• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.2
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• pp.253-261
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• 2009

The purpose of this study was to present new data on the timing and sequence of permanent teeth emergence and to compare these findings with the results of earlier studies. The dental examinations had been performed to E-elementary school students, who visited the Yonsei University Dental Hospital between 1998 and 2005; 1,307 boys and 1,312 girls with the age ranging from 6 to 12 years old. The followings were concluded. 1. Eruption time of the maxillary permanent teeth is as follows. It was 6.81 years in male and 6.73 years in female for the central incisor, 7.78 years in male and 7.65 years in female for the lateral incisor, 10.48 years in male and 9.92 years in female for the canine, 9.76 years in male and 9.63 years in female for the first premolar, 10.66 years in male and 10.49 years in female for the second premolar, 6.39 years in male and 6.26 years in female for the first permanent molar, and 12.13 years in male and 12.03 years in female for the second permanent molar. 2. Eruption time of the mandibular permanent teeth is as follows. The central incisor could not be determined in this study, but it is assumed to erupt before the age of 6.08. In the mandible, eruption time was 6.78 years in male and 6.65 years in female for the lateral incisor, 9.76 years in male and 9.05 years in female for the canine, 9.82 years in male and 9.59 years in female for the first premolar, 10.67 years in male and 10.52 years in female for the second premolar, 6.22 years in male and 6.12 years in female for the first permanent molar, and 11.58 years in male and 11.14 years in female for the second permanent molar. 3. The eruption sequence is as follows. In the maxilla, the first permanent molar erupted first, followed by the central incisor, the lateral incisor, the first premolar, the canine, the second premolar, and the second permanent molar. In the mandible, the central incisor erupted first, followed by the first permanent molar, the lateral incisor, the canine, the first premolar, the second premolar, and the second permanent molar. 4. Tooth eruption occurred earlier in female compared to male by average of 0.19 year in the maxilla and 0.29 year in the mandible. 5. In both male and female, the hiatus (interval of rest) occurred between the emergence of lateral incisor and first premolar in the maxilla while it was observed between the lateral incisor and canine in the mandible. Male had a hiatus of 1.98 years in the maxilla and 2.90 years in the mandible, while the female's were 1.98 years and 2.40 years, respectively.

• The Korean Journal of Oral and Maxillofacial Pathology
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• v.42 no.6
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• pp.183-187
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• 2018

The supernumerary tooth which is extra tooth in comparison to normal dentition is one of the developmental problems. The most common type of supernumerary tooth is mesiodens which may cause several complications like delayed eruption, crowding, spacing et al. Moral Incisor Hypomineralization (MIH) describes the clinical appearance of enamel hypomineralization of systemic origin affecting one or more permanent first molars that associated frequently with affected incisors. We report a case of a 6 - year - old boy who visited our clinic for removal of mesiodentes. The patient was diagnosed by mesiodentes and MIH by clinical examination and radiographic examination. Under local anesthesia, Mesiodentes were removed surgically. The demarcated opacities, a feature of MIH, were observed in the removed mesiodentes. After removal of mesiodentes, the maxillary central incisors erupted normally and in order to manage the teeth affected MIH, follow-up and fluoride varnish application were done every 3 months.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.4
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• pp.337-347
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• 2011

The basic structure of the primary crowns usually resemble their succeeding permanent teeth. However, maxillary second primary molars resemble ipsilateral first permanent molars. Accordingly in this study, odontometric data of the two teeth was obtained, then analyzed to verify the morphological relationship and sex difference between the two teeth. Dental study casts were examined for their mesiodistal and buccolingual width of the crowns, diameter of each cusps, and intercuspal distances. Photographs of the crowns were taken to measure the angles between each cusp tip. The results are as follows : 1. In boys, PrI, PaI, DBC angle, and MBC angle did not show any statistically significant difference between the two teeth(p>0.05), and moderate level of correlations were observed. 2. In girls, crown index, DBC angle, and MBC angle of the two teeth did not show any statistically significant difference(p>0.05), and moderate level of correlations were recognized. 3. Measurements that did not show statistically significant difference between the two teeth in both boys and girls were DBC angle and MBC angle(p>0.05). In DLC angle, however, statistically significant difference was observed(p<0.01). 4. Most of the measurements showed sex differences, except DBC angle, which did not show any sex difference in both teeth(p>0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.2
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• pp.281-287
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• 2009

