meanthat they are equivalent in clinicalperformance. It just signifies thatthe clinical performance of thesystem has been documented inpeer-reviewed journals, not neces-sarily shown to exhibit high clinicalperformance. The reliability ofapplying the coding of A to D inTable 5 to different implant systemscan also be debated. We acknowl-edge that it is impossible to drawstrict criteria between when animplant brand can be consideredextensively documented versus thenext level of evidence of docu-mentation etc, so the subjectivenature of this categorisation isrecognised.

One needs also to take intoconsideration that the output ofnew research findings is not static,so Table 5 needs to be interpretedwith some caution. What remains,

however, is that among the manyimplant systems marketed today,only a minority is adequately docu-mented scientifically, and worse,many implant systems are marketedwithout any clinical documentationat all of the alleged clinical benefitfor patients.

In general, a substantial numberof claims made by different manu-facturers on claimed superioritydue to implant geometry, materialand surface treatment are not basedon sound clinical scientific research.We have deliberately not includedspecific examples of claims madeby named manufacturers of clinicalsuperiority related to particularimplant features for two reasons.Firstly, because we regard to labelspecific manufacturers selectively iscontra-productive, and secondlybecause the contents of advertise-ment and on websites changecontinuously.

Implant characterisation

Categorising implants according totheir geometry is a complex task,especially when also taking intoaccount that many implants displayvariations along the vertical axis dueto selective different surface treat-ments. Systems for classification ofimplants can be constructed accord-ing to morphological differences.However, the concept of such clas-sification systems and construct ofsubcategories needs to reflect clini-cally relevant data in order to bemeaningful. Since we still lack thisbasic knowledge it remains difficultto establish a valid categorisationsystem for dental implants. Thiscalls for a very critical appraisalof the relevance of differentimplant characteristics for theclinical performance. Ideally, themanufacturer should provide thisinformation, but regrettably this isnot usually the case. The rationalefor the continuous redesigning ofnew geometric shapes is often basedon finite element studies and also,for particular implants, histologicalevaluations in animal studies. The

validity of these studies to predictclinically significant improvementsremains uncertain. On the otherhand, the few clinical studies thatdo exist do not clearly identifyimplant geometry as an importantfactor when it comes to treatmentsuccess.

Implant material

The majority of manufacturerstoday limit the production to c.p.titanium implants and many manu-facturers who previously sold anarray of titanium, titanium-alloy, andcalcium-phosphate implants havediscontinued manufacturing the lastcategory. One may infer that c.p.titanium and titanium-alloy with orwithout a hydroxyapatite coatingare the materials of choice fordental implants. Dental implantsmade from any other materialshould not be used if the manufac-turer cannot demonstrate scientifi-cally sound evidence of an at-leastequivalent clinical record comparedto titanium-based implants.

Implant surface treatment

Although one may suspect thatmarketing distinction can be a driv-ing force for promoting new andalternative surface-treated dentalimplants this issue is complex. Onemust bear in mind that the scienceon integration between bone tissuesand alloplasts is relatively young.New knowledge and alternativehypotheses have been generatedcontinuously during the last decades,but the research community stilldoes not understand the exactbiological mechanisms that regu-late and control optimal boneintegration.

The first implants made in themid-1970s were machined with aturning process, and several manu-facturers attempted to replicate thismanufacturing practice. Today,several manufacturers have aban-doned this method in preferencefor different surface treatments. Thisdecision is mainly based on results

from various experimental studiesshowing faster and firmer bonefixation for surface enlarged implants.The clinical reason for using thenew surface modifications is thepossibility of speeding up the heal-ing process and loading the surfacemodified implants at an earlier timethan generally recommended forturned implants.

Influence of implantcharacteristics on clinicalperformance

Differences in quality of dentalimplants may or may not have aninfluence on clinical success, andthese differences will be reflectedby different problems encounteredat the different phases of the treat-ment. A few implant manufactur-ers carry out elaborate animal and/or laboratory studies to minimisethe risk of a non-predictive clinicaloutcome. Such experimental datamust be confirmed by clinicalobservations reported in peer-reviewed scientific journals. Thereporting of results in company-sponsored literature alone is notsufficient and should be appraisedvery critically.

‘Ease of placement’ is a rathervague description for a characteristicof a dental implant. It comprisesthe obvious benefit of a taperedform versus a straight implant insituations with limited space for asingle tooth replacement. The issuebecomes more complex whenaddressing self-tapping versus non-self-tapping implants, and claimsof benefit of specific implant apexmorphologies related to primaryimplant stability. The clinical signof a ‘difficult placement’ is conceiv-ably a lack of primary implantstability. Regarding the first issue,the choice of a tapered versus astraight implant is more a questionof correct diagnosis and propertreatment planning rather than anindication of implant quality per se.Thus this feature cannot be regardedas an indication of ‘good’ and ‘lessgood’ implant quality. Primary

implant stability can reflect howwell the site was prepared to receivethe actual implant rather than qual-ity marks of the implant per se. It iscritical that the exact set of bursrelevant to the implant product isemployed and that they are notworn. Moreover, any deviationsfrom the standard site preparationprocedure as advocated by themanufacturer for the specific implantsystem, either accidentally or inten-tionally, will jeopardise the primarystability of the inserted implant.

A lack of strict adherence toadequate bone site preparation maybe more detrimental for the initialstability than specific morphologi-cal characteristics of the implants.Moreover, given the required surgi-cal proficiency needed to preparebone for implants, it is improbablethat small differences in implantgeometry would have any effecton the surgeons’ impression of‘ease of placement’. Finally, it shouldbe noted that ‘ease of placement’ isnot necessarily related to ‘time’. Anysurgical procedure that increases therisk for overheating of bone is defi-nitely not recommended.

