• Korean Journal of Cleft Lip And Palate
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• v.4 no.2
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• pp.19-27
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• 2001

This study was performed to determine the prevalence of hypodontia and hyperdontia of permanent teeth among Korean schoolchildren, and to compare differences in the prevalence between Korea, other country, and other ethnic groups. The sample consisted of 346 girls aged 6.9～0.3 yr and 375 boys aged 6.8～0.4 yr on whom a panoramic radiograph was taken at Yeonchun-Gun community in Korea. The prevalence of congenitally missing teeth (third molars excluded) was 6.7% in boys and somewhat higher, 9.5% in girls, and 8.0% for both sexes combined. On the average, number of missing teeth per affected child was 1.9 teeth. The most commonly congenitally missing teeth were the mandibular second premolar (32.7%), followed by the mandibular incisor (28.7%), the maxillary second premolar (16.7%), and the maxillary lateral incisors (10.2%). The prevalence of supernumerary teeth was 2.1 % in boys, 1.4% in girls, and 1.8% for both sexes combined. The most common supernumerary teeth were the mesiodens (76.9%), followed by the supernumerary premolar (23.1 %). The affected male-female ratio was 1.6: 1.0. The prevalence of congenital missing teeth in this study was similar to in studies of Japanese, Danish, American and German. The frequency of hyperdontia was lower in this study than in studies of Chinese children, Japanese and American.

• Imaging Science in Dentistry
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• v.44 no.1
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• pp.7-13
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• 2014

Purpose: This study was performed to evaluate the prevalence of all types and subtypes of dental anomalies among 7- to 35-year-old patients by using panoramic radiographs. Materials and Methods: This cross-sectional study was conducted on 1649 people in Hamadan City, in 2012-2013. The prevalence of four types and 12 subtypes of dental anomalies was evaluated by two observers separately by using panoramic radiography. Dental anomalies were divided into four types: (a) shape (including fusion, taurodontism, and dens invagination); (b) number (including hypodontia, oligodontia, and hyperdontia); (c) structure (including amelogenesis imperfecta, dentinogenesis imperfecta, and dentin dysplasia); and (d) position (including displacement, impaction, and dilacerations). Results: The reliability between the two observers was 79.56% according to the Kappa statistics. The prevalence of dental anomalies diagnosed by panoramic radiographs was 29%. Anomalies of position and number were the most common types of abnormalities, and anomalies of shape and structure were the least in both genders. Anomalies of impaction (44.76%), dilacerations (21.11%), hypodontia (15.88%), taurodontism (9.29%), and hyperdontia (6.76%) were the most common subtypes of dental anomalies. The anomalies of shape and number were more common in the age groups of 7-12 years and 13-15 years, respectively, while the anomalies of structure and position were more common among the other age groups. Conclusion: Anomalies of tooth position were the most common type of dental anomalies, and structure anomalies were the least in this Iranian population. The frequency and type of dental anomalies vary within and between populations, confirming the role of racial factors in the prevalence of dental anomalies.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.4
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• pp.274-282
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• 2013

The goal of this study was to analyze prevalence and distribution of congenitally missing teeth in 3302 patients from 7 to 15 years old, who had visited and taken panoramic radiographs at the Department of Pediatric Dentistry, from January 2008 to December 2012. The prevalence of hypodontia in the males (5.9%) was slightly higher than in the females (4.7%). In the affected patients, the mean number of congenitally missing teeth in the mandible was statistically higher than in the maxilla (p < 0.05). However, there was no significant difference in the number of congenitally missing teeth between left and right dentitions (p > 0.05). Excluding the Mn. third molars, the most frequent congenitally missing teeth site was the Mn. second premolars. In contrast, the most infrequent congenitally missing teeth sites were the Mx. and Mn. first premolars, and Mx. central incisors. The bilateral combination or antagonistic quadrants combination of congenitally missing teeth in hypodontia patients was 80.3%. The result of this study will contribute to clinicians to make accurate diagnosis and establish favorable treatment plans, by offering invaluable data about the number and distribution of congenitally missing teeth.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.1
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• pp.122-130
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• 2006

