Influence of different maintenance times of torque application on the removal torque values to loosen the prosthetic abutment screws of external hexagon implants.

PURPOSE To analyze the torque application on prosthetic abutment screws using different maintenance times, to determine an influence on the removal torque values. MATERIALS AND METHODS A total of 40 external hexagon implants, 40 titanium screws, and 40 customized abutments were used. In group 1, the screws received a torque of 30 N·cm by instant torque application; in groups 2, 3, and 4, torque of 30 N·cm was applied and maintained for 10, 20, and 30 seconds, respectively. Removal torque was performed 10 minutes after torque application. Data were statistically analyzed using 1-way ANOVA and Tukey HSD test (α = 0.05). RESULTS The mean and standard deviation (±SD) of removal torque values found were 11.61 ± 1.43 N·cm for group 1; 18.64 ± 1.71 N·cm for group 2; 21.62 ± 0.97 N·cm for group 3; and 21.48 ± 1.55 N·cm for group 4. Groups 3 and 4 exhibited statistically higher values than group 2, which demonstrated significantly higher values than group 1 (P < 0.05). CONCLUSIONS A torque of 30 N·cm applied for 20 seconds seemed to be the best option when considering the removal torque values of external hexagon implants.