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。     

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。     

上颌恒侧切牙牙冠解剖变异调查

目的:揭示上颌恒侧切牙牙冠变异的解剖特点及发生规律。方法:对乌鲁木齐市一个汉族中学生人群(3 422人)进行口腔检查,调查上颌侧切牙的牙冠变异情况,记录畸形舌侧尖、过小牙及侧切牙先天缺失的发生状况。统计各项变异的发生率。双侧相关性采用Kendall检验。结果:畸形舌侧尖的个体发生率为1.14%(39/3 422),牙齿发生率为0.89%(61/6 832),双侧共同发生率为56.41%(22/39)。过小牙个体发生率为3.10%(106/3 422),牙齿发生率为2.33%(159/6 832),双侧共同发生率为50%(53/106)。上颌侧切牙先天缺失的个体发生率为0.26%(9/3 422),双侧共同发生率为33.33%(3/9)。畸形舌侧尖、过小牙及先天缺失左右侧发生的相关系数tau分别为0.724,0.682和0.520(P<0.05)。以上变异男女组间以及左右组间差异均无统计学意义(P>0.05)。结论:上颌侧切牙畸形舌侧尖、过小牙及先天缺失在汉族人中发生率均较低,但双侧共同发生率相对较高。     

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。     

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。     

第二前磨牙及下颌侧切牙先天性缺失一例

先天性牙缺失是临床上见到的一种先天性的一颗或多颗牙缺失的牙发育异常性疾病。最多见者为第三磨牙缺失,其次为上颌侧切牙或下颌第二前磨牙缺失。本文报告一例第二前磨牙及下颌侧切牙先天性缺失病例。     

儿童口腔科门诊先天缺牙患者临床特征和发病因素研究

目的    研究儿童口腔科门诊先天缺牙患者的临床特征和可能影响发病的因素。方法    对2014年1—12月于中国医科大学附属口腔医院儿童口腔科就诊的16 320例患者进行先天缺牙的临床调查,针对先天缺牙的部位、数目及可能影响发病的因素等进行分析。结果    326例患者确诊为先天缺牙,占调查患者人数的2.0 %。其中,多数牙缺失患者44例,平均缺牙数为（7.98 ± 2.98）颗;个别牙缺失患者282例,平均缺牙数为（2.09 ± 1.04）颗。多数牙缺失患者中具有家族遗传史者所占比例明显高于个别牙缺失患者。缺牙好发部位依次为下颌第二前磨牙、上颌第二前磨牙、上颌侧切牙、下颌中切牙、第一前磨牙、上颌尖牙。采用非条件Logistic回归对先天缺牙的可能影响因素进行分析,发现家族史是先天缺牙的危险因素（P < 0.01）,而患者父母的文化程度、母亲受孕年龄、母亲妊娠期放射线接触史及是否为早产儿等因素,均不是先天缺牙的影响因素（P > 0.05）。结论    先天缺牙多为个别牙缺失,好发部位主要为下颌第二前磨牙;多数牙缺失可能与家族遗传密切相关。     

不同安氏错(牙合)类型病人第三磨牙缺失情况的分析研究

目的：探讨第三磨牙先天缺失与错殆畸形之间的关系。方法：选取我科收治的正畸病人800例，年龄13～23岁。按照Angle错殆分类法，将样本分属于三类错[牙合]畸形，通过全景曲面断层片判定第三磨牙先天缺失的情况。对不同错[牙合]畸形的第三磨牙先天缺失情况进行统计学分析。结果：在全部病人中，第三磨牙先天缺失率以人数计为32．63％、以牙胚数计为18．72％；无论上颌还是下颌，第三磨牙牙胚缺失率与左右侧无关；上颌第三磨牙牙胚的缺失率明显大于下颌（P〈0．05）；Ⅰ类、Ⅱ类、Ⅲ类错[牙合]畸形之间第三磨牙的先天缺失无论在上颌、下颌以及全颌间均无统计学意义（P〉0．05）。结论：在错[牙合]畸形病人中，约30％存在一个或数个第三磨牙的缺失；安氏I、Ⅱ、Ⅲ类错[牙合]畸形与第三磨牙先天缺失之间没有直接关联。     

