• Restorative Dentistry and Endodontics
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• v.46 no.1
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• pp.2.1-2.8
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• 2021

Objectives: New premixed bioceramic root repair materials require moisture for setting. Using micro-computed tomography (micro-CT), this study evaluated the filling ability and volumetric changes of calcium silicate-based repair materials (mineral trioxide aggregate repair high-plasticity [MTA HP] and Bio-C Repair, Angelus), in comparison with a zinc oxide and eugenol-based material (intermediate restorative material [IRM]; Dentsply DeTrey). Materials and Methods: Gypsum models with cavities 3 mm deep and 1 mm in diameter were manufactured and scanned using micro-CT (SkyScan 1272. Bruker). The cavities were filled with the cements and scanned again to evaluate their filling capacity. Another scan was performed after immersing the samples in distilled water for 7 days to assess the volumetric changes of the cements. The statistical significance of differences in the data was evaluated using analysis of variance and the Tukey test with a 5% significance level. Results: Bio-C Repair had a greater filling ability than MTA HP (p < 0.05). IRM was similar to Bio-C and MTA HP (p > 0.05). MTA HP presented the largest volumetric change (p < 0.05), showing more volume loss than Bio-C and IRM, which were similar (p > 0.05). Conclusions: Bio-C Repair is a new endodontic material with excellent filling capacity and low volumetric change. The gypsum model proposed for evaluating filling ability and volumetric changes by micro-CT had appropriate and reproducible results. This model may enhance the physicochemical evaluation of premixed bioceramic materials, which need moisture for setting.

• Restorative Dentistry and Endodontics
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• v.25 no.4
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• pp.536-542
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• 2000

임상에서 점차 Mineral Trioxide Aggregate (MTA)에 대한 우수성이 소개되면서, apical matrix로의 사용은 주목할 만하다 할 수 있다. 본 연구의 목적은 개방형근관에서 MTA가 apical matrix로 사용될 때의 치근단 밀폐효과를 알아 보고, 근관충전의 시기와 matrix의 두께가 치근단 밀폐에 미치는 영향을 치근단 미세누출의 측면과 matrix탈락빈도의 측면에서 관찰하고자 하는 것이다. 개방형 근관을 재현하고자 45개의 발거된 단근치에 #90크기로 근단공을 형성하였고, 투명레진등을 이용하여 치근단 병소를 갖는 치조골을 재현한 후, 4개의 실험 군과 1개의 대조 군으로 분류하였다. A군: 2mm두께의 MTA matrix 형성후, 열연화된 Gutta-percha와 AH26 sealer를 이용하여 즉시 근관충전. B군: 2mm 두께의 MTA matrix 형성후, A군과 같은 방법으로 24시간 후 근관충전. C군: 4mm 두께의 MTA matrix 형성후, A군과 같은 방법으로 즉시 근관충전. D군: 4mm 두께의 MTA matrix 형성후, A군과 같은 방법으로 24시간 후 근관충전. 대조군: matrix를 사용하지 않고 열연화된 Gutta-percha와 AH26 sealer를 이용하여 근관충전하였다. Matrix의 탈락이 있는 경우 기록하고 완전 수세 후 다시 시행하였다. 색소침투정도의 평가를 위해 methylene blue에 치아를 48시간 침수시킨 후 협설로 양분하였다. 각 시편들을 고배율 현미경 관찰 후 비디오촬영 하였고, digitalized image analysing program을 이용하여 두명의 관찰자가 누출의 정도를 평가한 후, One-way ANOVA로 통계적 유의성을 검증하여 다음과 같은 결과를 얻었다. 1. Matrix를 사용한 실험 군이 matrix를 사용하지 않은 대조 군에 비해 유의성 있게 낮은 누출을 보였다(p<0.05). 그러나 근관충전시기와 matrix의 두께를 달리한 실험군 내에서는 누출에 유의성 있는 차이가 나타나지 않았다. 2. 모든 실험군에서 gutta-percha를 이용한 근관충전의 시기에 matrix탈락 및 gutta-percha의 압출은 발생하지 않았다.

• Restorative Dentistry and Endodontics
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• v.45 no.1
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• pp.10.1-10.8
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• 2020

Objectives: This study aimed to compare the shear bond strength (SBS) of a self-adhering flowable composite (Dyad Flow) and a bulk-fill flowable composite (Smart Dentin Replacement [SDR]) to several pulp-capping materials, including MTA Plus, Dycal, Biodentine, and TheraCal. Materials and Methods: Eighty acrylic blocks with 2-mm-deep central holes that were 4 mm in diameter were prepared and divided into 2 groups (n = 40 each) according to the composite used (Dyad Flow or SDR). They were further divided into 4 sub-groups (n = 10 each) according to the pulp-capping agent used. SBS was tested using a universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed using 2-way analysis of variance. A p value of < 0.05 was considered to indicate statistical significance. Results: A statistically significant difference (p = 0.040) was found between Dyad Flow and SDR in terms of bond strength to MTA Plus, Dycal, Biodentine, and TheraCal. Conclusions: Among the 8 sub-groups, the combination of TheraCal and SDR exhibited the highest SBS.

