The Anatomical Relationship of the Mandibular Canal and Related Structures in Immature and Mature Dried Mandibles

The anatomical relationship of the mandibular canal and related structures were examined in 29 dried human mandibles (21 mature and eight immature). First and second premolars and molars were sectioned in a buccal-lingual plane. The molars were separated into mesial and\u27 distal sections. A total of 322 sections were examined according to age (immature or mature), left or right, and type of tooth/root. Thirteen measurements were taken of each section and the results were statistically analysed. The results indicated no significant difference between the mean averages when comparing the 13 data points between the left and right side of mandibles using the Pearson correlation test (P\u3c.05). It was found that the apices of mature second molars and second premolars had the closest proximity to the mandibular canal in the vertical and horizontal planes. Twenty percent of the second premolar apices and 17% of the second molar apices were located within a vertical distance of 2.0mm and a horizontal distance of 1.5mm to the mandibular canal. The mean distance between second molar apices and mandibular canal was 3.7mm. With a mean of 6.9mm, the apices of the mesial roots of the first molars were located the furthest from the mandibular canal. In the immature mandibles, the closest approximation between the apices and the mandibular canal was noted in the distal root of the first molar (69%) and both roots of the second molar (64-69%). The mean average for these teeth was 1.4mm. The pathway of the canal in relationship to the apices of the teeth in the mature mandible followed an S-shaped curve in 31% of the mandibles, lingually in 19%, buccally in 17%, and apically in 5%. In 28% of the cases this pathway could not be determined due to the lack of a definite canal wall. In the S-shaped curve, the canal is located to the buccal of the distal root of the second molar, crosses to the lingual close to the mesial root, runs lingual to the first molar and then crosses back to the buccal apically to the second premolar. The canal in the buccal pathway is located buccal to the long axis of the posterior teeth while the lingual pathway is located to the lingual. In 69% of the immature mandibles the canal is located apically to most of the posterior apices and in close approximation to them. Also observed was the S-shaped pathway (18%); however, no buccal or lingual pathways were seen in the immature mandibles. The pathway of the canal in 18% could not be determined due to the lack of a canal wall