Agenesis of permanent teeth in 8138 Danish schoolchildren: prevalence and intra-oral distribution according to gender

Objective.  The purpose of this study was to describe agenesis of permanent teeth in children with respect to prevalence and intra-oral distribution according to gender.
Methods and subjects.  The study was population based and included all children in one district of the municipality of Aarhus, Denmark, in 1974–1979 (1657 girls and 1668 boys) and 1992–2002 (2409 girls and 2404 boys). The children underwent systematical clinical and radiographic examination.
Results.  The period prevalence rates were almost identical for the two time periods (1972–1979: 7.8%; 1992–2002: 7.1%). Girls were affected more frequently than boys, and affected girls had more congenitally missing teeth than affected boys. Unilateral agenesis of the second premolars was more frequent than bilateral agenesis. In children with only one congenitally missing tooth, agenesis of the upper lateral incisors was asymmetrical in girls, but not in boys, whereas the opposite was true for the lower second premolars in boys.
Conclusion.  The prevalence of agenesis of permanent teeth in Danish schoolchildren seems to be constant over time, and similar to that found in other large, population-based studies. Intra-oral distributions of congenitally missing teeth indicate gender-specific patterns.     

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.     

Hypodontia in 9-year-old Norwegians related to need of orthodontic treatment

The present study reports on the prevalence of hypodontia in a Norwegian population and classifies children with hypodontia according to need of orthodontic treatment. Orthopantomograms of 1953 children (960 girls and 993 boys) at the age of 9 were available for examination. Of the boys registered with hypodontia of second premolars at the age of 9, 11.3% showed late mineralization between the ages of 9 and 12. Only 2.9% of the girls showed late mineralization. The corrected prevalence of hypodontia, excluding third molars, in the girls was 7.2%, in the boys 5.8%, and in both sexes combined 6.5%, the difference between sexes not being statistically significant. Of the children with hypodontia, 86.6% lacked only one or two permanent teeth. The most frequently missing teeth were the mandibular second premolars, the maxillary second premolars, and the maxillary lateral incisors, in that order. Classification of children with hypodontia according to need of orthodontic treatment showed that about two-thirds had hypodontia only of single posterior teeth with a moderate need of treatment. About one-third had hypodontia involving anterior teeth, and only 3.1% had hypodontia of two or more teeth in the same quadrant with a great need of treatment.     

Prevalence of hypodontia and malformations of permanent teeth in Iceland

This study was performed to elucidate the prevalence of hypodontia and congenital malformations of permanent teeth in Iceland. Computer analysis was done on the basis of results from examining 1,116 children (521 boys and 595 girls), or about 9.5% of all schoolchildren in Reykjavík in stages DS 3 (canines and premolars erupting) and DS 4 (canines and premolars fully erupted) of dental development at the time of the study. The age range was mainly from 8-16 years. The prevalence of congenitally missing teeth (second and third molars excluded) was 6.7% in boys and somewhat higher, 8.9%, in girls, 7.9% for both sexes combined. On the average, each child was missing 1.9 teeth. In the girls, the most commonly absent teeth were the mandibular second premolar (55%), the maxillary second premolar (19%), and the maxillary lateral incisors (18%). In the boys the figures were 51%, 18%, and 10%, respectively. Malformation of permanent teeth, mainly in the form of pegshaped maxillary laterals, was also less common in the boys, 1.3% against 3.0% in the girls, and 2.2% for both sexes combined. Among Icelandic children hypodontia and/or congenital malformation of permanent teeth were found in 9.1%.     

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.     

Has hypodontia increased in Caucasians during the 20th century? A meta-analysis

It has been claimed that agenesis of permanent teeth has increased over the years. The present study tested this hypothesis in Caucasians. Published data on the prevalence of children with one or more congenitally missing permanent teeth were selected on the basis of strictly imposed criteria. Using a meta-analysis, the data were evaluated and presented chronologically. Furthermore, the selected publications were checked for differences in the prevalence of agenesis between the male and female populations. Finally, information on the occurrence of upper and lower premolars as well as upper incisor agenesis was collected and calculated as a percentage of the total number of congenitally missing teeth. From 42 studies on this subject, 19 were selected based upon six stringently applied criteria. Chronological classification of the percentage of children with congenital absence of one or more permanent teeth revealed relatively higher percentages since 1957. Fourteen out of the selected studies presented data on sex distribution. In all but one publication girls tended to have a slightly higher occurrence of missing teeth compared with boys of the same age. The second lower premolars were most often agenetic, whereas missing upper laterals occurred almost equally as agenesis of the upper second premolars. The considered period of time is too short and the available data too limited to describe a possible trend in the human dentition. However, this meta-analysis seems to confirm that hypodontia has been diagnosed more often in recent studies.     

