지각과민처치제가 초음파 스케일링 처리한 비우식성 치경부 병소가 있는 치아의 지각과민증에 주는 영향

조재형(Jae-Hyung Cho),석수황(Soohwang Seok),이상혁(Sang-Hyeok Lee),임범순(Bum-Soon Lim) 대한치과재료학회 2016 대한치과재료학회지 Vol.43 No.1

The aim of this study was to evaluate the changes in dentinal permeability after application of dentin desensitizer on exposed dentin immediately after ultrasonic scaling to teeth with non-carious cervical lesions. Thirty caries-free extracted molars were fixed to slide glasses after horizontally being sectioned at 5 mm below the cemento- enamel junction (CEJ). The prepared specimen was connected to a fluid flow measuring device (nano-Flow), and a V-shaped cavity was formed at the CEJ to imitate the non-carious cervical lesion. After no fluid leakage was confirmed in the connected system with specimen, tooth surface was treated ultrasonic cleaning with piezoelectric ultrasonic scalers until dentinal tubules were exposed. And 6 different desensitizers were applied on exposed dentin. Real-time measurements of dentinal fluid flow were performed during ultrasonic scaling and application of dentin desensitizer. To evaluate the occlusion of exposed dentinal tubules, tooth surface was examined by SEM. Following results were observed. After ultrasonic scaling, more dentinal tubules were exposed on the tooth with non-carious cervical lesions compared to tooth without lesions. The rate of fluid flow measured with nano-Flow system had correlation with the degree of dentin occlusion observed with SEM after application of desensitizers on exposed dentin. Desensitizers with glutaraldehyde and HEMA did not decrease the rate of fluid flow and did not show dentin occlusion. Desensitizers with oxalate showed the limited effects on the rate of fluid flow and dentinal tubule occlusion. Desensitizer with resin monomer showed the significant effect on the rate of fluid flow and dentin occlusion.

3D 프린팅법으로 제조한 티타늄 시편의 물성 평가

오윤정(Yun-Jeong Oh),석수황 (Soohwang Seok),이상혁(Sang-Hyeok Lee),김광만(Kwang-Mahn Kim),권재성(Jae-Sung Kwon),임범순(Bum-Soon Lim) 대한치과재료학회 2016 대한치과재료학회지 Vol.43 No.1

The interest of the additive manufacturing technology, commonly called 3D printing, is rapidly increasing. Selective laser sintering (SLS) is the one of the method for 3D printing that has potential to produce metallic prostheses in dentistry. The purpose of this study was to evaluate physical properties of titanium specimen fabricated by SLS for dental implant system. Specimens were fabricated from Ti6Al4V alloy powder with median particle size (D50) of 34 μm. The SLS 3D printing was carried out using YAG laser with wavelength of 1075 nm with power of 190 W, and thickness of each layer was 30 μm. Machined specimens with sandblasting treatment were used as control group. Density, porosity, yield strength (30o compression), elastic modulus and fatigue limit were estimated. Density measurement and microCT analysis gave valuable informations about impurity inclusions and manufacturing defects. Yield strength and elastic modulus of 3D printing dense specimen showed similar value with the machined specimens. However, fatigue limit of 3D printing dense specimens was significantly lower than the machined specimen. 3D printing porous specimen showed lower yield strength and elastic modulus than the 3D printing dense specimens. Before 3D printing porous dental prosthesis application in clinic, fatigue limit should be evaluated carefully.

연고형 mineral trioxide aggregates (MTA)와 분말-용액 혼합형 MTA의 물성 비교 연구

권영대(Young-Dae Kwon),석수황(Soohwang Seok),이상혁(Sang-Hyeok Lee),임범순(Bum-Soon Lim) 대한치과재료학회 2017 대한치과재료학회지 Vol.44 No.1

The aim of this study was to compare the physical properties of the paste type MTAs with the powder-liquid mix type MTAs. The MTAs evaluated were 4 kinds of powder-liquid mix type and 2 kinds of paste type. Physical properties, such as, flow, film thickness, setting time, solubility, and radiopacity were evaluated in accordance with ISO 6876:2012. Experimental results were analysed using the Tukey multiple comparison test (p=0.05). Paste type MTAs showed higher flow and lower film thickness than powder-liquid mix type MTAs. The setting time of paste type MTAs was significantly shorter than for the powder-liquid mix type MTAs (p<0.05). Paste type MTAs showed similar solubility and radiopacity to powder-liquid mix type MTAs. Based on the results of this study, paste type MTA can be used as substitute for the conventional powder-liquid mix type MTA.

