• International Journal of Oral Biology
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• 제36권4호
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• pp.195-201
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• 2011

Matrix metalloproteinases (MMPs) have been implicated in tissue development and re-modeling. Dynamic morphological changes of tooth germs reflect involvement of these enzymes during odontogenesis. The present study was performed to investigate expression and localization of MMP-2 and MMP-9, which have been known to have type IV collagenase activities, in rat tooth germs at different developmental stages. MMP-2 expression was increased gradually in the tooth germs from cap to crown staged germs at both transcription and translation levels. The localization of this molecule was detected in secretory ameloblasts and preameloblasts. The strong immunoreactivities were occasionally seen along the basement membrane between ameloblasts (or preameloblasts) and odontoblasts (preodontoblasts). However, weak reactivity was detected in odontoblasts and reduced enamel epithelium. The level of MMP-9 expression in the tooth germs was higher in cap stage than in crown staged germs at both transcription and translation levels. They were strongly expressed in both ameloblasts and odontoblasts. Even though reduced enamel epithelium after enamel formation and inner enamel epithelium at the cap stage exhibited weak reactivity, strong reactivity was detected in dental follicles and perifollicular tissues surrounding cap staged germs. These results suggested that MMP-2 may involve degradation of the basement membrane during hard tissue formation, whereas MMP-9 might be involved in remodeling of follicular tissues.

• 대한소아치과학회지
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• 제38권3호
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• pp.290-295
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• 2011

치아형성 과정 중 치배 주위의 물리적 작용이나 대사 환경의 변화로 치아 발생은 영향을 받을 수 있다. 유치열기에 가해진 외상은 계승 영구치의 발생에 장애를 초래시킬 수 있는 가장 대표적인 물리적 요인으로 이로 인한 합병증으로 계승 영구치의 법랑질 변색 및 저형성증이 가장 흔히 발생하고 드물게 매복, 이소 맹출, 치근 형성 정지 및 치근 만곡 등이 나타난다. 본 증례에서는 만 6세 5개월의 여자 어린이 환자가 안면부 외상을 주소로 내원하여 상악 좌우 유중절치의 정출성 탈구, 상악 우측 유측절치의 함입성 탈구, 상악 좌측 유측절치의 구개측 측방 탈구로 진단되었고, 상악 치은부의 열상과 상악 전치부의 치조골 골절이 관찰되었다. 내원 당일 치과 응급실에서 동요도가 심한 상악 좌우 유중절치의 발치 후 치은 봉합술을 시행하였다. 24개월 정기 검진 중 방사선 사진 상에서 상악 좌,우측 측절치의 백악 법랑 경계(Cemento enamel junction, CEJ) 근방에 치근 만곡이 관찰되었고 상악 중절치 치근의 치관부 1/3부위에서 치근 형성이 정지되고 있는 양상이 관찰되었다. 치조골 골절이 어린이에서 흔하게 나타나는 외상의 유형은 아니나 본 증례에서와 같이 치근 발육이상 등 여러 합병증을 일으킬 수 있으므로 외상을 입은 환아에서 치조골 골절 여부에 대한 면밀한 검사 및 주기적인 검진은 예후 예측 및 향후 치료에 있어서 중요할 것이다.

• 대한치과교정학회지
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• 제37권5호
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• pp.351-363
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• 2007

유성견에서 periodontal distraction 과정을 통해 급속 견인 후에 치수와 치주조직의 변화를 평가하였다. 유성견의 상악 제2소구치를 발거하고 제3소구치 근심의 치간골을 부분 제거하였다. 견인장치는 6일 동안 하루에 2번씩 견인하고, 강화기 동안 0주, 1주, 3주, 5주, 7주, 9주에 치수와 치주조직의 변화를 임상적, 방사선학적, 조직학적, 면역조직화화학적으로 관찰하였다. 신장된 치주인대 내에서 견인 직후부터 4주까지 활발한 골밀도 증가를 보였으며, 특히 2-3주 사이에서 가장 활발하였다. 강화기 0주에 압박측 치조골의 흡수 및 파골세포 출현, 염증세포 침윤이 가장 많이 관찰되었고 1주의 신장측 치주인대에서 특징적인 골형성을 보이기 시작하였다. 신생골 형성은 1주와 3주에 가장 많이 관찰되었으며 9주에는 성숙골로의 대치 및 치주인대의 재생으로 대조군과 차이가 없었다. 실험군의 calcitonin gene-related peptide의 발현은 치수, 치주인대 내의 염증 부위에서 나타났으며 0주, 1주에 압박측 치주인대에서 증가하였다가 5주 이후에는 감소하여 대조군과 차이가 없었다. 이상과 같은 소견은 periodontal distraction에 의한 급속 치아 이동이 정상적인 골 재형성 과정을 도모하는 새로운 치아이동 방법이 될 수 있음을 시사한다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제38권1호
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• pp.2-8
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• 2012

