乌鲁木齐地区青少年恒牙形态及数目异常的分析

目的探讨乌鲁木齐地区青少年先天缺失牙、多生牙、过小牙的发生率及好发部位。方法本文观察和分析了620例患者的全颌曲面体层X线片．均无恒牙拔牙史或牙齿损伤史。结果先天缺失牙（包括第三磨牙）的发生率为45．48％，第三磨牙的缺失发生率为32．58％，缺失牙的好发部位依次为上颌第三磨牙、下颌第三磨牙、下颌侧切牙、下颌中切牙、上颌第二双尖牙等;多生牙发生率为2．58％，好发部位是上颌切牙区。过小牙的发生率为6．30％．其主要为上颌侧切牙。结论牙齿先天缺失在人群中的发生率明显高于多生牙．缺失牙主要发生在功能相对弱的牙位上：缺失牙与过小牙之间存在一定联系．

A survey of number and morphology anomalies of permanent teeth in Urumgi adolescents

Objective The purpose of this study was to investigate the prevalences and locations of number and morphology anomalies in permanent teeth in Urumgi adolescent. Methods 620 panoramic radiographs were observed and analyzed. Adolescents with no permanent teeth extracted or hurt were included in the study. Results The prevalence of hypodontia including the third molar was 45.48%. The prevalence of missing third molar was 32.58%. Hypodontia often involved maxillary third molars, mandibular third molars, mandibular lateral incisors, mandibular middle incisors, maxillary second premolars and etc. The prevalence of supernumerary teeth was 2.58%, mostly involving maxillary incisors. The prevalence of microdontia was 6.30%, while predominantly in maxillary lateral incisor. Conclusions The prevalence of hypodontia was higher than that of supernumerary teeth. Hypodontia was mostly occurred in teeth owning weaker masticatory forces, and had some kind of connection with microdontia.