• Journal of the korean academy of Pediatric Dentistry
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• v.42 no.1
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• pp.87-101
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• 2015

The premature loss of the mandibular primary canine is relatively frequent and a sign of the upcoming space problems in the transitional period. This situation is caused by the permanent lateral incisor resorbing the root of the primary canine during its eruption. Bilateral loss of primary canines in a crowded arch leads to the lingual tipping of the permanent incisors, with the consequent reduction in the arch perimeter and increase in overbite. When the loss of a primary canine is unilateral, tipping of the adjacent incisors occurs toward the space, resulting in midline deviation. In these situations, treatment possibilities, such as extraction of the antimeric tooth or placement of a passive lingual arch, can be applied; although there are some controversies concerning this. Most space problems with less than 4 mm can be resolved through preservation of the leeway space using sequential disking of the primary teeth and a passive lingual arch, regaining space or limited arch expansion in the late mixed dentition. In cases with 4~6 mm of space problems, arch expansion (A-P or transverse) can be applied. Space problems with more than 6 mm should be treated through diagnosis and treatment planning. Most of these cases will require extraction of permanent teeth including serial extraction (guidance of eruption).

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.1
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• pp.11-19
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• 2017

The purpose of the study was to investigate the distribution of primary fused teeth and identify the correlation between primary fused teeth and their effect on permanent dentition. 2575 children between the age of 4 and 6 in Kyungpook National University Hospital from January 2009 to August 2015 were investigated. A total of 84 children (46 boys and 38 girls) had fused teeth. 14 of these children had two fused teeth. Prevalence of caries involvement was in 65% of maxilla and 6% of mandible. Prevalence of permanent successors missing was 86.3% in the cases involving maxillary central and lateral incisor, 70% in mandibular lateral incisor and cuspid, 11.7% in mandibular central and lateral incisor. 27 of 84 children (32.1%) had supernumerary teeth. The highest prevalence rate is seen in the cases involving maxillary central and lateral incisor. Delayed permanent tooth eruption was only observed in the maxilla because of developing supernumerary tooth. Early diagnosis of fused tooth in the primary dentition can allow the dentist to make treatment plan at the appropriate time in accordance with the tooth arrangement and tooth development.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.3
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• pp.362-371
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• 2004

It is essential to have adequate knowledge of the timing of root resorption of deciduous teeth for diagnosis and treatment planning in pediatric and orthodontic dentistry. Dental development is also influenced by hereditary characteristics, environmental factors, race, sex, endocrine reaction, nutrition, socioeconomic condition and secular factor. The aims of the present study were to determine the mean age of root resorption of deciduous teeth in contemporary Korean children and to compare the mean age of root resorption time of deciduous teeth between early 1990s and early 2000s. The study population was made up of Korean children attending the pediatric dentistry ward of Kyungpook National University Hospital. One thousand thirty seven children's panoramic radiograph (girls: 528 persons, boys: 509 persons) in $1990{\sim}1992$ and one thousand sixty five children's panoramic radiograph (girls: 394 persons, boys: 671 persons) in $2001{\sim}2003$ were examined. This study utilized a cross-sectional design. Due to the problems of imaging in the maxillary region and the mandibular incisor region, the mandibular deciduous canine, the mandibular deciduous first molar and the mandibular deciduous second molar were chosen for examination. The results were as follows. 1. There is a tendency for the teeth to resort earlier in the early 2000s group than the in early 1990s group. At the Res c stage, the difference of the mean age was 0.4 years. 2. At the Res c stage, the order of difference of the mean age from smaller to larger for the girls was the mandibular deciduous canine, the mandibular first deciduous molar, and the mandibular second deciduous molar. On the other hand, for the boys, the order was the mandibular second deciduous molar, the mandibular first deciduous molar, and the mandibular deciduous canine. The difference was larger with aging in girls and smaller with aging in boys. 3. There is a tendency for the teeth to resort earlier in girls in both the early 1990s group and the early 2000s group. The difference of the mean age between girls and boys was 0.3 year. 4. The commencement of root resorption of the mandibular deciduous canine was slower than that of the mandibular first deciduous molar. However, the completion of root resorption of the mandibular deciduous canine is faster than that of the mandibular first deciduous molar. The total elapsed time of root resorption from commencement to completion was shortest in the mandibular deciduous canine. 5. For each of the teeth in the early 1990s and the early 2000s groups, the speed of root resorption was in the later stage faster than in the earlier stage. In order to know about the exact timing of root resorption of deciduous teeth, periodic and longitudinal studies preferably covering the entire period of growth, is required.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.3
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• pp.448-452
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• 2004

