Comparison of Effect of Salivary Contamination on the Reverse Torque Values of Abutment Screws in Two Different Types of Internal Hex Implant-Abutment Connections: An In vitro Study.

Abstract

Aim: The aim of this study was to compare the effect of salivary contamination on the reverse torque values (RTVs) of abutment screws in two different types of internal hex implant-abutment connections, namely, standard internal hex and conical hex, before and after occlusal loading at different time intervals.

Settings and design: This was an in vitro study.

Materials and methods: Fifteen implants (Adin) and corresponding abutments with standard internal hex connection and 15 implants (Osstem) and corresponding abutments with conical hex connection were embedded in acrylic resin blocks. The screw-access holes of the fixture bodies were contaminated with artificial saliva. The abutments were inserted into the fixture screw holes, and an initial torque of 25 Ncm and a second torque of 25 Ncm after 15 min were applied with a digital torque meter. The implant-abutment units were then immersed in a beaker containing artificial saliva. RTVs were measured at 24, 48, and 72 h intervals. Occlusal load simulating occlusal force (400N) was exerted onto the specimens using universal testing machine. The specimens were submerged in artificial saliva again, and the RTVs were recorded at intervals of 24 h, 48 h, and 72 h.

Statistical analysis: An Independent t-test was done for comparing the RTVs of the sample groups.

Results: Statistically significant reduction in torque loss was observed in conical hex implant-abutment connections when compared to internal hex connections at various time intervals, before and after occlusal loading.

Conclusion: With respect to microleakage and screw loosening, conical hex connections demonstrated an advantage over internal hex implant-abutment connections.