The most important outcomefollowing an implant installation isof course that the implantosseointegrates with a high degreeof predictability. An additionalfocus today, however, is how fastthis osseointegration can beachieved. Although there may betreatment situations where rapidosseointegration is desirable, themerits of a rapid osseointegrationmust not overshadow the long-termclinical outcomes. Rather few stud-ies present data from long timefollow-up, i.e. more than five years,and the few that are available canat best be characterised as prospec-tive case series of single implants,and occasionally it is just tooapparent that the study is publishedmerely as a covert promotion of aspecific implant brand. Hardly anycomparable data of differentimplants exists that have beenfollowed for five years, and to datenone beyond five year’s observa-

tion. That the short Brånemarksystem® implants failed morefrequently than longer implants wasreported in most clinical reports inthe 1980s and early1990s, both incontrolled clinical trials as well as incase series descriptions54,65,78,103.Other studies evaluating otherimplants associate also more fail-ures to ‘short’ implants, e.g.Omniloc implants90, ITI® implants71,Bicon implants82 and 3i turnedimplants104. One must pay atten-tion to the term ‘short’, which insome papers means implants 6–7mm in length, while in others theterm ‘shorter’ can be defined asanything less than, for example,14mm72.

Some manufacturers highlightthat this is not the case with theirproducts. Such claims needs care-ful evaluation since reports oftencited to support such claims haveeither severe statistical flaws or aremethodologically weak. For exam-ple, ITI® advertisements cite onelarge study with extensive follow-up time19, but the paper lacksproper multivariate survival statis-tics such as Cox regression orproportional hazards modelling.Another example is a study evalu-ating Osseotite® implants where theauthors emphasised that ‘the shorterimplants performed similarly tolonger implants’, although the studywas not designed to address thatissue13.

An intriguing finding is that aninvestigator group in Leuven,Belgium, who earlier reported anassociation between implant lengthand failure risk, do not demon-strate such a clear relationshipfollowing a reanalysis of the studymaterial using more complexmultivariate statistics74,75. It has evenbeen reported in a recent clinicalstudy that the failure of Brånemarksystem® implants in this study wasmore frequent among the longer (15–18mm) compared to the shorterimplants79.

What must be remembered isthat any study with a retrospectivedesign is at risk from potential

recall and examiner bias. More-over, any demonstrable numericalrelationship between two clinicalvariables in an often extensive andheterogeneous data set may intheory also be due to confoundingclinical or patient factors, or it canbe just a spurious statistical phenom-enon. A prospective study thataddresses the influence of implantlength on treatment success, pref-erably randomised and/or blinded,can provide indications as to theextent to which this may be anaetiological factor for implant fail-ure. As no such studies have beencarried out, it cannot be ruled outthat the reported associationbetween implant lengths and clini-cal failure is a reflection of anatomi-cal limitations in actual treatmentsituations. In other words, implantlength is a surrogate variable forwhat actually represents differencesin case and site selections in clinicaltrials. In the same line of discussionis the controversy of alleged benefitof wide diameter implants. Chuanget al.82 applied multivariate regres-sion on data of 2,349 Bicon implantsand associated failures with shortimplant length, but not with implantdiameter. Also Davarpanah et al.105

and Friberg et al.106 reported posi-tive experiences with placing wideimplants, while findings from otherinvestigators should caution againsttheir indiscriminate use107–110. It hasbeen proposed that different alloycompositions used for differentcomponents of the reconstructioncan create galvanic effects andthereby cause adverse soft-tissuereactions and perhaps even implantfailure111. This would theoreticallysignify that implant systems wherethis is the case should be avoided.However, the hypothesis remainsunconfirmed and is not based onsolid clinical evidence.

The clinical significance of thereported differences in bone lossamong the implant systems mustbe considered in relation the factthat reliable bone loss measurementsof less than 0.2mm is difficult toachieve, even in in vitro situations112.

Moreover, in many reports thevariations in bone loss among theindividuals in the study samplevaries considerably, as indicated byvery large standard deviations (SD).The SD exceeds, often many times,the differences between implantbrands. This signifies that the rela-tive importance of the implantfactor as such is minor in relationto other confounding factors asso-ciated with the patient and theclinicians. Moreover, short-termresults on bone loss require cautiousinterpretation, especially in studieswhere one- and two-surgicalstages implant systems are beingcompared24,27,29,32,33,38. Short-termstudies help to elucidate the physi-ological remodelling that occursaround implants of differentdesigns, but it is information aboutthe long-term prognosis of animplant that allows the patient todecide whether implant-basedprosthetics is a therapy option forthem or not. Although it is knownthat the largest bone loss aroundimplants occurs during the firsttwelve months following the surgi-cal insertion113, there is currently noconsensus as to what extent resultsfrom short-term clinical studies canpredict long-term performance ofdental implants.

Mechanical problems of theimplant/ abutment/ superstructureconnections arising as a function ofconnection morphology are a verycomplex and much debated topicin the dental literature. The reasonis partly due to the lack of system-atic collection of prospective clini-cal data, and the heterogeneity ofresults presented in the manypublished case series of singleimplant or implant system. The verylow incidence of mechanical prob-lems calls for very large studysamples over a long time span tofind meaningful results. Thus, theonly realistic study design toemploy is careful examination offailed implants and/or retrospec-tive data analyses. An alternativestrategy is to maintain a databaseof placed and removed dental

implants, but the only country tohave implemented this so far isFinland96. One may question whyother countries have not done thesame, especially those that have setup national registers for breastand/or hip implants.

The main engineering goal ofabutment designing is to providewhat, in the language of basicmechanics, would be termed a‘fixed joint’ between implant andabutment. That is, one that canresist all six components of forceand moment applied to the jointduring service conditions. In assess-ing the success or failure of a fixedjoint, two questions arise: ‘What arethe three force and three momentcomponents that are typically appliedduring service conditions of thejoint? and, how well do the variousimplant-abutment geometries standup to these service conditions?’ Thefundamental problem is that fulldata are lacking on exactly whatthese loading components really arein vivo. Limited data exist, but areinsufficient to permit conclusionsabout in vivo loading conditions onimplants in every location in themouth, under all conceivable pros-thetic conditions in any givenpatient114. Consequently, it remainsdifficult to assess laboratory test-ing of abutment systems withoutknowing the relationship to loadsintraorally. Overall, with laboratorytesting of abutment-implant systemsof various types, the challengeremains to ‘close the loop’ in relat-ing laboratory test data to actualclinical conditions. Currently it ispremature to make sweepingconclusions about which systemsare clinically best without test datalinked directly to in vivo conditions.

