White spot lesions, plaque accumulation and salivary caries-associated bacteria in clear aligners compared to fixed orthodontic treatment. A systematic review and meta- analysis

OBJECTIVE: To analyse the available evidence regarding the incidence and severity of white spot lesions (WSLs), plaque accumulation and salivary caries-associated bacteria(SCB) in clear aligners (CA) verses conventional fixed (CF) orthodontic appliances. METHODS: Electronic searches of MEDLINE, Scopus, Embase, Google Scholar, Clinical trial registry, OpenGrey and ProQuest were done for all relevant studies. Eligibility criteria were; Randomized Controlled Trials and Non-Randomized Studies that compared the incidence and severity of WSLs, plaque accumulation and SCB between CA and CF appliances in patients undergoing orthodontic treatment. The risk of bias(ROB) and certainty of evidence was assessed independently by two reviewers using Cochrane’s ROB and GRADEpro, respectively. Standardized mean difference (SMD) was used to estimate the effect size using STATA 17 software. RESULTS: A total of 14 studies met the eligibility criteria, and eight were suitable for meta-analysis. The qualitative results showed lower incidence and severity of WSLs, plaque accumulation, and SCB in CA group compared to CF appliances. The pooled results showed significantly lower plaque accumulation(SMD − 1.58;95%CI:-2.57,0.58;p = 0.002) in CA compared to CF appliances. CONCLUSIONS: A moderate-quality evidence reveals less plaque accumulation and less SCB in CA, which might be related to the reduced incidence and severity of WSLs associated with CA when compared with CF appliances. However, the results of the present study should be interpreted with caution given the high ROB among some of the included studies as well as the marked heterogeneity across the studies. CLINICAL RELEVANCE: For patients who can be treated with either CA or CF appliances, CA may be a better choice concerning oral health. REGISTRATION: Open Science Framework (DOI:10.17605/osf.io/kcpvb). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12903-023-03257-8.