Relationship between Mandibular Canal Size and Mandibular Height and Width

Location of mandibular canal must be known prior to fixture installation. The canal outline can usually be defined in consecutive cross-sectional radiographic images. However, in some images, definite outline cannot be traced though center of canal is estimated based on adjacent images. If a certain ratio between size of canal and mandible has a likelihood, canal size can be calculated. Objectives: To assess ratio between size of mandibular canal and mandible and to correlate size of mandibular canal to mandible. Methods: Three hundreds and fifty-six cross-sectional images of 100 mandibles of Thai patients examined by computed tomography were selected. The patients comprised 44 males (average age, 48.27 +/- 15.99 years) and 56 females (average age, 43.00 +/- 13.28 years). The images comprised 65 and 51 images in area #35 and #45, 45 and 49 images in area #36 and #46, 67 and 79 images in area #37 and #47, respectively. The canal diameter, mandibular bone height from root apex to lower border of mandible and bone width were measured. A second measurement was performed to calculate measurement precision using Dahlberg's formula. The ratios between mandibular canal size and mandibular bone height and width were calculated and described. The correlations between mandibular canal size and mandibular bone height and width were investigated using Spearman's rho. Results: The measurement precision was from 0.12 to 0.19 mm. The ratio between canal size and bone height was from 0.05 to 0.30. The ratio between canal size and bone width was from 0.11 to 0.51. The correlations between canal size and bone height and width were less than 0.32. Conclusions: A likelihood of a representative ratio between mandibular canal size and mandibular bone height and width was not found. Supported by Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand. Grant 3205312 #15/2548