Trauma from occlusion(TFO) is injury to the periodontal tissue as a result of occlusal forces. Mobility is a common clinical sign of occlusal trauma. In acute occlusal trauma, this may be accomanied by pain, tenderness to percussion, thermal sensitivity, and pathologic tooth migration. Chronic occlusal trauma may be marked by excessive wear and gingival recession. Radiographic finding include a widened periodontal ligament space, radiolucence and condensation of the alveolar bone and root resorption. TFO is related to the pathogenesis of periodontal disease. It can cause increased tooth mobility TFO itself does not initate or aggravate marginal gingivitis or initiate periodontal pockets. Active trauma can accelerate bone loss, pocket formation and gingival recession depending on the presence of local irritants and inflammation. Gingival recession associated with occlusal forces includes traumatic crescent, McCall's festoon and Stillman's cleft. TFO plays a minor role in the pathogenesis of early to moderate periodontitis. A 5-year-old male visited Yonsei University Pedodontics clinic with a chief complaint about gingival recession. Mobility, excessive wear, gingival recession were detected by clinical exam on the both mandibular deciduous ca nine. On the radiographic view, vertical alveolar bone loss was observed on both mandibular deciduous canine.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.4
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• pp.453-460
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• 2010

This study was one of the caries pattern studies. The purpose was to investigate the degree of intraoral symmetry of dental caries in the primary dentition. The dmfs data from children aged 36 to 71 months were analyzed. Pearson correlation coefficients between right teeth and left teeth were from 0.558 (upper canines) to 0.847 (upper central incisors) and 0.905 in total (P<0.01). Differences between right teeth and left teeth were mostly not significant (P>0.05). Pearson correlation coefficients between upper teeth and lower teeth were from 0.150 (right lateral incisors) to 0.506 (right first molars) and 0.680 in total (P<0.01). Differences between upper teeth and lower teeth were mostly significant (P<0.05). Percentages of bilateral caries experience cases per cases having caries experience were from 34.0% (upper canines) to 80.1% (upper central incisors), and from 53.9% (distal) to 84.9% (mesial) in upper central incisors, from 34.1% (mesial) to 45.0% (occlusal) in upper first molars, from 20.7% (distal) to 48.0% (occlusal) in upper second molars, from 34.4% (buccal) to 58.1% (occlusal) in lower first molars, and from 29.7% (distal) to 61.4% (occlusal) in lower second molars, respectively.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.2
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• pp.159-167
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• 2010

The purpose of this study was to identify patterns of caries in the dentition of preschool children using cluster analysis and multidimensional scaling. 815 preschool children aged 36-71 months old were examined for caries experience. The first four clusters in the cluster analysis were (1) molars, (2) upper incisors, (3) lower 1st molars, and (4) upper 1st molars in teeth, (1) occlusal surfaces of lower molars and upper 2nd molars, (2) mesial surfaces of upper central incisors, (3) occlusal surfaces of lower 1st molars, and (4) separation between occlusal surfaces of upper and lower 2nd molars in tooth surfaces, and (1) proximal surfaces of upper anterior teeth, (2) occlusal surfaces of lower molars, (3) buccolingual surfaces of upper anterior teeth and (4) buccolingual, proximal, and occlusal surfaces of upper molars and buccolingual and proximal surfaces of lower molars in tooth surfaces groups. In the multidimensional scaling analysis, teeth could be divided into lower 1st molars, upper 1st molars, upper central incisors, upper lateral incisors, lower 2nd molars, upper 2nd molars, and the rest(canines, lower incisors), tooth surfaces could be divided into occlusal surfaces of lower molars, mesial surfaces of upper central incisors, occlusal surfaces of upper molars, and the rest, and tooth surface groups could be divided into proximal surfaces of upper anterior teeth, buccolingual surfaces of upper anteiror teeth, occlusal surfaces of lower molars, and the rest in the order of the distance from others. In the cluster analysis and the multidimensional scaling analysis, caries patterns were different according to the age.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.4
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• pp.397-402
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• 2017

The aim of this study was to assess the spacing and crowding of the anterior teeth in the primary dentition in Hwaseong city. Photographs of the anterior segment of 237 children satisfied the criteria. The presence of primate spaces and developmental spaces was assessed by the proximal contacts. Physiologic spacing was observed in 47.3% and 38.0% of the cases in the upper and lower arches, respectively. 43.5% showed the presence of two-segment contact or crowded dentition. Physiologic spacing was observed more in boys than in girls. In the maxilla, primate space was more frequent than developmental space; however, in the mandible, the difference was low. In the maxilla, the space between the central incisor and the lateral incisor was more frequent than the space between both central incisors. In contrast, in the mandible, the space between both central incisors was more common than the space between the central and lateral incisors or between the lateral incisors and canine. The present study describes the tendency for anterior spacing and crowding in the primary dentition. Further longitudinal studies with a larger sample are needed. Dentists should consider these concepts of spacing or contact/crowding when performing full coronal restorations of primary anterior teeth.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.4
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• pp.731-736
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• 2008

