title: Use of panoramic radiography to predict postsurgical sensory impairment following extraction of impacted mandibular third molars.
abstract: BACKGROUND
  The purpose of this study was to use panoramic radiographic findings to predict postsurgical sensory impairment following the extraction of impacted mandibular third molars.
  
  
  METHODS
  There were 120 patients enrolled in this study (55 male and 65 female). A total of 120 impacted mandibular third molars were included due to the proximity between the inferior alveolar nerve (IAN) canal and the roots of the impacted third molar on the panoramic radiograph. Seven radiographic signs were the predictor variables: (1) darkening of the root(s); (2) interruption of the radiopaque line of the inferior alveolar canal; (3) diversion of the inferior alveolar canal; (4) dark and bifid apex; (5) deflection of the root(s); (6) narrowing of the inferior alveolar canal; and (7) narrowing of the root(s). The outcome variable was the postoperative IAN sensory impairment. The retrospective cohort study model was used, and univariable and bivariable statistics was computed with the statistically significant level at p ≤ 0.05.
  
  
  RESULTS
  Three of the radiographic signs were statistically associated with IAN sensory impairment (p<0.05). They include: (1) interruption of the radiopaque line [sensitivity = 0.92, specificity = 0.45, positive predictive value (PPV) = 0.17, negative predictive value (NPV) = 0.02]; (2) diversion of the IAN canal (sensitivity = 0.77, specificity = 0.84, PPV = 0.37, NPV = 0.03); and (3) narrowing of the IAN canal (sensitivity = 0.69, specificity = 0.65, PPV = 0.19, NPV = 0.05). However, the other four radiographic signs, namely darkening of the root(s), dark and bifid apex, deflection of the root(s), and narrowing of the root(s), were not statistically associated with IAN sensory impairment (p>0.05).
  
  
  CONCLUSIONS
  There are three radiographic signs: (1) interruption of the radiopaque line; (2) diversion of the IAN canal; and (3) narrowing of the IAN canal. These signs are valuable in presurgical evaluation of the risk of postoperative sensory impairment after surgical removal of impacted mandibular third molar.
authors.affiliation: Oral and Maxillofacial Surgery, Department of Stomatology, Taipei Veterans General Hospital, Taipei, Taiwan, ROC.
authors.forename: Chuan-Kuei
authors.initials: CK
authors.lastname: Huang
authors.affiliation: Oral and Maxillofacial Surgery, Department of Stomatology, Taipei Veterans General Hospital, Taipei, Taiwan, ROC; School of Dentistry, National Yang-Ming University, Taipei, Taiwan, ROC.
authors.forename: Man-Tin
authors.initials: MT
authors.lastname: Lui
authors.affiliation: Oral and Maxillofacial Surgery, Department of Stomatology, Taipei Veterans General Hospital, Taipei, Taiwan, ROC; School of Dentistry, National Yang-Ming University, Taipei, Taiwan, ROC. Electronic address: dhcheng@vghtpe.gov.tw.
authors.forename: Dong-Hui
authors.initials: DH
authors.lastname: Cheng
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008334:Mandible; D008964:Molar, Third / Q000000981:diagnostic imaging / Q000601:surgery*; D011183:Postoperative Complications / Q000000981:diagnostic imaging*; D011862:Radiography, Panoramic / Q000379:methods*; D012189:Retrospective Studies; D012678:Sensation Disorders / Q000000981:diagnostic imaging*; D014081:Tooth Extraction / Q000009:adverse effects*; D014095:Tooth, Impacted / Q000000981:diagnostic imaging / Q000601:surgery*
keywords: inferior alveolar nerve; mandibular third molar; panoramic radiograph; sensory impairment