title: External root resorption during orthodontic treatment in root-filled teeth and contralateral teeth with vital pulp: A clinical study of contributing factors.
abstract: BACKGROUND
  There is a lack of research to support the belief that root canal treatment can be considered for stopping or decreasing external apical root resorption (EARR). There is conflicting evidence as to whether root-filled teeth are more or less likely to experience EARR after orthodontic treatment. The purpose of this study was to compare the degree of EARR of root-filled teeth with that of contralateral teeth with vital pulp after fixed orthodontic treatment.
  
  
  METHODS
  The study sample consisted of 35 patients aged 25.23 ± 4.92 years who had at least 1 root-filled tooth before orthodontic treatment. Digital panoramic radiographs of each patient taken before and after orthodontic treatment were used to measure the EARR. The Student t test for matched pairs and the Pearson correlation analysis were applied.
  
  
  RESULTS
  The mean EARR values were 0.22 (0.14, 0.35) for root-filled teeth and 0.87 (0.59, 1.31) for contralateral teeth with vital pulp, indicating significantly less EARR for root-filled teeth compared with the contralateral teeth with vital pulp after orthodontic treatment. EARR was influenced by the patient's age, treatment duration, treatment type, and periapical pathosis, but not by tooth type and sex.
  
  
  CONCLUSIONS
  Root-filled teeth appear to be associated with significantly less EARR than are contralateral teeth with vital pulp. This study suggests that the possible complication of EARR in root-filled teeth may not be an important consideration in orthodontic treatment planning, and root canal treatment can be considered for stopping or decreasing EARR when severe EARR occurs during orthodontic treatment.
authors.affiliation: Resident, Department of Orthodontics, Yeouido St Mary's Hospital, Catholic University of Korea, Seoul, Korea.
authors.forename: Yun Ju
authors.initials: YJ
authors.lastname: Lee
authors.affiliation: Clinical assistant professor, Department of Conservative Dentistry, Yeouido St Mary's Hospital, Catholic University of Korea, Seoul, Korea. Electronic address: llotus@hanmail.net.
authors.forename: Tae Yeon
authors.initials: TY
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D003782:Dental Pulp / Q000502:physiology*; D005260:Female; D006801:Humans; D007180:Incisor / Q000000981:diagnostic imaging; D008297:Male; D008963:Molar / Q000000981:diagnostic imaging; D009971:Orthodontics, Corrective / Q000009:adverse effects*; D010483:Periapical Diseases / Q000150:complications; D019252:Radiography, Dental, Digital / Q000379:methods; D011862:Radiography, Panoramic / Q000379:methods; D012189:Retrospective Studies; D012307:Risk Factors; D012391:Root Resorption / Q000000981:diagnostic imaging / Q000209:etiology*; D012737:Sex Factors; D013997:Time Factors; D019227:Tooth Apex / Q000000981:diagnostic imaging / Q000473:pathology*; D019228:Tooth Crown / Q000000981:diagnostic imaging; D014081:Tooth Extraction; D014092:Tooth Root / Q000000981:diagnostic imaging; D019553:Tooth, Nonvital / Q000000981:diagnostic imaging / Q000503:physiopathology*; D055815:Young Adult