顎顔面骨格と咬合湾曲の関連性に関する研究

Abstract

Introduction : Owing to recent advancements in simulation software, it has become easy to perform three-dimensional simulation of tooth movement. However, a method for identifying the correct position of dentition in patients with various skeletal facial types has not been established. Therefore, this study aimed to define three types of occlusal curvature and compare the relationship between craniomaxillofacial morphology and the types of occlusal curvature at the time of initial examination. Materials and Methods: We enrolled 24 patients with skeletal Class Ⅱ brachyfacial pattern, 20 with skeletal Class Ⅲ dolicofacial pattern, and 20 with skeletal Class Ⅰ mesiofacial pattern. Three occlusal curvatures obtained by cephalometric tracing were defined as follows: 1) loading occlusal curvature: the occlusal curvature obtained by connecting three points of strong occlusal contact; 2) mechanical occlusal curvature: the occlusal curvature obtained by connecting two points of strong occlusal contact and the top of the condyle; and 3) morphological occlusal curvature: the occlusal curvature approximating the buccal cusp of all mandibular teeth. We then compared these three occlusal curvatures with maxillofacial morphology, overjet, and overbite. Results: In all three maxillofacial patterns, the center point of the mechanical occlusal curvature was located around the nasion. However, the radius of the mechanical occlusal curvature was significantly longer in patients with skeletal Class Ⅰ mesiofacial patterns than in patients with Class Ⅱ brachyfacial or Class Ⅲ dolicofacial skeletal patterns. In addition, there was a moderate negative correlation between the radius of the loading occlusal curvature and overjet in patients with skeletal Class Ⅰ mesiofacial patterns. Conclusion: In all three maxillofacial patterns, an upward mechanical occlusal curvature was observed, and the center point was located around the nasion.