title: Proximity of impacted mandibular third molars to the inferior alveolar canal and its radiographic predictors: a panoramic radiographic study.
abstract: OBJECTIVE
  To assess the radiographic proximity of impacted mandibular third molars to the inferior alveolar canal on panoramic radiographs. The radiographic distance between the impacted mandibular third molars and inferior alveolar canal and the reliable radiographic risk predictor signs that indicate close proximity between these two structures were evaluated.
  
  
  METHODS
  The study comprised of 64 subjects with 68 symptomatic impacted mandibular third molars for whom panoramic radiographs were made. The radiographs were interpreted for type of impaction, radiographic distance between impacted mandibular third molars to inferior alveolar canal and presence of one or more of the seven radiographic risk predictor signs. Further, these teeth were surgically removed and the proximity was assessed based on the exposure of inferior alveolar canal/nerve which was considered as Gold standard.
  
  
  RESULTS
  The overall mean distance from the impacted mandibular third molars to inferior alveolar canal was -0.50 mm. Most of the samples (61.8 %) extended beyond the superior border of the inferior alveolar canal with a mean distance of -1.40 mm. Mesioangular impactions were found to be in the close proximity (-1.14 mm) to inferior alveolar canal than any other type. Interruption of the white line was the only statistically significant radiographic risk predictor sign p = 0.006 (< 0.05) that indicated close proximity of impacted mandibular third molars to inferior alveolar canal.
  
  
  CONCLUSIONS
  It can be concluded that panoramic radiographs are reliable in assessing the proximity of impacted mandibular third molars to inferior alveolar canal. Mesioangular impactions are more closely placed to inferior alveolar canal and interruption of the white line is the most reliable risk predictor sign on the panoramic radiographs.
authors.affiliation: Department of Oral Medicine and Radiology, JSS Dental College and Hospital, Mysore, 570015 India.
authors.forename: Prasannasrinivas
authors.initials: P
authors.lastname: Deshpande
authors.affiliation: Department of Oral Medicine and Radiology, JSS Dental College and Hospital, Mysore, 570015 India.
authors.forename: Mahima
authors.initials: M
authors.lastname: V Guledgud
authors.affiliation: Department of Oral Medicine and Radiology, JSS Dental College and Hospital, Mysore, 570015 India.
authors.forename: Karthikeya
authors.initials: K
authors.lastname: Patil
keywords: Impacted mandibular third molars; Inferior alveolar canal/nerve; Panoramic radiographs; Radiographic risk predictor sign