title: A radiographic study of external apical root resorption in patients treated with single-phase fixed orthodontic therapy.
abstract: BACKGROUND
  External apical root resorption (EARR) is one of the most common iatrogenic consequences of orthodontic tooth movement. Many factors like gender, duration, orthodontic force and duration of orthodontic treatment have been implicated to cause EARR.
  
  
  METHODS
  Pre- and post-treatment OPGs of 60 orthodontic patients (30 males and 30 females) who had undergone treatment with a single phase of fixed orthodontic therapy were randomly selected from institutional archives. The root apices were evaluated for EARR by a single operator on an radiograph viewing box at a standardized source of light using a four-grade ordinal scale. Anterior EARR was measured on the maxillary and mandibular canines. Posterior EARR was measured on premolars, mesiobuccal and distobuccal roots of maxillary first molars and mesial and distal roots of mandibular first molars. The results were compiled and subjected to statistical analysis.
  
  
  RESULTS
  The cases in which the patients underwent therapeutic extraction had a relatively higher amount of EARR compared to the cases in which the patients were treated by non-extraction therapy (P< 0.001). Odds ratio indicated that extraction cases had two-fold increased risk of EARR than non-extraction cases (P< 0.001). No statistically significant difference was observed in the distribution of EARR based on gender or duration of orthodontic treatment (P> 0.05).
  
  
  CONCLUSIONS
  Therapeutic extraction is an important determinant of post-treatment EARR. Gender and duration of orthodontic treatment may not be important variables in the causation of EARR according to the findings of this study. However, longitudinal studies with larger sample size are required to validate the results of this study.
authors.affiliation: Graded Specialist (Orthodontics), 4 Corps Dental Unit, C/O 99 APO, India.
authors.forename: S S
authors.initials: SS
authors.lastname: Agarwal
authors.affiliation: Classified Specialist (Orthodontics), Army Dental Centre (R&R), New Delhi, India.
authors.forename: S S
authors.initials: SS
authors.lastname: Chopra
authors.affiliation: Associate Professor (Orthodontics), Dept of Dental Surgery, Armed Forces Medical College, Pune 411040, India.
authors.forename: Prasanna
authors.initials: P
authors.lastname: Kumar
authors.affiliation: Consultant (Orthodontics), Army Dental Centre (R&R), New Delhi, India.
authors.forename: B
authors.initials: B
authors.lastname: Jayan
authors.affiliation: Assistant Professor (Orthodontics), Dept of Dental Surgery, Armed Forces Medical College, Pune 411040, India.
authors.forename: K
authors.initials: K
authors.lastname: Nehra
authors.affiliation: Assistant Professor (Orthodontics), Dept of Dental Surgery, Armed Forces Medical College, Pune 411040, India.
authors.forename: Mohit
authors.initials: M
authors.lastname: Sharma
keywords: External apical root resorption; Orthodontically induced EARR; Root resorption