Endo Toshiya, Ozoe Rieko, Yoshino Sugako, Shimooka Shohachi
Department of Orthodontics, The Nippon Dental University Niigata Hospital, Niigata, Japan.
Angle Orthod. 2006 Nov;76(6):996-1003. doi: 10.2319/082905-303.
The purpose of this study was to explore the association of hypodontia patterns and variations in craniofacial morphology in Japanese orthodontic patients.
A total of 50 girls with hypodontia (the total group) were selected and categorized into anterior, posterior, and anterior-posterior groups according to the location of the congenitally missing teeth. By using the lateral cephalograms of each subject, 28 angular and 37 linear measurements were made. The cephalometric data were statistically analyzed and compared among the groups and with the Japanese cephalometric standards from 36 age-matched female subjects without hypodontia or malocclusion (the control group).
Every hypodontia group showed shorter anterior and overall cranial base lengths, shorter maxillary length, greater retroclination and elongation of mandibular incisors, and a larger interincisal angle than the control group. The total and anterior-posterior groups especially exhibited a significantly more prognathic mandible, larger retroclination of maxillary incisors, and a more counterclockwise-rotated occlusal plane. Furthermore, these skeletal and dental deviations were more remarkable in the anterior-posterior group than in either the anterior or the posterior group. Anterior hypodontia exerted as much influence on craniofacial morphology as posterior hypodontia.
When orthodontic treatment is performed on patients with hypodontia, not only the number but also the distribution of missing teeth should be taken into consideration, though there was no significant difference in craniofacial morphology between anterior hypodontia and posterior hypodontia.
本研究旨在探讨日本正畸患者缺牙模式与颅面形态变化之间的关联。
共选取50名患有缺牙症的女孩（总样本组），并根据先天性缺牙的位置将其分为前牙区、后牙区和前后牙区组。利用每位受试者的头颅侧位片，进行了28项角度测量和37项线性测量。对头颅测量数据进行统计学分析，并在各样本组之间进行比较，同时与36名年龄匹配、无缺牙症或错牙合畸形的女性受试者的日本头颅测量标准（对照组）进行比较。
与对照组相比，每个缺牙症组均表现出前颅底和整个颅底长度较短、上颌长度较短、下颌切牙的倾斜度更大且牙体长轴更长以及切牙间角度更大。总样本组和前后牙区组尤其表现出明显更前突的下颌、上颌切牙更大的倾斜度以及更逆时针旋转的牙合平面。此外，这些骨骼和牙齿偏差在前后牙区组中比在前牙区组或后牙区组中更为明显。前牙区缺牙对颅面形态的影响与后牙区缺牙一样大。
在对缺牙症患者进行正畸治疗时，虽然前牙区缺牙和后牙区缺牙在颅面形态上没有显著差异，但不仅应考虑缺牙的数量，还应考虑缺牙的分布情况。
