Finite element analysis of biomechanical interactions of a tooth-implant splinting system for various bone qualities

Background: The splinting of an implant and tooth is a rational alternative in some clinical situations. The complex biomechanical aspects of a tooth-implant system are derived from the dissimilar mobility between the osseointegrated implant and the tooth. The aim of this study was to analyze the biomechanics in a tooth-implant splinting system for various bone qualities with different occlusal forces using non-linear finite element (FE) analysis. Methods: A 3D FE model containing one Frialit-2 implant splinted to the mandibular second premolar and a simplified bony segment was constructed. Four bone quality categories were established by varying the elastic parameters assigned to the bone volumes. Contact elements (frictional surface) were used to simulate the realistic frictional interface condition within the implant system. The stress distributions in the splinting system were observed for four loading types. Results: The simulated results indicated that the lateral occlusal forces significantly increased the implant system (σI, max), alveolar bone (σAB, max) and prosthesis (σP, max) stress values when compared with the axial occlusal forces. The σI, max and σP, max values did not exhibit significant differences between the four bone qualities. Conversely, the σAB, max values increased with reduction in bone quality, in particular for type IV bone quality. The σI, max, σAB, max and σP, max stress values were significantly reduced in centric or lateral contact situations once the occlusal forces on the pontic were decreased. Conclusions: This study suggests that implants connected to natural teeth should be used with caution in softer bone regions. Utilizing occlusal adjustment to minimize the occlusal loading force on the pontic could reduce the stress/strain values in the splinting system.