All implants may be subject tomechanical fractures. However,technical failures of implants arerelatively sparsely described in theliterature115. Although there havebeen a few clinical reports of frac-ture of the implants, in contrast tothe more common fractures ofabutment screws and prostheticscrews, fractures are important

because of the significant conse-quences to the patient. Overloadseems not to be an aetiologicalfactor as a cause for implant frac-ture clinically116,117.

General aspects of the clinicalperformance of implants

It must be emphasised that there isan inherent danger in limiting thefocus of qualitative patient care tojust the actual dental implant hard-ware. Surgical skills may be moreimportant for clinical success thandifferences in implant characteris-tics118. An absolute requirement forthe clinician before providingimplant therapy is that adequatetraining has been obtained. Ofimportance is an awareness ofpossible risk factors involved, andthe knowledge of which patient torefer to more specialised centresand which patient one may copewith based on one’s own clinicalproficiency. Careful preparation ofthe implant site with adequate cool-ing and under adequate asepsis is aprecondition for implanting foreignmaterials into bone. A number ofclinical studies have reported asignificant influence on the treat-ment result depending on the skillsof the surgeon, which may be sepa-rated into erroneous treatmentplanning or the operator’s actualhandling skills103,119,120.

Particular products seem toperform well in the hands of specificclinicians, but fail when used byother operators. This leads to thequestion whether some implantbrands contain ‘technique sensitivecharacteristics’, confounding theissue of whether it is inadequatetraining or technique sensitivity char-acteristics that explain the lack ofsuccess in the hands of otheroperators. Both lecturers and sale-persons promoting specific implantsoccasionally insinuate that particu-lar implants are ‘more forgiving’than others in the sense that theimplants perform satisfactorily inspite of highly developed surgicalproficiency. It is clearly impossible

to conduct clinical studies to clarifysuch an issue for logistical and ethi-cal reasons. Thus, any claims ofsuperior technique sensitivity cannotbe entirely disregarded, but shouldperhaps be regarded with a certainlevel of scepticism. Moreover, ithas also been suggested that froma clinical or microbiological perspec-tive implant failures seem primarilyto be at a patient level rather thanat an implant level121,122,183. Thus,besides the operator, even tangibleand intangible patient aspects maybe more relevant aetiological factorsin implant failure than the actualimplant hardware.

The report of the Finnish nationalimplant register states that the mostcommon reason for implant failureis a lack of osseointegration withinthe first year after the surgical opera-tion. Latter sudden loss of osseo-integration is usually unexpected,and is often not preceded by anyclinical observable special event96.It is unknown whether the underly-ing reason may be due to thepatient, the operation team, thesuperconstruction or the actualimplant. Patient-related reasonsinclude medical condition beforeoperation, smoking, accidents orperhaps irresponsible use of implantand neglect of home care. Reasonsrelated to the operation teaminclude wrong indication or neglectof contra-indications, lack ofexperience, or the prevailing implantculture (implant selection, operationtechnique, inadequate equipment orstaff, decisions during the opera-tion and treatment, neglect ofsignals received during follow-up,neglect of systematic follow-up).Finally, potential failures due to theimplant per se may include inad-equate design of the implant, rawmaterial imperfection, manufactur-ing defects, and deficiency insterilising and storing96.

Factors besides the implanthardware

Also, other hardware componentsbesides the actual implant body and

abutment may influence the clinicalresult. Several clinical studies havefocused on comparing fixed versusremovable prostheses on implantsor on two versus another numberof implants, e.g. four implants.Other studies have appraisedcemented versus screw-retainedfixed prostheses as well as betweendifferent types of attachment systemsfor removable prostheses. Additionalpotentially confounding factorsidentified in laboratory experimentsare the effects of the material usedfor the prosthetic superstructuresand/or unpredictable loading dueto superstructure misfit. The signifi-cance of the presence of, and onthe location of, an interface or‘microgap’ between the implant andabutment/restoration in 2-piececonfigurations remains debatable.Several factors may influence theresultant level of the crestal boneunder conditions where a gapexists, including possible movementsbetween implant components andthe size of the microgap (interface)between the implant and abutment123.At present, possible microgaps arenot regarded as an aetiologicalfactor in causes of early implantbone loss113. Possible other negativeelements for a successful clinicalresult that have been identified inlaboratory experiments are theeffects of the occlusal anatomy andcantilever situations due to theimplants’ locations and/or theprosthesis extension, inadequatetorque used to tighten screws, etc.These study data are not includedin the present paper. It should beacknowledged that at least someof these issues are indirectly associ-ated with design characteristics anddifferences in component tolerancelimits of dental implant systems.

Considerations for futureresearch

The extensive diversity of implantcharacteristics is not necessarily onlya result of manufacturers trying toobtain a brand distinction in fiercecommercial competition. Patent

infringement lawsuits have alsoplayed an important role duringthe last decades, especially in theUSA. However, the diversity is alsoa sign of the confusion regardingwhich implant characteristic shouldbe considered to be clinicallyimportant. It is probable that thisdilemma will continue until there isconsensus on the most appropriaterequirements – patient based orclinician based – for minimum clini-cal performance of this treatmentmodality102. Moreover, until fairlyrecently, implant manufacturershave been reluctant to support clini-cal trials where different implantcharacteristics have been comparedand especially if these have includedan element of comparison betweendifferent manufacturers. The rela-tively few clinical studies that havebeen conducted (Table 3) havemostly compared different implantbrands, whereby the influence onoutcome due to implant geometry,material and surface topography isconfounded. Few clear conclusionsregarding the relative importanceof these elements individually cantherefore be determined. We willremain ignorant as long as there islack of clinical trials properlydesigned to study such basic factors.Added to this complexity is theincreasingly common study aim ofcomparing immediate, early andconventional loading done in one-stage surgery. Apart from the termi-nology dispute about what shouldbe considered ‘early’, we mayperhaps discover that some combi-nations of material/geometry/surface-treatment are required forsome special treatment situations,while some other combinationsmay be optimal for others. Thereis also an ethical dilemma incomparing different implants. Oneneeds a hypothesis that it is possi-ble to offer the patient a bettertreatment than the best documentedresults available, to justify a compari-son in vivo. The documented implantbrands all show very good resultswith almost no serious complica-tions. Hence, a significant number

of subjects are needed to separateone implant from the other. Theproblem is that historically, a system-atic approach to elucidate thesemechanisms has not been publishedin the literature and does not seemto be part of the internationalresearch agenda. Finally, new trialsshould preferably compare posi-tive effects/outcomes, in contrastto the more common analyses ofthe adverse biological and mechani-cal problems (i.e. when the failuresare counted under the assumptionthat the non-failures are survivals).

