title: Mesial inclination of impacted third molars and its propensity to stimulate external root resorption in second molars--a cone-beam computed tomographic evaluation.
abstract: OBJECTIVE
  To investigate the presence of external root resorption (ERR) in second molars adjacent to horizontally and mesioangular impacted mandibular third molars by cone-beam computed tomography. In addition, patient characteristics (age and gender) and third molar depth were correlated with the presence of ERR.
  
  
  METHODS
  The sample consisted of 116 scans (58 acquired on the i-CAT Classic and 58 on the Picasso-Trio) of 70 women and 46 men (mean age, 23.7 yr). Two observers recorded the presence of ERR in the second molars, inclination and depth of third molars in relation to bone and soft tissues, third molars classification according to Pell and Gregory, and location and severity of ERR. Data were analyzed by analysis of variance, Mann-Whitney test, and χ(2) test. The κ test was used to analyze intraobserver agreement.
  
  
  RESULTS
  The overall prevalence of ERR was 49.43%. There were no statistically significant differences in the detection of ERR by gender, images from the 2 devices, or third molar inclination (P > .05). The κ test showed excellent reproducibility values (κ = 0.7778). There was a smaller proportion of affected patients 14 to 24 years old and ERR in teeth adjacent to Class C third molars.
  
  
  CONCLUSIONS
  Mesially inclined third molars (mesioangular and horizontal) have a greater potential of being associated with ERR in second molars, which was shown by the high prevalence of the condition in the overall sample. Class A and B third molars in patients older than 24 years were more associated with the presence of ERR in adjacent teeth.
authors.affiliation: Associate Researcher, Division of Oral Radiology, Department of Oral Diagnosis, Piracicaba Dental School, University of Campinas, São Paulo, Brazil. Electronic address: anne.oenning@gmail.com.
authors.forename: Anne Caroline Costa
authors.initials: AC
authors.lastname: Oenning
authors.affiliation: Resident, Department of Oral Pathology, Radiology and Medicine, University of Iowa College of Dentistry, Iowa City, IA.
authors.forename: Saulo Leonardo Sousa
authors.initials: SL
authors.lastname: Melo
authors.affiliation: Professor, Division of Pharmacology, Department of Morphology, Piracicaba Dental School, University of Campinas, São Paulo, Brazil.
authors.forename: Francisco Carlos
authors.initials: FC
authors.lastname: Groppo
authors.affiliation: Professor, Division of Oral Radiology, Department of Oral Diagnosis, Piracicaba Dental School, University of Campinas, São Paulo, Brazil.
authors.forename: Francisco
authors.initials: F
authors.lastname: Haiter-Neto
mesh_terms: D000293:Adolescent; D000328:Adult; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D003430:Cross-Sectional Studies; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D008963:Molar / Q000000981:diagnostic imaging*; D008964:Molar, Third / Q000000981:diagnostic imaging*; D015588:Observer Variation; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012391:Root Resorption / Q000000981:diagnostic imaging*; D014095:Tooth, Impacted / Q000000981:diagnostic imaging*; D014097:Tooth, Unerupted / Q000000981:diagnostic imaging; D055815:Young Adult