title: The relationship between apical root resorption and orthodontic tooth movement in growing subjects.
abstract: OBJECTIVE
  To investigate the relationship between apical root resorption and orthodontic tooth movement in growing subjects.
  
  
  METHODS
  58 growing subjects were collected randomly into the study sample and another 40 non-treated cases were used as control. The apical resoption of the upper central incisors was measured on periapical film and the incisor displacement was measured on lateral cephalogram. Using multiple linear regression analysis to examine the relationship between root resoption and the displacement of the upper incisor apex in each of four direction (retraction, advancement, intrusion and extrusion).
  
  
  RESULTS
  The statistically significant negative association were found between resorption and both intrusion (P < 0.001) and extrusion (P < 0.05), but no significant association was found between resorption and both retraction and advancement. The regression analysis implied an average of 2.29 mm resorption in the absence of apical displacement.
  
  
  CONCLUSIONS
  The likelihood that the magnitude of displacement of the incisor root is positively associated with root resoption in the population of treated growing subjects is very small.
authors.affiliation: Department of Orthodontics, Peking University School of Stomatology, Beijing 100081, China.
authors.forename: Tianmin
authors.initials: T
authors.lastname: Xu
authors.forename: S
authors.initials: S
authors.lastname: Baumrind
mesh_terms: D006801:Humans; D007180:Incisor; D008437:Maxilla; D012391:Root Resorption; D019227:Tooth Apex; D014087:Tooth Movement Techniques