Comparision of anatomiacal position of the root of third mandibular incisor relative to the alveolar canal in the two methods of panoramic radiograpy and CBCT

In impacted third molar surgery, panoramic radiography is a preliminary technique for assessing the consequences associated with inferior alveolar nerve injury. However, this technique cannot provide enough information to determine the true risk in all cases. The aim of this study was to compare the accuracy of panoramic and CBCT radiographs in evaluating the relationship between the mandibular impacted third molars and the inferior alveolar nerve.

In this cross-sectional study, the relationship between mandibular third molar and inferior alveolar nerve in 15 patients referred to the oral and maxillofacial radiology department of Birjand dental school including 20 mandibular third molars were evaluated using two panoramic and CBCT radiographs. Data were analyzed using descriptive statistics and chi-square test and sensitivity analysis in SPSS22.

In the evaluation of the teeth using panoramic radiography, the highest frequency was related to root darkening (65%) and root deflection (65%), and the lowest frequency was related to root narrowing (20%) and canal deviation (5%). The highest sensitivity of panoramic criteria was related to the root darkening with 100% sensitivity and the lowest sensitivity was related to the canal deviation with 17% sensitivity. On the other hand, the highest specificity of panoramic criteria between the mandibular third molars with the inferior alveolar nervewas was related to the two criteria of bifid apex and canal deviation with 100% specificity. The lowest specificity was related to the root deflection with 21% of specificity.

According to the results of this study, the probability of observing relationship between the mandibular third molars with the inferior alveolar nerve in CBCT radiography was very high.