title: Influence of orthodontic extrusion on pulpal vitality of traumatized maxillary incisors.
abstract: BACKGROUND
  The aim of this retrospective study was to examine the effect of orthodontic extrusion on the pulpal vitality of maxillary incisors with a history of trauma.
  
  
  METHODS
  Pulpal condition was examined clinically (rating of crown color and sensitivity testing with a cryogenic spray) and radiologically (periapical and panoramic radiographs) after orthodontic extrusion of previously traumatized (Orthodontics/Trauma group, n = 77) and nontraumatized teeth (Orthodontics group, n = 400) and after previous dental trauma without subsequent orthodontic treatment (Trauma group, n = 193). Dental traumata were divided into hard tissue injuries (fracture of enamel and enamel chipping, fracture of enamel-dentin without pulpal involvement, fracture of enamel-dentin with pulpal involvement, root fracture, crown-root fracture) and periodontal injuries (concussion, subluxation, intrusion, extrusion, lateral luxation, and avulsion).
  
  
  RESULTS
  Teeth in the Orthodontics/Trauma group showed a significantly higher frequency of pulp necrosis than teeth in the Orthodontics group (P < .001) or teeth in the Trauma group (P < .009). In addition, teeth in the Orthodontics/Trauma group with periodontal injuries showed a significantly higher rate of pulp necrosis than teeth in the Orthodontics group (P < .001) or the corresponding teeth in the Trauma group (P = .004). No significant differences were observed between teeth in the Orthodontics/Trauma group with previous hard tissue injuries and teeth in the Orthodontics group or the corresponding teeth in the Trauma group. In addition, no statistically significant differences were determined between central and lateral incisors.
  
  
  CONCLUSIONS
  The results indicated that maxillary incisors with a history of severe periodontal injury have a higher susceptibility to pulp necrosis during orthodontic extrusion than nontraumatized teeth.
authors.affiliation: Hannover Medical School, Hannover, Germany. o.bauss@praxisbauss.de
authors.forename: Oskar
authors.initials: O
authors.lastname: Bauss
authors.forename: Winfried
authors.initials: W
authors.lastname: Schäfer
authors.forename: Reza
authors.initials: R
authors.lastname: Sadat-Khonsari
authors.forename: Michael
authors.initials: M
authors.lastname: Knösel
mesh_terms: D000293:Adolescent; D000328:Adult; D016009:Chi-Square Distribution; D002648:Child; D003782:Dental Pulp / Q000473:pathology / Q000502:physiology*; D003790:Dental Pulp Necrosis / Q000209:etiology* / Q000473:pathology; D005260:Female; D006801:Humans; D007180:Incisor / Q000293:injuries*; D008297:Male; D008437:Maxilla; D050793:Orthodontic Extrusion / Q000009:adverse effects*; D010519:Periodontium / Q000293:injuries; D012189:Retrospective Studies; D018570:Risk Assessment; D013997:Time Factors; D018677:Tooth Injuries / Q000145:classification / Q000628:therapy*; D016896:Treatment Outcome; D055815:Young Adult