From the Postgraduate School of Orthodontics, University of Ferrara, Ferrara, Italy.
From the Postgraduate School of Orthodontics, University of Ferrara, Ferrara, Italy.
Am J Orthod Dentofacial Orthop. 2024 Aug;166(2):171-178. doi: 10.1016/j.ajodo.2024.04.011. Epub 2024 May 18.
The objective of this study was to identify the soft-tissue profile changes and the potential pretreatment cephalometric parameters that clinicians could use to predict the lip response after premolar extraction treatment in adult patients.
Pretreatment and posttreatment lateral cephalograms of 75 white patients treated with premolar extractions were analyzed. The following initial cephalometric measurements were recorded: upper and lower lip to E-plane, vermilion thickness, lip length, maxillary and mandibular incisor inclination, and mentolabial and nasolabial angle. Pretreatment and posttreatment radiographs were superimposed using the Björk structural method to record lip retraction and incisor/lip retraction ratio. Pearson correlation and Kruskal-Wallis tests were used to compare lip retraction and incisor/lip retraction ratio with the cephalometric variables. The sample was divided according to different extraction patterns.
The mean upper and lower lip retraction values were 1.4 mm and 1.7 mm, respectively. Vermilion thickness showed a negative and statistically significant correlation (P <0.05) with lip retraction and incisor/lip retraction ratio. In addition, the mean incisor/lip retraction ratio was 61% and 98% for the upper and lower thin lip, respectively, whereas the mean incisor/lip retraction ratio was 17% and 44% for the upper and lower thick lip, respectively. The comparison among extraction patterns did not highlight any noticeable difference.
The choice of a specific extraction pattern did not impact lip response. The vermilion thickness was the key factor influencing lip retraction: an increase in this parameter was related to a decrease in lip retraction and vice versa.
本研究的目的是确定软组织侧貌变化和潜在的术前头影测量参数，以便临床医生预测成人患者双尖牙拔除治疗后唇部的反应。
对 75 例接受双尖牙拔除治疗的白人患者的治疗前后侧头颅侧位片进行分析。记录以下初始头影测量值：上、下唇与 E 平面的距离、唇红厚度、唇长、上颌和下颌切牙倾斜度以及颏唇沟和鼻唇角。使用 Björk 结构法对治疗前后的 X 光片进行叠加，以记录唇部退缩和切牙/唇退缩比。采用 Pearson 相关和 Kruskal-Wallis 检验比较唇退缩和切牙/唇退缩比与头影测量变量之间的关系。根据不同的拔牙模式对样本进行分组。
上、下唇退缩的平均值分别为 1.4mm 和 1.7mm。唇红厚度与唇退缩和切牙/唇退缩比呈负相关（P<0.05）。此外，薄唇的平均切牙/唇退缩比分别为上唇 61%和下唇 98%，而上唇和下唇的厚唇平均切牙/唇退缩比分别为 17%和 44%。不同拔牙模式之间的比较并未发现明显差异。
特定拔牙模式的选择不会影响唇部反应。唇红厚度是影响唇退缩的关键因素：该参数增加与唇退缩减少相关，反之亦然。