Considerations for thepracticing dentist

The existing scientific clinical docu-mentation should be the majorconsideration factor for selectingdental implants. However, giventhat several implant systems seemscomparable, it would seem legiti-mate that dentists should alsoconsider other factors that may beregarded as implant system ‘qual-ity’ in a broad context. Other factorsthat may be taken into considera-tion beyond the scientific data canbe:• Is the manufacturer represented

locally and can be consultedeasily?

• Can they deliver required prod-ucts timely and reliably inextraordinary situations?

• The manufacturer’s ethical andal reputation. Is the manufac-turer’s promotion exact, fair andcomprehensive?

• Does the manufacturer provideservice and training possibilities?

• Ease of use. Are the trainingrequirements for using theimplant system intricate?

• Flexibility of applications. Somedentists may prefer a wideselection of alternative prostho-dontic options such as o-rings,attachments and choice of screwretained or cemented super-constructions, possibility for castand cemented abutments, angledabutments and anti-rotationalabutments.

• Stock inventory. Is it necessaryfor the dentist to acquire anextensive supply of hardwareto meet different treatment situ-ations and thereby induce highinventory costs?

• Engineering design. Since mecha-nical defects will occur sooneror later, are elaborate and/ortime-consuming techniques nec-essary in order to make adjust-ments or remakes?

• Costs. The cost of the surgicaland prosthetic start-up kit, thecost per implant and per compo-nent, and the course/trainingcosts needs to be taken intoaccount. Also the accumulatedtime required for adjustmentsand mechanical failures needsto be taken into account as thisinvolves other issues such aspatient trust and opportunitycost.

Conclusions

The scientific evidence of the influ-ence of dental implant materials,geometry and surface topographyon clinical performance is limitedand not particularly methodologi-cally sound. There is therefore littlebasis for promoting specific implantsor implant systems as more or lesshigh quality. However, it wouldseem prudent to avoid using dentalimplants with no records of clini-cal documentation, especially if themanufacturer has not disclosedwhether the manufacturing processis carried out according to generalprinciples of good manufacturingpractice, e.g. according to the qual-ity assurance systems developed byISO or FDA.

A general characteristic of thetrials identified in this paper is thealmost unanimous focus on clinicalcriteria that address implant leveltreatment outcomes, rather thanprosthesis, patient and societalperspectives. It can be questionedwhether many of the outcomecriteria described in this paper arein fact only surrogate criteria fortreatment success, which in the last

instance is the patient’s experiencerelative to the patient’s expectations.Cost-benefit and cost-utility analy-ses to differentiate between dentalimplant systems need therefore tobe addressed in future research.

References

1. Brånemark PI, Hansson BO, Adell R,

et al. Osseointegrated implants in the

treatment of the edentulous jaw.

Experience from a 10-year period.

Stockholm: Almqvist & Wiksell

International, 1977.

2. Albrektsson T, Brånemark PI, Hansson

HA, et al. Osseointegrated titanium

implants. Requirements for ensuring a

long-lasting, direct bone-to-implant

anchorage in man. Acta Orthop Scand

1981 52: 155–170.

3. Binon PP. Implants and components:

entering the new millennium. Int J Oral

Maxillofac Implants 2000 15: 76–94.

4. Sahiwal IG, Woody RD, Benson BW,

et al. Macro design morphology of

endoseous dental implants. J Prosthet

Dent 2002 87: 543–551.

5. Rangert B, Krogh PHJ, Langer B, et al.

Bending overload and implant frac-

tures: a retrospective clinical analysis.

Int J Oral Maxillofac Implants 1995 10:

326–334.

6. Hallgren C, Sawase T, Ortengren U, et

al. Histomorphometric and mechani-

cal evaluation of the bone-tissue

response to implants prepared with

different orientation of surface topo-

graphy. Clin Implant Dent Relat Res

2001 3: 194–203.

7. Wennerberg A, Hallgren C, Johansson

C, et al. A histomorphometric evalua-

tion of screw-shaped implants each

prepared with two surface roughness.

Clin Oral Implants Res 2001 12: 128–

134.

8. Roos J, Sennerby L, Albrektsson T.

An update on the clinical documenta-

tion on currently used bone-anchored

endosseous implants. Clinical Update

1997 24: 194–200.

9. Eckert SE, Parein A, Myshin HL, et

al. Validation of dental implant systems

through a review of the literature sup-

plied by system manufacturers. J

Prosthet Dent 1997 77: 271–279.

10. Palmer RM, Palmer PJ, Smith BJ. A 5-

year prospective study of Astra single

tooth implants. Clin Oral Implant Res

2000 11: 179–182.

11. Norton MR. A 4–7 year follow-up on

the biological and mechanical stability

of single tooth implants. Clin Implant

Dent Relat Res 2001 3: 214–220.

12. Sullivan DY, Sherwood RL, Porter

SS. Long-term performance of Osseo-

tite implants: A 6-year clinical follow-

up. Compendium 2001 22: 326–333.

13. Testori T, Wiseman L, Woolfe S, et al.

A prospective multicenter clinical

study of the Osseotite implant: four-

year interim report. Int J Oral Maxillofac

Implants 2001 16: 193–200.

