title: The flaws in tooth root resorption assessment algorithms: the role of source position.
abstract: OBJECTIVE
  The purpose of this project was to analyse the effects of X-ray source location on mathematical compensations used in the clinical assessment of external apical root resorption (EARR).
  
  
  METHODS
  Using geometric constructions, governing equations were derived to express the relationships between actual tooth, root and crown lengths, and their image sizes on "before" and "after" radiographs.
  
  
  RESULTS
  Good agreement was found between calculated and published experimental results. More importantly, errors associated with the assessment methods are demonstrated.
  
  
  CONCLUSIONS
  It is established that root resorption assessment algorithms cannot reliably compensate for the inherent distortions in radiographic evaluations of EARR, even in the best-case scenario of an idealized, precisely characterized, linear tooth.
authors: Department of Orthodontics and Oral Facial Genetics, Indiana University School of Dentistry, Room DS250, 1121 West Michigan Street, Indianapolis, IN 46202, USA. tkatona@iupui.edu
authors: T R
authors: TR
authors: Katona
mesh_terms: D000465:Algorithms; D006801:Humans; D008954:Models, Biological; D009811:Odontometry / Q000706:statistics & numerical data*; D011859:Radiography; D015203:Reproducibility of Results; D012391:Root Resorption / Q000000981:diagnostic imaging*; D019227:Tooth Apex / Q000000981:diagnostic imaging*; D019237:Tooth Cervix / Q000000981:diagnostic imaging; D019228:Tooth Crown / Q000000981:diagnostic imaging; D014092:Tooth Root / Q000000981:diagnostic imaging