Stress Analysis of Different Tooth-Implant Supported Fixed Prosthesis Designs

Objectives: OBJECTIVE: To assess the effect of non-rigid (NR) connection on the stress distribution of hybrid tooth-implant fixed partial denture (FPD) using different implant lengths and diameters.
Methods: MATERIALS&METHODS: 10 geometric models of mandibular 3-unit tooth-implant FPDs with implant abutment in second molar site, and natural second premolar tooth as mesial abutment in distal extension situations were evaluated using three-dimensional finite element analysis (FEA) by (Solidworks® Premium 2018 x 64 Edition). The models were divided into two groups. Group A: tooth-implant FPD was constructed with both mesial and distal rigid connectors, while group B: tooth-implant FPD models used a NR connection at the tooth side. Group A was simulated using a (5.7 Diameter x 10 Length) distal implant while for Group B, different lengths (L) (10, 11.5, 13mm) and diameters (D) (3.7, 4.7, 5.7mm respectively) were used. The models were analyzed to determine the maximum equivalent von Mises stress at five critical zones (FPD, Bone around distal implant, Bone around tooth, Cementum, Periodontal Ligament, Implant) under vertical occlusal loading of (150 N) after meshing and assigning the material properties.
Results: RESULTS: FEA showed that tooth-implant FPD model with rigid connection (5.7 D x 10 L) had the least stress values and the most even distribution of stresses across all the FPDs components, compared to all other NR FPD models. Furthermore, it was observed that the use of NR connection with (5.7 D x 10 L) distal implant had more even stress patterns and better average stress values, across the critical zones than all the other NR FPD models.
Conclusions: Conclusion: Using NR connection was not significantly effective in distributing the stresses more evenly on tooth-implant FPDs. Moreover; increasing the implant diameter was effective in reaching more desired stress patterns for implant tooth FPDs aiding in improving its longevity and survival rate.