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．     

单纯型恒牙先天缺失患者缺牙特点的临床分析

目的了解单纯型恒牙先天缺失患者的缺牙牙位和临床统计学特点。方法收集183例单纯型恒牙先天缺失患者的病史、口腔检查及曲面断层X线片等资料，分类进行统计学分析。结果牙齿缺失数目、性别差异无统计学意义（P〉0.05）；上下颌、左右侧之间牙齿缺失差异无统计学意义（P〉0.05）；最易缺失的牙齿为下颌第二前磨牙，共缺失154颗；多数牙缺失患者磨牙缺失率为25.00％，较个别牙缺失患者磨牙缺失率（3．05％）明显增高，差异有统计学意义（P〈0．05）。结论不同患者恒牙缺失的临床表现不同；单纯型恒牙先天缺失患者中，除第三磨牙外，最易缺失的牙齿是下颌第二前磨牙，其次是下颌切牙、上颌第二前磨牙及上颌侧切牙     

先天缺牙与牙形态、大小异常相互关系的研究

目的 探讨先天缺牙与牙形态异常及牙大小异常的相互关系。方法 对79例先天缺牙患者的缺牙部位、缺牙数目，余留牙异常的牙体形态进行分析。并按缺牙程度及部位分成4组，测量其牙冠宽度。结果 （1）上颌侧切牙、下颌中切牙为临床最常见牙先天缺失部位，上颌中切牙，上下颌第一磨牙为牙列中最不易先天缺失的牙齿，但上颌中切牙在先天缺牙患者中常呈轻度的锥形牙冠。（2）先天缺牙常伴牙齿形态异常，以上颌侧切牙，下颌尖牙、上颌第二前磨牙，上下颌第二磨牙多见。（3）轻度先天缺牙患者余留牙大小无异常，随着先天缺牙严重程度增加，前牙有逐渐减小趋势而后牙大小较稳定。结论 （1）上颌侧切牙为牙列中最不稳定的牙齿：（2）牙齿形态、大小、数目异常可能是一个连续的变异过程，可能为同一机制的不同表现。     

145例少牙多牙症的回顾性研究

目的 应用曲面体层技术探讨少牙多牙症（CHH）的发生率和临床特征。 方法 收集2019年1月—2021年5月就诊的41 648例儿童口腔科患者的曲面体层片,纳入CHH患者145例,观察记录CHH的发生情况。应用SPSS 24.0软件统计分析所得的数据。 结果 CHH的发生率为0.35%（145/41 648）,男性（102例）多于女性（43例）,性别间差异有统计学意义（P<0.001）。恒牙先天缺失特征：缺失1~2颗为主;最好发下颌侧切牙和下颌第二前磨牙;下颌恒牙先天缺失多于上颌恒牙先天缺失,二者差异有统计学意义（P<0.001）;左侧先天缺失与右侧先天缺失差异无统计学意义（P=0.84）。多生牙特征：数目1~2颗;多见于上颌前牙区;多为圆锥形;垂直倒置生长和垂直正位生长为主。 结论 CHH是一种少见的混合牙齿数目异常,男性多于女性,恒牙先天缺失和多生牙的特征与单独发生的恒牙先天缺失/多生牙的特征相似,建议早期诊断和多学科治疗。     

先天缺牙与牙颌畸形

部份恒牙先天缺失是牙颌畸形常见先天病因之一。当先天缺牙并伴有其它某些局部、全身或遗传因素时,畸形可能更加复杂,给治疗带来一定的困难。有关先天缺牙问题,早在100多年前已有报告,其发生率为2.3～6.0%,可能缺失一个或多个乳牙或恒牙,缺失最多者为下颌第二双尖牙,其次为上颌侧切牙,上颌第二双尖牙,下颌中切牙。本文的目的是探讨     

