Impacted third molars and its propensity to stimulate external root resorption in second molars: Comparison of orthopantomogram and cone beam computed tomography

Aim: This study was designed to compare the efficiency of cone-beam computed tomography (CBCT) with panoramic radiography to discern external root resorption (ERR) in second molars. Materials and methods: This was a retrospective study with a sample size of 50 participants who had a total of 120 impacted third molars visible on panoramic radiographs and CBCT images. The presence of ERR on the neighboring second molar was assessed and the position of impacted third molar was determined using Pell and Gregory classification. The ERR was registered according to Al-Khateeb and Bataineh’s criteria. The location and severity were assessed by Ericson et al criteria, and grading of ERR was done as per the criteria given by Nemcovsky. Results: The CBCT was able to locate and identify extremely large number of cases with ERR on second molars in comparison with the panoramic radiographs. Based on Pell and Gregory classification, position B was most common. The ERR on second molars was most commonly seen at the cervical region. Most of the cases had mild severity. As per grading mentioned by Nemcovsky, maximum number of cases were given grade A followed by grade B. Conclusion: According to our study and considering the three-dimensional information obtained from CBCT, we found that ERR was better detected with CBCT. Clinical significance: If on panoramic radiographs, a close contact is detected between the second molar and an impacted third molar, CBCT can be advised taking into account the “risk vs reward ratio.”.