title: Changes in mandibular third molar angle and position after unilateral mandibular first molar extraction.
abstract: BACKGROUND
  Third molars often become impacted because of lack of space for their eruption. Because the third molars play an important role occlusally, premolars or second molars are sometimes extracted to create space. First molars are seldom extracted to create space, but they are occasionally extracted for other reasons, especially caries. The aim of this study was to investigate the spontaneous angular and positional changes in mandibular third molars when mandibular first molars are extracted.
  
  
  METHODS
  The sample consisted of panoramic radiographs of 107 patients (age, 18-40 years; mean, 25.69 years) who had unilateral mandibular first-molar extractions (because of caries) before age 16. Ramus relationship, impaction depth, and angulation of third molars on the extraction and nonextraction sides were assessed. A chi-square test was performed to compare the differences.
  
  
  RESULTS
  The prevalence of third molars at the anterior border of the mandibular ramus was significantly greater on the extraction side than on the nonextraction side (P < .001). Third molars were positioned more occlusally in the mandible on the nonextraction side than on the extraction side (P < .001). The prevalence of vertically angulated third molars was greater on the extraction side than on the nonextraction side (P < .001).
  
  
  CONCLUSIONS
  Mandibular first-molar extraction increases the space for mandibular third-molar eruption and helps the third molars move into better positions. But early extraction can lead to uncontrolled tipping of adjacent teeth into the extraction space. Only third-molar angle and position were evaluated in this study; problems such as dental asymmetry, premature contacts, and uncontrolled tipping should be assessed in the future.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Cumhuriyet University, Faculty of Dentistry, Sivas, Turkey. sinanay@cumhuriyet.edu.tr
authors.forename: Sinan
authors.initials: S
authors.lastname: Ay
authors.forename: Ugur
authors.initials: U
authors.lastname: Agar
authors.forename: A Altug
authors.initials: AA
authors.lastname: Biçakçi
authors.forename: H Hüseyin
authors.initials: HH
authors.lastname: Köşger
mesh_terms: D000293:Adolescent; D000328:Adult; D003766:Dental Occlusion; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible; D008963:Molar / Q000601:surgery*; D008964:Molar, Third / Q000000981:diagnostic imaging / Q000473:pathology*; D011862:Radiography, Panoramic; D012189:Retrospective Studies; D014078:Tooth Eruption; D014081:Tooth Extraction; D014095:Tooth, Impacted / Q000145:classification / Q000000981:diagnostic imaging