The Role of Lingual Frame on Stability of Mandibular Subperiosteal Implant: A Patient-Specific Finite Element Study

Dental reconstruction using conventional implants for patients diagnosed with atrophic ridge is usually impossible because of insufficient bone volume or quality. One treatment option would be using custom-made subperiosteal implants that consist of supporting frames at the buccal and lingual; However, some morphologies include negative geometry and undercut area at the lingual side which makes it impossible to register the implant. A possible solution would be removing the lingual frame. In this study, finite element analyses were performed to compare the resulting micromotion of two subperiosteal implants concept, one with a lingual frame and the other without it. 50 N normal and lateral load was applied on each abutment to extract the resulting stress distribution and micromotion of the model. The results revealed that by the absence of lingual frame, the stress values in U-shaped frames increased from 50 MPa to 160 MPa and the micromotion of the implant ranged between 120 to 180 microns. The presence of lingual frames would result in better implant stability to some extent. However, by considering the design functionality and possible clinical complications with the presence of lingual frames, it was suggested to design this subperiosteal implant without the lingual frames.