十堰地区下切牙先天缺失错(牙合)的临床分析

先天性缺牙是常见的发育异常，多发生于上下第三磨牙、下颌切牙、上颌第二前磨牙、下颌第二前磨牙及上颌切牙。下切牙先天缺失是先天缺牙中最常见的类型之一，目前国内尚无单独下切牙缺失及其临床表现的报告。现将十堰市东风口腔医院近几年收治的下切牙先天缺失的病例进行调查统计，结果报道如下。     

6453名17～21岁青年人恒牙发育异常的调查

目的调查青年人恒牙牙齿形态和数目异常的状况。方法2002至2004年对3所北京高校6453名17～21岁学生进行恒牙数目和形态异常的调查。对不同性别和不同牙位发育异常的患病率进行卡方检验，并对2种牙齿异常伴发的情况进行卡方检验。结果牙齿数目和形态异常的总患病率为16．07％。女性锥形牙或桶状牙、畸形中央尖和先天缺牙的患病率高于男性，差异有统计学意义（P〈0．05）。牙内陷、锥形牙或桶状牙好发于上颌侧切牙，畸形中央尖好发于下颌第二前磨牙，融合牙和先天缺牙好发于下颌切牙，差异均有统计学意义（P〈0．01）。锥形牙或桶状牙与先天缺牙伴发的比率高，差异有统计学意义（P〈0．01）。结论各种牙齿数目和形态异常的患病率、性别差异和好发牙位与以往的研究基本相符。但锥形牙或桶状牙、畸形中央尖的女性患病率均高于男性。     

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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。     

牙列间隙修复前正畸治疗体会

随着社会发展和人民生活水平提高,越来越多人开始重视牙齿、咬合、面容的协调关系,其中因牙列间隙影响美观及发音的求治者与日俱增,特别是成人患者。作者自2001年以来对牙列间隙患者在修复前进行辅助性正畸治疗后,再进行牙列缺损及过小牙的修复,既恢复了患者颜面部的美观,又使患者获得了良好的咀嚼功能,取得了令人满意的效果。1.临床资料个别前牙或前磨牙缺失及过小牙致牙列散在间隙者10例。男性6例,女性4例;年龄15-42岁。其中1例2缺失,2例2缺失,2例下颌侧切牙均缺失,3例4缺失,2例上颌侧切牙均为过小牙。Angle I类咬合关系3例,AngleⅡ类咬…     

36例下切牙先天缺失正畸治疗的临床体会

目的探讨下切牙先天缺失的矫治设计。方法以伴有下切牙先天缺失的36例错畸形患者为研究对象,对下切牙缺失的部位、数目、错类型、矫治方法进行分析,并对缺失1颗下中切牙、拔除上颌2颗第一前磨牙和下颌1颗非缺牙侧第一前磨牙的病例及缺失2颗下中切牙、拔除上颌2颗第一前磨牙的病例的Bolton指数分析进行统计学检验。结果36例患者正畸治疗后均取得了较好的疗效。两组拔牙病例之间的Bolton指数全牙比无统计学差异（P>0.05）,而前牙比和前牙不调量有统计学差异（P<0.01）。结论先天缺1颗下中切牙上下颌均需拔牙者,在下颌非缺牙侧选择拔1颗前磨牙比拔1颗中切牙对Bolton指数影响要小     

The prevalence of congenitally missing permanent teeth in Japanese children: A survey conducted in south-west area of Kanto district

AimThe purpose of this study was to investigate the prevalence of congenitally missing permanent teeth in Japanese children residing in south-west area of Kanto district in recent years.MethodsPanoramic radiographs taken for dental treatment between 1990 and 2007 were used to evaluate the congenitally missing permanent teeth excluding the third molar. The participants of this study consisted of 2,125 children aged between 7 and 20 years.ResultsThe congenitally missing teeth were observed in 251 participants (11.8%). The majority of the participants (114) presented with only one tooth missing, and there was a general tendency that the number of participants gradually decreased as the number of missing teeth increased. A total of 539 teeth were congenitally missing, and mandibular second premolar was the most frequently missing tooth (153 teeth), followed by mandibular lateral incisor (86 teeth), maxillary second premolar (71 teeth), maxillary lateral incisor (61 teeth). Only one missing tooth (114 participants) was found most frequently in mandibular lateral incisor (30 participants), followed by mandibular second premolar (28 participants). There was a tendency that congenitally missing teeth occurred symmetrically; especially most of the participants who had two missing teeth (80 in 88 participants) were symmetrically missing.ConclusionThe prevalence of congenitally missing permanent teeth in this study was 11.8% and it was comparable to those reported in previous studies of Japanese population evaluated using panoramic radiographs.     

