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 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.     

Hypodontia of permanent teeth in Danish schoolchildren

Hypodontia, congenitally missing teeth, is one of the conditions recorded during systematic orthodontic screening of groups of children attending a community child dental health service. The present investigation reports the prevalence of hypodontia in 3325 9–10-year-old children in the 3rd schoolgrade examined with an orthopantornographic radiograph. The prevalence of children with hypodontia was found to be 7.8%. Fifty percent of these children were missing only one tooth while 85% were missing either one or two teeth. More teeth were missing in the mandible than in the maxilla. The teeth most frequently missing were the second premolars, representing 67% of the congenitally missing teeth. Symmetrical hypodontia of second premolars occurred approximately twice as often in girls as in boys. Though more teeth were congenitally missing in girls than in boys, no difference could be seen in the prevalence of hypodontia in boys (7.7%) and girls (7.8%).     

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%.     

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.     

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.     

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 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.     

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)     

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.     

Severe hypodontia: diversities in manifestations

The material comprises 33 cases, 12 boys and 21 girls with 4 or more lacking teeth in the permanent dentition, randomly collected among patients referred to the Department of Pedodontics, University of Bergen. The total number of lacking teeth were 332, mean number in boys was 11.4, in girls 9.3, ranging from 4 to 24 (third molars excluded). The most prevalently lacking teeth were second premolars in both jaws, maxillary lateral incisors, mandibular central incisors and maxillary first premolars. The maxillary central incisors were the most stable teeth, lacking in only one patient. The female group was closest to this "classical" scheme by lacking teeth mostly in posterior segments. In males the anterior segments were most often afflicted. There was no significant difference between right and left sides in both sexes, but in girls the maxillary jaw was more afflicted than the mandibular jaw. The individual analyses of cases showed great diversities in the manifestation of hypodontia. Eighteen of them behaved fairly "balanced" with respect to lack of teeth in the different quadrants. Six cases were lacking most of the teeth in the maxillary jaw (total 34 maxillary teeth versus 11 mandibular). Five cases were lacking most of the teeth in the mandibular jaw (total 30 mandibular teeth versus 14 maxillary). One patient was lacking 10 of his 12 front teeth, but only 4 of his 20 posterior teeth, and one patient was lacking 12 of his 16 posterior teeth, but none of his front teeth. The author cannot offer any explanation for these strange and varying patterns of manifestations.     

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 caries prevalence and CPITN of 12-year-old rural schoolchildren in Transkei

The study investigated the prevalence and pattern of caries with particular reference to tooth and surface type and the CPITN of 12-y-old rural schoolchildren in Engcobo, Transkei. 349 schoolchildren, with a 4:6 male:female ratio were examined. The fluoride content of the water varied from 0-0.5 p.p.m. The results indicate that caries levels are low--47 per cent of the sample was caries-free. Both the median DMFT and DMFS was 1.0 (with a mean 1.7 and 2.8). The D component comprised 89 per cent, the M-10 and F-1 per cent of the total DMFT. Amongst boys, caries was distributed almost equally between the maxillary (112) and mandibular (114) arches whereas for girls more teeth were affected in the mandibular arch. Molar teeth in boys and girls accounted for 90 per cent of all teeth affected with the first molars accounting for 50 per cent and the second molars 40 per cent. In the maxillary and mandibular arch for the total group, a greater number of first molars were affected than the second molars. For girls in both the maxilla and mandible, the second molars were affected more frequently than the first molars. Overall the occlusal surfaces were affected most frequently followed by the buccal, distal, lingual and mesial. Gingival bleeding and calculus were prevalent in most sextants. Less than 6 per cent of the total subjects had no periodontal disease. Calculus was found in over 70 per cent of the children. The vast majority of the sample (94 per cent) needed oral hygiene instruction.     

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.     