自体牙移植术新进展

自体牙移植术是将自体牙完整摘出 ,移植于自身其它的缺牙部位 .供牙不仅包括牙胚或牙根未发育完成的牙齿 ,也包括牙根已发育完成的牙齿 .广泛应用于外伤、恒牙早失以及先天发育不全造成的牙齿缺失 .移植牙的来源多是完全埋伏或行将萌出的第三磨牙以及需要拔除的牙齿 ,如多生牙或正畸需减数的牙齿 [1] .1　自体牙移植术应用近况 :　目前应用最多的仍是将未发育完全的下颌第三磨牙移植于下颌第一磨牙处 .Bowden- DE等报告多例应用双尖牙移植于上颌前牙缺牙区 ,获得满意的功能和美观效果 [2 ] .Kugelberg- R等应用类似的方法治疗年轻人上颌 1…     

Hypodontia in children with various types of clefts

The prevalence of hypodontia in children with clefts, both inside and outside the cleft region, and the possible association between the side of the cleft and the side of the missing teeth were studied using radiographs of 278 patients with cleft lip, cleft palate, or both (158 boys and 120 girls), age 5 to 18 years (mean age 10.4 years). A hypodontia prevalence of 77% (excluding third molars) was found for the total cleft sample. This was significantly higher, both statistically and clinically, than the incidence of hypodontia reported for noncleft populations, and considerably higher than the prevalence reported in other studies of children with clefts. The maxillary permanent lateral incisors were the teeth most frequently missing on the cleft side (259 teeth) followed by the maxillary (47 teeth) and mandibular (23 teeth) second premolars, in both boys and girls. The teeth that were most often missing on the noncleft side were the maxillary second premolars (12 teeth), followed by the maxillary lateral incisors (10 teeth) and mandibular second premolars (6 teeth). Hypodontia of both the maxillary lateral incisors and second premolars was found more frequently on the left side, which also has a higher frequency of clefting.     

Radiographic assessment of congenitally missing teeth in orthodontic patients

Summary. Objective. To estimate the prevalence of congenitally missing teeth (CMT) in patients evaluated for orthodontic care. A sample of 668 panoramic radiographs from Mexican population was reviewed from orthodontic healthy patients, 9–20 years old. Method. Statistical tests were used to compare maxillary and mandibular hypodontia in right and left quadrants between males and females. Results. Prevalence was 27% when all teeth were included, and was 2·7% when third molars were excluded. A significant difference was found between maxillary and mandibular symmetrical CMT in third maxillary molars, lateral incisors and second premolars (P < 0·001), and in mandibular third molars and central incisors (P < 0·001). Conclusions. We confirmed that occurrence of CMT in the permanent dentition of a Mexican population most often affects third molars, followed by maxillary lateral incisors and then mandibular second premolars.     

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.     

石家庄地区正畸患者恒牙先天缺失的调查分析

目的调查分析石家庄地区正畸患者恒牙先天缺失的发病率及特征。方法对河北医科大学口腔医院正畸科2010~2012年正畸患者中3274名有效病例的病历资料进行回顾分析。通过观察其全颌曲面断层片,分析恒牙先天缺失的发病率及分布差异。结果除第三磨牙外恒牙先天缺失的发病率为9.13,性别间差异无统计学意义（P〉0.05）。个别缺牙例数（缺牙数〈6）占总缺牙例数的95,其中缺失1~2颗牙的例数占总缺牙例数的88.6;多数缺牙例数（缺牙数≥6）占总缺牙例数的5。前、后牙区的缺牙发病情况在缺失1~2颗牙时,主要发生在前牙区,缺失2颗以上时,后牙区的缺失发病率高于前牙区（P〈0.05）;下颌缺牙发病率高于上颌（P〈0.05）。缺牙频率最高的是下颌侧切牙（25.3）,其次是下颌第二前磨牙（18.3）。结论石家庄地区正畸患者恒牙先天缺失（不包括第三磨牙）发病率为9.13,。其中以缺失1~2颗牙最常见,恒牙先天缺失更多的发生在前牙区及下颌,最常见的缺失牙位是下颌侧切牙和下颌第二前磨牙。     

