• 자원환경지질
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• 제54권5호
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• pp.595-603
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• 2021

하천 및 육상 골재 자원의 주 대상인 모래층의 분포는 제4기 퇴적 환경 중 충적 및 하천 퇴적환경에 주로 속한다. 충청남도 금산군 일대의 골재 자원 분포는 특징적으로 감입곡류 하천이 우세한 퇴적 환경 중심으로 발달하고 있는 반면, 붕적이나 선상지성 퇴적환경에서 형성된 퇴적층은 육상 및 하천 골재 분포 비율이 상대적으로 낮다. 봉황천 주변과 소하천들이 합류하는 부근 일대는 소규모이지만 하천의 범람원이 발달하며 골재 분포 지역에 해당된다. 금산군 제4기 퇴적층의 수직 분포는 약 5~12m 범위와 평균 8m의 제4기 퇴적층 두께를 갖는다. 골재 부존 구간은 평균 3.6m 두께이며 평균 입도는 점토-실트 약 21%, 모래 67%, 그리고 자갈 12%이다. 골재 부존 구간의 주요 특징은 조립질 모래가 우세하고 자갈은 아각형 또는 아원형, 분급은 일반적으로 불량하고 괴상의 형태를 띠며 암회색~황갈색 범위의 토색을 보인다. 금산군 내에서 골재 개발 가능성이 큰 분포 지역은 금강본류, 봉황천과 소하천 지류의 현 하상과 구하상을 따라 분포하는 충적 퇴적층 및 하천 퇴적층이다.

• Computers and Concrete
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• 제10권2호
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• pp.95-104
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• 2012

This study uses recycled green building materials based on a Taiwan-made recycled mineral admixture (including fly ash, slag, glass sand and rubber powder) as replacements for fine aggregates in concrete and tests the properties of the resulting mixtures. Fine aggregate contents of 5% and 10% were replaced by waste LCD glass sand and waste tire rubber powder, respectively. According to ACI concrete-mixture design, the above materials were mixed into lightweight aggregate concrete at a constant water-to-binder ratio (W/B = 0.4). Hardening (mechanical), non-destructive and durability tests were then performed at curing ages of 7, 28, 56 and 91 days and the engineering properties were studied. The results of these experiments showed that, although they vary with the type of recycling green building material added, the slumps of these admixtures meet design requirements. Lightweight aggregate yields better hardened properties than normal-weight concrete, indicating that green building materials can be successfully applied in lightweight aggregate concrete, enabling an increase in the use of green building materials, the improved utilization of waste resources, and environmental protection. In addition to representing an important part of a "sustainable cycle of development", green building materials represent a beneficial reutilization of waste resources.

• 대한소아치과학회지
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• 제41권2호
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• pp.174-179
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• 2014

치내치란 치아 조직의 석회화가 일어나기 이전에 법랑기가 치유두 내로 함입되어 나타나는 발육성 이상을 말한다. 치내치는 임상적, 방사선학적으로 다양한 변이를 나타내며, 치내치의 여러 분류법 중 Oehlers(1957)가 제안한 분류법이 가장 널리 이용되고 있다. 치수는 건강한 채로 남아 있으나 함입부가 치주염과 연관된 Type III 병소를 치료하는데 다양한 술식들이 설명되어져왔다. 가장 우선시 되어야 하는 목표는 가능하다면 치수를 건전하게 보존하는 것이며, 치수질환의 명백한 증거가 없다면, 함입부를 치근과 별개로 치료하는 보존적인 접근법이 필요하다. 그러나, Type III 치내치의 근관치료는 근관과 함입의 충분한 잔사제거, 재현가능한 근관장의 조절, 일관된 충전등을 충분히 달성하기 어렵다는 문제점이 있다. 본 증례는 치근단 병소를 보이는 Type III 치내치의 치료에 함입부에만 제한된 보존적 근관치료 및 Mineral Trioxide Aggregate(MTA)를 이용한 폐쇄를 통해 양호한 결과를 얻었기에 보고하는 바이다.

• Restorative Dentistry and Endodontics
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• 제39권3호
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• pp.187-194
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• 2014

Objectives: The effects of bone morphogenetic protein-2 (BMP-2) and enamel matrix derivative (EMD) respectively with mineral trioxide aggregate (MTA) on hard tissue regeneration have been investigated in previous studies. This study aimed to compare the osteogenic effects of MTA/BMP-2 and MTA/EMD treatment in MC3T3-E1 cells. Materials and Methods: MC3T3-E1 cells were treated with MTA (ProRoot, Dentsply), BMP-2 (R&D Systems), EMD (Emdogain, Straumann) separately and MTA/BMP-2 or MTA/EMD combination. Mineralization was evaluated by staining the calcium deposits with alkaline phosphatase (ALP, Sigma-Aldrich) and Alizarin red (Sigma-Aldrich). The effects on the osteoblast differentiation were evaluated by the expressions of osteogenic markers, including ALP, bone sialoprotein (BSP), osteocalcin (OCN), osteopontin (OPN) and osteonectin (OSN), as determined by reverse-transcription polymerase chain reaction analysis (RT-PCR, AccuPower PCR, Bioneer). Results: Mineralization increased in the BMP-2 and MTA/BMP-2 groups and increased to a lesser extent in the MTA/EMD group but appeared to decrease in the MTA-only group based on Alizarin red staining. ALP expression largely decreased in the EMD and MTA/EMD groups based on ALP staining. In the MTA/BMP-2 group, mRNA expression of OPN on day 3 and BSP and OCN on day 7 significantly increased. In the MTA/EMD group, OSN and OCN gene expression significantly increased on day 7, whereas ALP expression decreased on days 3 and 7 (p < 0.05). Conclusions: These results suggest the MTA/BMP-2 combination promoted more rapid differentiation in MC3T3-E1 cells than did MTA/EMD during the early mineralization period.

