A review of the relation between peripheral anatomical structures and external apical root resorption during orthodontic treatment

External apical root resorption(EARR)is one of the most common side effects of orthodontic treatment. Contact with surrounding anatomical structures during tooth movement is a significant cause for EARR. However, a comprehensive review of factors leading to EARR due to direct contact of surrounding anatomical structures with the root apex during orthodontic treatment is still lacking. This review summarizes the anatomical structures related to EARR, including alveolar bone, incisive canal, maxillary sinus, adjacent teeth, and bone islands. Alveolar bone, incisive canal, and adjacent teeth can directly cause EARR during orthodontic treatment, while the impact of the maxillary sinus and bone islands on EARR has not been discovered so far. Analyzing the anatomical structures around the tooth roots can help develop more effective methods to prevent or reduce the occurrence of EARR during orthodontic treatment.