Root resorption factors associated with orthodontic treatment with fixed appliances: A systematic review and meta-analysis

External apical root resorption (EARR) is a serious complication that should be avoided during orthodontic treatment; this pathology depends on multiple factors. Data from clinical studies should be assessed to determine the influence these factors have on the development of EARR. This systematic review aims to compare EARR produced by different factors (orthodontic systems, dental trauma, and dental vitality). The protocol was registered on the PROSPERO database. The search was performed on 5 databases. Accepted study designs included randomized controlled trials, nonrandomized clinical trials, and observational studies. Full-text articles from clinical studies of EARR associated with orthodontic treatment in English, Spanish, or Portuguese with no publication date restrictions were selected. Data from the studies, such as age, population, study groups, and outcome measures, were recorded. Multiple meta-analyses were performed with data from the included studies. Evidence suggests that EARR induced by orthodontic treatment is similar, regardless of the technique used. Evidence of the effect of previous dental trauma on EARR during orthodontic treatment is limited. There is less EARR associated with orthodontic treatment in endodontically treated teeth than in vital teeth. These conclusions should be considered with caution due to the low certainty of the evidence.