Evaluation of Stress Patterns in Mandibular Bone Around Implant-Retained Overdentures: A Three Dimensional Finite Element Study on Attachment Design Variability

Abstract

Statement of Problem: Implant retained mandibular overdentures with splinted and unsplinted attachments have become an acceptable treatment modality in cases of compromised completely edentulous patients. However, owing to controversial data regarding the superiority of different attachment systems, the present study was conducted to evaluate stress distribution in mandibular bone surrounding implant retained overdentures with hader bar-clip attachment, ball attachment and combination of hader bar-clip with distally placed ball attachment using three dimensional finite element analysis.

Materials and Method: The physical models of implants, conventional mandibular complete denture and different attachments were converted to finite element model by series of software programs. A total number of 4 models were generated. Model A comprised of an edentulous mandible supporting removable mandibular complete denture. Model B, C and D comprised of a model of edentulous mandible supporting overdenture retained by hader bar with clip attachment, ball attachment and hader bar-clip system with distally placed ball attachment respectively. A static load of 100 N was applied perpendicular to the incisal surface of lower central incisors. The amount of stress distribution at canine region was evaluated and compared.

Results: The maximum von mises stresses recorded at the canine region for cortical and cancellous bone was 1.5 MPa and 0.14 MPa for model A, 3.11 MPa and 0.81 MPa for model B, 2.16 MPa and 0.27 MPa for model C and 2.90 MPa and 0.38 MPa for model D respectively.

Conclusion: Maximum von mises stress were greatest for hader bar with clip attachment followed by hader bar-clip with distally placed ball attachment and least by the ball attachment in mandibular bone surrounding implants retained overdenture. All three attachments had higher stresses at the canine region in comparison to conventional mandibular complete denture.