Implant biomechanics relating to the dental implant and prosthesis design: In-vitro strain gauge analysis and finite element analysis

Abstract

Background: Biomechanics of an implant-supported prosthesis play a key role in the success or failure of rehabilitation of missing teeth. This study aimed to analyze biomechanical factors, such as an implant design and prosthesis design for a single implant-supported prosthesis. An in-vitro strain gauge analysis and finite element analysis were performed to assess different implant thread shapes and prosthesis retention modes for their strain-producing property in the peri-implant region of bone. Methodology: Four study models were prepared. Two models were fitted with Bio Horizon Tapered-Pro implants having predominant buttress-shaped threads (BT) and then two models were fitted with Grande Morse Neo Dent implants having trapezoid-shaped threads (TT). Each design was used with two types of retention modes for prostheses, BP-C and TT-C for cement-retained prostheses and similarly BT-S and TT-S for screw-retained prostheses. The strain gauges were bonded to the models and connected to a strain meter. Using an opposing porcelain fused to a metal prosthesis, a combined (axial and non-axial) load of 50–300 N at a strain rate of 0.95 mm/s was applied stepwise to each prosthesis. The strain values were recorded, and the collected data were organized and analyzed using SPSS version 22. For the finite element analysis, four 3-D models were designed. The bone, dental implants, and prostheses for each group were designed using Solid Works. A static, linear simulation was conducted in Ansys software. Results and discussion: The strain values recorded were all less than 3000μɛ and within the physiological loading zone as per Frost’s theory. Statistically significant differences were found between all groups with p-values <0.05, suggesting that changes in implant design led to differences in peri-implant bone strains. At the maximum loading of 300 N, i.e., at the mean biting force of an individual adult, the maximum strain value of 1812 με was recorded for group TT-C. At the minimum loading, all strain values were less than 500 με except for group TT-C for which 518 με was recorded. The peri-implant bone next to the implant’s crest showed maximum strain, which means that this site is more subjected to the effects of overloading than any other part. The von Mises stress was seen concentrated at the implant neck. Conclusion: TT-C implant-supported prostheses give a high strain profile. In comparison, the BT-C implant-supported prostheses give a low strain profile at mean biting forces.