Comparative study of torque resistance and microgaps between a combined Octatorx-cone connection and an internal hexagon implant-abutment connection.

STATEMENT OF PROBLEM Although the implant-abutment connection may prevent crestal bone loss around dental implants, its failure often leads to treatment failure. Microgap and micromovement of the implant-abutment connection could be causes of bone resorption around dental implant neck. PURPOSE The purpose of this study was to compare torque resistance and microgaps between a new cone and index connection (Octatorx) and an internal hexagon implant-abutment connection (Internal hex). MATERIAL AND METHODS Twenty Octatorx and 20 internal hexagon connections were attached with retaining screws at 30 Ncm. In a torsion resistance test, 10 of each type of connection were attached to a universal testing machine. Torque resistance with 90 degrees per minute rotation speed was recorded. For microgap measurement, each of 10 connections was embedded in clear acrylic resin. The blocks were cut longitudinally. Twenty specimens of each connection were evaluated. Twelve measurements of microgaps (6 on each side of specimen) were recorded under scanning electron microscopy. RESULTS The average torsion resistance of Octatorx (203.6 ±17.4 Ncm) was significantly greater than that of the internal hexagon (146.4 ±16.1 Ncm, P<.05). For the microgap, there was a significant difference (P=.001) between the median values of Octatorx (1.19 μm) and the internal hexagon (3.80 μm). CONCLUSIONS In this study, the new connection, Octatorx, had a smaller microgap and greater torque resistance than the internal hexagon connection.