Introduction: Auto-tooth bone graft material consists of 55% inorganic hydroxyapatite (HA) and 45% organic substances. Inorganic HA possesses properties of bone in terms of the combining and dissociating of calcium and phosphate. The organic substances include bone morphogenetic protein and proteins which have osteoinduction capacity, as well as the type I collagen identical to that found in alveolar bone. Auto-tooth bone graft material is useful as it supports excellent bone regeneration capacity and minimizes the possibility of foreign body reaction,genetic diseases and disease transmission. Materials and Methods: Implant placement combined with osteoinductive regeneration,preservation of extraction socket, maxillary sinus augmentation, and ridge augmentation using block type,powder type, and block+powder type autobone graft materialwere performed for 250 patients with alveolar bone defect and who visited the Department of Oral and Maxillofacial Surgery, College of Dentistry, Dankook University from September 2009 to August 2011. Results: Clinical assessment: Among the 250 patients of auto-tooth bone graft, clinical assessment was performed for 133 cases of implant placement. The average initial stabilization of placed implants was 74 implant stability quotient (ISQ). Radiological assessment: The average loss of crestal bone in the mandible as measured 6 months on the average after the application of prosthesis load was 0.29 mm, ranging from 0 mm to 3.0 mm. Histological assessment: In the histological assessment, formation of new bone, densified lamellated bone, trabecular bones, osteoblast, and planting fixtures were investigated. Conclusion: Based on these results, we concluded that auto-tooth bone graft material should be researched further as a good bone graft material with osteoconduction and osteoinduction capacities to replace autogenous bone, which has many limitations.

• International Journal of Oral Biology
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• 제40권1호
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• pp.1-9
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• 2015

Osteocalcin (OC) is the most abundant noncollagenous protein of extracellular matrix in the bone. In an OC deficient mouse, bone formation rates are increased in cancellous and cortical bones. OC is known as a negative regulator of mineral apposition. OC is also expressed in the tooth of the rat, bovine, and human. However, little is known about OC during tooth development in Xenopus. The purpose of this study is to compare the expression of OC with mineralization in the developing tooth of Xenopus, by using von Kossa staining and in situ hybridization. At stage 56, the developmental stage of tooth germ corresponds to the cap stage, and an acellular zone was apparent between the dental papilla and the enamel organ. From stage 57, calcium deposition was revealed by von Kossa staining prior to OC expression, and the differentiated odontoblasts forming predentin were located at adjoining predentin. At stage 58, OC transcripts were detected in the differentiated odontoblasts. At stage 66, OC mRNA was expressed in the odontoblasts, which was aligned in a single layer at the periphery of the pulp. These findings suggest that OC may play a role in mineralization and odontogenesis of tooth development in Xenopus.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제49권2호
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• pp.68-74
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• 2023

Objectives: Drug holidays are suggested to reduce the formation of osteonecrosis in patients under intravenous (IV) bisphosphonates (BPs) therapy. The objectives of this study are to evaluate the incidence of medication-related osteonecrosis of the jaw (MRONJ) following tooth extraction in cancer patients using IV BP, and to assess the effect of drug holiday on the development of MRONJ. Patients and Methods: A manuel search of the patient folders of Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Hacettepe University was undertaken to identify cancer patients who used IV BPs and had at least one tooth extraction between 2012 and 2022. Patents' age, sex, systemic condition, the type of BP used, duration of BP used, number of tooth extraction, duration of drug holiday, localization of tooth extraction and incidence of MRONJ were recorded. Results: One hundred nine teeth were removed from 57 jaws in 51 patients. All tooth extractions were performed under perioperative antibiotic prophylaxis and with primary wound closure. The incidence of MRONJ was 5.3%. Stage 1 MRONJ developed in 3 patients (only one had a drug holiday). The median duration of drug holiday was 2 months. No significant difference between the patients with and without a drug holiday and MRONJ development was found (P=0.315). The mean age of patients developed MRONJ was 40.33±8.08 years. A statistically significant difference was found between age and MRONJ development (P=0.002). Conclusion: The effect of a short-term drug holiday on the development of MRONJ may be limited because BPs remain in bone tissue for a long time. Drug holidays should be applied with the approval of an oncologist with other preventive measurements.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제31권2호
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• pp.173-179
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• 2009

