• Journal of Korean Dental Science
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• 제9권1호
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• pp.9-18
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• 2016

Purpose: Wnt signaling plays an essential role in the dental epithelium and mesenchyme during tooth morphogenesis. Deletion of the Wntless (Wls) gene in odontoblasts appears to reduce canonical Wnt activity, leading to inhibition of odontoblast maturation. However, it remains unclear if autonomous Wnt ligands are necessary for differentiation of dental pulp cells into odontoblast-like cells to induce reparative dentinogenesis, one of well-known feature of pulp repair to form tertiary dentin. Materials and Methods: To analyze the autonomous role of Wls for differentiation of dental pulp cells into odontoblast-like cells, we used primary dental pulp cells from unerupted molars of Wls-floxed allele mouse after infection with adenovirus for Cre recombinase expression to knockout the floxed Wls gene or control GFP expression. The differentiation of dental pulp cells into odontoblast-like cells was analyzed by quantitative real-time polymerase chain reaction. Result: Proliferation rate was significantly decreased in dental pulp cells with Cre expression for Wls knockout. The expression levels of Osterix (Osx), runt-related transcription factor 2 (Runx2), and nuclear factor I-C (Nfic) were all significantly decreased by 0.3-fold, 0.2-fold, and 0.3-fold respectively in dental pulp cells with Wls knockout. In addition, the expression levels of Bsp, Col1a1, Opn, and Alpl were significantly decreased by 0.7-fold, 0.3-fold, 0.8-fold, and 0.6-fold respectively in dental pulp cells with Wls knockout. Conclusion: Wnt ligands produced autonomously are necessary for proper proliferation and odontoblastic differentiation of mouse dental pulp cells toward further tertiary dentinogenesis.

• 대한소아치과학회지
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• 제48권3호
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• pp.255-268
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• 2021

이 연구의 목적은 한국 아동의 골 성숙 단계와 여러 치아들의 석회화 단계 간의 상관관계를 알아보고자 하는 것이다. 만 6 - 14세의 남아 359명, 여아 384명의 수완부 방사선사진, 측방두부규격 방사선사진, 파노라마 방사선사진을 분석하여 평가하였다. 하악 좌측의 7개 영구치의 치아 석회화 단계는 Demirjian이 제시한 방법에 의해 평가되었다. 골 성숙도 단계를 평가하기 위하여 수완부 방사선 사진은 Fishman이 제시한 skeletal maturity indicators(SMI)에 따라 평가되었고, 측방두부규격 방사선사진은 Baccetti가 제시한 cervical vertebral maturation(CVM) 방법에 따라 평가되었다. Spearman의 순위상관분석을 시행한 결과 치아 석회화 단계와 골 성숙도 간에 유의미하게 높은 상관관계가 나타났다(r = 0.40-0.84, p < 0.001). 7개의 영구치 중에서 하악 제2대구치가 골 성숙도와 가장 높은 상관관계를 보인 반면 중절치가 가장 낮은 상관관계를 나타내었다. 남녀 모두에서 하악 견치의 stage G와 하악 제2대구치의 stage F가 SMI 6단계와 CS 3단계에서 나타날 확률이 가장 높았다. 이 연구의 결과에 따르면 치아 성숙도와 골 성숙도 사이에 높은 상관관계가 있으므로, 파노라마 방사선사진에서의 치아 성숙도 평가는 성장기 아동의 골 성숙도를 평가하는 보조적 수단으로 활용될 수 있다.

• Journal of Periodontal and Implant Science
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• 제29권4호
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• pp.929-942
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• 1999

Three beagle dogs aged over one and half years were used in this study. All mandibular premolars were carefully extracted. Two AVANA implants(Sumin, Korea) and two 3i implants(Implant Innovation, USA) were installed at each right and left side respectively. Each dog was sacrificed at 4, 8. 12 weeks. Non-decalcified specimens were made and stained for a light microscopic study. The results were as follows ; 1. Inflammation was not observed in the area of bone tissue adjacent to the implant body. 2. With time, quantity of osseointe-gration increased in each type of den-dental implant. There was no difference between AVANA implant and 3i implant. 3. Maturation of the bone around each type of the dental implant increased with time. 12 weeks after implant installation, the bone around dental implant represented compact bone-like appreance. 4. In case implants were located adjacent to a root, newly-formed periodontal ligament tissue was observed around the implant. And the direction of the periodontal ligament fiber was parallel to the surface of the implant . Within the results of this study, AVANA implants represented similar osseointegra-tion in comparision with 3i implants.