• Restorative Dentistry and Endodontics
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• 제45권2호
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• pp.4.1-4.6
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• 2020

Although numerous studies have been conducted on apexification using mineral trioxide aggregate (MTA), direct observation of extracted human teeth after the procedure has been rarely reported. This case report describes a mandibular premolar treated 2.5 years ago and extracted recently for orthodontic treatment. The tubercle of the right mandibular premolar of a 12-year-old boy with dens evaginatus was fractured and the pulp was exposed. The tooth was diagnosed with pulp necrosis and asymptomatic periapical abscess. During the first visit, copious irrigation was performed with 2.5% sodium hypochlorite. Calcium hydroxide paste was placed as an intracanal medicament. The sinus tract had disappeared at the second visit after 3 weeks. MTA was applied on to the bleeding point as a 4-mm-thick layer, followed by a 3-mm-thick gutta-percha filling and resin core build-up. After 2.5 years, the tooth and three other premolars were extracted for orthodontic treatment. The right and left mandibular premolars were scanned with micro-computed tomography to determine the root shape and canal anatomy. Irregular root growth was observed and the root outline of the right mandibular premolar differed from that of the contralateral tooth. Apexification with MTA leads to the formation of roots with irregular morphology, without any pulpal space.

• Restorative Dentistry and Endodontics
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• 제42권3호
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• pp.176-187
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• 2017

Objectives: This study aimed to evaluate the chemical and biological properties of fast-set white mineral trioxide aggregate (FS WMTA), which was WMTA combined with calcium chloride dihydrate ($CaCl_2{\cdot}2H_2O$), compared to that of WMTA. Materials and Methods: Surface morphology, elemental, and phase analysis were examined using scanning electron microscope (SEM), energy dispersive X-ray microanalysis (EDX), and X-ray diffraction (XRD), respectively. The cytotoxicity and cell attachment properties were evaluated on human periodontal ligament fibroblasts (HPLFs) using methyl-thiazoldiphenyltetrazolium (MTT) assay and under SEM after 24 and 72 hours, respectively. Results: Results showed that the addition of $CaCl_2{\cdot}2H_2O$ to WMTA affected the surface morphology and chemical composition. Although FS WMTA exhibited a non-cytotoxic profile, the cell viability values of this combination were lesser than WMTA, and the difference was significant in 7 out of 10 concentrations at the 2 time intervals (p < 0.05). HPLFs adhered over the surface of WMTA and at the interface, after 24 hours of incubation. After 72 hours, there were increased numbers of HPLFs with prominent cytoplasmic processes. Similar findings were observed with FS WMTA, but the cells were not as confluent as with WMTA. Conclusions: The addition of $CaCl_2{\cdot}2H_2O$ to WMTA affected its chemical properties. The favorable biological profile of FS WMTA towards HPLFs may have a potential impact on its clinical application for repair of perforation defects.

• Restorative Dentistry and Endodontics
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• 제39권4호
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• pp.253-257
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• 2014

Objectives: This study aimed to compare the surface microhardness of mineral trioxide aggregate (MTA) samples having different thicknesses and exposed to human blood from one side and with or without a moist cotton pellet on the other side. Materials and Methods: Ninety cylindrical molds with three heights of 2, 4, and 6 mm were fabricated. In group 1 (dry condition), molds with heights of 2, 4, and 6 mm (10 molds of each) were filled with ProRoot MTA (Dentsply Tulsa Dental), and the upper surface of the material was not exposed to any additional moisture. In groups 2 and 3, a distilled water- or phosphate-buffered saline (PBS)-moistened cotton pellet was placed on the upper side of MTA, respectively. The lower side of the molds in all the groups was in contact with human blood-wetted foams. After 4 day, the Vickers microhardness of the upper surface of MTA was measured. Results: In the dry condition, the 4 and 6 mm-thick MTA samples showed significantly lower microhardness than the 2 mm-thick samples (p = 0.003 and p = 0.001, respectively). However, when a distilled water- or PBS-moistened cotton pellet was placed over the MTA, no significant difference was found between the surface microhardness of samples having the abovementioned three thicknesses of the material (p = 0.210 and p = 0.112, respectively). Conclusions: It could be concluded that a moist cotton pellet must be placed over the 4 to 6 mm-thick MTA for better hydration of the material. However, this might not be necessary when 2 mm-thick MTA is used.

