Accuracy of mechanical torque-limiting devices for implant screw tightening: A systematic review and meta-analysis

Ying S. Wang, Clinical Assistant Professor, Department of Periodontics, School of Dentistry, Texas A&M University, Dallas, Texas.
Chun-Teh Lee, Associate Professor, Department of Periodontics and Dental Hygiene, University of Texas Health Science Center at Houston, Houston, Texas.
Eswar Kandaswamy, Assistant Professor, Department of Periodontics, Louisiana State University School of Dentistry, New Orleans, La.
Kalia Theodorou, Graduate student, Graduate Periodontics, Division of Periodontology, College of Dentistry, The Ohio State University, Columbus, Ohio.
Hua-Hong Chien, Clinical Professor, Division of Periodontology, College of Dentistry, The Ohio State University, Columbus, Ohio. Electronic address:


STATEMENT OF PROBLEM: A consensus is lacking on the accuracy of torque value on different types of mechanical torque-limiting devices. PURPOSE: The purpose of this systematic review and meta-analysis was to determine the accuracy of unused mechanical torque-limiting devices. MATERIAL AND METHODS: Electronic searches were conducted until October 2021 in 6 electronic databases. Relevant articles were manually screened in 5 journals from January 2000 to October 2021. Two reviewers screened titles, abstracts, and full texts and extracted the data independently. A meta-analysis was conducted to evaluate the weighted mean difference in torque value deviation from target torque between spring-style and friction-style devices as a primary outcome. Deviations of output torque value from target value in spring-style or friction-style devices were also analyzed as a secondary outcome. RESULTS: A total of 11 595 articles were identified, and 16 articles were included for final statistical analysis. Meta-analysis of the included articles showed that torque value deviation in the spring-style was significantly lower than in the friction-style devices (-0.99 Ncm, 95% confidence interval [CI]: [-1.89, -0.09], P=.030). Deviations of output torque value from target value was -0.54 Ncm in the spring-style group (CI: [-1.23, 0.15], P=.122) and -0.18 Ncm in the friction-style group (95% CI: [-1.40, 1.04], P=.770). Meta-regression analysis indicated that target value was significantly associated with the mean deviation from target value only in the spring-style group. High heterogeneity was found, suggesting more studies with standardized research design are required. CONCLUSIONS: Both spring- and friction-style mechanical torque-limiting devices can produce relatively accurate torque values; however, unused spring-type devices tend to have lower deviation from target torque value than unused friction-type devices.