Abstract:

Objective To evaluate the biomechanics of Kennedy class Ⅱ removable partial denture with polyacetal resin as the major connector utilizing photoelastic model. Methods Mandible photoelastic model was established to simulate the partial edentulous (76-6 edentulous) situation of Kennedy class Ⅱ Removable partial dentures with three kinds of major connector designs (polyacetal resin, metal framework and hybrid of metal and polyacetal resin) were fabricated. Stress was loaded on the posterior teeth bilaterally and unilaterally for each of the design. Stress patterns of the roots and alveolar bone were pictured and evaluated. Results On both bilateral and unilateral load, the polyacetal removable partial denture exhibited the highest stress both on the abutment teeth and on the edentulous alveolar ridge. The traditional metal framework removable partial denture design exhibited the lowest and well-distributed stress both on the abutment teeth and on the alveolar ridge, and the stress transferred to the abutments though the long axel of teeth. Conclusion Among Kennedy class Ⅱ removable partial dentures, the removable partial denture design with polyacetal resin as major connector may injure the abutment and alveolar ridge, while the traditional metal framework design exhibits the best stress pattern and should be considered as the first choice.

Key words: polyacetal resin denture, photoelastic model, biomechanics, removable partial denture