• Imaging Science in Dentistry
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• 제43권4호
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• pp.267-272
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• 2013

Purpose: Demirjian's dental maturity scores and curves have been widely used for human age determination. Several authors have reported considerable differences between the true and estimated age based on the Demirjian curves, which have been accounted for by ethnicity. The purpose of the current study was to assess the role of ethnicity-specific dental maturation curves in age estimation of Saudi children. Materials and Methods: A sample of 452 healthy Saudi children aged 4 to 14 years were aged based on the original French-Canadian Demirjian curves and several modified Demirjian curves specified for certain ethnic groups: Saudi, Kuwaiti, Polish, Dutch, Pakistani, and Belgian. One-way ANOVA and a post hoc Scheff$\acute{e}$'s test were used to assess the differences between chronological age and dental age estimated by the different curves (P<0.05). Results: The curves designed for Dutch, Polish, Saudi, and Belgian (5th percentile) populations had a significantly lower error in estimating age than the original French-Canadian and Belgian (50th percentile) curves. The optimal curve for males was the Saudi one, with a mean absolute difference between estimated age and chronological age of 8.6 months. For females, the optimal curve was the Polish one, with a mean absolute difference of 7.4 months. It was revealed that accurate age determination was not related to certain ethnicity-specific curves. Conclusion: We conclude that ethnicity might play a role in age determination, but not a principal one.

• 대한소아치과학회지
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• 제26권1호
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• pp.146-150
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• 1999

치아발육시기의 항암치료는 치아에 영향을 줄 수 있으며 이에 대한 예상 및 적절한 치료계획수립이 필요하다. 본 증례에서 환자의 왜소치는 항암 화학요법과 관련되어 발생한 것으로 추정되며, 이에 대한 장기적 관찰 및 치료가 필요할 것으로 사료된다.

• Molecules and Cells
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• 제41권1호
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• pp.50-54
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• 2018

Atg5 and Atg7 have long been considered as essential molecules for autophagy. However, we found that cells lacking these molecules still form autophagic vacuoles and perform autophagic protein degradation when subjected to certain stressors. During this unconventional autophagy pathway, autophagosomes appeared to be generated in a Rab9-dependent manner by the fusion of vesicles derived from the trans-Golgi and late endosomes. Therefore, mammalian autophagy can occur via at least two different pathways; the Atg5/Atg7-dependent conventional pathway and an Atg5/Atg7-independent alternative pathway.

• Restorative Dentistry and Endodontics
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• 제42권1호
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• pp.65-71
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• 2017

A revascularization procedure was shown to be the best alternative therapy for immature teeth with necrotic pulp and apical infection. A 12 year old female with a history of trauma to her upper central incisor and a sinus tract was referred for endodontic treatment. She was an active orthodontic patient and had undergone regenerative endodontic treatment for the past 2 years. Clinical examination revealed no response to sensibility, percussion, and palpation tests. The preoperative radiograph showed an open apex and apical rarefaction. The case was diagnosed as previously treated tooth with asymptomatic apical periodontitis. Regenerative endodontic retreatment was performed, and the case was followed for 3 years. Clinical, radiographic, and cone-beam computed tomography follow-up examination revealed an asymptomatic tooth, with evidence of periapical healing and root maturation.

• Restorative Dentistry and Endodontics
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• 제38권3호
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• pp.178-181
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• 2013

Traumatic injuries to an immature permanent tooth may result in cessation of dentin deposition and root maturation. Endodontic treatment is often complicated in premature tooth with an uncertain prognosis. This article describes successful treatment of two traumatized maxillary central incisors with complicated crown fracture three months after trauma. The radiographic examination showed immature roots in maxillary central incisors of a 9-year-old boy with a radiolucent lesion adjacent to the right central incisor. Apexogenesis was performed for the left central incisor and revascularization treatment was considered for the right one. In 18-month clinical and radiographic follow-up both teeth were asymptomatic, roots continued to develop, and periapical radiolucency of the right central incisor healed. Considering the root development of these contralateral teeth it can be concluded that revascularization is an appropriate treatment method in immature necrotic teeth.

