Effect of using a titanium washer on the removal torque of an abutment screw in the external connection type of dental implant

Purpose: The aim of this study was to determine the effect of using a washer on the removal torque of an abutment screw in the external connection type of dental implant and abutment complex. Materials and Methods: Four experimental groups with titanium washers of different types (CP titanium or Ti6Al4V titanium alloy) and thicknesses (1.0 or 2.0 mm) included between the abutment and external connection type of implant were investigated. No washer was applied in the control group. The removal torque was measured with a resolution of 0.1 Ncm. One-way analysis of variance (α = 0.05) and Scheffé's post hoc test were used for statistical analysis. Results: The removal torque was higher in all the groups with a washer than in the control group (α = 0.05), higher with a CP titanium washer than with a titanium alloy washer of the same thickness, and higher with a 2.0-mm-thick washer than with a 1.0-mm-thick washer (α = 0.05). Conclusions: Inclusion of a washer between the titanium screw and the abutment seems to increase the removal torque. A 2.0-mm-thick CP titanium washer might provide the largest increase in the removal torque.