Evaluation of Effect of Connector Designs in Implant Tooth-supported Fixed Partial Denture: A Two-dimensional Finite Element Analysis.

AIM: The aim of this study was to evaluate the effect of connector designs on scale and distribution pattern of the stress generated in the supporting bone of implant tooth-supported three-unit fixed partial denture in distal extension situation.

MATERIALS AND METHODS: Three-unit fixed partial denture geometric models with implant abutment in second molar, pontic in first molar, and second premolar as mesial abutment in distal extension situations were evaluated using a two-dimensional (2D) finite element analysis. Three models were designed and constructed with mesial and distal rigid connectors, mesial nonrigid connector, and distal nonrigid connector respectively, using the software ANSYS, version 10.0 (University Intermediate). The models were analyzed to determine the maximum equivalent von Mises stress at five critical zones (maximum value) under static axial loading (240 N) after meshing and assigning the material properties.

RESULTS: The maximum stress concentration values at mesial and distal alveolar crest of the implant-supporting bone were 60.59 and 68.57 MPa, respectively, in Model No 1. The high equivalent von Mises stress concentration values at the mesial and distal alveolar crest of the implant-supporting bone were 1.65 and 0.747 MPa with 0.1 mm vertical movement and 7.88 and 9.34 MPa with 0.5 mm vertical movement of the connector respectively, in Model No 2. The high equivalent von Mises stress concentration values at mesial and distal alveolar crest of the implant-supporting bone were 10.45 and 3.43 MPa with 0.1 mm vertical movement and 4.50 and 5.71 MPa with 0.5 mm vertical movement of the connector respectively, in Model No 3.

CONCLUSION: In the supporting bone around the implant in Model No 1, the maximum von Mises stress concentrations were displayed in the crestal zones. In the supporting bone around the implant abutment, the von Mises stress concentrations were minimal toward the apical third zone in all the models. The stress concentrations were minimal in the supporting bone around the implant and the natural tooth in the models with nonrigid connector.

CLINICAL SIGNIFICANCE: When implant is used as distal abutment in three-unit implant tooth-supported fixed partial denture with pontic at first molar in distal extension situation, it is recommended to place the nonrigid connector in the mesial side of the distal implant abutment.