Influence of reverse torque values in abutments with or without internal hexagon indexes.

Statement Of Problem: The mechanical stability of the implant-abutment connection is of fundamental importance for successful implant-supported restorations. Therefore, understanding removal torque values is essential.

Purpose: The purpose of this study was to evaluate the reverse torque values of indexed and nonindexed abutments of the Morse Taper system.

Material And Methods: Twelve Morse taper implants with their respective abutments were divided into 2 groups (n=6): group NI, nonindexed abutments; and group IN, indexed abutments. Each abutment received a sequence of 2 consecutive torques for insertion (15 Ncm) at an interval of 10 minutes, and 1 reverse torque, all measured with a digital torque wrench. The Student t test with a 5% significance level was used to evaluate the data.

Results: Statistical analysis showed no significant difference in reverse torque values between nonindexed and indexed abutments (P=.57). When comparing insertion torque and reverse torque values between the groups, group NI presented a mean torque loosening percentage of 8% (P=.013), whereas group IN presented a loosening of 15.33% (P<.001).

Conclusion: The use of indexed abutments for the Morse taper system presented similar biomechanical stability when compared with nonindexed abutments, both with a significant reduction in reverse torque values.