Dentigerous cyst is an odontogenic cyst which occurs in unerupted tooth crown. After the crown formation, enamel epithelium remnants surrounded continuously proliferates and it forms effusionfluid cyst and expands due to increased internal osmotic pressure. Treatments of cysts are mainly enucleation, marsupialization and de-compression. When deciding the way of treatment, the age of a patient, the anatomical circumstances, the region of lesion and the size of cyst should be considered. Marsupialization is that some parts of internal cystic wall would be converted into oral mucosa if the cyst is large size and is concerned about neighboring anatomic structure. It can be accompanied by enucleation later and eruption of related tooth can be possible. If there is a limitation of spontaneous tooth eruption, eruption of tooth can be induced by orthodontic apparatus. There were 3 patients had dentigerous cyst and underwent marsupialization, their impacted teeth had preserved and had induced eruption, all showing satisfactory results.

• 소성∙가공
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• 제17권6호
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• pp.429-435
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• 2008

In this paper, the serrated forming process is analyzed with finite element method. The seal should secure the overlapping portions of ligature, which has teeth for ligature to prevent from slipping each other after clamping. In the simulation, rigid-plastic finite element model has been applied to the serration forming process. Serration or teeth forming characteristics has been analyzed numerically in terms of teeth geometry based on different forming conditions. Analyses are focused to find the influence of different die movements and geometries on the tooth geometry, which is crucial for securing overlapping portions of ligature. Two major process variables are selected, which are the face angle and entry angle of punch, respectively. Extensive investigation has been performed to reveal the influences of different entry and face angles on the geometry of teeth formation in the simulation. Three different face angles of punch have been selected to apply to each simulation of serrated sheet forming process with every case of punch entry angles. Furthermore, tooth geometries predicted from simulation have been applied to the indention process for comparing proper tooth geometries to secure the sealing.

• 대한치과교정학회지
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• 제54권1호
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• pp.3-15
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• 2024

The prevalence of intrabony defects in patients with advanced periodontitis stages III and IV is high. These patients usually need both periodontal treatment and orthodontic therapy, including tooth movement through bone defects, to improve masticatory function, aesthetics, and overall quality of life. Clinical practice guidelines recommend periodontal regenerative surgical interventions to resolve these defects and propose initiating orthodontic tooth movement (OTM) once periodontal therapy goals have been met. Surgical interventions using various regenerative technologies like barrier membranes and enamel matrix proteins, combined or not with bone replacement grafts, have proven effective in regenerating lost periodontal tissues. However, the combination of periodontal and orthodontic treatments requires consideration of how periodontal regenerative therapies influence OTM. Studies suggest that regenerated bone may differ in density, composition, vascularity, and cellular activity, potentially affecting the speed and efficiency of OTM, and potential root resorption of moved teeth. Understanding the sequence and timing of implementing OTM after regenerative periodontal interventions is crucial due to their interlinked processes of bone resorption and formation. This narrative review aims to uncover scientific evidence regarding these combined treatments, examining the impacts of different regenerative technologies on OTM and delineating their advantages, limitations, and best practices.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.810-813
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• 2000

Burr makes trobles on manufacturing process due to deburring cost, quality of products and productivity. This paper described the results of experimental study on the influence of the cutting parameters on the formation of exit burrs in face milling. The cutting parameters were investigated changing exit angle, rake nagle , lead angle in tool geometry as well as feed per tooth. Also we carried out experimets on several materials. Using the result of experimental study, burr types are classified according to appearance and formation mechanism in exit burr and we are considered the burr formation in each type of burr.