한국인 배자 및 태아에서 유치 발생의 조직학적 변화

김희진,임희식,최병재,오현주,박형우 大韓小兒齒科學會 1998 大韓小兒齒科學會誌 Vol.25 No.2

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 need to establish a standard timetable of 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.

유치의 외상에 의한 계승 영구치의 발육 장애

김지영,김영진,김현정,남순현 大韓小兒齒科學會 2010 大韓小兒齒科學會誌 Vol.37 No.2

유치에 가해진 외력은 하방으로 전달되어, 계승 영구치의 손상이라는 합병증이 야기시킬 수 있기 때문에 유치에 손상이 가해진 경우의 치료계획은 영구치의 안전성에 초점을 두어야만 한다. 유치의 외상에 의한 계승 영구치 발육 장애의 정도는, 외상 당시 소아의 연령 및 치아의 발육 상태, 손상의 종류와 정도 및 외상 후부터 치료 전까지의 경과 시간 등에 따라서 달라지며, 그 정도는 미약한 석회화 부전에서 성장 정지에 이르기까지 다양하게 나타난다. 본 증례는 33개월, 만 5세, 26개월의 소아에서 각각 유치의 함입, 완전탈구, 아탈구 등의 외상성 손상이 발생한 후, 후속 영구치의 발육 장애가 관찰된 경우로 비슷한 연령대엄에도 불구하고, 아탈구와 같은 경미한 외상이 발생한 경우에는 법랑질 저형성증과 같은 경미한 수준의 발육 장애가 나타났지만, 합입이 일어난 경우는 치근의 만곡이 관찰되었다. 또한 영구치의 교환 시기에 가까운 나이인 5세경이라 하더라도 완전탈구가 일어난 경우에는 치근의 형성부전 등 보다 심각한 합병증이 관찰되어, 유치의 손상양상과 외상을 당한 시기의 환아의 나이에 따라 계승 영구치에 미치는 영향이 달라진다는 사실을 확인 할 수 있었다. 따라서 유치의 변위를 초래하는 모든 종류의 외상이 발생한 경우, 술자는 외상의 유형 및 영구치의 발육상태를 고려하여 적절한 치료 계획을 세워나가는 것이 중요하리라 사료된다. Trauma to the primary teeth may have an effect on the successive permanent teeth. Thus, the treatment plans should be focused on safety of their permanent teeth. The degree of developmental disturbances in those permanent teeth depends upon many factors including the age of the children, developmental conditions of the affected teeth, types and severities of trauma and time interval from the moment of trauma to the initial treatment the patients received. The complications of the effected permanent teeth vary from the mild enamel hypoplasia to the premature finishing of teeth development. In this study, children whose ages were 33 months, 5 years, and 26 months presented the developmental disturbances to their permanent teeth, which resulted from the trauma to the primary teeth: the intrusion, the avulsion, and the SUbluxation. There showed a mild complication in the case of subluxation resulting in enamel hypoplasia, but, the more severe complication of the root dilacerations occurred in the case of intrusion. Furthermore, the 5-year-old patient whose primary dentition was near in transition period to the permanent one, the more complicated problem such as stop of root development of the permanent teeth was resulted from the avulsion. Thus, one should assume that the types of trauma and the age of the children at the moment of trauma have different effects on those successive permanent teeth. In conclusion, when the trauma that causes changes in the position of primary teeth happened, it is important to arrange an appropriate treatment procedure considering the types of trauma and the developmental conditions of the permanent teeth.

Identification and characterization of a novel tooth germ-expressing gene, Dachshund1 in mice embryogenesis

김재영 한국발생생물학회 2013 한국발생생물학회 학술발표대회 Vol.2013 No.8

Tooth bud is initiated by dental epithelium thickening and invaginated epithelium forms cap-like structure with condensed underlying mesenchyme. From this cap stage, specific epithelial cells form a cluster of non-dividing cells, primary enamel knot (PEK), and this PEK expresses abundant signaling molecules and functions as a signaling center for tooth development. Recently, hundreds of genes involved in tooth development have been reported by advanced genome-wide screening technology, but still remained unidentified genes obstruct elucidation of the precise molecular mechanisms underlying tooth development. In this work, we examined the expression patterns and developmental functions of a novel tooth germ-expressing gene, Dachshund1 (Dach1). Dach1, known as the cell fate regulator via controlling the transcription in various cell types, expressed in PEK region from cap stage to bell stage. In order to evaluate the developmental functions of Dach1 in tooth development, we cultivated the lower first molar at E12.5 for 2 and 4 days with or without treatments of antisense-oligodeoxynucleotides (AS-ODNs) against Dach1. After the knocking down of Dach1, morphological changes and cell physiology such as proliferation, cell death and migration patterns were examined. In addition, the expression levels of PEK-expressing genes such as Bmp2, Bmp7, Fgf4, Shh and Wnt5a were examined by using RT-qPCR and in situ hybridization methods. Based on these results, we suggest that Dach1 would involve in mice tooth morphogenesis through regulating the expressions of PEK related genes and cellular events to form the proper tooth structural formation.

