Abstract: Objective To reevaluate the systematic review of root resorption in the orthodontic treatment of clear aligners. Methods To search PubMed, EMBASE, Cochrane Library, Chinese Academic Journal Online Publishing Database, Wanfang database, Chinese biomedical literature database, search the published systematic review of clear aligners, and the time limit is from the establishment of the database to April 2020. Two authors screened and extracted data independently. A measurement tool to access systematic review 2 (AMSTAR2) was used to evaluate each systematic review, and a descriptive study of outcome indicators was used to evaluate the quality of evidence. Results Three systematic reviews were included, including two of high quality and one of medium quality. There were 3 systematic reviews reports on the unified outcome indicators of root resorption degree. The quality of two outcome indicators was high, and the quality of one outcome indicator was medium. Compared with the fixed appliance, the root absorption of the clear aligners decreased. The root absorption of the clear aligner appliance was 0.44mm (SD = 0.12), the root absorption of the fixed appliance was 1.13mm (SD = 0.18), P < 0.05. The standardized mean difference of total teeth was SMD = -0.65, 95% CI [-0.74, - 0.55], P < 0.01; however, the degree of root resorption was also related to the tooth position, the application of light gravity, the design of correction, the degree of patient cooperation and other factors. According to individual systematic reviews, there was no significant difference in root resorption between clear aligner appliance and fixed appliance under individual tooth position and light force condition. Conclusions The results of overview show that the degree of the root resorption of clear aligner is lower than that of fixed appliance. However, the number of studies is small and some of the evidence conflict. The reliability of outcome indicators is general. So clinicians need to have a choice of reference.

Key words: clear aligners, overview, systematic reviews, Metaanalysis, root resorption