• 전기학회논문지
• /
• 제67권1호
• /
• pp.124-130
• /
• 2018

The EMG amplitude estimator, which has been investigated as an indicator of muscle force, is of high relevance not only in biomechanical studies but also more and more in clinical applications. This paper presents a new approach to estimate surface EMG amplitude by using the mean spike and mean turn amplitude(MSA and MTA) variables. Surface EMG signals, a total of 198 signals, were recorded from biceps brachii muscle over the range of 20-80%MVC isometric contraction and performance of the MSA and MTA variables applied to amplitude estimation of the EMG signals were investigated. To examine the performance, a SNR(signal-to-noise ratio) was computed from each amplitude estimate. The results of the study indicate that MSA and MTA amplitude estimations with first order whitening filter and 300[ms]-350[ms] moving average window length are optimal and show better performance(mean SNR improvement of 6%-15%) than the most frequently used variables(ARV and RMS).

• 치위생과학회지
• /
• 제22권3호
• /
• pp.191-198
• /
• 2022

Background: The purpose of this study was to evaluate the composition of the crystal phases of various calcium silicate-based materials (CSMs): ProRoot white MTA^Ⓡ (mineral trioxide aggregate) (WMTA), Ortho MTA^Ⓡ (OM), Endocem MTA^Ⓡ (EM), Retro MTA^Ⓡ (RM), Endocem Zr^Ⓡ (EN-Z), Biodentine^TM (BD), EZ-seal^TM (EZ), and OrthoMTA III (OM3). Methods: In a sample holder, 5 g of the powder sample was placed and the top surface of the material was packed flat using a sterilized glass slide. The prepared slides were mounted on an X-ray diffraction (XRD) instrument (D8 Advance; Bruker AXS GmbH, Germany). The X-ray beam 2θ angle range was set at 10~90° and scanned at 1.2° per minute. The Cu X-ray source set to operate at 40 kV and 40 mA in the continuous mode. The peaks in the diffraction pattern of each sample were analyzed using the software Diffrac (version 2.1). Then, the peaks were compared and matched with those of standard materials in the corresponding Powder Diffraction File (PDF-2, JCPDS International Center for Diffraction Data). A powder samples of the materials were analyzed using XRD and the peaks in diffraction pattern were compared to the Powder Diffraction File data. Results: Eight CSMs showed a similar diffraction pattern because their main component was calcium silicate. Eight CSMs showed similar diffraction peaks because calcium silicate was their main component. Two components were observed to have been added as radiopacifiers: bismuth oxide was detected in WMTA, OM, and EM while zirconium oxide was detected in RM, EN-Z, BD, EZ, and OM3. Unusual patterns were detected for the new material, OM3, which had strong peaks at low angles. Conclusion: It was caused by the presence of Brushite, which is believed to have resulted in crystal growth in a particular direction for a specific purpose.

• Restorative Dentistry and Endodontics
• /
• 제48권1호
• /
• pp.8.1-8.8
• /
• 2023

Objectives: This study was designed to evaluate the parameters of bonding performance to root dentin, including push-out bond strength and dentinal tubular biomineralization, of a hydraulic bioceramic root-end filling material premixed with dimethyl sulfoxide (Endocem MTA Premixed) in comparison to a conventional powder-liquid-type cement (ProRoot MTA). Materials and Methods: The root canal of a single-rooted premolar was filled with either ProRoot MTA or Endocem MTA Premixed (n = 15). A slice of dentin was obtained from each root. Using the sliced specimen, the push-out bond strength was measured, and the failure pattern was observed under a stereomicroscope. The apical segment was divided into halves; the split surface was observed under a scanning electron microscope, and intratubular biomineralization was examined by observing the precipitates formed in the dentinal tubule. Then, the chemical characteristics of the precipitates were evaluated with energy-dispersive X-ray spectroscopic (EDS) analysis. The data were analyzed using the Student's t-test followed by the Mann-Whitney U test (p < 0.05). Results: No significant difference was found between the 2 tested groups in push-out bond strength, and cohesive failure was the predominant failure type. In both groups, flake-shaped precipitates were observed along dentinal tubules. The EDS analysis indicated that the mass percentage of calcium and phosphorus in the precipitate was similar to that found in hydroxyapatite. Conclusions: Regarding bonding to root dentin, Endocem MTA Premixed may have potential for use as an acceptable root-end filling material.

