Effect of mucosa thickness and resilience on overdentures stress distribution

Objectives: Evaluate the effect of different mucosa thickness and resilience on stress distribution of implant-retained overdentures with two different attachment systems using a two-dimensional finite element analysis (FEA-2D). Methods: Finite element models were used to simulate two situations. In group A, a model represented an edentulous mandible supporting an overdenture retained by two splinted implants connected with bar-clip system while in group B, the model simulated an edentulous mandible supporting an overdenture retained by two splinted implants connected with bar-clip system associated with two distally o'ring system. In each group, mucosa was characterized as hard, resilient and soft according to three different thickness (1, 3 and 5mm), respectively. Evaluation was performed on Ansys software, with 100N vertical load applied on lower central incisive teeth. The principal stress was used as analysis criteria. Results: Group A showed higher stress values than group B regardless mucosa thickness and resilience. Overall, the stress decreased at the supporting tissues as mucosa thickness and resilience increased. In relation to supporting tissues, cortical bone showed the highest stress values in both groups. Conclusions: The use of bar-clip attachment system with distally placed o'ring attachment design optimized the stress distribution.

Financial Support: FAPESP (grant number: 06/59770-6).