Comparative Morphological Study on the Embryonic and Neonatal Development of the Filiform Papillae and Teeth in Mice

정순정 한국치위생과학회 2020 치위생과학회지 Vol.20 No.2

Background: In the early stages of development, teeth and lingual papillae are induced and developed through special and complex epithelial-mesenchymal interactions. Tooth completion indicates the beginning of the weaning phase, and accordingly, many oral tissues and organs are completed, and it is thought that their developmental completion times are related to each other. The purpose of this study was to clarify the embryonic and neonatal development of the filiform papillae and mandibular molar tooth, and discuss the developmental relationship between these organs by comparing the developmental completion times.Methods: Embryos at embryonic day 15 (EM15), 17 (EM17), and 21 (EM21) and mice at neonatal day 1 (NE1), 5 (NE5), 10 (NE10), and 21 (NE21) were used for experimentation. Tissues dissected from embryos and mice were fixed, and processed for histological analysis. Sections from the tissues were stained with hematoxylin and eosin for observation under a light microscope.Results: Based on the histological analysis results, the developmental process of the lingual epithelium covering the dorsal surface of the tongue was classified into three stages: initiation, morphogenesis, and functional. The development of the filiform papillae begins at EM17; undergoes rapid morphological changes in epithelial cells at EM21, PN1 and PN5, and reaches the functional stage at PN10, which is the sucking phase. Tooth development begins at EM13 or 15 and is completed at NE21 through prenatal and postnatal development.Conclusion: The development of the filiform papillae was initiated late and completed quickly through embryonic and neonatal development in comparison with the mandibular molar tooth. The filiform papillae are considered to play an important role in sucking rather than mastication as it is completed in the sucking phase.

Age Estimation Based on Mandibular Premolar and Molar Development: A Pilot Study

노병윤,김의주,서인수,김형건,류혜원,이주헌,서요섭,유지원,안종모 대한안면통증∙구강내과학회 2021 Journal of Oral Medicine and Pain Vol.46 No.4

Purpose: The dental age estimation of children is performed using dental maturity. Postmortem missing of the anterior teeth or the distortion of image of the anterior teeth in panoramic radiographs can make it difficult to analyze the development of the anterior teeth. This pilot study was conducted to derive a new age estimation method based only on the developmental stage of mandibular posterior teeth. Methods: This study was conducted using panoramic radiographs of 650 subjects aged 3 to 15 years old. The dental developmental stages of the lower left first premolar, second premolar, first molar and second molar were evaluated according to the Demirjian’s criteria. The intra-/inter-observer reliability was evaluated, and multiple linear regression analyses were performed including the developmental stage of each tooth as an independent variable. Results: The intra-/inter-observer reliability was 0.9626 and 0.8877, respectively, and showed very high reproducibility. Multiple linear regression analyses were performed for males and females, and the age calculation table was derived by obtaining the intercept and the coefficient according to the development stage of each tooth. The coefficient of determination (r 2 ) of the age calculation method was 0.9634 for male and 0.9570 for female subjects, and the mean difference between chronological age and estimated dental age was –0.42 and –0.21, respectively. Conclusions: This pilot study evaluated the developmental stages of four lower posterior teeth in the Korean group according to Demirjian’s criteria, and derived age estimation method. The accuracy was lower than when more teeth were used, but it will be useful to estimate age of children when the anterior teeth are difficult to accurately analyze

Morphological Study on the Correlation of Prenatal and Postnatal Development between Mouse Parotid Salivary Gland and Tooth

Jeong, Soon-Jeong,Jeong, Moon-Jin Korean Society of Microscopy 2017 Applied microscopy Vol.47 No.4

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.

Apoptosis during Rat Tooth Development

Min-Ju Kim,Yu-Seong Kim,Yeon-Hee Moon,Na-Ri Jung,Jung-Sun Moon,Sun-Hun Kim,Min-Seok Kim KOREAN ACADAMY OF ORAL BIOLOGY 2011 International Journal of Oral Biology Vol.36 No.1

Teeth develop via a reciprocal induction between the ectomesenchyme originating from the neural crest and the ectodermal epithelium. During complete formation of the tooth morphology and structure, many cells proliferate, differentiate, and can be replaced with other structures. Apoptosis is a type of genetically-controlled cell death and a biological process arising at the cellular level during development. To determine if apoptosis is an effective mechanism for eliminating cells during tooth development, this process was examined in the rat mandible including the developing molar teeth using the transferase-mediated dUTP-biotin nick labeling (TUNEL) method. The tooth germ of the mandibular first molar in the postnatal rat showed a variety of morphological appearances from the bell stage to the crown stage. Strong TUNEL-positive reactivity was observed in the ameloblasts and cells of the stellate reticulum. Odontoblasts near the prospective cusp area also showed a TUNEL positive reaction and several cells in the dental papilla, which are the forming pulp, were also stained intensively in this assay. Our results thus show that apoptosis may take place not only in epithelial-derived dental organs but also in the mesenchyme-derived dental papilla. Hence, apoptosis may be an essential biological process in tooth development.

