ASSESSMENT OF FRACTURE RESISTANCE OF IMPLANT-SUPPORTED FIXED PARTIAL PROSTHESES CONSTRUCTED OF TWO DIFFERENT MATERIALS WITH DIFFERENT PONTIC DESIGNS

Objective: The aim of this study is to evaluate the effect of different pontic framework designs, constructed from two different materials: monolithic zirconia and Polyether ether ketone (PEEK), on the fracture resistance of implant supported fixed partial prosthesis. Material and Methods: The study conducted assess the effect of pontic design on the fracture resistance of a four units implant supported fixed partial denture; the pontic constructed replaces the second premolar and first molar with two different designs: modified ridge lap and sanitary designs. A total of forty implants were used in this research; the implants are embedded in poly-urethane foam blocks (20 pounds per cubic foot (20 PCF)) to resemble supporting bone structure. Specimens are divided according to material of construction into two groups, monolithic zirconia group (n=10) and PEEK group (n=10). Then, the specimens are sub-divided into two subgroups according to pontic design modified ridge lap group (n=5) and sanitary group (n=5). All specimens are subjected to loading test in a computerized universal testing machine until fracture occurs. Results: According to statistical results, there is a significant difference between the zirconia and PEEK in different pontic designs. The monolithic Zirconia displayed higher results the PEEK upon testing p≤0.05. All the tested materials were within the acceptable range for functioning under mastication. Conclusions: Zirconia and PEEK are materials of choice when designing a long span bridges due to their high fracture strength values. Aside from the pontic design, the restorative material has a great impact on the fracture resistance, behavior of the material and stress distribution.