14. Roccuzzo M, Bunino M, Prioglio F, et

al. Early loading of sandblasted and

acid-etched (SLA) implants: a pros-

pective split-mouth comparative

study. Clin Oral Implants Res 2001 12:

572–578.

15. Cochran DL, Buser D, ten Bruggenkate

CM, et al. The use of reduced healing

times on ITI implants with a sand-

blasted and acid-etched (SLA) surface:

Early results from clinical trials on ITI

SLA implants. Clin Oral Implants Res

2002 13: 144–153.

16. Tawse-Smith A, Payne AG, Kumara

R, et al. One-stage operative proce-

dure using two different implant sys-

tems: a prospective study on implant

overdentures in the edentulous man-

dible. Clin Implant Dent Relat Res 2001

3: 185–193.

17. Deporter D, Watson P, Pharoah M, et

al. Ten-year results of a prospective

study using porous-surfaced dental

implants and a mandibular over-

denture. Clin Implant Dent Relat Res

2002 4: 183–189.

18. Graf HL, Geu B, Knöfler W, et al.

Klinisches Verhalten des ZL-dura-

plant-Implantatsystems mit Ticer

Oberfläche. Prospektive Studie Mit-

teilung 1: Überlebensraten. Z Zahnärtzl

Implant 2001 17: 124–131.

19. Buser D, Mericske-Stern R, Bernard

JP, et al. Long-term evaluation of non-

submerged ITI implants. Part 1: 8-

year life table analysis of a prospective

multi-center study with 2359 im-

plants. Clin Oral Implants Res 1997 8:

161–172.

20. Merickse-Stern R, Aerni D, Geering

AH, et al. Long-term evaluation of

sub-merged hollow cylinder implants.

Clinical and radiographic results. Clin

Oral Implant Res 2001 12: 252–259.

21. Morra M, Cassinelli C, Bruzzone G, et

al. Surface chemistry effects of topo-

graphic modification of titanium den-

tal implant surfaces: 1. Surface analy-

sis. Int J Oral Maxillofac Implants 2003

18: 40–45.

22. Esposito M, Coulthard P, Worthington

HV, et al. Quality Assessment of

Randomized Controlled Trials of Oral

Implants. Int J Oral Maxillofacial Implants

2001 16: 783–792.

23. Jokstad A, Esposito M, Coulthard P,

et al. The Reporting of Randomized

Controlled Trials in Prosthodontics.

Int J Prosthodont 2002 15: 230–242.

24. Batenburg RHK, Meijer HJA, Raghoebar

GM, et al. Mandibular overdentures

supported by two Brånemark, IMZ or

ITI implants. A prospective compara-

tive preliminary study: one-year results.


383.

25. Engquist B, Åstrand P, Dahlgren S, et

al. Marginal bone reaction to oral

implants: a prospective comparative

study of Astra Tech and Brånemark

system implants. Clin Oral Implants Res

2002 13: 30–37.

26. Åstrand P, Engquist B, Dahlgren S, et

al. Astra Tech and Brånemark system

implants: a prospective 5-year com-

parative study. Results after one year.

Clin Implant Dent Relat Res 1999 1:

17–26.

27. Kemppainen P, Eskola S, Ylipaavalniemi

P. A comparative prospective clinical

study of two single-tooth implants: a

preliminary report of 102 implants. J

Prosthet Dent 1997 77: 382–387.

28. Meijer HJ, Raghoebar GM, Van ‘t Hof

MA, et al. A controlled clinical trial of

implant-retained mandibular over-

dentures five-years’ results of clinical

aspects and aftercare of IMZ implants

and Branemark implants. Clin Oral

Implants Res 2000 11: 441–447.

29. Moberg LE, Kondell PA, Sagulin GB,

et al. Brånemark system and ITI Den-

tal Implant System for treatment of

mandibular edentulism. Clin Oral

Implants Res 2001 12: 450–461.

30. Tawse-Smith A, Payne AG, Kumara

R, et al. Early loading of unsplinted

implants supporting mandibular over-

dentures using a one-stage operative

procedure with two different implant

systems: a 2-year report. Clin Implant

Dent Relat Res 2002 4: 33–42.

31. Heydenrijk K, Raghoebar GM, Meijer

HJ, et al. Clinical and radiologic evalu-

ation of 2-stage IMZ implants placed

in a single-stage procedure: 2-year

results of a prospective comparative

study. Int J Oral Maxillofac Implants

2003 18: 424–432.

32. Heydenrijk K, Raghoebar GM, Meijer

HJ, et al. Two-stage IMZ implants and

ITI implants inserted in a single-stage

procedure. A prospective comparative

study. Clin Oral Implants Res 2002 13:

371–380.

33. Meijer HJ, Heijdenrijk K, Raghoebar

GM. Mucosal and radiographic aspects

during the healing period of implants

placed in a one-stage procedure. Int J

Prosthodont 2003 16: 397–402.

34. Jones JD, Lupori J, Van Sickels JE, et

al. A 5-year comparison of hydroxya-

patite-coated titanium plasma-sprayed

and titanium plasma-sprayed cylinder

dental implants. Oral Surg Oral Med

Oral Pathol Oral Radiol Endod 1999 87:

649–652.

35. Jones JD, Saigusa M, Van Sickels JE,

et al. Clinical evaluation of hydroxya-

patite-coated titanium plasma-sprayed

and titanium plasma-sprayed cylinder

dental implants. A preliminary report.

Oral Surg Oral Med Oral Pathol Oral

Radiol Endod 1997 84: 137–141.

36. Mau J, Behneke A, Behneke N, et al.

Randomized multicenter comparison

of two coatings of intramobile cylin-

der implants in 313 partially edentu-

lous mandibles followed up for 5 years.


487.

37. Rocci A, Martignoni M, Gottlow J.

Immediate loading of Branemark Sys-

tem TiUnite and machined-surface

implants in the posterior mandible: a

randomized open-ended clinical trial.

Clin Implant Dent Relat Res 2003 5

Suppl 1: 57–63.

38. Åstrand P, Engquist B, Anzen B, et al.

Nonsubmerged and submerged implants

in the treatment of partially edentu-

lous maxilla. Clin Implant Dent Related

Res 2002 4: 115–127.

