Abstract
BACKGROUND: All-on-4(®) concept allows the immediate rehabilitation of edentulous arches having anatomical limitations with provisional restoration. However, the acrylic provisional prosthesis has a critical liability to fracture, that's why a reinforcement with splinting bar is a good solution for a longer-term success. Poly Ether Ether ketone has been used as a splinting material since they are biocompatible with an elastic modulus similar to native bone and dentin with shock-absorbing characteristics. The purpose of this study was to evaluate the effect of different cross sections of Poly Ether Ether ketone splinting bars in maxillary All-on-4(®) implant supported interim prosthesis. METHODS: The current study involved two steps: virtual model construction and three-dimensional Finite Element Analysis. The virtual model composed of an edentulous maxillary cast, four dental implants placed according to the All-on-4(®)concept and an acrylic prosthetic superstructure reinforced with Poly Ether Ether ketone bar. Two virtual models were made. In the virtual model RB, a Poly Ether Ether ketone bar with rounded cross section was used. However, in the virtual model SB, a square bar was used. Each model was subjected to two types of loads: vertical load and oblique load. Each model was analyzed, and the stresses displayed in the current study are the von-Mises stress (SEqv) for the implants, marginal part of the bone cylinder, Poly Ether Ether ketone bar, prosthesis and the entire model. RESULTS: Higher stress values were observed in the model RB compared to the model SB in the implants, peri-implant bone and overlying prosthetic superstructure. However, higher stress values were recorded for the splinting bar in the model SB compared to the RB one. The highest recorded value in model RB was 120.26 MPa(*) which recorded in the prosthetic superstructure during unilateral oblique loading while the highest recorded value in model SB model was 110.51 MPa(*) which recorded in the posterior implant during unilateral oblique loading. CONCLUSION: Square cross sectioned Poly Ether Ether ketone bar induce less stress in All-On-4(®) Implant Supported Interim Prosthesis compared to the round one.