• Restorative Dentistry and Endodontics
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• 제45권4호
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• pp.50.1-50.11
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• 2020

Objectives: In this study, we investigated the potential of amoxicillin-loaded polymeric microspheres to be delivered to tooth root infection sites via a bioactive reparative cement. Materials and Methods: Amoxicillin-loaded microspheres were synthesized by a spray-dray method and incorporated at 2.5% and 5% into a mineral trioxide aggregate cement clinically used to induce a mineralized barrier at the root tip of young permanent teeth with incomplete root development and necrotic pulp. The formulations were modified in liquid:powder ratios and in composition by the microspheres. The optimized formulations were evaluated in vitro for physical and mechanical eligibility. The morphology of microspheres was observed under scanning electron microscopy. Results: The optimized cement formulation containing microspheres at 5% exhibited a delayed-release response and maintained its fundamental functional properties. When mixed with amoxicillin-loaded microspheres, the setting times of both test materials significantly increased. The diametral tensile strength of cement containing microspheres at 5% was similar to control. However, phytic acid had no effect on this outcome (p > 0.05). When mixed with modified liquid:powder ratio, the setting time was significantly longer than that original liquid:powder ratio (p < 0.05). Conclusions: Lack of optimal concentrations of antibiotics at anatomical sites of the dental tissues is a hallmark of recurrent endodontic infections. Therefore, targeting the controlled release of broad-spectrum antibiotics may improve the therapeutic outcomes of current treatments. Overall, these results indicate that the carry of amoxicillin by microspheres could provide an alternative strategy for the local delivery of antibiotics for the management of tooth infections.

• 한국지반신소재학회논문집
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• 제23권1호
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• pp.17-25
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• 2024

골재 간극률은 구조적 강도, 내구성, 배수 및 투수성 등 다양한 아스팔트의 특성에 직접적인 영향을 미친다. 따라서 아스팔트 포장이 사용되는 위치, 기후, 환경 등에 적절하도록 골재 간극률이 설계되어야한다. 하지만 골재 간극률은 다양한 요인들에 의해 영향을 받으므로 그 설계가 쉽지 않다. 예를 들어 골재 입자의 크기 분포, 구성이나 아스팔트 바인더의 양, 다짐 수준 등 다양한 영향인자가 존재한다. 본 연구에서는 골재 간극률에 영향을 미치는 요인들로부터 골재 간극률을 예측하고자 하였다. 이를 위해 다양한 기계학습 모델 방법을 적용하였고 단일 기계학습 모델을 적용했을 때보다 높은 정확도로 골재 간극률을 예측할 수 있음을 보였다. 본 연구의 결과는 경험과 노동집약적인 실험에 의존하는 골재 간극률 예측에 데이터 기반의 접근방법을 적용할 수 있음을 보였으며 향후 최적 골재 간극률 설계 등에 활용 가능할 것으로 기대된다.

• 치위생과학회지
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• 제16권4호
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• pp.317-322
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• 2016

최근 성장 중인 아동에서 치근의 성장이 계속됨에 따라 치수가 괴사되어 치근의 병변이 있는 미성숙 영구치에서도 치수의 재혈관화(revascularization)가 실제로 일어날 수 있다는 가능성이 제시되고 있다. 소아치과영역에서 자주 접하게 되는 미성숙 영구치의 치근단 형성술의 목적은 열린 치근단에서 세균 침입을 제한하고 치근단 장벽 형성을 촉진하는 것이다. 미성숙 치아의 근관 치료에서 기존의 수산화칼슘을 이용한 치근단 형성술은 빈번한 내원과 장기간 소요되는 치료 기간, 환자협조 요구, 최종 처치의 지연, 장기간의 수산화칼슘 적용 이후 치아 파절 가능성의 증가 등의 단점이 보고되었다. 기존의 수산화칼슘 치근단형성술의 대체방법으로 MTA를 이용한 1-visit 치근단형성술을 시행하고 있다. MTA는 1990년대 초반 근관치료 분야에서 다양한 적용을 위해 개발되었다. MTA의 우수한 임상적 성질에 힘입어 국내에서도 OrthoMTA 및 Endo CEM 등의 mineral aggregate 제품이 출시되어 있다. 따라서 본 증례에서는 우리나라의 청소년에서 MTA 적용한 사례를 보고하는 데 있다. 이 연구를 통해 MTA를 이용하여 진료하는 임상가에게 소개하고자 한다. 이 연구는 11~12세의 파절이 된 치아에 MTA를 적용하여 근관 치료를 하였다. 치료 받은 환자의 치아 상태를 12개월 동안 추적 관찰하였고, 국내에서 개발된 OrthoMTA를 이용한 치근단형성술을 시행한 후 임상적 및 방사선학적 관찰 결과를 통해 근관치료재생술(REP)에 관한 만족할 만한 결과를 얻었으며, 치수괴사가 생긴 경우에서도 성공적으로 치수재생술을 적용할 수 있다는 정보를 제공하고 그 결과를 공유하기 위함이다.