39. Geurs NC, Jeffcoat RL, McGlumphy

EA, et al. Influence of implant geo-

metry and surface characteristics on

progressive osseointegration. Int J Oral


40. Jeffcoat MK, McGlumphy EA, Reddy

MS, et al. A comparison of hydroxya-

patite (HA) -coated threaded, HA-

coated cylindric, and titanium threaded

endosseous dental implants. Int J Oral


41. Orenstein IH, Tarnow DP, Morris HF,

et al. Factors affecting implant mobil-

ity at placement and integration of

mobile implants at uncovering. J

Periodontol 1998 69: 1404–1412.

42. Truhlar RS, Farish SE, Scheitler LE,

et al. Bone quality and implant design-

related outcomes through stage II sur-

gical uncovering of Spectra-System

root form implants. J Oral Maxillofac

Surg 1997 55 (12 Suppl 5): 46–54.

43. Ochi S, Morris HF, Winkler S. The

influence of implant type, material,

coating, diameter, and length on

periotest values at second-stage sur-

gery: DICRG interim report no. 4.

Dental Implant Clinical Research

Group. Implant Dent 1994 3: 159–162.

44. van Steenberghe D, De Mars G,

Quirynen M, et al. A prospective split-

mouth comparative study of two

screw-shaped self-tapping pure tita-

nium implant systems. Clin Oral

Implants Res 2000 11: 202–209.

45. Friberg B, Jisander S, Widmark G, et

al. One-year prospective three-center

study comparing the outcome of a

‘soft bone implant’ (prototype Mk IV)

and the standard Branemark implant.


71–77.

46. Gotfredsen K, Karlsson U. A prospec-

tive 5-year study of fixed partial pros-

theses supported by implants with

machined and TiO2-blasted surface. J

Prosthodont 2001 10: 2–7.

47. Karlsson U, Gotfredsen K, Olsson C.

A 2-year report on maxillary and man-

dibular fixed partial dentures sup-

ported by Astra Tech dental implants.

A comparison of 2 implants with dif-

ferent surface textures. Clin Oral

Implants Res 1998 9: 235–242.

48. Khang W, Feldman S, Hawley CE, et

al. A Multi-Center Study Comparing

Dual Acid-Etched and Machined-Sur-

faced Implants in Various Bone Quali-

ties. J Periodontol 2001 72: 1384–1390.

49. Becker W, Becker BE, Ricci A, et al.

A prospective multicenter clinical trial

comparing one- and two-stage tita-

nium screw-shaped fixtures with one-

stage plasma-sprayed solid-screw fix-

tures. Clin Implant Dent Relat Res 2000

2: 159–165.

50. Chiapasco M, Gatti C. Implant-

retained mandibular overdentures

with immediate loading: a 3- to 8-year

prospective study on 328 implants.


29–38.

51. Pinholt EM. Branemark and ITI den-

tal implants in the human bone-grafted

maxilla: a comparative evaluation.


592.

52. Røynesdal AK, Ambjørnsen E, Haanes

HR. A comparison of 3 different

endosseous nonsubmerged implants in

edentulous mandibles: A clinical

report. Int J Oral Maxillofac Implants

1999 14: 543–548.

53. Røynesdal AK, Ambjornsen E, Støvne

S, et al. A comparative clinical study

of three different endosseous implants

in edentulous mandibles. Int J Oral


54. Friberg B, Gröndahl K, Lekholm U. A

new self-tapping Brånemark system

implant: Clinical and radiographic

evaluation. Int J Oral Maxillofac

Implants 1992 7: 80–85.

55. Olsson M, Friberg B, Nilson H, et al.

MKII – a modified self-tapping

Brånemark system implant: 3-year

results of a controlled prospective

pilot study. Int J Oral Maxillofac

Implants 1995 10: 15–21.

56. Friberg B, Nilson H, Olsson M, et al.

Mk II: the self-tapping Brånemark

system implant: 5-year results of a pro-

spective 3-center study. Clin Oral

Implants Res 1997 8: 279–285.

57. De Bruyn H, Collaert B, Linden U, et

al. A comparative study of the clinical

efficacy of Screw Vent implants ver-

sus Branemark fixtures, installed in a

periodontal clinic. Clin Oral Implants

Res 1992 3: 32–41.

58. Gómez-Roman G, Schulte W, Seiler

M, et al. Implantationen im zahnlosen

Unterkiefer Ergebnisse mit unter-

schiedlichen Implantatsystemen. Z

Zahnärztl Implantol 1998 14: 8–16.

59. Ellegaard B, Baelum V, Karring T.

Implant therapy in periodontally com-

promised patients. Clin Oral Implants

Res 1997 8: 180–188.

60. Ellegaard B, Kølsen-Petersen J, Baelum

V. Implant therapy involving maxil-

lary sinus lift in periodontally compro-

mised patients. Clin Oral Implants Res

1997 8: 305–315.

61. Graf HL, Geu B, Knöfler W, et al.

Klinisches Verhalten des ZL-dura-

plant-Implantatsystems mit Ticer

Oberfläche. Mitteilung 2: Zustands-

beschreibende Parameter. Z Zahnärtzl

Implant 2002 18: 1–8.

62. Puchades-Roman L, Palmer RM,

Palmer PJ, et al. A clinical, radio-

graphic, and microbiologic compari-

son of Astra Tech and Brånemark

single tooth implants. Clin Implant Dent

Relat Res 2000 2: 78–84.

63. Krausse A, Forster J, Gerds T, et al.

Implantologische und prothetische

Erfolgsraten von Hybridprothesen

zweier verschiedener Implantatsys-

teme. Dtsch Zahnärztl Z 2001 56: 680–

683.

64. Noack N, Willer J, Hoffmann J. Long-

term results after placement of dental

implants: longitudinal study of 1,964

implants over 16 years. Int J Oral


65. Scurria MS, Morgan ZV 4th, Guckes

AD, et al. Prognostic variables associ-

ated with implant failure: a retrospec-

tive effectiveness study. Int J Oral


66. Spiekermann H, Jansen VK, Richter

EJ. A 10-year follow-up study of IMZ

and TPS implants in the edentulous

mandible using bar-retained over-

dentures. Int J Oral Maxillofac Implants

1995 10: 231–243.

