Necessity of CBCT - examination in assessment of the surgical approach for the extraction of impacted lower third molars

Aim: The aim of this research is to demonstrate the necessity of CBCT - examination for evaluation of the surgical approach of high risk impacted lower third molars. As `high risk` we defined lower third molars which have signs of proximity to the mandibular canal seen on standard panoramic radiography. Material and methods: All patients who had undergone a CT examination between september 2015 and october 2016 were reviewed. We included images from conical-beam computed tomograph made in the Department of radiologic diagnose, University medical and dental centre of the Medical university of Varna. The device used is Planmeca ProMax 3D Max with software for images Planmeca Romexis. We chose 100 images randomly. From these images we selected 39 images with high-risk lower third molars. We examined different signs with which we defined the exact position to the mandibular canal of 60 wisdom teeth and we managed to asses the risk of damaging the IAN during a classical odontectomy of these teeth. In the research we included the panoramic radiographs of 20 patients from these 39 cases. Results: From the examination of the CBCT images we found: 28 lower third molars where the mandibular canal runs apical and have contact; 11 where the mandibular canal runs apical in contact with the tooth and it`s seen penetration of the apices of the tooth; 10 where the mandibular canal runs buccal with contact; 8 where the mandibular canal runs lingual with contact; 3 where the mandibular canal runs between the roots touching one/both of them. In three of the cases we found severe deviation of the root apices. From the examination of the panoramic radiographs we found: 5 cases with darkening of roots in the apical area; 8 with interruption of white line (lamina dura) of the mandibular canal; 1 with diversion of the mandibular canal with/without narrowing of the mandibular canal; 6 without any of these three signs. Conclusion: The development and rapid commercialization of new technologies like CBCT allows us to have precise images and exact diagnosis of the diseases in the oral and maxillofacial area. Our study confirmed the high diagnostic value of CBCT regarding to precise the position of the lower third molars to the mandibular canal and IAN. This gives the clinician the opportunity to determine which lower third molars are `high risk` teeth and to choose the best method for surgical treatment