800例正畸患者中先天缺失牙及其与多生牙、锥形牙相关性分析

目的：观察正畸患者中伴有恒牙先天缺失、多生牙和锥形牙或过小牙的发生率及分布，并分析其相关性。方法：随机抽取正畸患者800例，男260例，女540例，年龄12-40岁。通过石膏模型和曲面断层片统计先天缺牙、多生牙、锥形牙或过小牙的发生率及分布。通过分类变量的关联性来分析多生牙和锥形牙或过小牙与先天缺牙的相关性，假设检验采用列联表的独立性x2检验，并采用Pearson列联系数r来描述两变量关联程度。结果：800例中发生恒牙先天缺失100例，发生率为12．5％。常见的缺失牙位从多到少依次为下颌侧切牙、下颌第二前磨牙、下颌中切牙、上颌侧切牙、上颌第二前磨牙。多生牙的发生率为3．1％，锥形牙或过小牙占8．3％。通过分类变量的关联性分析得出，锥形牙或过小牙的发生与先天缺牙有相关性，Pearson列联系数r为0．173。结论：正畸患者中恒牙先天缺失的发生率为12．5％，最常见的缺失牙位是下颌侧切牙和下颌第二前磨牙；正畸患者中恒牙先天缺失和锥形牙或过小牙的发生具有相关性。

Hypodontia and correlation analysis between it with peg-shaped teeth or supernumerary teeth in 800 cases of ;orthodontic patients

Objective： The purpose of this study was to evaluate the prevalence and distribution of hypodontia / super- numerary teeth/peg-shaped teeth and the correlation with them. Method： the random cases of 800 orthodontic patients （260 males, 540 females）between 12 to 40 Yrs. By observing the plaster east and panoramic x-ray,the prevalence and distribu- tion of hypodontia/supernumerary teeth/peg-shaped teeth or too-small teeth were statisticalled.Investigate the correlation be- tween each dental anomaly and hypodontia by the relevance of classification variables, using the independence chi-aquare test, and describe the degree of correlation with Pearson contingency coefficient. Result：There are 100 cases of hypodontia in the 800 cases, The prevalence of hypodontia was 12.5 %. the frequently missing tooth were the mandibular lateral incisor, the mandibular second premolar, the mandibular middle incisor, the maxillary lateral incisor, the maxillary second premolar decrease progressively, the prevalence of supernumerary teeth was 3.1%, the prevalence of peg-shaped teeth was 8.3 %.Sta- tistically significant correlations were found between peg-shaped teeth and hypodontia, Pearson contingency coefficient are 0.173. Conclusion：The prevalence of hypodontia was 12.5 %. The most frequently mossing tooth is the mandibular lateral incisor and the mandibular second premolar.There were the correlations between the incidence of peg-shaped teeth and hy- podontia.