Congenital Missing Teeth(hypodontia, oligodontia) is the developmental absence of one or more teeth. It has been reported as being the most common anomaly of dental development in human, relatively common in the permanent dentition. In a recent review, Vastardis has quoted incidence ranges of $1.6%{\sim}9.6%$ in the permanent dentition. Brook has quoted a prevalence of $3.5%{\sim}6.5%$ in most populations, with severe hypodontia, defined as the absence of six or more teeth, having a prevalence of $0.3{\sim}0.4%$. The most commonly affected teeth are third molars, followed by maxillary lateral incisor, and second premolars. The etiology is unknown, several hypotheses include trauma, nutritional deficiency, infection, metabolic abnormalities, systemic disease and genetic influence. The multiple congenital missing is commonly associated with specific syndrome or severe systemic abnormalities such as cleft lip & palate and Down's syndrome. These cases present that children have multiple congenital missing teeth in the permanent dentition, without any systemic disease. Management of this condition must be considered orthodontic and prosthodontic treatment comprehensively. In these cases, children were treated by space maintainer or orthodontic appliance and follow-up checked.

• The korean journal of orthodontics
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• v.51 no.1
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• pp.55-74
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• 2021

Objective: To systematically review studies on canine agenesis prevalence in different populations and continents, based on the jaw, sex, location, and associated dental anomalies. Methods: Electronic and hand searches of English literature in PubMed, Web of Science, Scopus, OpenGrey, and Science Direct were conducted, and the authors were contacted when necessary. Observational studies (population-based, hospital/clinic-based, and cross-sectional) were included. For study appraisal and synthesis, duplicate selection was performed independently by two reviewers. Study quality was assessed using a modified Strengthening the Reporting of Observational Studies in Epidemiology checklist, with main outcome of prevalence of canine agenesis. Results: The global population prevalence of canine agenesis was 0.30% (0.0-4.7%), highest in Asia (0.54%), followed by Africa (0.33%), and the least in Europe and South America (0.19% in both continents). Canine agenesis was more common in the maxilla (88.57%), followed by both maxilla and mandible (8.57%), and the least common was mandible-only presentation (2.86%). The condition was more common in females (female:male ratio = 1.23), except in Asia (female:male ratio = 0.88) and Africa (female:male ratio = 1). In Asia, unilateral agenesis was almost twice as prevalent as bilateral, but in Europe, the bilateral form was more common. Conclusions: The overall prevalence of canine agenesis is 0.30%, with the highest prevalence in Asia, followed by Africa, Europe, and South America. The condition is more common in the maxilla than the mandible, and in females than males (except in Asia and Africa), with unilateral agenesis being more common in Asia and the bilateral form showing a greater prevalence in Europe.

• The korean journal of orthodontics
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• v.51 no.5
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• pp.355-362
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• 2021

Objective: This study aimed to establish the prevalence and patterns of nonsyndromic tooth agenesis in patients referred to a tertiary health care facility. Methods: The intraoral records and panoramic radiographs of 9,874 patients aged 12-22 years were evaluated. The study group included 716 patients (371 male, 345 female) with non-syndromic agenesis of at least one tooth (except the third molars). The study data were assessed using descriptive statistics, chi-square test, and Mann-Whitney U test, while patterns were evaluated using a tooth agenesis code (TAC) tool. Results: A total of 1,627 congenitally missing teeth, were found in patients with non-syndromic tooth agenesis, with an average of 2.27 missing teeth per patient. The prevalence of tooth agenesis was 7.25%, and the most commonly missing teeth were the left mandibular second premolars (10.17%). The age group comparison revealed no significant difference in the median number of missing teeth per patient according to the cutoff values for ages between 12 and 22 years. When the missing teeth were examined separately according to quadrants, 114 different tooth agenesis patterns (upper right quadrant = 28, upper left quadrant = 27, lower left quadrant = 31, and lower right quadrant = 28) were identified, and 81 of these patterns appeared only once. Conclusions: This study highlights the benefits of applying the TAC tool in a large sample population. The application of the TAC tool in such studies will enable the development of template treatment plans by determining homogenous patterns of tooth agenesis in certain populations.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.4 no.1
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• pp.12-16
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• 2008

