title: Using Micro-Computed Tomography to Evaluate the Dynamics of Orthodontically Induced Root Resorption Repair in a Rat Model.
abstract: OBJECTIVE
  To observe dynamic changes in root resorption repair, tooth movement relapse and alveolar bone microstructure following the application of orthodontic force.
  
  
  METHODS
  Forces of 20 g, 50 g or 100 g were delivered to the left maxillary first molars of fifteen 10-week-old rats for 14 days. Each rat was subjected to micro-computed tomography scanning at 0, 3, 7, 10, 14, 28 and 42 days after force removal. The root resorption crater volume, tooth movement relapse and alveolar bone microarchitecture were measured at each time point.
  
  
  RESULTS
  From day 3 to day 14, the root resorption volume decreased significantly in each group. In the 20-g force group, the root resorption volume gradually stabilized after 14 days, whereas in the 50-g and 100-g force groups, it stabilized after 28 days. In all groups, tooth movement relapsed significantly from day 0 to day 14 and then remained stable. From day 3 to day 10, the 20-g group exhibited faster relapse than the 50-g and 100-g groups. In all groups, the structure model index and trabecular separation decreased slowly from day 0 to day 10 and eventually stabilized. Trabecular number increased slowly from day 0 to day 7 and then stabilized.
  
  
  CONCLUSIONS
  The initial stage of root resorption repair did not change significantly and was followed by a dramatic repair period before stabilizing. The most serious tooth movement relapse occurred immediately after the appliance was removed, and then the tooth completely returned to the original position.
authors.affiliation: Department of Orthodontics, College of Stomatology, Chongqing Medical University, Chongqing, China.|Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing, China.
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Xu
authors.affiliation: Department of Orthodontics, College of Stomatology, Chongqing Medical University, Chongqing, China.|Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing, China.
authors.forename: Jianping
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Department of Pediatric Dentistry, College of Stomatology, Chongqing Medical University, Chongqing, China.
authors.forename: Fengxue
authors.initials: F
authors.lastname: Yang
authors.affiliation: Department of Prosthodontics, School and Hospital of 7 Stomatology, Peking University, Beijing, China.
authors.forename: Shicheng
authors.initials: S
authors.lastname: Wei
authors.affiliation: Department of Orthodontics, College of Stomatology, Chongqing Medical University, Chongqing, China.|Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing, China.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Dai
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000000981:diagnostic imaging*; D008297:Male; D008963:Molar / Q000000981:diagnostic imaging*; D011859:Radiography; D051381:Rats; D017207:Rats, Sprague-Dawley; D012391:Root Resorption / Q000000981:diagnostic imaging*; D014087:Tooth Movement Techniques; D014092:Tooth Root / Q000000981:diagnostic imaging*