800??????????????????????????

目的调查分析大连地区正畸患者恒牙先天缺失的发生率及分布,包括第三磨牙。方法随机抽取2008年7月至2011年6月来大连市口腔医院就诊的正畸患者800例(男260例,女540例;年龄9～40岁),通过观察其全颌曲面断层片,分析恒牙先天缺失的发生率及分布。结果包括第三磨牙在内的恒牙先天缺失发生率为36.13%,除第三磨牙外的恒牙先天缺失发生率为12.5%。性别间差异无统计学意义(P>0.05)。除第三磨牙外的轻度先天缺牙例数(缺失1～2颗牙)占87%,中度先天缺牙例数(缺失3～5颗牙)占10%,重度先天缺牙例数(缺失牙≥6颗)占3%。常见的缺失牙位因缺牙程度的不同而不同,轻度缺失时,最常见的缺失牙位在前牙(最多见的是右下侧切牙),随着缺牙程度的加重,常见的缺失牙位在后牙(最常见的是下颌第二前磨牙)。上、下颌的缺牙情况是,轻度缺牙(缺失1～2颗)时,下颌的发生率高于上颌;中、重度缺牙时,上、下颌之间差异无统计学意义(P>0.05)。上、下牙弓左右侧的缺牙发生率差异无统计学意义(P>0.05)。缺失牙≥2颗时,对称缺失占大多数,最常见的对称缺失牙位是下颌第二前磨牙。结论除第三磨牙外,大连地区正畸患者最常见的缺失牙位是下颌侧切牙;随先天缺牙程度加重,则以下颌第二前磨牙先天缺失最常见。

Investigation of the hypodontia in permanent dentition in 800 orthodontic patients

Objective To evaluate the prevalence and distribution of hypodontia in the permanent dentition, including the third molars, in a sample of Dalian orthodontic patients. Methods Based on pretreatment diagnostic records, the 800 orthodontic patients（260 males, 540 females） aged between 9 to 40 years in Stomatology Hospital of Dalian from July of 2008 to June of 2011 were examined. Results The prevalence of bypodontia was 36.13%（including the third mo- lar） and 12.5% （excluding the third molar）. No significant statistical gender difference was observed. The prevalence of mild hypodontia patients was 87% and the serious hypodontia patients was 3%, the moderate hypodontia patients 10%. The most frequently missing tooth was different according to the severity of hypodontia. The most frequently missing tooth was anterior tooth in mild hypodontia and posterior in moderate or severe hypodontia. The prevalence in mandibular was higher than maxillary in mild hypodontia, but there was no difference in moderate or sevece hypodontia. There was no difference between the prevalence of the left and right. Posterior tooth agenesis increased with hypodontia severity, symmetrical hypodontia was predominant, and the most frequently missing tooth was the mandibular second premolar. Conclusion Excluding the third molar, the most frequently missing tooth is the mandibular lateral incisor, but with the increase of the number of absence, the most frequently missing tooth becomes the mandibular second premolar.