锥形束CT在上颌尖牙埋伏病因机制中的应用

目的:利用三维锥形束CT技术研究上颌尖牙唇侧和腭侧埋伏的病因学机制?方法:选取262例有上颌尖牙埋伏和262例无尖牙埋伏的患者为研究对象,其中前者分为唇侧埋伏组和腭侧埋伏组,在治疗前均接受CBCT扫描?在单盲条件下对CBCT数据进行分析,以获取牙齿?牙弓和颌骨的定性和定量资料?采用 SPSS13.0 软件包对测量结果进行统计学分析?结果:腭侧埋伏组侧切牙牙冠的近远中宽度显著小于其他组(P < 0.001)?唇侧埋伏组的上牙弓前段宽度和上颌骨宽度都显著小于对照组(P < 0.001)?腭侧埋伏组中锥形侧切牙和唇侧埋伏组中切牙埋伏的发生率均显著提高(P < 0.001)?唇侧埋伏组和腭侧埋伏组尖牙牙尖所处的部位分别位于侧切牙长轴的近中和远中?结论:中国人群上颌尖牙唇侧埋伏阻生主要与上颌前部牙弓和颌骨宽度不足以及切牙埋伏有关,而上颌尖牙腭侧埋伏主要与相邻侧切牙过小或缺失有关?上尖牙萌出路径受上述局部因素作用而产生变化导致不同方位的埋伏阻生?

Application of cone-beam computed tomography analyses on etiologic factors for maxillary canine impaction

Objective:To identify the etiologic factors associated with palatally impacted canines and buccally impacted canines in a Chinese population using the cone-beam computed tomography (CBCT) technique. Methods:CBCT images of 262 Chinese subjects with impacted maxillary canines(buccally impacted canines and palatally impacted canines) and 262 age- and sex-matched subjects without impaction were admitted to the study. All CBCT records were analyzed in software programs for quatitative and quantitative variables of the teeth,dental arch and skeletal components by one rater. The differences among groups were compared statistically (SPSS 13.0 software). Results:The mesiodistal dimension of the lateral incisor was significantly smaller in the palatally impacted canine group than that in the other groups(P < 0.001). Both anterior maxillary dental width and skeletal width in the buccally impacted canine group were significantly smaller than those in the control group (P < 0.001). The groups with palatally impacted and buccally impacted canines had significantly increased prevalence of peg-shaped lateral incisors and incisor impaction,respectively(P < 0.001). The average mesiodistal location of the canine cusp tip was significantly different between the buccally impacted canines and the palatally impacted canines groups,being mesial and distal to the lateral incisor long axis,respectively. Conclusion:In Chinese subjects,buccal canine impaction is mostly associated with anterior transverse(dental and skeletal) deficiency and incisor impaction,however,palatal impaction is mostly associated with small or missing lateral incisors,consistent with the guidance theory. A mechanism is proposed to explain the processes leading to different fates of canine eruption in response to varied local factors.