67. Valentini P, Abensur DJ. Maxillary

sinus grafting with anorganic bovine

bone: a clinical report of long-term

results. Int J Oral Maxillofac Implants

2003 18: 556–560.

68. Bianco G, Di Raimondo R, Luongo G,

et al. Osseointegrated implant for sin-

gle-tooth replacement: a retrospective

multicenter study on routine use in

private practice. Clin Implant Dent Relat

Res 2000 2: 152–158.

69. Carr AB, Choi YG, Eckert SE, et al.

Retrospective cohort study of the

clinical performance of 1-stage dental

implants. Int J Oral Maxillofac Implants

2003 18: 399–405.

70. Engquist B, Nilson H, Åstrand P. Sin-

gle-tooth replacement by osseointe-

grated Brånemark system implants. A

retrospective study of 82 implants.


245.

71. Ferrigno N, Laureti M, Fanali S, et al.

A long-term follow-up study of non-

submerged ITI implants in the treat-

ment of totally edentulous jaws. Part

I: Ten-year life table analysis of a pro-

spective multicenter study with 1286

implants. Clin Oral Implants Res 2002

13: 260–273.

72. Lentke A, Dahm G, Kerschbaum T, et

al. Langzeitergebnisse von Brånemark-

Implantaten in der Kölner Universi-

tätszahnklinik. Dtsch Zahnärztl Z 2003

58: 88–93.

73. Malevez C, Hermans M, Daelemans P.

Marginal bone levels at Brånemark

system implants used for single tooth

restoration. The influence of implant

design and anatomical region. Clin Oral

Implants Res 1996 7: 162–169.

74. Naert I, Koutsikakis G, Duyck J, et al.

Biologic outcome of single-implant

restorations as tooth replacements: a

long-term follow-up study. Clin Implant

Dent Relat Res 2000 2: 209–218.

75. Naert I, Duyck J, Hosny M, et al.

Evaluation of factors influencing the

marginal bone stability around implants

in the treatment of partial edentulism.


30–38.

76. Naert IE, Koutsikakis G, Duyck JA, et

al. Biologic outcome of implant-sup-

ported restorations in the treatment

of partial edentulism. Part I: A longi-

tudinal clinical evaluation. Clin Oral

Implants Res 2002 13: 381–389.

77. Naert IE, Koutsikakis G, Quirynen

M, et al. Biologic outcome of implant-

supported restorations in the treat-

ment of partial edentulism. Part 2: A

longitudinal radiographic evaluation.


395.

78. Quirynen M, Naert I, van Steenberghe

D. Fixture design and overload influ-

ence marginal bone loss and fixture

success in the Brånemark system. Clin

Oral Implants Res 1992 3: 104–111.

79. Raghoebar GM, Friberg B, Grunert I,

et al. 3-year prospective multicenter

study on one-stage implant surgery and

early loading in the edentulous mandi-

ble. Clin Implant Dent Relat Res 2003

5: 39–46.

80. Romeo E, Chiapasco M, Ghisolfi M, et

al. Long-term clinical effectiveness of

oral implants in the treatment of par-

tial edentulism. Seven-year life table

analysis of a prospective study with

ITI dental implants system used for

single-tooth restorations. Clin Oral

Implants Res 2002 13: 133–143.

81. Wheeler S. Use of the Frialit-2 Im-

plant System in private practice: a

clinical report. Int J Oral Maxillofac

Implants 2003 18: 552–555.

82. Chuang SK, Wei LJ, Douglass CW, et

al. Risk factors for dental implant

failure: a strategy for the analysis of

clustered failure-time observations. J

Dent Res 2002 81: 572–577.

83. Weyant RJ, Burt BA. An assessment

of survival rates and within-patient

clustering of failures for endosseous

oral implants. J Dent Res 1993 72: 2–

8.

84. Davarpanah M, Martinez H, Etienne

D, et al. A prospective multicenter

evaluation of 1,583 3i implants: 1- to

5-year data. Int J Oral Maxillofac

Implants 2002 17: 820–828.

85. Gatti C, Chiapasco M. Immediate

loading of Brånemark implants: a 24-

month follow-up of a comparative

prospective pilot study between man-

dibular overdentures supported by

conical transmucosal and standard

MKII implants. Clin Implant Dent

Related Res 2002 4: 190–199.

86. Andersson B, Taylor A, Lang BR, et al.

Alumina ceramic implant abutments

used for single-tooth replacement: a

prospective 1- to 3-year multicenter

study. Int J Prosthodont 2001 14: 432–

438.

87. Barclay CW, Last KS, Williams R. The

clinical assessment of a ceramic-coated

transmucosal dental implant collar. Int

J Prosthodont 1996 9: 466–472.

88. Bollen CML, Papaioanno W, Van

Eldere J, et al. The influence of abut-

ment surface roughness on plaque

accumulation and peri-implant muco-

sitis. Clin Oral Implants Res 1996 7:

201–211.

89. Quirynen M, Bollen CM, Papaioannou

W, et al. The influence of titanium

abutment surface roughness on plaque

accumulation and gingivitis: short-

term observations. Int J Oral Maxillofac

Implants 1996 11: 169–178.

90. McGlumphy EA, Peterson LJ, Larsen

PE, et al. Prospective study of 429

hydroxyapatite-coated cylindric omniloc

implants placed in 121 patients. Int J

Oral Maxillofac Implants 2003 18: 82–

92.

91. Behr M, Lang R, Leibrock A, et al.

Complication rate with prosthodontic

reconstructions on ITI and IMZ

dental implants. Clin Oral Implants Res

1998 9: 51–58.

92. Bambini F, Muzio LL, Procaccini.

Retrospective analysis of the influence

of abutment structure design on the

success of implant unit: a 3-year con-

trolled follow up study. Clin Oral

Implants Res 2001 12: 319–324.

