Fracture of NiTi engine-files in clinic: Systematic review and meta-analysis.

Abstract

Objectives: Nickel-titanium (NiTi) instruments are frequently used in root canal treatment nowadays. However, instrument breakage is a recognized complication with the use of NiTi engine-files. This systematic review aimed to examine reports of the fracture rate of various brands of NiTi system and to identify any design factors that may influence the chance of NiTi files to break during clinical use. Methods: A comprehensive electronic search of articles published from 1980 to December 2016, both in Chinese and in English language, was conducted using 3 electronic databases (PubMed, EMBASE and SCOPUS). After de-duplication, these articles were screened for relevance, and their reference lists were also subjected to hand search. Only clinical studies were included. Relevant data were extracted systematically and pooled for meta-analysis at a significance level of α=0.05. Results: The final number of articles included for meta-analysis was 23. Overall incidence of fracture was generally below 9% for all instruments reported, with no significant difference found between cross-sectional designs (p>0.05). When the “single use” instruments were identified and compared with those for “multiple uses”, the former showed significantly fewer breakages (p<0.05), but an influence of the design failed to achieve statistical significance. Conclusions: Designating the NiTi engine-files for “single use” significantly reduces the risk of breakages, but there is little impact due to the design of the instrument.