• The Journal of Advanced Prosthodontics
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• 제10권3호
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• pp.197-204
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• 2018

PURPOSE. To determine the extent of treatment traces, the roughness depth, and the quantity of titanium nitride (TiN) removed from the surface of CAD/CAM abutments after treatment with various instruments. MATERIALS AND METHODS. Twelve TiN coated CAD/CAM abutments were investigated for an in vitro study. In the test group (9), each abutment surface was subjected twice (150 g vs. 200 g pressure) to standardized treatment in a simulated prophylaxis measure with the following instruments: acrylic scaler, titanium curette, and ultrasonic scaler with steel tip. Three abutments were used as control group. Average surface roughness (Sa) and developed interfacial area ratio (Sdr) of treated and untreated surfaces were measured with a profilometer. The extent of treatment traces were analyzed by scanning electron microscopy. RESULTS. Manipulation with ultrasonic scalers resulted in a significant increase of average surface roughness (Sa, P<.05) and developed interfacial area ratio (Sdr, P<.018). Variable contact pressure did not yield any statistically significant difference on Sa-values for all instruments (P=.8). Ultrasonic treatment resulted in pronounced surface traces and partially detachment of the TiN coating. While titanium curettes caused predominantly moderate treatment traces, no traces or detectable substance removal has been determined after manipulation with acrylic curettes. CONCLUSION. Inappropriate instruments during regular plaque control may have an adverse effect on the integrity of the TiN coating of CAD/CAM abutments. To prevent defects and an increased surface roughness at the transmucosal zone of TiN abutments, only acrylic scaling instruments can be recommended for regular maintenance care.

• 대한치과보철학회지
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• 제55권3호
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• pp.305-310
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• 2017

최근, CAD/CAM 기술이 발전하면서 하이브리드 보철물의 제작에 이용되고 있다. Double scanning technique은 시적용 납의치와 주모형을 스캔 후 중첩하여, 가상 디자인의 현실화와 보철 기공 과정의 간소화를 이루었다. 본 증례에서는 금속 혹은 지르코니아 대신 고성능 중합체인 Polyetherketoneketone (Pekkton, Cendres+$M{\acute{e}}taux$, Biel, Switzerland)를 framework의 재료로 사용했으며, 콤포짓이나 세라믹 혹은 의치용 치아 대신 Polymethyl methacrylate (PMMA) 비니어링 치아(Visio-lign, Bredent, Senden, Germany)를 최종 보철물로 사용하였다. Pekkton과 Visio-lign을 사용한 본 증례에서 만족할만한 치료 결과와 환자의 만족을 얻었으며, 추후 주기적인 유지관리 및 평가가 필요할 것으로 사료된다.

• 소성∙가공
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• 제15권8호
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• pp.539-543
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• 2006

Experimental studies are carried out in order to investigate the effects of heat treatment on the surface machined by W-EDM. In this work, two ways of heat treatment after W-EDM are considered. As a comparison, the machined surface by a traditional method such as milling/grinding is also considered. Thereby, specimens are prepared by four different machining methods. Those are (1) milling and then grinding, (2) wire-cut electric discharge machining (W-EDM), and (3) low temperature heat treatment or (4) high temperature heat treatment after W-EDM. The resulting surface roughness are measured and the changes of surface microstructures are investigated using the scanning electron microscope (SEM) with energy dispersive X-ray spectrometer (EDS). In general, heat treatment after W-EDM result in smoother surface and better chemical composition at the machined surface. Especially, high temperature tempering could remove defects in the thermally affected zone, which cause an overall deterioration of the surface machined by W-EDM.

• 박물관보존과학
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• 제25권
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• pp.85-94
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• 2021

부식생성물, 이물질 등이 고착된 금속유물의 보존처리는 처리 전·후 형태와 특성, 유물의 중량 및 두께가 변한다. 지금까지 보존처리 전·후 변화에 대한 기록은 주로 육안관찰, 사진촬영 등을 통해 수행되었으나, 이 방법들은 보존처리 변화에 대한 정량적 결과를 파악하는 데 어려움이 있다. 본 연구에서는 환두부를 중심으로 이물질 제거, 균열부 메움, 복원 등의 과정을 3차원 스캐닝으로 기록하여 보존처리에 따른 형상 변화를 정량적으로 분석하였다. 3차원 스캐닝 결과를 기반으로 보존처리에 따른 부피 변화를 산출하고 형상 변화에 대한 수치자료를 분석하였다. 이 결과, 전체적으로 이물질 및 부식물은 보존처리 전 부피의 약 52%(18.1cm³)가 줄어들었고, 표면적으로 볼 때 약 98%가 제거된 것으로 확인되었다. 이 연구는 3차원 형상분석 기술이 유물의 보존처리 기록화 및 분석에 유용함을 보여주었다. 따라서 이 방법론은 금속유물뿐만 아니라 다양한 재질의 문화유산에 확대적용이 가능할 것으로 판단된다.