Williams syndrome is a rare genetic disorder with a frequency of one per 20,000~50,000 live births. It is caused by a deletion of one elastin allele located within chromosome subunit 7q11.23(long arm). This syndrome is frequently accompanied by disorders such as congenital heart disease, facial anomalies, mental retardation, and so on. The characteristic facial appearance includes full lips, rounded cheeks, broad forehead, periorbital fullness, flattened bridge of nose, small nose with anteverted nostril, long filtrum and low-set ears. In oral features, hypodontia, high prevalence of dental caries, microdontia, enamel hypoplasia, delayed eruption, and malocclusions have been found. Most adult patients with Williams syndrome lack social adaptability and lead seclusive lives, however, young patients are rather very friendly and talkative, and seem smarter than their actual intellectual quotients. They also tend to favor staying with grown-ups rather than mixing with their peers, and tend to present problematic temper tantrum during dental treatment.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.10 no.1
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• pp.26-30
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• 2014

Prader-Willi syndrome (PWS) is a rare neurodevelopmental disease caused by abnormality of chromosome 15q11-13. The estimated prevalence of PWS is 1/10,000-30,000. Most common features of this disease are feeding problems characterized by poor sucking habit related with neonatal or infantile hypotonia and obesity due to early childhood hyperphagia involved with lack of satiety. In the orodental findings, enamel hypoplasia, rampant caries, delayed eruption, poor oral hygiene, hypodontia, supernumerary teeth, increased tooth wear, decreased salivary flow and change in saliva composition were reported. This case report describes the dental treatment of 3-year-9-months-old male patient with PWS. Periodic check-ups and conservative treatments were followed, however, rapid dental caries progression caused by estimating hyposalivation was observed. Because of lack of patient cooperation, dental procedures were performed under general anesthesia.

• Journal of the korean academy of Pediatric Dentistry
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• v.41 no.3
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• pp.241-246
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• 2014

The purpose of this study was to find out prevalence of peg-laterals and to evaluate the frequency of dental anomalies in Korean children with peg-laterals. For this study, panoramic radiographs of 3,278 patients (aged 7 to 15 years) from the Department of Pediatric Dentistry admitted from January, 2008 to January, 2013 were selected for an investigation on peg-laterals distribution. The prevalence of peg-laterals was 2.62% (86 subjects). Among the peg-laterals children, the distribution of associated dental anomalies were as follows: congenitally missing teeth (29.1%), dens invaginatus (19.8%), impacted teeth (12.8%), supernumerary teeth (9.3%), and transposition (4.7%). Due to this study showing frequent occurrences of peg-laterals with other dental anomalies, one suggestion is to consider such relationships before deciding on a diagnosis and treatment plan.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.4
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• pp.658-665
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• 2007

Oligodontia is defined as the congenital absence of six or more teeth in dentition, excluding the third molars. The prevalence of congenital missing teeth is about 1.6 to 9.6% of population and the prevalence of oligidontia is about 0.08 to 1.1%. The mandibular second premolar is the most frequently absent after the third molar, followed by the maxillary lateral incisor and upper second premolar. Females seem to be affected slightly more than males. Oligodontia may occur either in isolation, or as a part of a syndrome such as ectodermal dysplasia. Different causes are possible for oligodontia: physical obstruction or distruction of the dental lamina, space limitation, functional abnormalities of the dental epithelium, failure of induction of the underlying mesenchyme, chemotherapy, radiotherapy or genetic factor. Because oligodontia would result in esthetic and functional problems, such as facial asymmetry or occlusal disharmony, early diagnosis from clinical and radiographic examination was necessary. And appropriate treatment plan should be followed. This case report was about oral conditions and treatment of the oligodontia patients who have no specific systemic disease.