6 lembar

8/13/2019 6 lembar

1/6

International Journal of Medical Dentistry 309

A COMPARATIVE STUDY ON THE EFFECTS OF THE POLYMER PROSTHETIC BASE PRESSURE OVER

THE PROSTHETIC FIELD

Abstract

Partially mobile polymeric prostheses constitute abso-

lutely necessary therapeutical means in all forms of partialedentations. As known, polymeric partial prostheses con-stitute temporary solutions for the treatment of edentatonstates. Nowadays, this treatment includes traditionalacrylic prostheses, as well as elastic prostheses made ofdifferent material systems. Such a system is Valplast,which uses a polyamide for the realization of the prostheticbase. Both the rigid and the elastic materials are nowadaysunder debate, different positive or negative opinionsbeing uttered in relation with their utilization. The scopeof the present study is to support the intensive applicationof the elastic materials. Extremely important is the identi-fication of the intrinsic qualities of the materials influenc-ing the behaviour in the oral cavity, especially the effectsof pressure upon the biological structures of the prostheticfield.

Keywords: rigidelastic polymeric prostheses, pressure ofthe polymeric prosthetic base, texture, hydrophillicity .

INTRODUCTION

The temporary treatment of partial edenta-tions makes use of two types of mobile monoma-terial prostheses, completely different as to theirstructure, namely the rigid and the elastic poly-meric prostheses (Valplast, TCS, BioDentaplast,Flexiplast, and Dentalos Polyana systems). Pro-cessing of recent statistical data shows the situ-ation plotted graphically in the figure below:

A COMPARATIVE STUDY ON THE EFFECTS OF THE POLYMERPROSTHETIC BASE PRESSURE OVER THE PROSTHETIC FIELD

A.T. Cigu1, Ctlina Ciobanu2, t. Ioni3, G. Costin4

1. Univ. assist., PhD student, Didactic Dept. Dental Medicine, Apollonia University of Iasi2. Lecturer, PhD student, Didactic Dept. Dental Medicine, Apollonia University of Iasi3. Univ. assist., Didactic Dept. Dental Medicine, Apollonia University of Iasi4. Prof. univ. dr., Didactic Dept. Dental Medicine, Apollonia University of IasiContact person: Andor Cigu, e-mail: [email protected]

elastic prosthesis

acrylic prosthesis

temporary prosthesis superpont

temporary prothesis made of

various polymeric products

Fig. 1. Utilisation of temporary prostheses madeof various polymeric products

Source: authors data

The scope of the investigation was a com-parative determination of some physico-chemi-cal characteristics known as influencing thebehaviour of rigid acrylic prostheses versus thepolyiamidic ones from the Valplast system. Also,a minute analysis of the effects of pressure uponthe biological structures of the prosthetic fieldwas performed.

Prosthetic dentistry

8/13/2019 6 lembar

2/6

310 volume 2 issue 4 October / December 2012 pp. 309-314

A.T. Cigu, Ctlina Ciobanu, t. Ioni, G. Costin

MATERIALS AND METHOD

The main idea of the present investigationwas that essential in the appreciation of the

behaviour of these types of prostheses for use inthe oral cavity remain the problems of stabilityand manner of transmission of the pressureforces upon the prosthetic field [1,2].

The stability of partial prostheses is closelyrelated to the phenomenon of adhesion. Thereduced efficiency of the other natural means ofmaintainance and stabilization, such as attach-ment, anatomic retentivity and muscular tonusand of the prosthetic elements, in general suchas the simple wire hooks is recognized. Adhe-

sion remains the target of prosthesis mainte-nance on the prosthetic field, depending, in itsturn, on the density of the material, hydrophyl-licity, texture, all being the result of polymericchain arrangement [3,4].

Stabilization of prostheses through the colloi-dal hydrophyllic suspension created by salivarealizes connections between the contact surfaceof the prosthetic field and the prosthetic surface.The adhesion effect depends on the initiation ofa pH with a normal value and on the dimen-

sional uniformity of the salivary film.In the case of a sufficient amount of liquid atthe interface of the gingival mucous membranewith the prosthetic surface and its faithful adap-tation on the prosthetic field, the adhesion phe-nomenon is uniformly distributed over the wholesurface of the contact area, being directly propor-tional with the hydrophyllic qualities of the pros-thetic material [5].

