Comparative Evaluation of Stress Distribution at Bone Implant Interface in Implant Supported, Bar Retained Maxillary Over Denture with Different Bar Heights: A Finite Element Analysis

Abstract

Aim: Aim of the present study is to evaluate and compare the stress distribution produced by implant supported bar retained maxillary over denture with different bar heights at bone implant interface.

Materials and Methods: Proper stress distribution on dental implants is necessary in bar-retained implant overlay dentures. This study aimed to comparatively assess this stress distribution according to different bar heights using finite element models. A three- dimensional (3D) computer model of maxilla with 2 implants (13mm length and 3.5mm diameter) in canine region and an overlying implant-supported bar-retained overlay denture were simulated with 0, 1, 2, 3 and 4mm bar heights. A vertical force and oblique force of 50 N was applied at canine region bilaterally. The resultant stress distribution was evaluated at bone implant interface which includes cortical stress and cancellous stress, stress with in implant and stress within abutment.

Results: Model’s observations revealed that the stresses at bone implant interface i.e, both cortical stresses and cancellous stress, stresses within the implant and stresses within the abutment was more on vertical loading compared to oblique loading . As the position of hader bar is placed away from the ridge the stresses at bone implant interface, stresses within implant and stresses with in abutment was gradually decreased.

Conclusion: To reduce high stress peaks, attention must be paid to the direction of the bite force; but while the direction of the bite force cannot be changed, the magnitude can be influenced by the design of the overdenture. It is not yet possible to make reliable clinical conclusions based on the FEA assessments within the implant literature. Results of the present study may contribute to further interpret the findings from future retrospective or prospective clinical and radiologic studies.