Accuracy of mechanical torque-limiting devices for dental implants

Area of Science:

• Dental Implantology
• Biomaterials Science
• Mechanical Engineering

Background:

• Unintentional implant screw loosening is a common complication in implant dentistry.
• Accurate delivery of target torque values is critical for preventing screw loosening.
• Mechanical torque-limiting devices (MTLDs) are recommended by manufacturers, but limited data exists on the accuracy differences between friction-style and spring-style MTLDs.

Purpose of the Study:

• To compare the accuracy of spring-style and friction-style mechanical torque-limiting devices (MTLDs).

Main Methods:

• Five MTLDs from six dental implant manufacturers were tested.
• Three manufacturers for each style (friction and spring) were included.
• Torque measurements were recorded 10 times per device using a digital torque gauge.
• Nonparametric tests and Bonferroni post hoc tests were used for statistical analysis.

Main Results:

• The median absolute difference between delivered and target torque values was not significantly different between friction-style and spring-style MTLDs (P>.05).
• Accuracy varied among specific manufacturers; Astra Tech and Zimmer Dental friction-style devices showed significantly different accuracy compared to Biohorizons devices (P<.05).

Conclusions:

• New friction-style and spring-style MTLDs demonstrate comparable accuracy.
• All tested MTLDs delivered torque values within ±10% of the manufacturer-preset target torque.
• While some specific friction-style devices showed statistically significant accuracy differences, all remained within acceptable clinical tolerances.