Dental Findings in Patients with Ectodermal Dysplasia

BACKGROUND: Ectodermal dysplasia is an inherited disease causing malformations of all tissues originating from the ectoderm. The significance of this disease lies in severe hypodontia, and an accompanying hypoplasia of the alveolar process. The clinical situation is aggravated by a significant xerostomia. It was the aim of this study to document the distribution of hypodontia and tooth malformation. Furthermore, we aimed to elucidate the clinical impact of these findings. PATIENTS AND METHODS: Records of 30 patients (19 males, 11 females) suffering from ectodermal dysplasia were included. Their age ranged between 7 and 23 years. All patients had been examined clinically and radiographically. In every patient, a record was made of which teeth were missing or malformed, and which deciduous teeth persisted. Additionally, the entire treatment procedure was assessed. RESULTS: The third molars were missing in all of the patients. The number of aplastic permanent teeth ranged from 2 to 26. The maxillary lateral incisors were most frequently absent, followed by the mandibular central incisors. The most stable teeth were the central incisors of the upper jaw, and the canines and first molars in both jaws. However, the maxillary central incisors and canines were the teeth most affected by malformation. Deciduous canines and second molars were the most often persisting teeth due to agenesis of the maxillary lateral permanent incisors and mandibular second premolars. In two-thirds of the patients, missing teeth were replaced by removable dentures. Half of the patients received orthodontic treatment. CONCLUSIONS: Hypodontia and malformation are almost regular dental characteristics in patients suffering from ectodermal dysplasia. The distribution of absent teeth deviates remarkably from the general population. Treatment requires an interdisciplinary approach including orthodontics, prosthodontics and oral surgery.     

An orthopantomographic study of hypodontia in permanent teeth of Japanese pediatric patients

Hypodontia of permanent teeth was evaluated from orthopantomograms of 2072 apparently healthy pediatric patients at The Hospital of Nihon University School of Dentistry at Matsudo. The prevalence of congenitally missing teeth (CMT) was 8.7% in boys and 10.8% in girls, and 9.4% for both sexes combined. Most cases (67.8%) involved either one or two missing teeth. There were in total 574 CMT, and on average 2.8 teeth were missing per child. The most commonly absent tooth was the mandibular second premolar. On the other hand, no first molars were missing in any case. A high frequency of CMT mandibular incisors (18.82%) was observed, and this seems to be a characteristic peculiar to individuals of Asian ethnicity. Oligodontia (6 or more CMT excluding the third molar) ranged from 6 to 14 teeth, with a prevalence of 1.4% in general: 1.8% for girls and 0.9% for boys. Symmetry of CMT was predominant: 214 pairs for bilateral symmetry and 107 pairs for symmetry between two antagonistic quadrants. The distribution of CMT between maxillary and mandibular hypodontia in the right and left quadrants for boys and girls no had significant association (P < 0.05).     

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.     

Hypohyperdontia: Agenesis of three third molars and mandibular centrals associated with midline supernumerary tooth in mandible

Agenesis of teeth in a patient who also presents with a supernumerary tooth is one of the rare numerical anomalies in human dentition. Agenesis of third molars was shown to be associated with other missing permanent teeth. A review of literature on hypodontia including third molar agenesis, hyperdontia and a concomitant presence of these two conditions which is termed as hypohyperdontia is presented along with a case showing agenesis of three third molars, both mandibular central incisors and a midline supernumerary tooth.     

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.     

Non-syndromic hypodontia in an Iranian orthodontic population

To investigate the prevalence, characteristics (ie, malocclusion, location, type), and sex distribution of hypodontia in an Iranian orthodontic population. A retrospective study was conducted using periapical and panoramic radiographs and study models of 1,751 subjects attending university orthodontic clinics (870 females, 881 males, age 9-27 years). The Chi-square test was used to analyze differences in the distribution of hypodontia, after stratification by sex and malocclusion type. A total of 197 congenitally missing teeth were observed in 160 patients (9.1%; 74 boys and 86 girls); there were no statistically significant differences between sexes (Chi-square = 0.832, P = 0.36). Hypodontia was more common in patients with Class III malocclusion (45.2%), and was more prevalent in the maxilla (71%) than in the mandible (29%). Maxillary lateral incisors (35.6%) and maxillary second premolars (13.0%) were the most commonly missing teeth, followed by mandibular lateral incisors (9.6%) and mandibular second premolars (8.2%). The prevalence of missing teeth was higher in the anterior segment (incisors and canines) than in the posterior segment (premolars and molars). The prevalence of oligodontia was 0.34%. The prevalence and characteristics of the most frequently missing teeth accorded with the findings of most studies conducted in other countries.