• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.1
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• pp.35-42
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• 2006

The developmental process of a tooth is being presented as an important study subject to analyze formation of normal dental arch and tooth. The purpose of this study was to see the formation of tooth from a tooth bud transplanted in a white rat regarding that the jawbone could be used as a new donor site of a trasplant. The first molar of a matured white rat was extracted and the tooth bud of a 13.5 day rat embryo was transplanted. The histological and radiographical results after 4 and 8 weeks respectively are as the following. 1. Calcification in dentin, cementum, pulp and periodontal ligament was formed from the tooth bud transplanted in the alveolar socket. 2. The development of hard and soft tissue was delayed compared to the normal tooth formation and abnormal histologic features such as ankylosis and osteodentin were found. 3. The formed hard tissue did not erupt into the jaw within 8 weeks.

• Applied Microscopy
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• v.47 no.4
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• pp.242-250
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• 2017

The purpose of this study was to characterize the prenatal and postnatal development of the mouse parotid salivary gland and tooth, and to investigate the relationship between the developmental timing of the two organs. Development of parotid salivary gland begins on embryonic day 15 (E15), which is the prebud stage; E17 is the initial bud stage; E21 to postnatal day 3 (PN3) is the pseudoglandular stage; PN5 to PN10 is the canalicular stage; and PN21 is the terminal bud stage. At E15, the developing maxillary molar tissue is at the bud stage; at E17, it is at the cap stage; at E21, it is at the early bell stage; PN3 to PN5 comprises the advanced bell stage; at PN10, it is at the crown stage; at PN21, it is at the functional stage. Therefore, unlike the other major salivary glands, the development of mouse parotid salivary gland is completed through a process of prenatal and postnatal morphogenesis and becomes functional at about the same time as the developing tooth. The developmental completion times of the parotid salivary gland and tooth are closely related to the weaning time of animal.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.2
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• pp.383-399
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• 1998

Tooth development is usually described in four stages such as bud stage, cap stage, bell stage and crown stage. Exact time of appearance of tooth primordia is different among reports, and up to now there is no timetable regarding initial tooth development. To understand the congenital malformations and other disorders of the orofacial region, there is a need to establish a standard timetable on early tooth development. Till now, studies on the tooth development were mainly on later fetuses, and only few reports on early stage. Also, there were no reports on the time when bud stage turns to cap stage, and cap stage to bell stage. In this study, external morphology of face and the early development of the tooth, and transition of bud stage to cap stage, cap stage to bell stage were studied using 27 staged human embryos and 9 serially sectioned human fetuses. The results are as follows: 1. Mandibular region was formed by union of both mandibular arch at stage 15, and maxillary region by union of maxillary arch, medial nasal prominence, and intermaxillary segment at stage 19. 2. Ectodermal thickening which represents the primordia of tooth appeared in mandibular region at stage 13, and maxillary region at stage 15. 3. Bud stage began from mandibular primary central incisor at stage 17, and maxillary primary central incisor at stage 18. And the sequence of appearance was in the mandibular primary lateral incisor at stage 19, maxillary primary lateral incisor at stage 20, mandibular primary canine at stage 22, maxillary primary canine and primary first molar at stage 23, madibular primary first molar and maxillary primary second molar at 9th week, and mandibular primary second molar at 10th week of development. 4. Cap stage began from the primary anterior teeth at 9th week, and primary second molar still had the characteristics of cap stage at 12th week of development. 5. Transition to bell stage started from the primary anterior teeth at 12th week, and primary second molar started at 16th week of development. 6. Trnasition to crown stage started from primary anterior teeth at 16th week, and primary second molar at 26th week of development.

• Applied Microscopy
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• v.46 no.1
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• pp.58-66
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• 2016

Thymosin ${\beta}4$ ($T{\beta}4$) has been recently reported to play a role in dentinogenesis by regulating the expression of dentin matrix proteins. Based on previous studies, it is hypothesized that $T{\beta}4$ is associated with the formation of the enamel matrix and thus plays an important role in ameloblast. However, there is no report on the function of $T{\beta}4$ during tooth development so far. Therefore, in this study, we aimed to investigate the expression of $T{\beta}4$ and its function in ameloblasts during mouse tooth development. $T{\beta}4$ was expressed strongly in the tooth bud at the bud stage and in the dental lamina and oral epithelium at the cap stage. In advanced bell stage at postnatal day 4, large elongated ameloblasts were observed and the expression of the $T{\beta}4$ protein was the highest, with the enamel being was thicker than that in the early bell stage. The length of ameloblasts increased from the presecretory to the secretory stage and decreased from the maturation to the protective stage. These results suggest that $T{\beta}4$ participates not only in the proliferation of oral epithelial cells during the early stage of tooth development but also regulates enamel protein secretion in ameloblasts and enamel mineralization.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.3
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• pp.383-387
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• 2000

Fusion is defined as union of two separate tooth buds at some stage in their development with confluence of dentin and characterized by separate root canal and large single crown, while gemination is defined as an attempt of the single tooth bud to incompletely divide and usually result in a single root with one root canal and two completely or incompletely separated crowns. It is sometimes difficult to decide whether an abnormally large tooth is the result of fusion of a normal and a supernumerary tooth, or of gemination; use of the term 'Double tooth' may make the clinicians avoid this difficulty(Brook & Winter). Commonly there are no symptoms, but the problems associated with these anomalies include esthetics, possible loss of arch length and delayed or ectopic eruption of the permanent teeth, caries along the line of demarcation, and periodontal disease. Commonly, it dose not need to be treated in primary dentition but in case of permanent dentition, it may be requested to be treated due to esthetics and other problems. In our case, a 8 years old girl showed a Double tooth, we attained the favorable results by performing hemisection with apexification.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.25 no.4
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• pp.311-323
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• 1999

