Basal Dental Implants

DENTAL FORUM /1/2011/XXXIX 83PRACE KAZUISTYCZNE

Sigmar Kopp, Stefan Ihde

Radiological particularities in basal dental implants

Aspekty radiologiczne przy zastosowaniu bazalnych implantów stomatologicznych

International Implant Foundation, Münich, Germany

AbstractThe transosseous installation of basal dental implants and their cortical anchorage mandate a different postoperative diagnostic approach than screw type implants. This article exemplifies the particularities by clinical examples.

Key words: basal implant, cortical anchourage, maxillary sinus, transosseous implant, re-integration.

StreszczenieImplantacja śródkostnych wszczepów bazalnych oraz ich kortykalne zakotwiczenie wymagają odmiennego poopera-cyjnego podejścia diagnostycznego niż wszczepy typu śrubowego. Artykuł prezentuje różne aspekty związane z tą metodą w oparciu o przykłady kliniczne.

Słowa kluczowe: wszczepy bazalne, zakotwiczenie kortykalne, zatoka szczękowa, śródkostne wszczepy, reintegracja.

IntroductionBasal implants are often used in patients with

vertical bone deficits. Basal implants utilize the horizontal, cortical bone supply, rather than the vertical bone and they allow trans-sinusal implant placement with and even without sinus augmen-tation. In the case of non-augmented transsinusal implant placement, the cortical anchorage areas cannot be diagnosed by conventional x-ray; di-agnosis may require three-dimensional tomo- graphy. Therapeutic steps based on radiological diagnosis must consider the strong tendency of cortical bone to remineralize.

Case 1A 37-year-old male patient was referred to our

clinic for maxillary implant treatment. All teeth were present, with the exception of the upper right first premolar. Although both teeth distally of the missing premolar had been restored with crowns and an extension bridge alternative was suggested to the patient, he insisted in receiving an implant to replace the missing tooth. The bone in this region was too seriously atrophied to allow placement of a single implant without augmen-tation and a two-stage procedure with extended waiting periods (Figure 1). For this reason, we chose to insert a basal implant (BOI brand, Manu-facturer: Dr. Ihde Dental AG, Switzerland). Under local anaesthesia, a full-thickness flap was ele-vated, and the vertical and horizontal slots for the implant insertion were prepared (Figure 2). The maxillary sinus had expanded, but cortical wall in sufficient load-bearing capacity has remained. Pri-mary stability of the implant was achieved by fixa-

tion in the maxillary vestibular and palatal cortical bone (Figure 3). Basal implants allow transsinusal placement without bone augmentation [1, 2, 3, 4, 5]. To reduce bone resorption tendency in the vestibular maxilla and to mask extending parts of baseplates, lateral augmentation using resorb-able or non-resorbable materials is the method of choice. In this case, a synthetic SO2 connected HA material (NanoBone® by Artoss Germany) was used (Figure 4). The reason for this augmen-tation procedure was explicitly not to increase the available bone supply for anchorage, so an imme-

Figure 1. Case 1 with initial bone defect.

Rycina 1. Przypadek 1. z początkowym uszkodzeniem kości.


DENTAL FORUM /1/2011/XXXIX84 PRACE KAZUISTYCZNE

diate loading protocol was still applicable even in combination with the augmentation procedure. In this case, however, it was decided to provide for a covered healing period of 100 days. After that period, the site was re-entered, an impression was taken, and a metal-ceramic crown was per-manently cemented (Figure 5 shows the situation after a follow-up period of 18 months). The quality of the cortical anchorage cannot be determined

on conventional x-rays, so in the event of doubts about successful integration, 3-dimensional im-aging would be the diagnostic method of choice (Figures 6 & 7). In contrast with screw-type dental implants, basal implants allow corrective interven-tions like partial secondary augmentation without removing the implant even if this procedure was not necessary here [1, 2, 3, 4, 5].

Figure 2. Prepare slot for implant placement and opened sinus maxillaris.

Rycina 2. Łoże przygotowane dla wszczepu i otwarta zatoka szczękowa.

Figure 3. Inserted basal implant with cortical bone con-tact and stability.

Rycina 3. Implantowany wszczep bazalny ustabilizo- wany w kontakcie z kością kortykalną.

Figure 4. Applied augmentation material for secondary bone contouring.

Rycina 4. Zastosowany materiał augmentacyjny dla konturowania kości wyrostka zębodołowego.

Figure 5. Crown in situ and remodelled bone as support for gingiva.Rycina 5. Korona protetyczna in situ i remodelowana kość jako podparcie dla dziąsła.



Case 2The projection of structures on a flat level may

result in overlapping. This problem is not just in intra oral X-ray present but also in panoramic pro-jections. So even a panoramic X-ray may bring the illusion of implant hurting an adjacent root (Figure 8). The cone beam CT shows the correct relations (Figure 9).

Case 3A 56-year-old female patient received two

basal implants in the area of the right mandible. The implants were immediately loaded by a dou-ble crown. Six month later, the patient reported slight pain when chewing: the prosthetic screw on the distal implant had loosened, so all load was carried by the mesial implant. This had lead to se-vere overloading on the peri-implant bone, result-ing in a dramatic decrease of mineralisation in this bone area. These changes are the result of crack accumulation (Figure 10) and well diagnosable through X-ray. The clinical diagnosis is difficult, if implants are splinted through the prosthetical construction. The “Consensus on BOI” permits explantation of basal implants only when a sharp-rimmed, completely black ring around the basal plate of the implant is visible on the X-ray [6]. The block of crowns was immediately removed to re-duce the load on the implants. Six weeks later, the mesial implant appeared to have stabilised, and the crowns were re-inserted. Prophylactically

Figure 6. Intraoral X-ray suggests a free floating implant in the sinus.