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。     

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.     

Comments on the article 'Metal—ceramic bond strength'

The prevalence of different malocclusion features was investigated in 396 6-year-old Icelandic children, using the epidemiologic registration method described by Bjork et al. in 1964. Girls were ahead of boys with regard to dental stage (P<0.01). One or more permanent teeth were congenitally missing in 5% of the children. Postnormal occlusion was found in 27% of the boys and in 31% of the girls, and prenormal occlusion was found in 6% and 5%, respectively. Straight terminal plane at the second deciduous molars was found in individuals with either normal or postnormal occlusion. Thus, it can be misleading to use the relation of the terminal planes as a measurement of the sagittal relation between the jaws. The prevalence of hypodontia was much lower than has been reported previously for Icelandic children.     

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).     

Variations in number and morphology of permanent teeth in 7-year-old Swedish children

Summary. Objectives . To establish the prevalence of numerical and morphological variations of permanent teeth in Swedish 7-year-olds and to accept or reject the hypothesis of a higher prevalence for these conditions in northern Sweden compared to other areas.
Design . Cross-sectional.
Setting . Department of Odontology/Pedodontics, Umeå University, Sweden.
Sample and methods . A total of 739 healthy Caucasian 7-year-olds residing in the city of Umeå, northern Sweden in 1976. The children were examined clinically and radiographically.
Results . The prevalence of hypodontia (excluding third molars) in girls was 8·4%, in boys 6·5%, and in both sexes combined 7·4%. Of the children with hypodontia, the majority (90·9%) lacked one or two teeth. Lower second premolars were the teeth most frequently missing. The prevalence of hyperdontia was 1·9%; 11 girls and three boys were affected; 78% of the supernumerary teeth were mesiodenses. Of the morphological variations, peg-shaped upper lateral incisors were found in 0·8% of the children, double-formation (gemination) in 0·3%, taurodontism in 0·3% and dens invaginatus in 6·8%. One diagnosis was found in 18% of the children, and in almost 8% of them more than one diagnosis was found.
Conclusions . The results agree with those obtained in similar populations and are considered representative of this ethnic group. The hypothesis of a genetically determined higher prevalence of numerical and morphological variations in the study population was not verified.     

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.     

Prevalence of hypodontia in 4-18-year-old children in Department of Paediatric Dentistry, Faculty of Dentistry, University of Debrecen from 1999 to 2003

Hypodontia is one of the most common human dental anomalies. Its management is often complicated. This survey was carried out to study the prevalence, localisation and combination of congenital aplasia in Department of Paediatric Dentistry, Faculty of Dentistry, University of Debrecen. The study group consisted of 669 children, 283 boys and 386 girls, aged 4-18 years. Orthopantomograms and clinical examinations were used for the retrospective study. The prevalence of hypodontia was found to be 7.76 percent, excluding the third molars. Most of the congenitally absent teeth were the upper lateral incisors and the lower second premolars. The most frequent combinations were the 12-22 and the 35-45 ones. We found that our data were very similar to the different international results.     

Oligodontia in Danish schoolchildren

Oligodontia is a rare condition, and only limited data are available on its prevalence. The present paper is based on data from Danish schoolchildren. When these data are combined with comparable data on Danish schoolchildren published previously by the senior author, it is shown that oligodontia occurs in 0.16% of the children (95% confidence interval, 0.07% to 0.30%). Two of every three congenitally missing teeth were upper or lower second premolars or upper lateral incisors. When data from Danish schoolchildren were combined with population data from similar groups of schoolchildren from the Nordic countries, the condition was found to be more frequent in girls than in boys (P = 0.05).     

Oligodontia in Danish schoolchildren

Oligodontia is a rare condition, and only limited data are available on its prevalence. The present paper is based on data from Danish schoolchildren. When these data are combined with comparable data on Danish schoolchildren published previously by the senior author, it is shown that oligodontia occurs in 0.16% of the children (95% confidence interval, 0.07% to 0.30%). Two of every three congenitally missing teeth were upper or lower second premolars or upper lateral incisors. When data from Danish schoolchildren were combined with population data from similar groups of schoolchildren from the Nordic countries, the condition was found to be more frequent in girls than in boys (P = 0.05).     