• Journal of Korean Dental Science
• /
• 제17권1호
• /
• pp.36-44
• /
• 2024

Purpose: This study investigated the effect of dentin bonding agent acidity on surface microhardness of MTA. Materials and Methods: Forty cylindrical molds (3 mm×5 mm) were prepared, and three dentin bonding agents with different acidities: Adper Single Bond 2 (ASB), Single Bond Universal (SBU), and Clearfil SE bond 2 (CSE) were applied to the inner surface of the molds (n=10). No bonding agent was applied in the control group. MTA was mixed and inserted into the molds and sealed with a wet cotton pellet for 4 days. After setting, the Vickers microhardness (HV) test was done at 200, 400, 600 ㎛ from the inner surface of the mold. One-way ANOVA was conducted for all samples. A P-value of less than .05 was considered significant. Tukey HSD test was performed for post-hoc analysis. Results: The mean HV values and standard deviations were 67.02±11.38 (Con), 48.76±11.33 (ASB), 43.78±11.19 (CSE), 37.84±9.36 (SBU), respectively. The difference between the control group and the experimental groups was statistically significant (P<0.001). The difference between ASB and SBU was statistically significant (P<0.001), while the difference between SBU and CSE was not. There were no statistically significant differences between the various points from the inner surface of the mold within each group (P>0.05). Conclusion: Results of the current study indicate that use of dentin bonding agents with MTA can reduce the surface microhardness of MTA. Moreover, there is a direct relationship between the acidity of dentin bonding agents and the surface microhardness of MTA.

• 대한장애인치과학회지
• /
• 제12권2호
• /
• pp.45-49
• /
• 2016

This study investigates the success rate of pulpotomy using electrosurgery operated on a primary molar in caries. The pulpotomy using electrosurgery was done on 253 primary molars of 111 young patients from 2 to 9 years old during the period of the first day of January 2011 to the last day of December 2015. After the amputation of pulp and hemostasis of primary molar were done using electrosurgery, MTA as pulp capping material was applied to the primary molar and the tooth was restored with the stainless steel crown. The follow up period after the treatment ranged from 4-46 months. The clinical and radiographic success rate ranged from 92.1 - 94.3%. Which is comparable to formocresol and ferric sulfate pulpotomy. Due to its non-pharmacological characteristic, electrosurgery can minimize harmful effect on the pulp tissue. Its fast bleeding control makes it easy and safe to use in pediatric and disabled patients in comparatively simple manner. Electrosurgery can be an alternative for pulp therapy considering the side effects of pharmacological ways.

• 한국군사과학기술학회지
• /
• 제5권4호
• /
• pp.88-96
• /
• 2002

The CSCM Upwind method and Material Transport Analysis(MTA) have been used to predict the thermal response and shape changes for charring/non-charring material which can be used as thermal protection material(TPM) on blunt-body nose tip. We performed intensive flight trajectory simulations to compare 1-D MTA results with those of 2-D/Axisymmetric MTA by using MTAs and Navier-Stokes code. Theheat-transfer rate and pressure distribution were predicted at selected altitudes and wall temperature along the flight trajectory and the shape changes of blunt-body nose tip were predicted subsequently by using current procedure.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제32권3호
• /
• pp.236-241
• /
• 2010

Purpose: The purpose of this retrospective clinical study was to monitor the outcomes of periapical surgery in periapically infected tooth with or without retrograde filling materials (MTA or IRM). Patients and Methods: A total of 85 teeth in 63 patients were included in the study between November 2004 and August 2008. Randomly, MTA or IRM was used as a retrograde filling material or only apical resection without retrograde filling. Teeth with advanced periodontal bone loss or presence of root fracture were excluded from the study. The patients were subjected to a minimum follow-up period of 12 months, with a mean of 17.1 months. Results: Successful healing was observed in 83.3% of the MTA-treated teeth, 80% of the IRM-treated teeth and 75% of the teeth which was not retrograde filling. Doubtful healing was seen 9.3% (MTA), 13.3% (IRM), 12.5% (no retro-filling). The success rate of upper incisors (92%) was higher than lower lincisor and molars (66.7% and 50%, respectively). Conclusion: In this study, periapical surgery including retrograde filling improves the prognosis. And, no statistically significant differences were found between retrograde filling materials (MTA or IRM).

• Restorative Dentistry and Endodontics
• /
• 제44권2호
• /
• pp.18.1-18.9
• /
• 2019

