正畸拔除下切牙患者出现牙龈黑三角的病因研究

Black Triangle in Orthodontic Patients with Mandibular Incisor Extractions: Prevalence and Etiology

目的:探讨拔除一颗下颌切牙,正畸治疗后牙龈黑三角的发生率及影响因素。方法:本回顾性研究纳入80例拔除1颗下颌切牙的固定矫治患者,根据术后口内正面照中拔除牙邻牙间是否出现黑三角,将患者分为正常组和黑三角组。利用口内照片、数字化模型、全景片等临床资料,分析患者邻牙接触点位置、牙根角度、邻接点至牙槽嵴顶高度、楔状隙宽度及面积等临床参数。结果:拔除一颗下颌切牙后,邻牙间牙龈黑三角的发生率为72.5%,其中轻度发生率为57.5%,中度发生率为15%,无重度黑三角发生。正常组和黑三角组患者在年龄、邻牙接触点位置、牙根角度、邻接点至牙槽嵴顶高度、楔状隙宽度及面积上具有统计学差别。回归分析显示,邻牙牙根角度和邻接点至牙槽嵴顶高度是影响拔除一颗下颌切牙的患者固定矫治后产生黑三角的主要风险因素。结论:拔除1颗下颌切牙的患者黑三角的发生率较高,正畸治疗需要控制邻牙牙根平行度,维持牙周组织健康,以减少黑三角的发生。

Objective:To explore the incidence and influencing factors of black triangle in patients with single mandibular incisor extractions after orthodontic treatment.Methods:Eighty fixed orthodontic treatment patients who had one mandibular incisor extracted were enrolled in this retrospective study,and were divided retrospectively into the normal group and the black triangle group based on whether there was a black triangle between the adjacent teeth of the extracted tooth in the posttreatment intraoral frontal photos.According to the intraoral photos,digital models,panoramic radiographs,and other clinical data,the position of interdental contact point,root angle,distance from interdental contact point to alveolar bone crest,width and area of embrasure space,and other clinical parameters were measured and analyzed.Results:After extraction of one mandibular incisor,the incidence of black triangle was 72.5%,with mild incidence of 57.5%,moderate incidence of 15%,and no severe black triangle occurred.There were statistically significant differences between the normal group and the black triangle group in age,position of interdental contact point,root angle,distance from interdental contact point to alveolar bone crest,and width and area of embrasure space.Logistic regression analysis showed that the adjacent teeth root angle and the distance from interdental contact point to alveolar bone crest were the main risk factors for the black triangle after fixed orthodontic treatment in patients with mandibular incisor extraction.Conclusion:The incidence of black triangle was higher in patients who had one mandibular incisor extracted.Orthodontic treatment needs to control the root angle of the adjacent teeth and maintain the health of periodontal tissue so as to reduce the occurrence of black triangle.