Prevalence and distribution of traumatic injuries to the permanent teeth of Dominican children from private schools

Abstract The purpose of this study was to describe by age and sex, the prevalence, etiology, distribution and type of injury to permanent incisors of children from private schools of Santo Domingo, Dominican Republic, located in the Caribbean archipelago. The sample consisted of 1633 children, 5–14 yr enrolled in several private schools of Santo Domingo. The prevalence of injury was 10.0% (5.0% in boys and 5.1 % in girls). The largest number of injuries was found in the 5- and 6-yr-old children, followed by the 7- and 8-yr-olds. There was no significant difference in the number of teeth injured in both sexes (0.1 %). The most common type of injury in both sexes was concussion (42.7%) with no significant difference between sexes (5.7%). The most common cause of injury in both sexes was falling against an object (77.8% in boys and 78.3% in girls). Most boys injured their teeth playing baseball (86.4%) and most girls playing on roller skates (72.3%). More girls suffered injuries (not significantly) with the ratio of boys to girls being 0.91 to 1.     

Teeth condition in children aged 7 years in Warsaw and the province of Warsaw

Teeth were examined in 180 children aged 7 years of either sex in three randomly selected regions: Warsaw, Sulejówek and Wiazowna community by the routine method in school stomatological offices. The assessment of teeth was done according to the WHO principles. In the studied population 85.3% erupted permanent molars, 71.1% medial incisors, and 29.2% lateral incisors were found. No significant differences were found in the per cent of erupted permanent teeth between these three regions, but the proportion of erupted teeth was greater in girls than boys. The prevalence of caries in the permanent teeth in this population was 25%, and again no difference of this prevalence was found between these three regions, but in girls this prevalence was greater than in boys. The DMF index was not different in these regions, but in girls it was twice that in boys (0.6 vs 0.3).     

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.     

Dental development and tooth agenesis in children with velocardiofacial syndrome

BACKGROUND. Variations in dental development and tooth agenesis have been reported in children with velocardiofacial syndrome (VCFS). AIM. The aim was to evaluate the dental development and missing permanent teeth in children with VCFS. DESIGN. Forty-five children (23 girls) with VCFS who had visited the cleft palate and craniofacial centre were studied retrospectively from orthopantomograms taken at the mean age of 7.9 years (range 5.8-12.9). Thirteen of the children with VCFS had palatal clefts. The deletion of 22q11 was verified by FISH techniques. The dental stages were assessed by the method of Demirjian, and the dental age was calculated according to the Finnish dental maturity reference values. A paired Student's t-test was used in the statistical analysis. RESULTS. Eight children (17%), four with palatal clefts, had tooth agenesis. Four children (9%) had agenesis of mandibular incisors. The missing teeth (n = 19) were mainly mandibular incisors (n = 6), maxillary lateral incisors (n = 2), and maxillary second premolars (n = 4). The dental age of the children with VCFS was not different from their chronological age, but there was great individual variation. CONCLUSIONS. A high prevalence of missing permanent teeth, especially mandibular incisors, was observed. The need for thorough clinical and radiological dental examination in children with VCFS is emphasized.     

Congenitally missing permanent mandibular incisors and their association with missing primary teeth in the Southern Chinese (Hong Kong)

Abstract – A radiographic survey of a random sample of 454 girls aged 5.9 ± 0.5 yr and 521 boys aged 5.8 ± 0.4 y was undertaken to establish data on the incidence of Congenitally missing mandibular incisor teeth amongst the Southern Chinese and to compare these figures with those of a similar previous study of 12-yr-olds so to eliminate factors such a trauma or extractions which may have artificially inflated the 12-yr-old incidence data. The proportion of 5-yr-old girls and boys affected by hypodontia in the permanent mandibular incisor region was 0.086 and 0.046 respectively (a significant difference between sexes, P <0.02), compared with 0.047 and 0.034 for the 12-yr-olds (a non-significant difference) so other factors must have contributed to the discrepancy between the two groups of children. A very strong correlation ( P <10⁻²⁵) between missing primary and missing permanent mandibular incisors is present in this group, and this has implications for prognosis and treatment planning. A fundamental developmental defect is implied.