The Effect Of Weak Areas Of Mandible In SSRO Evaluated By Multislice Spiral CT And Three-dimensional Reconstruction

Objective:To investigate the weak area in mandible, which are the mandibular anterior border angle and the thickness from the lateral wall of mandibular nerver canal to lateral wall of mandibular ramus, to avoid mandible fracture and the inferior alveolar nerve injury, and to raise the achievement ratio in sagittal split ramus osteotomy (SSRO).Method:268 patients who underwent 3D reconstruction of multislice spiral CT were retrospectively reviewed.157 male cases,111 female cases, aging between 10～69 years old,17 male cases and 11 female cases between 15～19 years old; 20 male cases and 20 female cases between 20～29 y; 28 male cases and 14 female cases between 30～39 y; 24 male cases and 20 female cases between 40～49 y; 26 male cases and 10 female cases between 50～59 y; 42 male cases and 36 female cases between 60～69 y. Computerized tomography (CT) was taken and processed for 3D reconstruction to visualize the anatomy of the mandible. Mandibular anterior border angle and the thickness from the base of mandibular nerver canal to mandibular ramus lateral wall were measured on both sides of each mandible.Results:(1). There was no significant difference between two sides of mandibule in the mandibular anterior border angle and the distance from the lateral wall of mandibular nerver canal to lateral wall of mandibular ramus (P>0.05). There were statistical differences (P<0.05) between male and female; (2) Male subjects showed a larger mandibular anterior border angle than female subjects(P<0.05). (3).There were no statistical differences between male and female in the distance from the lateral wall of mandibular nerver canal to lateral wall of mandibular ramus (P>0.05). (4) There were stastistical differences in the age groups(P<0.05).Conclusion:3D Reconstruction of multislice spiral CT is now admitted as the most preferable method used for bone scan and reconstruction. The reconstructed image is constant even if it is rotated, zoomed, cut and so on.3D Reconstruction of multislice spiral CT and measurement can replace dissection measurement completely in three-dimensional viewing and measuring of human mandible for its higher accuracy, thus can totally replace the measurement by physical anatomy and make it feasible for the measurement in vivo. In vivo mandible 3D measurement database of the lower mandibular anterior border angle and the thickness from the base of mandibular nerver canal to mandibular ramus lateral wall and 3D displat system of which based on 3D reconstruction of multislice spiral CT technique is established. The normal value of every index on each side and group and sex is eatablished. We first report these two sets of data and expect guiding the clinical surgery and to enrich our database of human digitized data knowledge.