Odontogenic keratocyst is classified as a developmental odontogenic cyst and is believed to arise from cell rests of the dental lamina. It accounts for 3% to 11% of all jaw cysts and they occur twice as often in the mandible as in the maxilla. Histologically, the cysts are lined by stratified, keratinizing, squamous epithelium. Daugther cysts or microcysts are often observed microscopically. The recurrence rate has been reported variously, but is known by its high recurrence rate. These lesions are more common in males than in females, occur over a wide age range and are typically diagnosed during the 2nd and 3rd decade. The diagnosis depends on the cyst’s microscopic features and is independent of its location and radiographic appearances. This cyst is a radiolucent lesion that is often multiloculated, has a smooth or scalloped border. The cyst is characteristically located in the body and ramus of the mandible, and often occurs in conjunction with an impacted tooth. This case report describes an odontogenic keratocyst on the lower right molar area of an 8-year-old girl. The cyst was removed under the general anaesthesia, and is being checked regularly for any recurrences.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.1
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• pp.122-134
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• 2000

The aim of this study is (1) to establish the baseline information concerning the width of keratinized gingiva, depth of gingival sulcus and width of attached gingiva on the buccal surface of the teeth: and (2) to determine the relationship between the above values and tooth eruption: and (3) to estimate the frequency of mucogingival problems. The results were as follows; 1. The mean width of attached gingiva of the children aged $6\sim12$ proved to be wider in the maxilla than in the mandible. Of the primary teeth, the widest width was found in the areas of maxillary primary lateral incisors and maxillary primary canines(3.50mm and 3.55mm). The narrowest was noted in the area of mandibular first primary molars(1.34mm) In the permanent dentition, the greatest width was found in the areas of maxillary permanent lateral incisors (3.00mm). The narrowest was noted in the area of mandibular first premolars(0.55mm). 2. In the primary dentition, the width of attached gingiva of primary canines and first and second primary molars became wider from the age of six as the age increased. In the permanent dentition of the boys, only mandibular central incisors and maxillary first molars showed the tendency towards increase in the width of attached gingiva with increasing age. In the permanent dentition of girls, central and lateral incisors of both jaws and maxillary first molars showed statistically significant increase in the width of attached gingiva with increasing age(p<0.05). 3. At the age of tooth change, the attached gingiva of primary teeth were almost wider than those of successive permanent teeth (p<0.05). 4. During the period of 6 to 12 years of age, the width of keratinized gingiva and the depth of gingival sulcus of permanent tooth at the age of twelve were larger than those of primary tooth at the age of six (p<0.05). 5. The maximum in the frequency of mucogingival problems was found in the areas of upper and lower first primary molars of primary dentition, and in the upper and lower first premolars of permanent dentition regardless of sex. The frequency was higher in primary teeth than in the corresponding successive permanent teeth These teeth showed tendency towards increase in mucogingival problems with age.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.1
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• pp.175-179
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• 2001

Regional odontodysplasia is a relatively rare condition in which both enamel and dentin are hypoplastic and hypocalcified. The result is localized arrest in tooth development. The etiology of regional odontodysplasia is uncertain, but, disturbance in vascular supply, somatic mutation, latent virus infection, trauma, hyperpyrexia, irradiation, nutrition, metabolic disorders and hereditary transmission are supported to be etiologic factors. Females are more often affected than males. (1.4 : 1). The maxillary arch is more often affected than the mandibular arch with the maxillary left quadrant being the most commonly involved. Affected teeth are hypoplastic, typically discolored yellow or yellowish brown, smaller in size and display a variety of surface marking including pitting and grooving. Radiographically, the teeth affected have been described to have a "ghost like" appearance or "fuzzy" appearance. Pulp calcification and denticles may be present within the pulp chambers of the affected teeth. In it's case, a 2 years old male visited for a treatment of uneruption of lower right teeth. Partial eruption of lower right deciduous central incisor and unerupted deciduous lateral incisor, deciduous canine and deciduous first molar showed severly delayed eruption state. On radiographic appearance, "Ghost like appearance", shortened root and opened apexes on lower right region were observed. It was suspected regional odontodysplasia with clinical and radiographic condition.