EVALUATING THE THREE DIMENSIONAL SPREAD OF ANTERIOR LOOP OF MANDIBULAR NERVE FOR PREDICTABLE IMPLANT INSERTION IN MANDIBLE - A CBCT ANALYSIS ON NORTH-INDIAN POPULATION

Introduction: Implant placement requires an understanding of regional anatomy and a precise knowledge of the location of important anatomic structures such as the inferior alveolar nerve and maxillary sinus. At its anterior exit the inferior nerve creates a loop before exiting through the mental foramen. The dimensions of the anterior loop of inferior alveolar nerve are variable among individuals. This study was undertaken to assess the variability in the dimensions of this loop, so as to achieve predictable implant placement in the area of mental foramen.

Materials and Methods: Eighty one CBCT scans of patients after exclusion from a sample of hundred CBCTs were used in the study. Individual sections were evaluated for the greatest dimension of the loop in the antero-posterior and supero-inferior direction. The greatest dimension was transferred to the sagittal plane, and measured perpendicular to the inferior border of mandible. T-test was used for statistical analysis of the data.

Results: 68 of the 81 cases studied had an anterior loop in the mandibular nerve. The mean value obtained in males for the antero-posterior dimension was 3.65 mm on the right side, and 3.56 on the left side. For the females the value obtained was 3.02, and 2.91 mm for right and left side. In the supero-inferior dimension the corresponding values for males for the right and left side were 4.28mm and 4.18 mm. For the females group the values obtained were 3.24 mm and 3.17 on the right and left side. The results were statistically significant with p value <0.05.

Conclusion: A minimum distance of 6 mm is recommended to prevent damage to the anterior loop. Using the CBCT data for treatment planning is however the gold standard and should be prioritized over using average values for implant insertion.