title: [Predictive factors of third molar eruption].
abstract: BACKGROUND
  We studied the prognosis of upper and lower third molar evolution.
  
  
  METHODS
  Seventy-eight patients were included after a clinical examination, dental casts, panoramic and lateral cephalometric radiographs on inclusion (T1) and two years after (T2). Five parameters were studied: retromolar space (RMS) between the third molar (M3) and the anterior ridge of the ramus; RMS/M3 crown diameter ratio, distances (PTV-M(1)) and (X(i)-Mi(2)); and third molar angle with occlusal plane.
  
  
  RESULTS
  They were noted at T1 and T2. The gain of retromolar space from T1 to T2 reached 1.2 to 2.2mm without extraction, 2 to 2.7mm with PM extraction, and 4.5 to 6.8mm with M1 extraction. The "RMS/M3 diameter" ratio increased in the maxilla from 0.6 to 0.8 and from 0.5 to 0.8 in the mandible (P=0.01) between T1 and T2. PTV-M1 increased significantly from 17.1 to 19.9mm (P<0.001), and Xi-M2i increased significantly from 18.5 to 22.4mm (P<0.001) between T1 and T2.
  
  
  CONCLUSIONS
  The extraction of premolars has little influence on the variation of the retromolar space; conversely first molar extraction increases that space. Prognosis techniques for the evolution of third molars are helpful when considering avulsion.
authors.affiliation: Département d'orthopédie dentofaciale, faculté de médecine dentaire, université Hassan IIAin Chok, rue Abou Al Alaâ zahar (ex Vésal), Mers Sultan, Casablanca, Morocco. mouradsebbar@hotmail.com
authors.forename: M
authors.initials: M
authors.lastname: Sebbar
authors.forename: F
authors.initials: F
authors.lastname: Bourzgui
mesh_terms: D000293:Adolescent; D000328:Adult; D001641:Bicuspid / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D005544:Forecasting / Q000379:methods; D006801:Humans; D008297:Male; D008964:Molar, Third / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D011379:Prognosis; D011862:Radiography, Panoramic; D012189:Retrospective Studies; D012307:Risk Factors; D014078:Tooth Eruption / Q000502:physiology*; D014081:Tooth Extraction; D014095:Tooth, Impacted / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000209:etiology; D055815:Young Adult