Chunduru Ramyaja, Kailasam Vignesh, Ananthanarayanan Venkateswaran
Department of Orthodontics and Dentofacial Orthopedics, Sri Ramachandra Institute of Higher Education and Research (SRIHER), Chennai, India.
J Korean Assoc Oral Maxillofac Surg. 2024 Oct 31;50(5):265-272. doi: 10.5125/jkaoms.2024.50.5.265.
Skeletal class III malocclusion presents either with maxillary retrognathism, mandibular excess, or a combination. Dentoalveolar compensations occur with maxillary incisor proclination and mandibular incisor retroclination. The aim of this study is to quantify the amount of incisal compensation in class III skeletal malocclusion and correlate it to the severity of the skeletal base.
Eleven angular and 7 linear cephalometric measurements were digitized from 57 patients. Axial inclination of the upper and lower incisors was evaluated for compensation. Pearson's correlation coefficient was used to determine the dentoalveolar parameter among those measuring upper and lower incisor position and inclination that correlated most highly with the severity of class III. Linear regression analysis was used to identify the quantum of the incisal compensation.
Upper incisors were proclined and placed anteriorly. However, correlation analysis suggested a less responsive incisor with progressive change in skeletal base. Lower incisors began to compensate only as the severity of class III increased. For every degree of reduction of ANB angle from normal, the incisor mandibular plane angle (IMPA) and L1-GoMe decreased by 0.79° and the L1-GoGn decreased by 0.81°.
The upper incisors contributed more to compensation compared to the lower incisors in a class III skeletal base. As class III severity increased, the upper incisor compensation decreased while that of lower incisors increased. For every degree of reduction in ANB angle, the IMPA and L1-GoMe decreased by 0.79° and the L1-GoGn decreased by 0.81°.
骨性III类错牙合表现为上颌后缩、下颌前突或两者皆有。牙牙槽代偿表现为上颌切牙前倾和下颌切牙后倾。本研究的目的是量化III类骨性错牙合中切牙代偿的量，并将其与骨性基础的严重程度相关联。
对57例患者的11项角度和7项线性头影测量数据进行数字化处理。评估上下切牙的轴倾度以确定代偿情况。使用Pearson相关系数来确定在测量上下切牙位置和倾斜度的参数中，与III类严重程度相关性最高的牙牙槽参数。采用线性回归分析来确定切牙代偿的量。
上颌切牙前倾并位于前方。然而，相关分析表明，随着骨性基础的逐渐改变，切牙的反应性较小。下颌切牙仅在III类严重程度增加时才开始代偿。ANB角每从正常减小1度，下颌切牙平面角（IMPA）和L1-GoMe减小0.79°，L1-GoGn减小0.81°。
在III类骨性基础中，上颌切牙比下颌切牙对代偿的贡献更大。随着III类严重程度增加，上颌切牙代偿减少而下颌切牙代偿增加。ANB角每减小1度，IMPA和L1-GoMe减小0.79°，L1-GoGn减小0.81°。
