Construction of point-based mandibular median sagittal plane / 上海交通大学学报（医学版）

ABSTRACT

Objective: To develop a new point-based mandibular median sagittal plane (MMSP) by selecting from varied mandibular planes which were formed by combining bony landmarks derived from multiple regions of the mandible. Methods: Forty adult patients were evenly divided into two groups by the degree of chin deviation mandibular asymmetric group (MA group) and mandibular symmetric group (MS group). Three dimensional (3D) mandibular models were rebuilt by Mimics 19.0 software. In this software, 3D coordinates of 4 central landmarks and 6 pairs of lateral landmarks were collected. Then 120 candidate planes were constructed by point-based method, and compared with the reference plane formed by the iterative closest point (ICP) algorithm. All the planes were reordered and screened by geometric indices such as angle, distance and area in MS group. In addition, the clinical symmetrical indices such as point-to-plane distance, surface area difference, volume difference, and 3D deviation ratio of screened planes were compared in MA and MS groups. Results: The candidate planes co-constructed with landmarks from three mandibular regions (symphysis, mandibular angle and coronoid process) were the top 5% of all the planes. Among them, no statistical difference between B-Cor-Golat plane (constructed with supramentale, coronoid superius and gonion lateralis) and ICP plane was found (P >0.05), while there were significant differences between the rest screened planes and the reference plane (P<0.05). Conclusion: The B-Cor-Golat plane can be used as the mandibular median sagittal plane to reflect the symmetrical degree of the mandible well.