An eruption failure can be observed for child and adolescent periods when the primary dentition is changed to the permanent dentition through the mixed dentition frequently. The eruption failure can lead to miss erupting times of the tooth, then it will cause a lot of problems including root resorption, esthetic problem, transposition of adjacent tooth, malocclusoin and etc. Especially, the maxillary first molar is importantly concerned with occlusion and growth and is an essential tooth for development and maintenance of occlusion. So, it is a momentous part of more proper occlusal management to find these abnormal cases at the early stage and solve the problems. The sorts of eruption failures of the maxillary first molars can be divided into delayed eruption, impaction and the primary retention and the secondary retention. When physical obstacles cause impaction, first of all they must be removed then we can treat the impaction with observation after removal, surgical exposure or orthodontic traction. If the source of impaction is an ectopic eruption, the treatment can be a brasswire, a pendulum appliance, a space maintainer or space regainer after the extraction of the second deciduous tooth and etc. These cases are made a diagnosis of eruption failures of the maxillary first molars in mixed dentition period and have good prognosises after my treatments. So I reported them.

• The korean journal of orthodontics
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• v.49 no.3
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• pp.161-169
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• 2019

Objective: To evaluate the effectiveness of the Frog appliance in three dimensions by using cone-beam computed tomography (CBCT) images. Methods: Forty patients (21 boys and 19 girls), averaged 11.7 years old, with an Angle Class II division 1 malocclusion were included in our study. They had either late mixed dentition or early permanent dentition, and the maxillary second molars had not yet erupted. All patients underwent CBCT before and after the treatment for measuring changes in the maxillary first molars, second premolars, central incisors, and profile. Paired-samples t-test was used to compare the mean difference in each variable before treatment and after the first phase of treatment. Results: The maxillary first molars were effectively distalized by 4.25 mm (p < 0.001) and 3.53 mm (p < 0.05) in the dental crown and root apex, respectively. The tipping increased by $2.25^{\circ}$, but the difference was not significant. Moreover the teeth moved buccally by 0.84 mm (p < 0.05) and 2.87 mm (p < 0.01) in the mesiobuccal and distobuccal cusps, respectively, whereas no significant changes occurred in the root apex. Regarding the anchorage parts, the angle of the maxillary central incisor's long axis to the sella-nasion plane increased by $2.76^{\circ}$ (p < 0.05) and the distance from the upper lip to the esthetic plane decreased by 0.52 mm (p = 0.01). Conclusions: The Frog appliance effectively distalized the maxillary molars with an acceptable degree of tipping, distobuccal rotation, and buccal crown torque, with only slight anchorage loss. Furthermore, CBCT image demonstrated that it is a simple and reliable method for three-dimensional analysis.

• Journal of the korean academy of Pediatric Dentistry
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• v.48 no.3
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• pp.352-358
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• 2021

Molar-incisor malformation (MIM) is characterized by malformation in the root with a normal crown. While MIM mostly occurs in the permanent first molar, it has also been reported in the maxillary central incisor and the primary second molar (PSM), but anatomical analysis of the primary teeth with MIM has not been studied to date. In this case report, a patient with MIM was reported, and an extracted PSM with MIM was analyzed with micro computed tomography (CT). A cervical constriction morphology of the cementoenamel junction (CEJ) can be observed in extracted PSM. In micro CT analysis, characteristics such a mineralized plate (cervical mineralized diaphragm) in the CEJ area, complex root canal morphologies, a calcified mass inside the pulp chamber, and constricted pulp chamber of crown portion were observed.

• The korean journal of orthodontics
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• v.30 no.1 s.78
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• pp.43-52
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• 2000

