Document Type: Original Article


1 Assistant Professor of Oral and Maxillofacial Surgery Department, School of Dentistry, Shiraz University of Medical Sciences

2 Assistant Professor of Oral and Maxillofacial Radiology Department, School of Dentistry, Shiraz University of Medical Sciences

3 Dentist


Background: It is likely that the inferior alveolar nerve injury occurs following the removal of the lower third molars due to the anatomic proximity. So preoperative radiographic assessments are necessary to determine the position of the mandibular canal. Radiography is the most standard technique for assessing the anatomic relationship between the third molars and the mandibular canal. Panoramic view can help to determine the relationship and position of the mandibular canal to the mandibular third molar.Materials and Methods: 664 panoramic radiographs of the individuals aged 20-70 years who showed 1128 impacted third molars were assessed. Photos of these panoramic images were obtained with a digital camera in similar conditions. The incidence of proximity of the root tips of the third molars and mandibular canal (in range of 2 and 3 mm) was detected. Four radiological signs (deflected roots, diversion of the canal, interruption of the cortical white line of the canal and the narrowing at the canal) were recorded in both sides and in different agesResults: From 1128 impacted mandibular third molars, %79.3 had 2 roots and %20.7 had one root. In the teeth the roots of which had a distance with the mandibular canal, the proximity was observed in females more than in males. There was no significant relationship between proximity and age. In 558 teeth, one or both roots were superimposed over the mandibular canal. In those cases, there was no statistically significant relation between superimposition and age and sex. Deflection of the root and interruption of the white line of the canal were observed in the right side more than the left side. Diversion of the canal was seen more in the LT side. Narrowing of the canal showed no difference among the patients.Conclusion: In the present research, in significant cases of impacted third molars (in both gender and in both sides) there are radiographical signs for proximity of the mandibular canal and the root of impacted third molars, which increases the risk of inferior alveolar nerve injuryKey words: Mandibular third- Mandibular canal- Panoramic radiography