Hypodontia and hyperdontia of permanent teeth in Hong Kong schoolchildren

This study was performed to determine the prevalence of hypodontia and hyperdontia of permanent teeth amongst Southern Chinese children in Hong Kong. The sample consisted of 1093 12-yr-old children on whom a panoramic radiograph was taken. The prevalence of congenitally missing teeth (third molars excluded) was 6.1% in boys, 7.7% in girls, and 6.9% for both sexes combined. On the average, each child was missing 1.5 teeth. The most commonly absent tooth was the mandibular incisor, affecting 58.7% of the children with hypodontia. Thirty children (2.7%) had supernumerary teeth, with a male:female ratio of 6.5:1; in four cases the tooth had erupted. Three children had fourth molars and one case of a supplemental premolar was recorded (all unerupted). Four cases of a maxillary supernumerary tooth and hypodontia in the mandible were seen.     

The prevalence and pattern of hypodontia of the permanent teeth and crown size and shape deformity affecting upper lateral incisors in a sample of Jordanian dental patients

OBJECTIVE: The aim of this study was to determine the prevalence and pattern of hypodontia and the extent of congenital malformation in the permanent teeth of a sample of Jordanian adults. MATERIAL AND METHODS: Clinical examinations were carried out on 1045 dental patients aged 16 to 45 years to record any congenital absence of teeth except 3rd molars and to note any crown shape or size deformities affecting the upper lateral incisor. The congenital absence of permanent teeth was confirmed by taking complete dental history and orthopantomograms. Impacted teeth and teeth lost as a consequence of extraction or trauma were recorded as present. RESULTS: The prevalence of hypodontia was found to be 5.5% of the sample and the lower second premolar was the most frequently missing tooth. The number of missing upper lateral incisors was significantly higher than that of lower lateral incisors, (p < 0.05). Peg-shaped and reduced size upper lateral incisors were observed in 2.3% and 2.9% of the sample respectively. There were no significant differences according to gender, location of tooth according to arch or side of the jaw and hypodontic pattern. CONCLUSION: The prevalence of hypodontia was 5.5%, that of peg-shaped lateral incisor was 2.3% and that of reduced crown size was 2.9%.     

A survey of hypodontia in Japanese orthodontic patients.

INTRODUCTION: The purpose of this retrospective study was to assess the prevalence and distribution of hypodontia in the permanent dentition, excluding the third molars, in a sample of Japanese orthodontic patients. METHODS: Orthopantomograms of 3358 Japanese orthodontic patients (1453 boys and 1905 girls) between the ages of 5 and 15 years were examined for evidence of hypodontia. RESULTS: The prevalence of hypodontia was 8.5% (7.5% for boys, 9.3% for girls) with no statistically significant difference between the sexes. The average number of missing teeth per child was 2.4 (2.5 for boys, 2.4 for girls). Most (76.3%) children with hypodontia were missing either 1 or 2 teeth (77.1% for boys, 75.7% for girls). The prevalence of advanced hypodontia was 10.1% (11.0% for boys, 9.7% for girls). The most commonly missing teeth were the mandibular second premolars, followed by the mandibular and maxillary lateral incisors, and the maxillary second premolars; minor differences in the order of prevalence existed among groups of children classified by the number of missing teeth. Symmetrical hypodontia was predominant, and the most commonly symmetrical hypodontia was mandibular second premolar agenesis. No consistent finding was obtained as to which jaw had more missing teeth. The distribution of missing teeth was similar between the right and left sides of the dental arches in each group of children. Anterior tooth agenesis was predominant in children with minor hypodontia, and posterior tooth agenesis increased with hypodontia severity. CONCLUSIONS: The distinct characteristic of hypodontia in the Japanese population compared with other populations was a higher prevalence of both advanced hypodontia and mandibular lateral incisor agenesis in children with minor hypodontia.     

