Apical root resorption is associated with comprehensive orthodontic treatment but not clearly dependent on prior tooth characteristics or orthodontic techniques.

SYSTEMATIC REVIEW CONCLUSION: Increased incidence and severity of external apical root resorption (EARR) occurred in patients undergoing comprehensive orthodontic therapy, especially when therapy involved higher levels of force than those commonly used for orthodontic tooth movement. CRITICAL SUMMARY ASSESSMENT: Results from a high-quality systematic review of 11 randomized clinical trials (RCTs) suggests that EARR has a multifactorial etiology; is associated with comprehensive orthodontics; supports the clinical use of light forces, especially during intrusion of teeth; and requires higher-quality research. EVIDENCE QUALITY RATING: Limited.