Influence of Cantilever Extension and Crown-to-Implant Ratio in Posterior Maxilla: A Finite Element Analysis

Abstract

This study aimed to evaluate the effect of increased cantilever extension length and crown-to-implant ratio on stress distributions, both in peri-implant bone and implant structure under oblique loads, using three-dimensional finite element analysis method. Six three-dimensional models of an atrophic posterior maxilla were created with a solid implant (4.1 x 10 mm) placed in first maxillar premolar site. One implant supported two-unit fixed dental prostheses were modeled using three different cantilever extension lengths (5, 7 and 9 mm) and two different crown-to-implant ratio (1/1 and 1.5/1). An oblique load of 300 N was applied to each model. The minimum and maximum principal stresses and von Mises stresses were evaluated. The highest minimum principal stress value was 129.8 MPa in cortical bone and the highest von Mises stress value at the implant structure was 449.3 MPa. Regarding the simulation outcomes it can be concluded that increasing cantilever extension length and crown-to-implant ratio will also increase the stress distribution in peri-implant bone and implant structure. While crown-to-implant ratio has greater effect than cantilever extension length in the stress concentration in cortical bone, cantilever extension length is found to be more prominent stress factor for the implant structure.