Evaluation of the risk of inferior alveolar nerve injury during an implant procedure: A comparative study between OPG and CBCT

Abstract

Background and objectives: Dental implants are considered as one of the major options for replacement of missing teeth and this surgical procedure may be accompanied by trauma to the adjacent vital structure when there is inadequate information of the implant site. The use of OPG as a preliminary diagnostic instead of CBCT may expose the patient to a high risk of trauma to an inferior alveolar canal. To evaluate the possibility of the risk of endangering inferior alveolar nerve during implant placement using OPG or CBCT as a preoperative assessment tool. Patients and methods: This study is a prospective cross-sectional study carried out in outpatient clinic of the college of dentistry and Denta Plus private center in Erbil city during the period from 1st of January to 31st of August, 2018. A sample of 49 patients was selected according to special criteria: Group I consists of 33 patients who had implant in molar and premolar regions, in this group pre-implant assessment done by Orthopantomogram (OPG). Group II; consists of 16 patients who had implant in molar and premolar regions, in this group pre-implant assessment done by Cone beam computed tomography (CBCT). The measurement of the distance between a dental implant and inferior alveolar canal were analyzed by CBCT which classified into four levels of parameters (distances) a-Safety zone ≥2 mm, b-Risky zone 1-2 mm, c-Error and high risk >0-1 mm, d-Traumatized ≤0 mm. Results: the distance between implant and inferior alveolar canal (IAC) for group I (OPG) patients were as following: - in the safety zone for 30.3%, in the risky zone for 15.2%, in error & high risk for 21.2% and traumatized for 33.3%, while this distance for group II (CBCT) patients was in the safety zone for 75%, in the risky zone for 6.3%, in error & high risk for 12.5% and traumatized for 6.3%. Conclusion: Cone beam computed tomography is the best choice compared to OPG in the pre-implant evaluation and planning for placement as it showed a lower risk of injury to an inferior alveolar canal.