title: Bone structure effect on root resorption.
abstract: OBJECTIVE
  To explore if alveolar bone shape and density might promote external apical root resorption.
  
  
  METHODS
  Panoramic radiographs of 700 patients who had orthodontic treatment at Temple University were reviewed and 22 patients with radiographic evidence of root resorption on the lower incisors were selected for the study. Exclusion criteria included a history of systemic diseases, craniofacial abnormalities, tooth injury, endodontically treated teeth, and impacted teeth.
  
  
  METHODS
  Pre-treatment (T1) and post-treatment (T2) cephalometric radiographs were converted into digital format and enhanced to reduce contrast variability and improve edge definition. Tooth length, root length, root area, alveolar area around the root including cortical area, area of medullary bone, and area of the symphysis were measured using an interactive software algorithm. A region of interest within the symphysis was also defined and trabecular space area and fractal dimension calculated as an estimate of bone density.
  
  
  RESULTS
  Root area and tooth length were correlated negatively with changes in root area, tooth area, and root length. Larger teeth demonstrated a greater amount of root resorption. Dentoalveolar complex dimensions remained relatively unchanged during tooth movement. The amount of alveolar bone around the root, thickness of cortical bone, density of the trabecular network, and fractal dimension showed no significant correlation with the extent of the external apical root resorption.
  
  
  CONCLUSIONS
  The results of this study suggest that the density and morphology of the dentoalveolar complex are not significant factors in the etiology of external apical root resorption.
authors.affiliation: Oral & Maxillofacial Radiology, School of Dental Medicine, University of Pennsylvania, 4001 Spruce Street, Philadelphia, PA 19104, USA. lotis@pobox.upenn.edu
authors.forename: Linda L
authors.initials: LL
authors.lastname: Otis
authors.forename: Justin Sung-Ho
authors.initials: JS
authors.lastname: Hong
authors.forename: Orhan C
authors.initials: OC
authors.lastname: Tuncay
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D000539:Alveolar Process / Q000473:pathology* / Q000503:physiopathology; D015519:Bone Density / Q000502:physiology*; D002508:Cephalometry; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D017709:Fractals; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007180:Incisor / Q000473:pathology; D008297:Male; D009811:Odontometry; D011862:Radiography, Panoramic; D011897:Random Allocation; D012189:Retrospective Studies; D012391:Root Resorption / Q000209:etiology*; D012984:Software; D019227:Tooth Apex / Q000473:pathology; D014087:Tooth Movement Techniques / Q000009:adverse effects*; D014092:Tooth Root / Q000473:pathology