Prevalence of numeric anomalies in the permanent dentition of patients with Down syndrome

The purpose of this study was to evaluate the prevalence of numeric anomalies in the permanent dentition of patients with Down syndrome by means of panoramic radiographs. The sample consisted of panoramic radiographs from 70 subjects. We examiend the radiographs to detect hypodontia as well as supernumerary teeth. Our results confirm the high prevalence of hypodontia among patients with Down syndrome (60%), mostly with mild expression. The teeth most often missing were the upper lateral incisors, usually bilaterally, followed by the lower second premolars and upper second premolars. Supernumerary teeth were seen in 6% of the subjects, and the concomitant occurrence of hypodontia and supernumerary teeth occurred in one patient.     

Anomalies of deciduous teeth and findings in permanent dentition]

Prevalence of anomalies of deciduous teeth has been analyzed in the general population of Zagreb preschool children. The sample comprised 2,987 children from 3 to 6 years of age (1,582 boys and 1,405 girls). Hypodontia was found in 0.47%, hyperdontia in 0.10%, and double teeth in 0.43% of total sample. Total prevalence of all anomalies in the sample was 1.0%. The sample for the analysis of permanent dentition has been enlarged with the clinical sample of children having the same anomalies and comprised 48 children. In all children with anomalies of primary teeth the orthopantomograms were taken and the status of permanent dentition was analyzed. In children with hypodontia in primary dentition hypodontia of permanent teeth was found in 100% of cases. Patients with hyperdontia of primary teeth displayed anomalies in permanent dentition in 85.7%, while in children with primary double teeth, anomalies of permanent teeth were present in 61.1% of cases. Missing deciduous teeth were found in both jaws in only 8.7% of cases, and in 34.8% in permanent dentition. Symmetrical occurrence of hypodontia of primary teeth (i.e. in both sides of jaws) was significantly higher in boys (56.3%) than in girls (28.6%). In permanent dentition symmetrical occurrence of hypodontia was significantly higher than in primary dentition (81.3% in boys and 57.1% in girls). The most frequently missing primary teeth were maxillary lateral incisors (48.8%) followed by mandibular central incisors (34.9%). Hyperdontia of primary teeth has been found only in boys, and it related only to the maxillary lateral incisors. Anomalies of deciduous teeth show a high degree of association with the finding in the permanent dentition.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dental abnormalities in permanent dentition in children with submucous cleft palate

Seventy-three children with submucous cleft palate (38 girls and 35 boys), mean age 8.2 years (range 7.7-9.5), were studied retrospectively from orthopantomograms. Dental abnormalities in permanent dentition were found in 26 patients (36%). Missing teeth, mainly lower 2nd premolars, upper lateral incisors, and upper 2nd premolars, were found in 12 patients (16%). Most of the patients had 1 or 2 missing teeth, 2 had 3 missing teeth. In 5 patients hypodontia was associated with another dental abnormality. Other dental abnormalities included peg-shaped lateral incisors in 7 patients (10%), ectopic eruption of upper 1st molars in 6 patients (8%), transposition of upper canines and 1st premolars in 3 patients (4%), supernumerary teeth in 2 patients (3%), and palatally displaced upper canines in 1 patient (1%). As children with submucous cleft palate have a tendency towards increased frequency of missing teeth and other dental abnormalities, the need for thorough clinical and radiological dental examination is emphasized.     

The relationship between hypodontia in the second premolar region and heredity of cleft, lip and palate in children with isolated cleft palate

The aim of the investigation was to study the relationship between hypodontia in the second premolar region and heredity of cleft lip and palate (CLP) in children with isolated cleft palate (CP). The following null-hypothesis was tested: The heredity for CLP will not give rise to higher prevalence of hypodontia in the second premolar region of the maxilla and the mandible in CP-patients. The material consisted of 188 children born with non-syndromic CP (77 boys and 111 girls). Surgical files initiated at birth and panoramic radiographs at ten years of age have been studied concerning heredity for CLP and hypodontia of second premolars. For all CP-children, irrespective of hereditary background the prevalence of second premolar hypodontia did not differ significantly. However, there was a tendency to higher prevalence of hypodontia of the lower second premolars. The null-hypothesis: The heredity for CLP will not give rise to higher prevalence of hypodontia in the second premolar region of the maxilla and the mandible in CP-patients was not rejected.     

A multidisciplinary approach for the management of hypodontia: case report

Hypodontia is the congenital absence of one or more teeth and may affect permanent teeth. Several options are indicated to treat hypodontia, including the maintenance of primary teeth or space redistribution for restorative treatment with partial adhesive bridges, tooth transplantation, and implants. However, a multidisciplinary approach is the most important requirement for the ideal treatment of hypodontia. This paper describes a multidisciplinary treatment plan for congenitally missing permanent mandibular second premolars involving orthodontics, implantology and prosthodontic specialties.