Fig. 2. Atmospheric pressure betweenthe two contact surfaces

Source: *** SNF FLOERGER, Water-soluble polymers,web address: www.snf-group.com

To favourize this mechanism, the polymershould permit to a part of its polymeric or molec-ular chain to behave as a whole in the oral cavity.Generally, for attaining an optimum value, it hasbeen established that the concentration of poly-

mer and monomer should have an equal chemi-cal composition, and the procentage should beoptimized either volumetrically or ponderally.In the case of polyamides, these ratios resultfrom the synthesis of the product, our experi-ment demonstrating their conservation after thetechnical injection stage [6,7].

The loads between the two contact surfacesmay have different positive or negative ionicity, which will determine either static attrac-tion or ionic effect. For each polymer, the mannerof bridge formation depends mainly on twoparameters: the number of available places foradsorbtion on the surface of the particles contact-ing the mucous membrane, and the rate of inter-ferential collision of saliva [8,9].

According to the above-described mecha-nisms, adhesion between the two surfaces isobtained in several successive stages: Creation of polymers contact with the wet

medium; Realization of the solid-liquid interface; Adsorption of the two contact surfaces for

the formation of a connection bridge; Favorizing of adhesion through collision,

and occlusal contact [10-12].Analysis of these phenomena involved deter-

minations on a number of 10 prostheses: 5 acrylicand 5 polyamidic ones.

These prostheses were tested in the laborato-ries of the Institute of Macromolecular Chemis-try of Iasi as to their behaviour, from theviewpoint of density, hydrophyllicity, textureand resistance to pressure.

Other determinations, referring to the surfacecharacteristics of the areas contacting the mucousmembrane, evidenced the following aspects: the acrylic prosthesis has a porous mucous

surface, as due to its reduced density(altered texture) and to the reliefs similarto those of the prosthetic field;

the elastic prosthesis showed a less poroussurface, a proof of its increased density(corresponding texture) with the samereliefs, similar to those of the prostheticfield.

8/13/2019 6 lembar

3/6

8/13/2019 6 lembar

4/6



CLINICAL INVESTIGATIONS

Mucosal pathology is obvious in patients withacrylic prosthesis, evidencing installation of a

post-prothetic pathology at periodontal andmuco-periostic level, manifested as some con-gestive, edematious zones while, at the periph-ery of the prosthetic field, hypertrophic areascould be seen. In numerous cases, decubit lesions,requiring removals of material from the pros-thetic base, occurred in the first days.

The same phenomena appear in elastic pros-theses, as due to the compulsorily uniform thick-ness. The margins of prosthesiss base are thin,comparatively with the thickened ones of the

acrylic prostheses, producing immediate preju-dices at the periphery of the prosthetic field, dueto increased compressivity phenomena.

The difference between the two types of pros-theses is given by the better maintenance of thehealth condition of the mucous-bone support inelastic prostheses. The effect of elastic prosthesesis defined as bioactivity. That is why, a correctfollow up is absolutely necessary, as the patientwill better accept the elastic prosthesis even

under an abnromally higher occlusal pressure.In time, installation of a pathology different fromthat of the acrylic prostheses is favourized. In thecase of classical acrylic prostheses, if adaptationis initially correct, the patient does not feel othersubjective symptoms, apart from some discom-fort while, at the level of the mucous membrane,pseudo-keratinization occurs. The high atrophyrate and occlusal wearing favourize the rapidinstallation of cranio-mandibulary malocclu-sions and malrelations.

In the case of elastic prostheses, a precocioussubjective symptomatology is manifested, thepatients complaining of instability in occlusion,fatigue muscular pains during mastications, usu-ally 5 minutes after beginning the alimentationprocess. Also, intense pains appeared in side byside pulsion movements, in the retro-articularyspace and in the area of the temporo-mandibu-lary ligament.

Intense pains at the level of the mylohioidianand digastric muscles were felt on palpation.After a minute examination, an abnormal stressof the temporo-mandibular joint was observed,

as well as modification of the functional muscu-lar individual pattern. In time, this symptomatol-ogy is improved.