Probability of congenitally missing teeth: Results in 1,191 children in the Burlington Growth Centre in Toronto

abstract The position and frequency of anodontia was determined from oblique and postero-anterior cephalograms of 1,191 children (615 males and 576 females) from the Burlington Growth Centre. These children ranged from age 6 to 12 years and some were studied cross-sectionally while others were studied serially. The presence or absence of congenitally missing teeth were recorded from cephalograms. Of all the children studied, only 7.4% had congenitally missing teeth. Most frequently, only one or two teeth were congenitally absent. Males, most commonly, had only one tooth missing whereas females had a greater chance of having two or more teeth absent. The most commonly absent tooth was the mandibular second premolar, then the maxillary lateral incisor followed by the maxillary second premolar. When a tooth was missing, there was a greater probability that other teeth would be missing.     

Prevalence and distribution of anomalies of permanent dentition in 9584 Japanese high school students

This study investigated the prevalence and distribution of anomalies of permanent dentition in the current Japanese population by examining an unbiased sample. We conducted a survey of dental anomalies by mass dental screening at eight high schools in 2012. Participants were all students with permanent dentition. Dental anomalies were classified as hypodontia, supernumerary teeth, peg-shaped teeth, fused teeth, and talon cusps. Students with one or more dental anomalies on oral examination were given a differential diagnosis by three specialists. The final sample comprised 9584 participants (5062 boys, 4522 girls). Hypodontia was present in 372 students (3.88 %) with no significant sex difference (191 boys, 181 girls). Frequent sites were the right or left mandibular second premolar, right or left maxillary second premolar, and right or left maxillary lateral incisor. Supernumerary teeth were observed in three boys (0.06 %) and one girl (0.02 %). Peg-shaped teeth were observed in 74 students (0.77 %; 27 boys, 47 girls), differing significantly between sexes; they were most prevalent among maxillary lateral incisors. Of affected students, 18 students (0.19 %) also had hypodontia (3 boys, 15 girls). Fused teeth were present in two boys (0.04 %) and three girls (0.07 %) (gemination in one boy and fusion in the remaining four students). Sites were limited to maxillary and mandibular central and lateral incisors. Talon cusps were observed in two boys (0.04 %) and four girls (0.09 %). The present survey of a large unbiased sample can be considered to reflect the prevalence and distribution of anomalies of permanent dentition in the current Japanese population.     

Prevalence and patterns of permanent tooth agenesis in individuals with Down syndrome: a meta‐analysis

The aims of the present study were to evaluate the prevalence and patterns of permanent tooth agenesis in individuals with Down syndrome, using meta‐analysis methodology. Two independent investigators carried out a literature search to locate articles pertaining to permanent tooth agenesis in individuals with Down syndrome. The outcomes of interest were the prevalence and pattern of permanent tooth agenesis. Thirteen articles were selected for inclusion. The estimated overall prevalence of permanent tooth agenesis, excluding third molars, was 54.6% (95% CI: 44–66%). Considerable heterogeneity was present across the studies. Among subjects with tooth agenesis, approximately half had three or more missing teeth. The permanent teeth with the highest prevalence of agenesis were the maxillary lateral incisor (27%), mandibular second premolar (21%) and maxillary second premolar (18%). The single most commonly absent tooth, however, was the mandibular left second mandibular premolar (19.9%), followed by the maxillary left lateral incisor (19.4%). Little data describing specific tooth‐agenesis patterns were available. In conclusion, individuals with Down syndrome display high prevalence rates and severity of agenesis of permanent teeth. Proper and timely diagnosis of missing permanent teeth is thus necessary, to allow a more comprehensive long‐term treatment plan and a more favorable prognosis in these individuals.