Effect of different maintenance time of torque application on detorque values of abutment screws in full-arch implant-supported fixed prostheses.

BACKGROUND: The effect of different maintenance time of torque application and screw loosening in full-arch implant-supported prosthesis remains uninvestigated.

PURPOSE: To examine the effect of different maintenance time of torque application on detorque values of implant abutment screw in full-arch implant-supported fixed complete denture.

MATERIALS AND METHODS: Passively fitting framework supported by four implants stabilized on resin model torqued to 35 N-cm and maintained for different times; instant torque application (protocol A), 10 seconds (protocol B), and 30 seconds (protocol C) were used. Detorque values were recorded during removal of the screws. Comparison between mean torque and detorque values were made using paired sample t-test. The mean removal torque values of each protocol were compared using three-way analysis of variance (ANOVA).

RESULTS: The mean removal torque values were lower than the applied torque for all the protocols. The highest mean removal torque value was found in the immediate protocol (A) (24.44 ± 1.7), followed by the 30 seconds protocol (C) (23.37 ± 1.75), and then by the 10 seconds protocol (B) (23.35 ± 1.6). All these differences were found to be statistically significant between torque and detorque values (P = .001). However, the differences among detorque values were not statistically significant (P > .05).

CONCLUSION: The application of 35 N-cm for different maintenance time of torque application on implant abutment screw did not appear to affect the detorque value in a multiple implant-supported fixed prosthesis. Maintaining the torque for prolonged time (10 seconds or 30 seconds) was not significantly associated with higher preload than instant torque application in full-arch implant-supported prosthesis.