Fig. 4. Elastic Valplast prosthesis: mixed maxillarytreatment, the prosthesis frontally conjuncted

with Ceramage composite and the mobiletermino-terminal prosthesis and partial edentation,

intercalated mandibularly, combined prosthesis(conjunct and elastic prosthesis),

in a 62 year-old patient

An incorrect realization of the occlusion planof prostheses be them elastic or acrylic pro-duced the same symptoms as those describedwhen discussing the effects of the prosthetic baseupon the biological support. To attain the staticand dynamic stability of prostheses, necessaryfor a comparative study, special attention hasbeen paid to the rehabilitation through pros-thesizing of the cranio- mandibular relation, aswell as to the occlusal one. As known, a mobile

prosthesis is morpho-functionally integrated atthe level of the stomatognate system if a tripleprosthetic base-prosthetic field equilibrium isobtained at both occlusal level and at the level ofthe temporo-mandibulary joint.

RESULTS AND DISCUSSION

The realized, cited determinations, associ-ated with the results of the clinical observa-tions evidence wholly different characteristics

in the two types of prostheses, listed in thetable below with the following experimental

8/13/2019 6 lembar

5/6

International Journal of Medical Dentistry 313

A COMPARATIVE STUDY ON THE EFFECTS OF THE POLYMER PROSTHETIC BASE PRESSURE OVER

THE PROSTHETIC FIELD

8/13/2019 6 lembar

6/6



parameters: texture, hydrophillicity and resist-ance to pressure. These parameters influencethe stability of the prosthesis on the prostheticfield, dictating the forms of pressure exercisedupon the biological support.

CONCLUSIONS

Analysis of the intrinsic qualities of thematerials forming the prosthetic bases and ofthe effects produced at the level of the pros-thetic field by partially mobile prostheses evi-dence the superiority of the elastic ones, as dueto their physico-chemical characteristics andprocessability. Such qualities influence directly

the biological behaviour in the relation of theelastic prosthesis with the tissues of the pros-thetic field. However, prolongued analysisshows that occlusal-articulary modificationsappear for both types of prostheses. Essentially,the elastic prosthesis represents an advanta-geous alternative in the temporary therapy ofedentation situations.

References

1. Ash M., Ramfjord S., Ocluzia, Ed. a IV-a, Philadephia,1995.

2. Bell W., Dental Ocluzia, J. Dental. Med., 1992.3. Magne, Pascal, P.D., Dr. Med&Beslser, URS, Prof.,

Dr. Med. Dent, Restauraciones de porcelena adherida enlos dientes anteriores, Metodo Biomimetico, Ed. Quin-tessence, S.L., Barcelona, 2004.

4. Vasile Burlui, Catalina Morarasu, Gnatologie, EdituraApollonia, Iasi, 2000.

5. Vasile Burlui, Norina Forna, Gabriela Ifteni, Clinicasi Terapia Edentatiei Partiale Intercalate Reduse, Ed.Apollonia, Iasi, 2001.

6. Costin George, Tehnologia Aparatelor GnatoproteticeAmovibile, Ed. Apollonia, 2002.

7. SNF FLOERGER, Polimeri solubili in apa, adresa web:www.snf-group.com

8. Hasegawa T. (2010) in: Kumar C. (ed.) Structuralcharacterization technique of molecular aggregates,polymer and nano-particle films in nanomaterials for lifesciences, vol. 5, Wiley-VCH, Weinheim, pp. 397-417.

9. Griffiths P.R., De Haseth J.A. (2007) Fourier transforminfrared spectrometry, 2nded. Wiley, Hoboken.

10. Everall N.J., Chalmers J.M., Griffiths P.R. (2007)Vibrational spectroscopy of polymers: principles andpractice. Wiley, Chichester.

11. Ray B., Okamoto Y., Kamigaito M., Sawamoto M.,Seno K., Kanaoka S., Aoshima S. (2005) Polym J,37: 234-237.

12. Stuart B. (2002)Polymer Analysis

, Wiley, Chichester.

Documents

6 lembar