93. Eckert SE, Wollan PC. Retrospective

review of 1170 endosseous implants

placed in partially edentulous jaws. J

Prosthet Dent 1998 79: 415–421.

94. Scholander S. A retrospective evalua-

tion of 259 single-tooth replacements

by the use of Brånemark system

implants. Int J Prosthodont 1999 12:

483–491.

95. Davarpanah M, Martinez H, Tecucianu

JF, et al. The self-tapping and ICE 3i

implants: a prospective 3-year multi-

center evaluation. Int J Oral Maxillofac

Implants 2001 16: 52–60.

96. Pihakari A, Nevalainen J, Hirvonen

A, et al. The 2000 Dental Implant

Yearbook. Helsinki: National Agency

for Medicines 2001. [cited 2003 Jun 5]

Available from: URL: http://www.

nam.fi/uploads/julkaisut/78019_

Dental_Implant.pdf

97. d’Hoedt B, Schulte W. A comparative

study of results with various endos-

seous implant systems. Int J Oral


98. Eckert SE, Meraw SJ, Cal E, et al.

Analysis of incidence and associated

factors with fractured implants: a ret-

rospective study. Int J Oral Maxillofac

Implants 2000 15: 662–667.

99. Bahat O. Brånemark system implants

in the posterior maxilla: clinical study

of 660 implants followed for 5 to 12

years. Int J Oral Maxillofac Implants

2000 15: 646–653.

100.Balshi TJ. An analysis and manage-

ment of fractured implants: a clinical

report. Int J Oral Maxillofac Implants

1996 11: 660–666.

101.Berglundh T, Persson L, Klinge B. A

systematic review of the incidence of

biological and technical complications

in implant dentistry reported in pro-

spective longitudinal studies of at least

5 years. J Clin Periodontol 2002 29 (Sup-

plement 3): 197–212.

102.Anderson JD. The need for criteria on

reporting treatment outcomes. J

Prosthet Dent 1998 79: 49–55.

103. Sennerby L, Roos J. Surgical determi-

nants of clinical success of osseointe-

grated oral implants: a review of the

literature. Int J Prosthodont 1998 11:

408–420.

104. Weng D, Jacobson Z, Tarnow D, et

al. A prospective multicenter clinical

trial of 3i machined-surface implants:

results after 6 years of follow-up. Int

J Oral Maxillofac Implants 2003 18:

417–423.

105. Davarpanah M, Martinez H, Kebir

M, et al. Wide-diameter implants: new

concepts. Int J Periodontics Restorative

Dent 2001 21:149–159

106. Friberg B, Ekestubbe A, Sennerby L.

Clinical outcome of Branemark Sys-

tem implants of various diameters: a

retrospective study. Int J Oral


107. Aparicio C, Orozco P. Use of 5-mm-

diameter implants: Periotest values

related to a clinical and radiographic

evaluation. Clin Oral Implants Res

1998 9: 398–406.

108. Ivanoff CJ, Grondahl K, Sennerby L,

et al. Influence of variations in im-

plant diameters: a 3- to 5-year retro-

spective clinical report. Int J Oral


109.Eckert SE, Meraw SJ, Weaver AL, et

al. Early experience with Wide-Plat-

form Mk II implants. Part I: Implant

survival. Part II: Evaluation of risk

factors involving implant survival. Int

J Oral Maxillofac Implants 2001 16:

208–216.

110.Attard NJ, Zarb GA. Implant pros-

thodontic management of partially

edentulous patients missing posterior

teeth: The Toronto experience. J

Prosthet Dent 2003 89: 352–359.

111.Green NT, Machtei EE, Horwitz J, et

al. Fracture of dental implants: lit-

erature review and report of a case.

Implant Dent 2002 11: 137–143.

112.Benn DK. Estimating the validity of

radiographic measurements of mar-

ginal bone height changes around

osseointegrated implants. Implant

Dent 1992 1: 79–83.

113.Oh TJ, Yoon J, Misch CE, et al. The

causes of early implant bone loss: myth

or science? J Periodontol 2002 73: 322–

333.

114.Brunski JB, Puleo D, Nanci A. Bio-

materials and biomechanics of oral

and maxilloacal implants: current sta-

tus and future directions. Int J Oral


115.Luterbacher S, Fourmousis I, Lang

NP, et al. Fractured prosthetic abut-

ments in osseointegrated implants: a

technical complication to cope with.


170.

116.Morgan MJ, James DF, Pilliar RM.

Fractures of the implant component

of an osseointegrated implant. Int J

Oral Maxillofac Implants 1993 8: 409–

414.

117.Piatelli A, Piatelli M, Scarano A, et

al. Light and scanning electron micro-

scopic report of four fractured im-

plants. Int J Oral Maxillofac Implants

1998 13: 561–564.

118.Albrektsson T. Is surgical skills more

important for clinical success than

changes in implant hardware? Clin

Implant Dent Relat Res 2001 3: 174–

175.

119.Preiskel HW, Tsolka P. Treatment

outcomes in implant therapy: the in-

fluence of surgical and prosthodontic

experience. Int J Prosthodont 1995 8:

273–279.

120.Lambert PM, Morris HF, Ochi S.

Positive effect of surgical experience

with implants on second-stage im-

plant survival. J Oral Maxillofac Surg

1997 55(12 Suppl 5): 12–18.

121.Salcetti JM, Moriarty JD, Cooper LF,

Smith FW, Collins JG, Socransky SS,

et al. The clinical, microbial, and host

response characteristics of the failing

implant. Int J Oral Maxillofac Implants

1997 12: 32–42.

122.Kronström M, Svensson B. Humoral

immunity host factors in subjects

with failing or successful titanium

dental implants. J Clin Periodontol 2000

27: 875–882.

123.Hermann JS, Schoolfield JD, Schenk

RK, Buser D, Cochran DL. Influence

of the size of the microgap on crestal

bone changes around titanium implants.

A histometric evaluation of unloaded

non-submerged implants in the canine

mandible. J Periodontol 2001 72: 1372–

1383.

Documents

Calidad de Los Implantes Dentales