External apical root resorption in endodontically treated versus vital teeth following orthodontic treatment: a systematic review.

INTRODUCTION External apical root resorption (EARR) is a frequent iatrogenic effect of orthodontic tooth movement. Whether endodontically treated teeth (ETT) are more prone to EARR than teeth with vital pulp tissue (VPT) remains uncertain and is clinically relevant for interdisciplinary treatment planning. This review aimed to compare the extent of EARR in ETT versus VPT after orthodontic treatment and to identify factors associated with EARR in ETT.

EVIDENCE ACQUISITION A systematic review following PRISMA guidelines and the Cochrane Handbook was conducted. PubMed was searched for observational human studies assessing orthodontic movement in ETT with contralateral VPT as controls. Eligible studies used micro-CT, CBCT, or panoramic radiographs to measure EARR and adopted prospective or retrospective cohort designs. Extracted data included sample characteristics, tooth type, orthodontic mechanics, imaging methods, and EARR outcomes. Study quality and risk of bias were evaluated using the Newcastle-Ottawa Scale.

EVIDENCE SYNTHESIS Six studies met the inclusion criteria and involved both adolescent and adult patients. Overall, the evidence indicated that orthodontic treatment does not increase EARR in ETT compared with VPT. Four studies reported significantly less EARR in ETT, while two found no significant differences. Three-dimensional imaging generally demonstrated smaller resorption volumes or surface changes in ETT. Extraction-based mechanics tended to correlate with greater EARR in vital teeth, whereas unresolved periapical pathosis in ETT was associated with increased resorption. Findings regarding age, sex, treatment duration, and tooth type were inconsistent.

CONCLUSIONS Current evidence suggests that orthodontic movement of ETT is at least as safe - and often less associated with EARR - than movement of teeth with vital pulp. Orthodontic loading should be delayed in ETT presenting with untreated periapical lesions. Further high-quality studies using standardized 3D assessments are needed to guide interdisciplinary protocols.