• Restorative Dentistry and Endodontics
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• v.27 no.1
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• pp.24-33
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• 2002

Leakage studies have been performed frequently, since a fluid-tight seal provided by various dental fill-ing materials has been considered clinically important. The leakage of the various root-end filling materials has been widely investigated mostly dye penetration method. These dye studies cannot offer any information about the quality of the seal of a test material over a long period of time The purpose of this study was to evaluate the microleakage of root end cavities in blood contamination filed amalgam, intermediate restorative material(IRM), light cured glass ionomer cement(GI) and mineral trioxide aggregate(MTA) by means of a modified fluid transport model. Fifty standard human root sections, each 5mm high and with a central pulp lumen of 3mm in diameter, were and filled with our commonly used or potential root end fill ing materials after they were contaminated with blood. At 24h. 72h, 1, 2, 4, 8, and 12 weeks after filling, leakage along these filling materials was determined under a low pressure of 10KPa(0.1atm) using a fluid transport model. The results were as follows : 1 MTA group showed a tendency of decreasing percent of gross leakage (20m1/day) in process of time, whereas the other materials showed a tendency of increasing in the process time. 2. At the all time interval, GI group leaked significantly less than amalgam group and IRM group (p＜0.05). 3. At the 4 weeks, the percentage of gross leakage in MTA group decreased to 0% thereafter, the low per-centage of gross leakage was maintained in MTA group until the end of the experiment, whereas the percentage in IRM group increased to 100% 4. At the 12 weeks, percentage of gross leakage was significantly low in MTA group(0%), comparison with GI group(40%), amalgam group(90%) and IRM group(100%), but there was no significant difference between latter two materials.

• Journal of Navigation and Port Research
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• v.33 no.1
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• pp.9-19
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• 2009

This paper describes empirical approach methodology for the quantitative risk assessment of maritime transportation accident (MTA) of a merchant ship. The principal aim of this project is to estimate the risk of MTA that could degrade the ship safety by analyzing the underlying factors contributing to MTA based on the IMO's Formal Safety Assessment techniques and, by assessing the probabilistic risk level of MTA based on the quantitative risk assessment methodology. The probabilistic risk level of MTA to Risk Index (RI) composed with Probability Index (PI) and Severity Index (SI) can be estimated from proposed Maritime Transportation Accident Model (MTAM) based on Bayesian Network with Bayesian theorem Then the applicability of the proposed MTAM can be evaluated using the scenario group with 355 core damaged accident history. As evaluation results, the correction rate of estimated PI, $r_{Acc}$ is shown as 82.8%, the over ranged rate of PI variable sensitivity with $S_p{\gg}1.0$ and $S_p{\ll}1.0$ is shown within 10%, the averaged error of estimated SI, $\bar{d_{SI}}$ is shown as 0.0195 and, the correction rate of estimated RI, $r_{Acc}$(%), is shown as 91.8%. These results clearly shown that the proposed accident model and methodology can be use in the practical maritime transportation field.

• Journal of Dental Rehabilitation and Applied Science
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• v.39 no.1
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• pp.45-51
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• 2023

Apical sealing with proper retrograde filling material and technique is the key factor for successful apical surgery. In order to provide impeccable apical sealing and healing, various mechanical and chemical characteristics of retrograde filling material is required. MTA has been used as the gold standard of retrograde filling due to its unprecedented advantages. As MTA has long setting time and difficult handling properties, premixed putty type bioceramic material has been newly developed. For efficient retrofilling with premixed putty type biocreamic material, 'Lid technique' was also proposed. The following cases present apical surgery using newly developed premixed putty type bioceramic material with Lid technique.

• Restorative Dentistry and Endodontics
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• v.39 no.1
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• pp.78-78
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• 2014

• Microbiology and Biotechnology Letters
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• v.26 no.6
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• pp.558-561
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• 1998

In the screening for lipid peroxidation inhibitors from edible mushroom, Agrocybe cylindracea, a bioactive compound AG 8 was isolated. The AG 8 was purified from methanol extract of its fruit body by Diaion HP-20 column chromatography, ethyl acetate extraction, and silica gel column chromatography, consecutively. Based on various NMR studies including $^1$H irradiation and HMBC experiments, the AG 8 was identified as MTA, 5'-deoxy-5'-methylthioadenosine. This compound inhibited lipid peroxidation with an $IC_{50}$/ value of 3.2 $\mu\textrm{g}$/$m\ell$. The MTA was isolated for the first time from basidiomycetes.

• Restorative Dentistry and Endodontics
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• v.20 no.1
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• pp.17-32
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• 1995

The purpose of this study was to examine the response of periradicular tissues to amalgam, IRM, Ketac-silver and MTA(Mineral trioxide aggregate) used as a root end fillings. The lower third and fourth premolars of 5 mongrel dogs were used. Each root was resected, followed by root end fillings with experimental materials. The animals were sacrificed after 16 weeks and radiographic and histologic results were evaluated. The results were as follows : 1. Severe inflammation around apex and disruption of cortical were noted in relation to the amalgam. 2. With IRM, there was severe infiltration of inflammatory cells around filling material, but healing of cortical bone was noted. 3. With Ketac-silver, mild inflammation and thick band of fibrous connetive tissue around filling material were seen, with a cortical bone healing. 4. In case of MTA, complete regeneration of cortical bone was seen, and free MTA was surrounded with newly formed bone tissue.

• Restorative Dentistry and Endodontics
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• v.29 no.4
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• pp.365-369
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• 2004

The purpose of this study was to evaluate the apical sealing ability of Super-EBA, MTA and Dyract-flow as retrofilling materials. Forty-eight extracted human teeth with straight and single root canal were used in this study. The root canals were prepared to a #40 apical canal size and obturated with gutter-percha. Apicoectomies were performed and root end cavities were prepared to a depth of 3mm using an ultrasonic device. The root end cavities were filled with Super-EBA, MTA or Dyract-flow. Leakage was measured using an electrochemical technique for 4 weeks. According to this study, the results were as follows. 1. Increasing leakage with time was observed in all groups. 2. No significant difference was noted among the 3 groups with time (p =0.216). 3. No significant difference was noted among the 3 groups when measured within the same time interval (p =0.814). The results of this study suggest that the sealing ability of Dyract-flow is equal to that of Super-EBA and MTA, and Dyract-flow may be an alternative to other materials for root-end filling.