Biomechanical effects of implant number and diameter on stress distributions in maxillary implant-supported overdentures

Abstract

Statement of problem: Implant-supported overdentures (ISOs) are considered a good alternative to conventional removable dentures. However, varying rates of failure have been reported in some clinical studies. Excessive stress on surrounding tissues is one of the possible causes of implant failure. As stress is transmitted to the bone through the implant, careful planning, correct number of implants, and implant positioning are keys to ensuring appropriate stress distribution. However, research of the optimal number of implants necessary to support a maxillary ISO is insufficient.

Purpose: The purpose of this in vitro finite element study was to determine the optimal implant location, number, and diameter to support a maxillary ISO.

Material and methods: Three-dimensional models of an atrophic maxilla, dental implants, and ball attachments were modeled, and different loading conditions were applied to simulate realistic conditions. Six models with different numbers and diameters of implants, including mini-dental implants and differently located implants, were formed, and stress values were compared by implementing a finite element analysis.

Results: The study showed that, as the implant number increased, decreased stress values were observed in peri-implant bone and implants in the maxillary ISO prosthesis. However, changes in implant diameter had no significant effect on stresses.

Conclusions: Increasing the implant diameter was not advantageous; the use of mini-dental implants may be a viable alternative method. However, using 4 implants for maxillary ISOs is indicated.