Kraftfluss und Spannungsanalyse bei unterschiedlicher Implantatbelastung – eine Modellstudie

Kraftapplikation am Implantat führt zu Belastungen im Bereich des Alveolarknochens. Zur Darstellung und Analyse der resultierenden Spannungen wurden spannungsoptische Modelle gefertigt und 3–dimensionale Finite–Element–Modelle generiert. Die Implantatbelastungen erfolgten in axialer Richtung und extra–axial mit 2 cm Hebelabstand.

Der spannungsoptisch dargestellte Kraftfluss erscheint bei axialer Belastung symmetrisch, während bei extra–axialer Belastung erhöhte Spannungskonzentrationen im kortikalen Bereich der Belastungsseite auftreten.

Die qualitative Analyse der von Mises Vergleichsspannung und hydrostatischen Spannung ergab erhöhte Werte im kortikalen Bereich, die bei extra–axialer Belastung Höchstwerte erreichten und eine unsymmetrische Verteilung zeigten.

Die Spannungsspitzen im peri–implantären Bereich dürften mit dem dort beobachteten Knochenabbau in Verbindung stehen. Die enorme Erhöhung der Spannungen bei extra–axialer Belastung sollte dem Kliniker bewusst sein, sodass er bei der Planung von Implantation und Suprakonstruktion versucht, eine möglichst axiale Implantatbelastung zu gewährleisten.

The application of force at implant leads to loading of the surrounding alveolar bone. In order to illustrate and analyze the resulting stresses, photoelastic models were fabricated and three–dimensional finite element models were generated. Implant loading was carried out in axial and off–set direction with a lever arm of 2 cm.

The photoelastic force transfer shows a symmetrical image in axial loading, whereas off–set loading provoked increased stress concentrations in the cortical layer on the lever side.

The qualitative analysis of von Mises equivalent stress and hydrostatic stress exhibited increased values in the cortical layer which reached a peak under off–set loading beside an unsymmetrical stress distribution.

The peaks in stress in the peri–implant area can be considered related to the bone loss observed in this area. The clinician should be aware of the enormous stress increase in off–set loading. When planning implantation and superstructure he should try to achieve implant loading mainly in axial direction.

Schlüsselwörter

axiale Belastung - extra-axiale Belastung - Kraftfluss - kortikale Schicht - spannungsoptische Darstellung - Finite-Element-Analyse

Key words

Axial Loading - Off-set Loading - Force Transfer - Cortical Layer - Photoelastic Study - FE-Analysis

