Wan Jun, Wen Xi, Geng Jing, Gu Yan
Department of Orthodontics, Peking University School and Hospital of Stomatology, National Center of Stomatology, National Clinical Research Center for Oral Diseases, National Engineering Research Center of Oral Biomaterials and Digital Medical Devices, B.
Korean J Orthod. 2024 May 25;54(3):171-184. doi: 10.4041/kjod23.262. Epub 2024 Apr 18.
This study aimed to determine the maxillary and mandibular basal bone regions and explore the three-dimensional positional relationship between the dentition and basal bone regions in patients with skeletal Class I and Class II malocclusions with mandibular retrusion.
Eighty patients (40 each with Class I and Class II malocclusion) were enrolled. Maxillary and mandibular basal bone regions were determined using cone-beam computed tomography images. To measure the relationship between the dentition and basal bone region, the root position and root inclination were calculated using the coordinates of specific fixed points by a computer program written in Python.
In the Class II group, the mandibular anterior teeth inclined more labially ( < 0.05), with their apices positioned closer to the external boundary. The apex of the maxillary anterior root was positioned closer to the external boundary in both groups. Considering the molar region, the maxillary first molars tended to be more lingually inclined in females ( = 0.037), whereas the mandibular first molars were significantly more labially inclined in the Class II group ( < 0.05).
Mandibular anterior teeth in Class II malocclusion exhibit a compensatory labial inclination trend with the crown and apex relative to the basal bone region when mandibular retrusion occurs. Moreover, as the root apices of the maxillary anterior teeth are much closer to the labial side in Class I and Class II malocclusion, the range of movement at the root apex should be limited to avoid extensive labial movement.
本研究旨在确定上颌和下颌基骨区域，并探讨骨骼I类和II类错牙合伴下颌后缩患者牙列与基骨区域之间的三维位置关系。
纳入80例患者（I类和II类错牙合各40例）。使用锥形束计算机断层扫描图像确定上颌和下颌基骨区域。为了测量牙列与基骨区域之间的关系，通过用Python编写的计算机程序，使用特定固定点的坐标计算牙根位置和牙根倾斜度。
在II类组中，下颌前牙唇倾度更大（<0.05），其根尖更靠近外部边界。两组上颌前牙根尖均更靠近外部边界。在磨牙区，女性上颌第一磨牙倾向于更舌倾（=0.037），而II类组下颌第一磨牙唇倾度明显更大（<0.05）。
II类错牙合患者下颌后缩时，下颌前牙相对于基骨区域在牙冠和根尖处呈现代偿性唇倾趋势。此外，由于I类和II类错牙合患者上颌前牙的根尖更靠近唇侧，根尖的移动范围应受到限制，以避免广泛的唇向移动。
