Effect of Occlusal Scheme and Bone-Level Implant Number and Position on Stress Distribution in Kennedy Class II Implant-Assisted Removable Partial Dentures: A 3D Finite Element Analysis.

Objectives: To assess the effect of occlusion and implant number/position on stress distribution in Kennedy Class II implant-assisted removable partial denture (IARPD).

Materials And Methods: IARPDs were designed in six models: with one implant (bone level with a platform of 4 mm and length of 10 mm) at the site of (I) canine, (II) between first and second premolars, (III) first molar, (IV) second molar, or two implants at the sites of (V) canine-first molar, and (VI) canine-second molar. A conventional RPD served as control. Loads were applied according to the group function (GF) (500N load was applied to the left canine/premolar/molar teeth in the ratio of 1:1:2) or canine guidance (CG) (125N load was to the canine tooth) occlusions. Maximum displacement and Von Mises Stress in different components were analyzed by finite element analysis (FEA).

Results: The control model showed the highest displacement followed by the IARPD with a canine implant in both occlusal schemes. In GF, the maximum and minimum jaw stress were recorded in IARPDs with canine implants (16.45 MPa) and canine-first molar implants (13.47 MPa), respectively. In CG, the maximum and minimum jaw stress was recorded in IARPD with first/second premolar implant (15.91 MPa) and canine-first molar implants (12.38 MPa), respectively. The highest stress in resin, framework, and implant(s) was noted in IARPD with canine implant in both schemes. The lowest stress in the implant(s) was recorded in IARPD with canine-second molar implants in GP and IARPD with canine-first molar implants in CG.

Conclusion: Dental implants reduced the total displacement of IARPDs, increased stress in mechanical components, and did not affect stress distribution in biological components. Insertion of two implants decreased implant stress. The GP scheme caused greater stress on mechanical components.