title: External root resorption of the second molar associated with third molar impaction: comparison of panoramic radiography and cone beam computed tomography.
abstract: OBJECTIVE
  The aim of the present study was to compare panoramic radiography and cone beam computed tomography (CBCT) for the assessment of external root resorption (ERR) of second molars associated with impacted third molars. In addition, the prevalence of ERR in second molars and the inclinations of the third molars more associated with ERR were investigated in both imaging methods.
  
  
  METHODS
  The sample consisted of 66 individuals with maxillary and mandibular impacted third molars (n = 188) seen on panoramic radiographs and CBCT images. The presence of ERR on the adjacent second molar was investigated, and the position of the third molar was determined using Winter's classification (vertical, horizontal, mesioangular, distoangular, and transverse). Statistical analysis was performed using the χ(2) test, Fisher exact test, and 2-proportion Z test (the significance level was set at 5%).
  
  
  RESULTS
  A significantly greater number of cases of ERR (P < .0001) was diagnosed from CBCT images (n = 43, 22.88%) than panoramic radiographs (n = 10, 5.31%). The agreement between the panoramic radiographs and CBCT scans for diagnosing ERR was 4.3%. Mandibular third molars in mesioangular and horizontal inclinations were more likely to cause resorption of the adjacent teeth.
  
  
  CONCLUSIONS
  CBCT should be indicated for the diagnosis of ERR in second molars when direct contact between the mandibular second and third molars has been observed on panoramic radiographs, especially in mesioangular or horizontal impactions. Furthermore, considering the propensity of these teeth to cause ERR in second molars, third molar prophylactic extraction could be suggested.
authors.affiliation: Researcher, Division of Oral Radiology, Department of Oral Diagnosis, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil. Electronic address: anne.oenning@gmail.com.
authors.forename: Anne Caroline Costa
authors.initials: AC
authors.lastname: Oenning
authors.affiliation: Researcher, Division of Oral Radiology, Department of Oral Diagnosis, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Frederico Sampaio
authors.initials: FS
authors.lastname: Neves
authors.affiliation: PhD student, Division of Oral Radiology, Department of Oral Diagnosis, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Phillipe Nogueira Barbosa
authors.initials: PN
authors.lastname: Alencar
authors.affiliation: Student, Division of Oral Radiology, Department of Oral Diagnosis, Piracicaba Dental School, State University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Rodrigo Freire
authors.initials: RF
authors.lastname: Prado
authors.affiliation: Professor, Division of Pharmacology, Department of Morphology, Piracicaba Dental School, State University of Campinas, Piracicaba, 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, State University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Francisco
authors.initials: F
authors.lastname: Haiter-Neto
mesh_terms: D054893:Cone-Beam Computed Tomography / Q000379:methods*; D006801:Humans; D008963:Molar / Q000000981:diagnostic imaging*; D011862:Radiography, Panoramic / Q000379:methods*; D014091:Tooth Resorption; D014095:Tooth, Impacted / Q000000981:diagnostic imaging*