Fracture load resistance of pontic with different connector designs

Aim: This in-vitro study aims to assess the fracture load resistance of the central pontic of two implant-supported zirconia fixed partial dentures (FPDs) using five alternative connector designs. Methods: The CAD/CAM production technique was used to mill the FPD of a three-unit zirconia prosthesis (from the mandibular second premolar to the second molar) (DDS, 3D White Zirconia). The STL file was generated for two implant-supported 3-unit bridges. The zirconia fixed partial substructure was designed with five types of connector designs. The pontic is connected to an implant-supported bridge with round, square, rectangular, triangular, and reverse-triangular shape connectors. This study was designed for a cementless-retained implant-supported fixed partial denture (FPD) of 50μm interface gap. The fracture resistance of a pontic of a 3-unit zirconia FPD was assessed under a crosshead speed of 1mm/min using an Instron universal machine. The study data were statistically analyzed using the ANOVA (post hoc Games-Howell) test with a significant interval of (P≤0.05). Results: The highest fracture resistance was using the reverse-triangular design, and the lowest fracture resistance was using the triangular connector design with a significant mean difference of (P = .003). Conclusions: It seems that the reverse-triangular connector design for implant-supported zirconia fixed partial substructure.