Abstract:

Objective To study morphology feature of mandibular anatomical characteristics and mandibular nerve
canal of hemimandibular elongation（HE） using CT, and provide reference for the clinical treatment. Methods 19
patients with HE were scanned using multidetector CT. Mimics 10.0 software was used for three-dimensional reconstruction,
and CT images were reconstructed on different sections. The position of mandibular nerve canal, mandibular
foramen and thickness of mandibular cortical bone were measured, and compared with control group（without mandibular
lesion）. Results Compared with the control group, the distance between mandibular nerve canal and mandibular surface were statistically different at the section of long axis of mandibular first molar centre（LAMFM）-lingual, long axis of mandibular second molar centre（LAMSM）-buccal, LAMSM -superior, retromolar area centre to the mandibular angle（RAC-MA）-buccal, RAC-MA-superior, RAC-MA-inferior and horizontal level of mandibular foramen under 5 mm （HLMFU5）-lingual, HLMFU5-anterior, HLMFU5-posterior（P<0.05）; the thickness of mandibular cortical bone were statistically different at the LAMFM-buccal, LAMFM-inferior（P<0.05）; lowest point of mandibular foramen（LPMF）- superior border of mandibular ramus（SBMR） and LPMF-inferior border of mandibular ramus（IBMR） were statistically different（P<0.05）. Conclusion In the patients with hemimandibular elongation, the thickness of mandibular cortical bone gradually decreases in all directions from the mandibular first molar to the mandibular ramus. Compared with the control group, mandibular nerve canal located buccally and superiorly at mandibular second molar and retromolar area, mandibular foramen located more anterior and lower inside mandibular ramus.

Key words: condylar hyperplasia, mandibular protrusion, mandibular foramen, mandibular nerve canal