The purpose of this study was to conduct a systematic review and meta-analysis of in vitro studies regarding the effectiveness of reciprocating and rotary instrumentation on microbial reduction in root canals.

PubMed, Scopus, Web of Science, the Cochrane Library, and the gray literature were searched through December 2019. Studies comparing the influence of reciprocating and rotary instrumentation on the removal of microorganisms from root canals that quantified the antimicrobial effect were included. Data extraction was completed using a systematic form for data collection. The risk of bias of the studies was evaluated. Standardized mean differences (SMDs) and confidence intervals (CIs) were calculated using a random effects meta-analysis.

Seventeen in vitro studies were included in this systematic review, of which 7 provided adequate data for inclusion in the meta-analysis. Both reciprocating and rotary systems were similarly effective in reducing the microbial load in infected root canals (SMD [95% CI], 0.0481 [−0.271, 0.367]). Three studies showed a low risk of bias, whereas most of the studies (82%) presented a medium risk.

Although both techniques decrease the microbial content (with reductions of 23.32%–88.47% and 23.33%–89.86% for reciprocating and rotary instrumentation, respectively), they are not able to provide complete disinfection of root canals.