The osteonectin is a sort of glycoprotein which is secreted in human tissues. The osteonectin is generally detected in number of normal or neoplastic human tissues in vivo, but hasn't been studied the role of osteonectin in developing human teeth and odontogenic tumors. We evaluated degree of the expression of osteonectin immunohistochemically in 20 cases of developing tooth germ which growth from fetus 5 to 38 weeks, and total 51 odontogenic tumors whitch has taken from routine biopsy, such as 10 ameloblastomas, 5 cases of adenomatoid odontogenic tumors and odontomas and odontogenic fibromas, 4 cases of cementomas and calcifying epithelial odontogenic cyst and odontogenic keratocyst and dentigerous cysts and periapical cysts, and 3 cases of ameloblastic fibromas and myxomas. The results were as follows: 1. The osteonectin on the bud stage of tooth germ was strongly expressed in the epithelial dental lamina and in the outer dental epithelium on the early bell stage, and also strongly expressed in the inner dental epithelium on the late bell stage of tooth germs. 2. In ameloblastoma, the osteonectin was strongly expressed in the epithelial tumor component and especially in the acanthomatous types. 3. In both of calcifying epithelial odontogenic tumor and adenomatoid odontogenic tumors, the osteonectin was moderately expressed on the duct like spindle cells and epithelial tumor cells around calcification areas. 4. In odontogenic tumors originated from epithelial-mesenchymal tissues, the osteonectin was moderately expressed on the epithelial tumor components and in odontogenic cysts, it was expressed in ghost cells and calcification areas only. These were summaried the osteonectin may be strongly related to the developing tooth germ and odontogenic tumors and could be regulated hard tissue of human tooth in morphogenesis and involved with calcification mechanism in development odontogenic tumors.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.1
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• pp.51-55
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• 2011

Supernumerary teeth are dental abnormalies in the permanent dentition and the primary dentition. The etiology is unclear, but it may occur due to dichotomy of the tooth bud or hyperactivity of dental lamina. They occur more in the permanent dentition than in the primary dentition, with the most common site being the premaxillary area. Supernumerary teeth can be classified by morphology and position. Supplemental tooth refers to normal shape tooth. The treatment of supernumerary teeth depends on its shape, position, effect on dentition, and child's physiological condition. In this case, supernumerary primary tooth in the maxillary molar area was revealed by radiographical and clinical examination, but it was difficult to determine which is the supernumerary tooth. The tooth on the mesial side was extracted to induce the formation of adequate space and to prevent excessive space loss, and the result was favorable.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.2
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• pp.219-227
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• 2020

Tooth eruption involves a complex developmental process of tooth migration from the dental follicular origin to the final occlusion position in the oral cavity via the alveolar process. Disturbance of tooth eruption can occur at any point in a series of eruption stages; however, horizontal impaction of the mandibular first molar and primary retention of the primary mandibular second molar are rarely observed simultaneously. This study describes the treatment for two cases of horizontally impacted first molar with primary retention of primary molar. The primary retention of the primary mandibular second molar was extracted, and orthodontic traction was applied to the horizontally impacted primary mandibular first molar. Subsequently, displacement of the premolar tooth bud was improved and space regaining for eruption was achieved, guiding to normal eruption of the first molar.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.4
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• pp.704-709
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• 2006

Ectopic eruption should be understood as a change in the course of the normal eruption path of a dental bud at any moment in its origin. Transposition is a unique and extreme form of ectopic eruption. The treatment for ectopic eruption and transposition is various from simple observation to surgical exposure and orthodontic traction, according to direction of erupting tooth degree of developing root apex and eruption space etc. Autotransplantation is transplantation of tooth from one area of the mouth to another in the same individual or is moving a eruption tooth into extraction socket or surgically prepared socket, and autotransplantation is considered as a treatment of choice for the ectopic eruption when orthodontic traction is unable or when tooth movement is limited. These cases which were treated with autotransplantation of maxillary lateral incisor and maxillary canine were reported, and good esthetic and functional result were induced.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.4
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• pp.722-727
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• 2006

Most of impacted teeth reported are permanent teeth. Impaction of primary tooth caused by primary failure of eruption is rare and the most of impacted primary tooth are second primary molars. The etiology of a primary molar impaction would appear to be a physical barrier, early ankylosis of the tooth, abnormal development of the primary molar germ or malposition of the successor bud. Transposition has been described as an interchange in the position of two teeth within the same quadrant of the dental arch. It is most commonly seen with canine and lateral incisor teeth, but is rarely associated with the primary dentition. The two cases show the transposition of impacted primary molar and the tooth germ of second premolar in their clinical and radiographic examinations. In case 1, lower second primary molar was deeply impacted inferiorly to the tooth germ suspected to be a second premolar. In case 2, impacted all second primary molars were positioned inferiorly to the tooth germs suspected to be the successors. We extracted all second primary molars under general anesthesia and the extracted tooth germs appeared to be second premolars.