Hemifacial microsomia ( HFM ) is the second most common craniofacial abnormalies. HFM represnted a spectrum of clinical findings such as hypoplasia of the mandibular ramus and condyle, confinement of maxilla growth, external and/or middle ear defects, involvement of some cranial suture, buccal soft tissue, facial nerve, and muscles in the affected side. HFM often showed progressive facial asymmetry and occlusal plane slanting to the affected side with growth. There were several reports about asymmetry of tooth maturation, hypodontia, delayed eruption, enamel hypoplasia in HFM. Since teeth develope in close association with size and morphology of the maxillary and the mandible, it is highly likely that dental changes will be present in HFM. So the Purpose of this study was to investigate the differences of the primary and the permanent teeth dimensions in the maxillary and the mandibular dentition between the affected and the non-affected side of HFM.. The sample of this study consisted of 34 unilateral HFM Patients (18 males and 16 females, average age : 5 year 11 months old). The authors examined the mesiodistal and the faciolingual dimensions of the primary and the permanent teeth and performed statistical study by using paired t-test. The results were as follows 1. The mesiodistal dimensions of the mandibular second primary molar and the mandibular first permanent molar in the affected side of HFM were significantly smaller than those of non-affected side. But there were no significant differences in the anterior teeth and the mandibular first primary molar. It means that a gradient of severity from anterior teeth to posterior teeth was found in the mandibular dentition. 2. Although there were no significant differences in the faciolingual dimensions of the primary and the permanent teeth in the maxillary and the mandibular dentition between the affected and non-affected side of HFM, there were general trend of compensatory increase in faciolingual dimension of the mandibular primary and the permanent teeth in the affected side Therefore these results showed that HFM might affect on the abnormality of tooth dimension, especially the most posterior teeth, in the affected side of the mandible.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.1
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• pp.119-125
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• 2005

In the primary dentitions, the majority of dental injuries involve the anterior teeth, especially the maxillary primary central incisors. When injuries affecting primary and permanent teeth are compared, it appears that trauma to the primary dentition is usually confined to the supporting structures, i.e. luxation and exarticulation, while the largest proportion of injuries affecting the permanent dentition is represented by crown fractures. But, cases reporting trauma affecting primary molars are unusual in the literature and several reports describe fractures of posterior teeth. The main goal of this report is to describe the repositioning treatment using removable appliances to an uncommon case of lingual displacement of primary molar that happened to a 4 year 5 month-old female child.

• The korean journal of orthodontics
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• v.35 no.3 s.110
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• pp.182-195
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• 2005

The purpose of this retrospective study was to estimate the pretreatment characteristics of growing patients with Class II malocclusion. who had been treated with maxillary second molar extractions The sample comprised of 51 subjects; 18 subjects were classified into the molar extraction group, and 33 subjects were treated without extraction and classified into the nonextraction group. Pretreatment lateral cephalograms were calculated and analyzed by independent t-test and stepwise discriminant analysis. In measurements for skeletal pattern, no anteroposterior measurements and proportions of various vertical dimensions were significantly different. and only some measurements such as $AB-MP(^{\circ)$, Na-We(mm), AVD (mm) were significantly different between the two treatment groups (p<0.05). In measurements for dentoalveolar pattern. some measurements, which were related to the position and angulation of the upper and lower permanent first molars, and the angulation of the upper third molars, were significantly different between the two treatment groups In particular, the maxillary second molar extraction group exhibited more mesial angulation of maxillary first molar to the occlusal plane.

• The korean journal of orthodontics
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• v.12 no.1
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• pp.21-26
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• 1982

This study was undertaken to document relations between facial skeletal pattern and dental occlusion. The data in .this study were collected from pretreatment cephalometric radiographs and study models of patients' records present in the files of Orthodontic Department, Seoul National University Hospital. Patients were selected on the basis of a mandibular plane-sella nasion angle equal to or greater than $38^{\circ}$ (high SN-MP angle) or equal to or less than $26^{\circ}$ (low SN-MP angle). Patients in the mixed dentition and with missing permanent teeth were excluded for ease of assessing tooth size / arch circumference relationships and then 30 high SN-MP and 11 low SN-MP patients were selected among them. The mean age of these two groups of patients was high SN-MP, $12.8{\pm}1.23$ years and low SN-MP, $13.0{\pm}1.48$ years. The following conclusions were obtained. 1. In the maxilla and mandible the mean tooth size of high SN-MP patients was nearlly identical to the low SN-MP patients. 2. The mean maxillary arch circumference was increased in low SN-MP group compared with high SN-MP group and a smilar, but smaller, mean increase was present in mandible. 3. The difference between the mean maxillary circumference required and the mean maillary circumference present ranged from -4.8mm in the high SN-MP group to -1.3mm in the low SN-MP group. A small range of means occurred in the mandible (high SN-MP: -4.0mm to low SN-MP: -1.8mm). 4. In the maxilla and mandible the mean arch length was nearly identical in the high and low SN-MP groups. 5. The mean incisor inclination was increased as the SN-MP angle decreased in the maxilla and mandible. 6. The men distance of the maxillary first molar from anterior border of the pterygomaxillary fissure was nearly similar between high and low groups. 7. The mean mandibular intermolar width was increased from high SN-MP to low SN-MP patients.