하악 제2소구치 결손과 연관된 치아 결손 및 발육지연

박민지,김성오,송제선,이제호 대한소아치과학회 2018 大韓小兒齒科學會誌 Vol.45 No.4

선천적 치아의 결손은 비교적 흔한 치아 발육장애이며 하악 제2소구치의 결손은 치아 결손 중 가장 많이 나타나는 것으로 알려져있다. 이 연구의 목적은 하악 제2소구치 결손과 연관되어 나타나는 다른 치아의 결손 및 치아의 발육 지연에 대해 조사하는 것이다. 이 연구는 2014년부터 2016년까지 연세대학교 치과대학을 내원하여 파노라마 방사선을 찍은 만 9세-15세의 소아청소년 중 하악제2소구치 결손이 있는 환자를 대상으로 시행되었다. 하악 제2소구치의 결손을 가진 125명의 환자들 중 다른 치아의 결손은 58명(46.4%)에서 나타났으며 발육이 지연된 치아는 38명(30.4%)에서 나타났다. 이번 연구에서 하악 제2소구치의 결손을 가진 환자는 그렇지 않은 어린이와 비교하였을 때 치아 결손 및 치아 발육지연의 유병률이 높게 나타났다. Tooth agenesis is a common human dental anomaly and the agenesis of mandibular second premolars has been proven to be the most frequently observed. The aim of this study is to investigate tooth agenesis and delayed tooth development in patients with agenesis of mandibular second premolars. This study reviewed 9 to 15 year-old patients with agenesis of mandibular second premolars who visited the department of pediatric dentistry of Yonsei University Dental Hospital and took panoramic radiographs from January 2014 to December 2016. On panoramic radiographs, agenesis of teeth was observed and developmental delay of teeth was evaluated by the Nolla method. Among 125 patients with agenesis of mandibular second premolars, 58 patients (46.4%) showed agenesis of other teeth and 38 patients (30.4%) showed delayed tooth development. In this study, patients with agenesis of mandibular second premolars were more likely to have tooth agenesis or delayed eruption of other teeth.

성조숙증 여아의 치아 발육단계와 신체발육의 관련성

황다혜(Da-Hye Hwang),황태윤(Tae-Yoon Hwang) 한국구강보건과학회 2020 한국구강보건과학회지 Vol.8 No.3

Objectives: Precocious puberty is associated with abnormal development and especially altered development of the teeth. We conducted a case-control study between March 2014 and March 2015 to evaluate tooth development in children with precocious puberty. Methods: The patient group consisted of 55 girls who were diagnosed with precocious puberty in the pediatrics department of a university hospital and underwent no more than one round of medication. The control group consisted of 55 typically developing children who visited a dental clinic and were age-matched to participants in the patient group. Both the patient and the control group were subjected to panoramic radiography, while sexual maturity, bone age, and sex hormones were evaluated in the patient group. Results: 1. A later calcification developmental stage of the canines, 1 st premolars, 2 nd premolars, and 2 nd molars was associated with a higher rate of inclusion in the patient group. 2. In the patient group, there was a significant association between bone age and developmental stage for all evaluated teeth (p<0.01). Conclusions: The above results demonstrate a particular need for oral healthcare in girls with precocious puberty and prioritization of tooth health in their dental care.

Failure of Tooth Formation Mediated by miR-135a Overexpression <i>via</i> BMP Signaling

Kim, E.J.,Lee, M.J.,Li, L.,Yoon, K.S.,Kim, K.S.,Jung, H.S. SAGE Publications 2014 Journal of dental research Vol.93 No.6

<P>MicroRNAs (miRNAs) are known to regulate a variety of gene functions in many tissues and organs, but their expression and function in tooth development are not well-understood. A specific miRNA, miR-135a, was determined to be highly expressed at the bud stage. Interestingly, after the cap stage, miR-135a was expressed in the epithelium and mesenchyme but not in the inner enamel epithelium. To identify the relationship between miR-135a and its putative target genes, <I>Bmpr-Ia</I> and <I>Bmpr-Ib</I>, in early tooth development, miR-135a was ectopically overexpressed with a lentivirus. This overexpression resulted in the repression of Bmpr-Ia and Bmpr-Ib. Furthermore, miR-135a inhibited both Bmpr-Ia and Bmpr-Ib transcription. BMP2 proteins were expressed ectopically in tooth germs during the cap stage to determine the relationship between miR-135a and BMP signaling in early tooth development. When miR-135a was ectopically expressed, no tooth formation was observed after 4 wk of incubation in the kidney capsule. This study suggested that Bmp signaling, specifically Bmpr-Ia and Bmpr-Ib, regulates tooth formation <I>via</I> miR-135a.</P>