Rycina 6. Zdjęcie zębowe sugerujące nieustabilizowa- ny wszczep w zatoce szczękowej.

Figure 7. Screenshot of Kodak 9000 D cone beam CT with pseudo 3D view and three level views showing the exact position of the implant in space.

Rycina 7. Różne ujęcia położenia wszczepu w strukturach kostnych.


DENTAL FORUM /1/2011/XXXIX86 PRACE KAZUISTYCZNE

the crowns were reduced in width, and consider-able occlusal adjustments were performed. One year later, the mobility of the mesial implant was significantly reduced, and the radiological situa-tion (i.e. the visible degree of mineralisation in the vicinity of the base plate) had improved. Three years after implant placement, the implant was fully reintegrated, without any additional treat-ment being required (Figures 11 a, b).

DiscussionX-ray diagnostics of basal implant systems is

difficult for untrained dentists because there are some peculiarities with these implants. Although some practitioners may be able to diagnose the simple presence of a basal implant system and distinguish it from crestal systems (e.g. screw

types or blades), only very few practitioners will realise the radiological implications. A correct evaluation of the bone situation and the status of osseointegration are essential for subsequent treatment and preparing corrective interventions. A correct interpretation of X-rays of basal implants depends on the practitioner’s knowledge of tran-sosseous anchorage. Especially the indication of basal implants in transsinusal placement may contradict traditional 2-D X-ray analysis. 3-D im-aging may bring a better understanding of corti-

Figure 8. Case 2 panoramic X-ray with the illusion of implant in root application.

Rycina 8. Zdjęcie pantomograficzne 2. przypadku ze złudzeniem wszczepu zakotwiczenia korzeniowego.

Figure 9. Cone beam CT with proof of enough distance between implant and root.

Rycina 9. Wystarczająca odległość pomiędzy wszcze- pami i korzeniem diagnozowana badaniem tomografii komputerowej.

Figure 10. Case 3: First diagnose of overload in a basal implant in the distal mandible.

Rycina 10. Przypadek 3.: pierwsze rozpoznanie przecią- żenia wszczepu bazainego w bocznym rejonie żuchwy.



cal osseointegration, but the indications for and the cost – just for verifying the clinical findings of firm anchorage – should be carefully weighed.

Regarding Case 3 we would like to mention, that even severe demineralisation does not nec-essarily mean that a basal implant has to be re-moved, as long as some stability continues to be present and the endosseous site around the im-plant is free of infection. This is in strong contrast to the experience with crestal implants. The rea-sons are, that basal implants have a blank, ma-chined surface that does not promote descending of infection towards the base plate, and that hol-low bones tend to repair their cortical walls when-ever possible (whereas spongious bone, used for the anchorage for crestal implantes, i.e. screws, is not needed for trajectorial load transmission in jaw bone. It has to be considered, that the softened bone around unstable implants shows a higher degree of blood supply and this enhances the possibilities of fighting infections. The presence of bacterial “peri-implantitis” must not necessar-ily be assumed even in cases of severe deminer-alisations of cortical bone around basal implants. Occlusal changes or temporary unloading of im-plants are easy to perform. Since basal implants are more frequently used in today’s dental offices, we believe that it is important for the dental prac-titioner, that trans-sinusal implant placements as well as the large potential for remineralisation of bone around basal implants are published.

ConclusionSpecific knowledge of the anchorage mecha-

nism and possibilities of basal implants and the recovery of the peri-implant bone are required to prevent incorrect diagnoses and misinforma-tion of the patients, as well as unnecessary treat-ments or implant removals. The limits of different X-ray projections should be known and the real situation may be confirmed by cone beam CT.

Bibliography[1] Donsimoni J.M., Navarro G., Gaultier F., Dohan D.: Les

implants maxillo-faciaux ŕ plateaux d`assise; Concepts et technologies orthopédiques, réhabilitations, max-illomandibulaires, reconstructions maxillo-faciales, réhabilitation dentaires partielles, techniques de réin-tervention, méta-analyse 4čme partie: réhabilitations dentaires partielles. Implantodontie, 2004; 13 (13): 139-150.

[2] Ihde S.: Principles of BOI, 1 edn. Heidelberg: Springer; 2005.

[3] Scortecci G.: Immediate function of cortically anchored disk-design implants without bone augmentation in moderately to severely resorbed completely edentu-lous maxillae. J. Oral. Implantol., 1999; 25 (2): 70-79.

[4] Kopp S., Bienengräber V., Ihde S.: Basal implants as solide base for immediately loaded full arch bridges. Dental Forum, 2009; 37 (1): 51-60.

[5] Kopp S., Kopp W.: Comparison of immediate vs de-layed basal implants. JMOSI, 2008; 7 (1): 116-122.

[6] Besch K.J.: A consensus on basal osseointegrated im-plants. Schweiz Monatsschr. Zahnmed, 1999; 109 (9): 971-972, 996.

Figure 11 a & b. Case 3: two years later, under full function, complete re-mi-neralisation of the peri-implant bone can be diagnosed.

Rycina 11 a i b. Przypadek 3. – całkowita remineralizacja okołoimplantowego obszaru kostnego po 2 latach.

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Basal Dental Implants