RESUMEN
OBJECTIVE: This systematic review and meta-analysis aimed to investigate the effectiveness and safety of ozone therapy for treating dental caries. METHODS: We searched for randomized controlled trials (RCTs) in 8 databases, from inception to April 4, 2020 (MEDLINE, EMBASE, CENTRAL, LILACS, Bibliografia Brasileira de Odontologia, ClinicalTrials.gov, WHO, and OpenGrey). Primary outcome measures were antimicrobial effect and adverse events. We used the Cochrane risk of bias tool to evaluate methodological quality of included RCTs and GRADE approach to evaluate the certainty of the evidence. We used the Review Manager software to conduct meta-analyses. RESULTS: We included 12 RCTs comparing ozone therapy with no ozone, chlorhexidine digluconate, fissure sealants (alone and added to ozone), and fluoride. Considering primary outcomes, ozone therapy showed (a) lower reduction in the bacterial number than chlorhexidine digluconate in children (mean difference [MD]: -5.65 [-9.79 to -1.51]), but no difference was observed in adults (MD: -0.10 [-1.07 to 0.88]); (b) higher reduction in the bacterial number than sealant (MD: 12.60 [3.86-21.34]), but no difference was observed after final excavation (MD: -0.00 [-0.01 to 0.01]). Regarding safety of ozone therapy, results from individual studies presented no adverse events during or after treatment. Most of these results are imprecise and should be interpreted with caution because of clinical and methodological concerns, small sample size, and wide confidence interval, precluding to determine the real effect direction. CONCLUSION: Based on a very low certainty of evidence, there is not enough support from published RCTs to recommend the use of ozone for the treatment of dental caries. Well-conducted studies should be encouraged, measuring mainly the antimicrobial effects of ozone therapy at long term and following the recommendations of the CONSORT statement for the reporting of RCTs.