Objective: This study evaluated the presence of residual root canal filling material after retreatment using micro-computed tomography (micro-CT). Materials and Methods: Extracted human teeth (single- and double-rooted, n = 21/each; C-shaped, n = 15) were prepared with ProFile and randomly assigned to three subgroups for obturation with gutta-percha and three different sealers (EndoSeal MTA, EndoSequence BC sealer, and AH Plus). After 10 days, the filling material was removed and the root canals were instrumented one size up from the previous master apical file size. The teeth were scanned using micro-CT before and after retreatment. The percentage of remaining filling material after retreatment was calculated at the coronal, middle, and apical thirds. Data were analyzed using the Kruskal-Wallis test and Mann-Whitney U test with Bonferroni post hoc correction. Results: The tested sealers showed no significant differences in the percentage of remaining filling material in single- and double-rooted teeth, although EndoSeal MTA showed the highest value in C-shaped roots (p < 0.05). The percentage of remaining filling material of AH Plus and EndoSeal MTA was significantly higher in C-shaped roots than in single- or double-roots (p < 0.05), while that of BC sealer was similar across all root types. EndoSeal MTA showed the highest values at the apical thirds of single- and double-roots (p < 0.05); otherwise, no significant differences were observed among the coronal, middle, and apical thirds. Conclusions: Within the limitations of this study, a large amount of EndoSeal MTA remained after retreatment, especially in C-shaped root canals.

• 대한소아치과학회지
• /
• 제43권2호
• /
• pp.137-144
• /
• 2016

이 연구의 목적은 다양한 산성 환경에서 규산 삼칼슘 재료인 Biodentine$^{(R)}$, Theracal$^{(R)}$, ProRoot MTA$^{(R)}$의 압출강도를 측정하고 표면형태를 관찰하는 것이었다. 각각의 재료에 대해 샘플을 4개의 그룹으로 나누었다. 산성 조건 그룹은 pH 4.4, 5.4, 6.4의 부티르산 조건에서, 대조군 그룹은 pH 7.4의 인산완충식염수 조건에서 4일간 $37^{\circ}C$에서 보관하였다. 이후 압출강도를 측정하고 표면 형태를 분석하였다. Biodentine$^{(R)}$과 Theracal$^{(R)}$은 모든 산성 조건에서 ProRoot MTA$^{(R)}$ 보다 더 높은 압출강도를 보였고 pH 감소에 따라 압출강도가 감소하였다. 주사전자현미경을 이용한 관찰 결과 재료들 모두 산성 조건에서 표면 형태에 상당한 변화를 보였다. 결론적으로, Biodentine$^{(R)}$과 Theracal$^{(R)}$은 ProRoot MTA$^{(R)}$와 비교하여 더 높은 압출강도를 보였다. 또한 산성 조건은 규산삼칼슘 재료들의 압출강도와 미세구조를 약화시킬 수 있다.

• Restorative Dentistry and Endodontics
• /
• 제35권1호
• /
• pp.5-12
• /
• 2010

본 연구에서는 인위적으로 노출시킨 비글견의 치수조직을 기존의 수산화칼슘제재와 MTA, 접착성 레진, 광중합형 수산화칼슘제재를 사용하여 직접치수복조한 후 각 재료에 따른 치수의 반응을 광학현미경 하에서 조직학적으로 관찰하여 비교분석하였다. 2마리 비글견의 36개 치아를 이용하여, 실험적으로 치수를 노출시키고 노출된 치수에 치수복조재를 적용한 후 와동은 복합레진으로 충전하여 직접치수복조술을 시행하였다: (1) Mineral Trioxide Aggregate (MTA: $ProRoot^{(R)}$ MTA, Dentsply, Tulsa, USA), (2) Clearfil SE Bond (Dentin adhesive system: Kuraray, Osaka, Japan), (3) Ultra-Blend (Photopolymerized Calcium hydroxide: Ultradent, South Jordan, USA), (4) Dycal (Quick setting Calcium hydroxide: LD Caulk Co., Milford, USA). 희생전 90일, 30일, 7일 전에 각 복조재별로 3개씩의 와동을 충전하였고 비글견을 희생시키고 조직시편을 제작하였다. 시편을 H&E 염색 후 광학 현미경으로 치수염증반응과 경조직 형성 정도를 관찰하였다. MTA 군은 초기에는 경조직 형성이 관찰되지 않고 치수조직의 위축과 부분괴사가 관찰되었으나 시간이 지나면서 경조직 형성이 관찰되었다. Clearfil SE Bond군은 초기에 염증세포의 침윤과 치수세포의 괴사를 관찰할 수 있었고 시간이 지날수록 치수 세포의 괴사가 더욱 진행한 양상을 보였다. Ultra-blend 군과 Dycal 군은 MTA 군과 비슷하게 초기에는 경조직 형성을 보이지 않고 중등도의 염증반응이 관찰되었으며 시간이 지나면서 경조직 형성이 관찰되었다. MTA, 수산화칼슘제재와 광중합 수산화칼슘제재는 초기의 치수염증반응 이후 조상아세포층, 상아질교 형성을 보여 직접치수복조재로 적당하였으며, 접착성 레진은 심한 염증반응과 치수 조직의 괴사 양상을 보여 직접치수복조재로 부적당하다는 결론을 얻을 수 있었다.