• 치위생과학회지
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• 제6권1호
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• pp.1-9
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• 2006

기계적 자극에 의한 골조직의 개조에서 압박측은 일차적으로 파골세포에 의하여 골기질의 흡수를 위한 유전자 발현에 의하여 기시된다. 그러나 기질을 이루는 유기 단백질의 흡수에 관여하는 단백용해효소의 세포 내 작용 기전은 여전히 완전히 이해되지 않고 있다. 이 연구는 파골세포에서 용해용소체효소인 cathepsin k에 주목하여, cAMP 길항제와 PKA 억제제 및 adenylate cyclase 촉진제에 의한 cathepsin k 생성의 촉진 또는 억제 효과의 기전을 해명하는데 그 목적을 두었다. cAMP 길항제인 Rp-cAMP와 PKA 억제제인 KT5720과 H89는 cathepsin K의 세포 내성숙을 차단하였으며, 대조적으로 adenylate cyclase 촉진제 forskolin은 파골세포에서의 cathepsin K의 생성과 성숙을 유인하는 것으로 나타났다. 특히 cathepsin K의 생성과 성숙에 관여하는 신호전달이 protein kinase C(PKC)와 관련성을 검정하기 위하여 백서의 골세포를 PKC의 선택적 억제제인 calphostin C로 처리하였을 때 아무런 영향이 없는 것으로 나타남으로써 calphostin C는 파골 세포에 의해 매개된 cathepsin K의 생성과 성숙과는 무관한 것으로 밝혀졌다. 이는 파골세포에서의 cathepsin K의 성숙은 cAmp-PKA 신호전달 경로에 의해 조절됨을 의미한다. 분비된 전구효소는 M6P 수용체를 통하여 세포 내로 다시 진입할 수 있는 잠재성을 가지고 있기 때문에 이러한 가능성을 차단하기 위하여 M6P가 존재 또는 결여된 상태에서 cAMP 길항제인 Rp-cAMP와 PKA 억제제인 KT5720 및 H89를 시험하였다. 그 결과 Rp-cAMP, KT5720 또는 H89에 의한 cathepsin K의 M6P용량 비례적 생성 억제가 관찰 되었다. 또한 M6P를 주었을 때 Rp-cAMP, KT5720와 H89의 작용이 증가된을 보였다. 이상에서와 같이 Rp-cAMP, KT5720와 H89의 cathepsin K 생성 방해를 통한 골흡수 억제는 골다공증 또는 관절염의 치료와 같은 골흡수의 억제를 필요로 하는 분야에서의 임상적응용 가능성을 시사한다.

• 대한치과교정학회지
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• 제52권2호
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• pp.112-122
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• 2022

Objective: This study aimed to present and evaluate a new deep learning model for determining cervical vertebral maturation (CVM) degree and growth spurts by analyzing lateral cephalometric radiographs. Methods: The study sample included 890 cephalograms. The images were classified into six cervical stages independently by two orthodontists. The images were also categorized into three degrees on the basis of the growth spurt: pre-pubertal, growth spurt, and post-pubertal. Subsequently, the samples were fed to a transfer learning model implemented using the Python programming language and PyTorch library. In the last step, the test set of cephalograms was randomly coded and provided to two new orthodontists in order to compare their diagnosis to the artificial intelligence (AI) model's performance using weighted kappa and Cohen's kappa statistical analyses. Results: The model's validation and test accuracy for the six-class CVM diagnosis were 62.63% and 61.62%, respectively. Moreover, the model's validation and test accuracy for the three-class classification were 75.76% and 82.83%, respectively. Furthermore, substantial agreements were observed between the two orthodontists as well as one of them and the AI model. Conclusions: The newly developed AI model had reasonable accuracy in detecting the CVM stage and high reliability in detecting the pubertal stage. However, its accuracy was still less than that of human observers. With further improvements in data quality, this model should be able to provide practical assistance to practicing dentists in the future.