연고형 Mineral Trioxide Aggregates (MTA)와 분말-용액 혼합형 MTA의 골내 이식시험 비교 연구

권영대(Young-Dae Kwon),석수황(Soohwang Seok),이상혁(Sang-Hyeok Lee),임범순(Bum-Soon Lim) 대한치과재료학회 2017 대한치과재료학회지 Vol.44 No.3

The aim of this study was to evaluate the implantation of powder-liquid mix type MTA, paste type MTA, and resin-based endodontic sealer (AH Plus) in tibia of rabbits for 12 weeks. Intraosseous implantation was tested according to ISO 10993-6:2016. After anesthesia, the cortical bone of tibia was exposed, then three or two holes were formed (2 mm in diameter × 6 mm in depth) in each side. The mixed materials according to manufacturer’s instruction were placed into the cylindrical holes. After implantation, all animals received visual inspection at least once a week and inflammation, complication, and other specific figures were recorded. All animals were euthanized 12 weeks after implantation, and the specimens received visual and histologic evaluation, then following results were obtained. New bone formation were most-abundant and uniformly in the experimental group of implantation of paste type MTA, and were observed to some extent in the experimental group of implantation of powder-liquid mix type MTA and microvascular invasion around MTA was examined. As the control groups of implantation of epoxy resin based endodontic sealer, severe lymphocytes and neutrophils were observed. Histologic evaluation revealed that both paste type MTA and powder-liquid mix type MTA were non-irritant compared with AH Plus that had no potential risk biologically, and were seemed to meet the criteria of implantation test. As the paste type MTA has similar physical and biological properties with better handling behavior, so powder-liquid mix type MTA can be substituted by the paste type MTA.

산-처리 조건이 RBM처리한 티타늄 임플란트의 표면 특성에 주는 영향

이한아(Han-Ah Lee),석수황(Soohwang Seok),이상혁(Sang-Hyeok Lee),임범순(Bum-Soon Lim) 대한치과재료학회 2018 대한치과재료학회지 Vol.45 No.4

The purpose of this study was to evaluate the effect of acid-treatment conditions on the surface properties of the RBM (Resorbable Blast Media) treated titanium. Disk typed cp-titanium specimens were prepared and RBM treatments was performed with calcium phosphate ceramic powder. Acid solution was mixed using HCl, H₂SO₄ and deionized water with 4 different volume fraction. The RBM treated titanium was acid treated with different acid solutions at 3 different temperatures and for 3 different periods. After acid-treatments, samples were cleaned with 1 % Solujet solution for 30 min and deionized water for 30 min using ultrasonic cleanser, then dried in the electrical oven (37℃). Weight of samples before and after acid-treatment were measured using electric balance. Surface roughness was estimated using a confocal laser scanning microscopy, crystal phase in the surface of sample was analyzed using X-ray diffractometer. Surface morphology and components were evaluated using Scanning Electron Microscope (SEM) with Energy Dispersive X-ray spectroscopy (EDX) and X-ray Photoemission Spectroscopy (XPS). Values of the weight changes and surface roughness were statistically analyzed using Tukey-multiple comparison test (p=0.05). Weight change after acid treatments were significantly increased with increasing the concentration of H₂SO₄ and temperature of acid-solution. Acid-treatment conditions (concentration of H₂SO₄, temperature and time) did not produce consistent effects on the surface roughness, it showed the scattered results. From XRD analysis, formation of titanium hydrides in the titanium surface were observed in all specimens treated with acid-solutions. From XPS analysis, thin titanium oxide layer in the acid-treated specimens could be evaluated. Acid solution with 90℃ showed the strong effect on the titanium surface, it should be treated with caution to avoid the over-etching process.

다양한 조성의 3D 프린팅 임시치관용 레진의 물성 비교

박서진(Seo-Jin Park),이한아(Han-Ah Lee),이상혁(Sang-Hyeok Lee),석수황(Soohwang Seok),임범순(Bum-Soon Lim),권재성(Jae-Sung Kwon),김광만(Kwang-Mahn Kim) 대한치과재료학회 2019 대한치과재료학회지 Vol.46 No.3

Conventional dental resins for crown and bridge fulfill ISO 10477 and ISO 10993 before clinical application. Although 3D printing or rapid prototyping (RP) for the fabrication of temporary crown and bridge have been proposed, a little studies were reported for 3D printing resin for temporary crown and bridge. The purpose of this study was to evaluate the physical properties (such as water sorption and solubility, color stability and flexural strength) of the various 3D printing temporary crown and bridge resin following the ISO 10477:2018 and estimate the effect of chemical composition of resin on the physical properties. Four resins approved by KFDA and 4 experimental resins developed by different manufacturer were tested in this study. Samples were prepared with DLP typed 3D Printer (G-Printer) and post-cured using UV-light Cure Unit (Cure M). Proper 3D printing and post-curing conditions were selected for different 3D printing resins. Each test was performed according to the ISO 10477 and results were statistically analyzed using Tukey-multiple comparison test (p=0.05). Only group-B did not satisfied the ISO requirement (< 40 μg/ mm³) in water sorption test, but 3 groups (C, E and F) showed high solubility which exceeds the ISO requirement (< 7.5 μg/mm³). For color stability, the color difference were detected at 5 groups (A, E, F, G and H). Group-D and F showed the low flexural strength and some building direction did not satisfied the ISO requirement (> 60 MPa). Resin components may affect the flexural strength, then user should check the components of 3D printing resin. Deficient degree of polymerization may lead to large water sorption, water solubility and color changes. Further study should be done comparison between specimens printed with specific 3D printer recommended by manufacturer and specimens used in this study.