Mental Nerve Anterior Loop Detection in Panoramic and Cone Beam Computed Tomography Radiograph for Safe Dental Implant Placement.

Background and aim Different imaging modalities have been used as preoperative assessment tools since the emergence of dental implants. This study aimed to compare the detection and presence of mental nerve anterior loop in cone beam computed tomography (CBCT) radiograph and panoramic radiograph. Material and methods A descriptive, retrospective study was done. The optimal sample size was calculated using Epi Info software. According to the study population (795), the sample size was 259 cases which gave 95% power of the study. A previously taken CBCT and digital panoramic radiographs from the database of Taibah University Dental School and Hospital were observed by two trained and calibrated examiners to determine the presence of a mental nerve anterior loop and compare the two modalities. The mean length of the mental nerve anterior loop was also assessed.  Results Mental nerve anterior loops were detected bilaterally in 57.1% and 17.4% using CBCT and panoramic radiographs, respectively. In CBCT, the right side (20.8%) had a higher prevalence of mental nerve anterior loop than the left side (12%). The mental nerve anterior loop was not visible in 49.4% of the cases using a panoramic radiograph, while CBCT gave 10% of cases as not visible. The mental nerve anterior loop average length was 1.8 ± 0.35 mm and the width was 1.7 ± 0.28 mm. The average distance from the mental foramen to the inferior border of the mandible was 12.1 ± 0.87 mm and the average distance from the mental frogmen to the mandibular midline was 25.1 ± 0.68 mm. Conclusion As differences between CBCT and panoramic radiographs were statistically significant, CBCT is more accurate and reliable. CBCT is recommended to be used as a preoperative assessment tool to minimize nerve injury-related surgical complications during implant placement at the mandibular premolar area.