Literatur

• 1 Adell R, Lekholm U, Rockler B. et al. . Marginal tissue reactions at osseointegrated titanium fixtures. A 3–year lougitudinal prospective study.  Int J Oral Maxillofac Implants. 1986;  15 39-52
• 2 Akça K, Fanuscu MI, Caputo AA.. Effect of compromised cortical bone on implant load distribution.  J Prosthodont. 2008;  17 616-620
• 3 Barbier L, Schepers E.. Adaptive bone remodelling around oral implants under axial and nonaxial loading conditions in the dog mandible.  Int J Oral Maxillofac Implants. 1997;  12 215-223
• 4 Brånemark PL.. Introduction to osseointegration:. In: Brånemark PL, Zarb GA, Albrektsson T (Hrsg). Tissue Integrated Prostheses. Chicago: Quintessence 1985: 11-76
• 5 Brunski JB.. Biomechanics of oral implants: future research directions.  J Dent Educ. 1988;  52 775-787
• 6 Brunski JB, Puleo DA, Nanci A.. Biomaterials and biomechanics of oral and maxillofacial implants: current status and future developments.  Int J Oral Maxillofac Implants. 2000;  15 15-46
• 7 Caputo AA, Chaconas SJ, Hayashi RK.. Photoelastic visualization of orthodontic forces during canine retraction.  Am J Orthod. 1974;  65 250-259
• 8 Carlsson GE, Lindquist LW, Jemt T.. Long–term marginal periimplant bone loss in edentulous patients.  Int J Prosthodont. 2000;  13 295-302
• 9 Clelland NL, Lee JK, Bimbenet OC. et al. . Use of axisymmetric finite element method to compare maxillary bone variables for a loaded implant.  J Prosthodont. 1993;  2 183-189
• 10 Duyck J, Ronold HJ, Van Oosterwyck H. et al. . The influence of static and dynamic loading on marginal bone reactions around osseointegrated implants: an animal experimental study.  Clin Oral Implants Res. 2001;  12 207-218
• 11 Duyck J, Naert IE, Van Oosterwyck H. et al. . Biomechanics of oral implants: a review of the literature.  Technol Health Care. 1997;  5 253-273
• 12 Heckmann SM, Linke JJ, Graef F. et al. . Stress and inflammation as a detrimental combination for peri–implant bone loss.  J Dent Res. 2006;  85 711-716
• 13 Heckmann SM, Winter W, Meyer M. et al. . Overdenture attachment selection and the loading of implant and denture bearing area. Part 1: In vivo verification of stereolithographic model.  Clin Oral Implants Res. 2001;  12 617-623
• 14 Heckmann SM, Winter W, Meyer M. et al. . Overdenture attachment selection and the loading of implant and denture bearing area. Part 2: A methodical study using five types of attachment.  Clin Oral Implants Res. 2001;  12 640-647
• 15 Hipp JA, Brunski JB, Shepard MS. et al. .Finite Element models of implants in bone: Interfacial Assumptions. In: Perren SM, Schneider E (Hrsg). Biomechanics: Current Interdisciplinary Research. Heidelberg: Kluwer Academic Publishers 1986: 477-452
• 16 Karl M, Winter W, Taylor TD. et al. . Fixation of 5–unit implant–supported fixed partial dentures and resulting bone loading: a finite element assessment based on in vivo strain measurements.  Int J Oral Maxillofac Implants. 2006;  21 756-762
• 17 Keaveney TM, Hayes WC.. A 20–year perspective on the mechanical properties of trabecular bone.  J Biomech Eng. 1993;  115 534-542
• 18 Lang NP, Mombelli A, Tonetti MS. et al. . Clinical trials on therapies for peri–implant infections.  Ann Periodontol. 1997;  2 343-356
• 19 Lindquist LW, Rockler B, Carlsson GE.. Bone resorption around fixtures in edentulous patients treated with mandibular fixed tissue–integrated prostheses.  J Prosthet Dent. 1988;  59 59-63
• 20 Linkow LI, Rinaldi AW.. The significance of ”fibro–osseous integration" and ”Osseointegration" in endosseous dental implants.  Int J Oral Implantol. 1987;  4 41-46
• 21 Mellal A, Wiskott HW, Botsis J. et al. . Stimulating effect of implant loading on surrounding bone. Comparison of three numerical models and validation by in vivo data.  Clin Oral Implants Res. 2004;  15 239-248
• 22 Orr JF, Shelton JF.. Optical Measurement Methods in Biomechanics. London: Chapman and Hall 1997
• 23 Quirynen M, Naert I, Van Steenberghe D.. Implant design and overload influence on marginal bone loss and implant success in the Brånemark system.  Clin Oral Implants Res. 1992;  3 104-111
• 24 Roberts WE, Garetto LP, DeCastro RA.. Remodelling of devitalized bone threatens periosteal margin integrity of edosseous titanium implants with threaded or smooth surfaces: indication for provisional loading and axially directed occlusion.  J Indiana Dent Assoc. 1989;  68 19-24
• 25 Steinemann SG, Eulenberger J, Maeusli PA. et al. .Adhesion of bone to titanium. In: Christel P, Meunier A, Lee AJC (Hrsg). Biological and biomechanical performance of biomaterials. Amsterdam: Elsevier 1989: 409-414
• 26 Weber HP, Crohin CC, Fiorellini JP.. A 5–year prospective clinical and radiographic study of sub–merged dental implants.  Clin Oral Implants Res. 2000;  11 144-153

Korrespondenzadresse