• 대한치과보철학회지
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• 제44권5호
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• pp.617-627
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• 2006

Statement of problem: HA has been used as a coating material on Ti implants to improve osteoconductivity. However. it is difficult to form uniform HA coatings on implants with complex surface geometries using a plasma spraying technique. Purpose : To determine if Ti6Al4V sintered porous-surfaced implants coated with HA sol-gel coated and hydrothermal treated would accelerate osseointegration. Materials and Methods : Porous implants which were made by electric discharge were used in this study. Implants were anodized and hydrothermal treatment or HA sol-gel coating was performed. Hydrothermal treatment was conducted by high pressure steam at $300^{\circ}C$ for 2 hours using a autoclave. To make a HA sol, triethyl phosphite and calcium nitrate were diluted and dissolved in anhydrous ethanol and mixed. Then anodized implant were spin-coated with the prepared HA sols and heat treated. Samples were soaked in the Hanks solution with pH 7.4 at $37^{\circ}C$ for 6 weeks. The microstructure of the specimens was observed with a scanning electron microscope (SEM), and the composition of the surface layer was analyzed with an energy dispersive spectroscope (EDS). Results : The scanning electron micrographs of HA sol-gel coated and hydrothermal treated surface did not show any significant change in the size or shape of the pores. After immersion in Hanks' solution the precipitated HA crystals covered macro- and micro-pores The precipitated Ca and P increased in Hanks' solution that surface treatment caused increased activity. Conclusion : This study shows that sol-gel coated HA and hydrothermal treatment significantly enhance the rate of HA formation due to the altered surface chemistry.

• Restorative Dentistry and Endodontics
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• 제40권3호
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• pp.195-201
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• 2015

Objectives: The use of chitosan nanoparticles (CNPs) in endodontics is of interest due to their antibiofilm properties. This study was to investigate the ability of bioactive CNPs to remove the smear layer and inhibit bacterial recolonization on dentin. Materials and Methods: One hundred bovine dentin sections were divided into five groups (n = 20 per group) according to the treatment. The irrigating solutions used were 2.5% sodium hypochlorite (NaOCl) for 20 min, 17% ethylenediaminetetraacetic acid (EDTA) for 3 min and 1.29 mg/mL CNPs for 3 min. The samples were irrigated with either distilled water (control), NaOCl, NaOCl-EDTA, NaOCl-EDTA-CNPs or NaOCl-CNPs. After the treatment, half of the samples (n = 50) were used to assess the chelating effect of the solutions using portable scanning electronic microscopy, while the other half (n = 50) were infected intra-orally to examine the post-treatment bacterial biofilm forming capacity. The biovolume and cellular viability of the biofilms were analysed under confocal laser scanning microscopy. The Kappa test was performed for examiner calibration, and the non-parametric Kruskal-Wallis and Dunn tests (p < 0.05) were used for comparisons among the groups. Results: The smear layer was significantly reduced in all of the groups except the control and NaOCl groups (p < 0.05). The CNPs-treated samples were able to resist biofilm formation significantly better than other treatment groups (p < 0.05). Conclusions: CNPs could be used as a final irrigant during root canal treatment with the dual benefit of removing the smear layer and inhibiting bacterial recolonization on root dentin.

• 한국의학물리학회지:의학물리
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• 제32권3호
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• pp.59-69
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• 2021

Purpose: The relationship between computed tomography (CT) number and electron density (ED) has been investigated in previous studies. However, the role of these measures for guiding cancer treatment remains unclear. Methods: The CT number was plotted against ED for different imaging protocols. The CT number was imported into ED tables for the Pinnacle treatment planning system (TPS) and was used to determine the effect on dose calculations. Conversion tables for radiation dose calculations were generated and subsequently monitored using a dosimeter to determine the effect of different CT scanning protocols and treatment sites. These tables were used to retrospectively recalculate the radiation therapy plans for 41 patients after an incorrect scanning protocol was inadvertently used. The gamma index was further used to assess the dose distribution, percentage dose difference (DD), and distance-to-agreement (DTA). Results: For densities <1.1 g/cm³, the standard deviation of the CT number was ±0.6% and the greatest variation was noted for brain protocol conditions. For densities >1.1 g/cm³, the standard deviation of the CT number was ±21.2% and the greatest variation occurred for the tube voltage and head and neck (H&N) protocol conditions. These findings suggest that the factors most affecting the CT number are the tube voltage and treatment site (brain and H&N). Gamma index analyses for the 41 retrospective clinical cases, as well as brain metastases and H&N tumors, showed gamma passing rates >90% and <90% for the passing criterion of 2%/2 and 1%/1 mm, respectively. Conclusions: The CT protocol should be carefully decided for TPS. The correct protocol should be used for the corresponding TPS based on the treatment site because this especially affects the dose distribution for brain metastases and H&N tumor recognition. Such steps could help reduce systematic errors.

• Bulletin of the Korean Chemical Society
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• 제31권2호
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• pp.335-338
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• 2010

In this study, the atmospheric plasma treatment with $He/O_2$ was conducted to modify the surface chemistry of carbon fibers. The effects of plasma treatment parameters on the surface energetics of carbon fibers were experimentally investigated with respect to gas flow ratio, power intensity, and treatment time. Surface characteristics of the carbon fibers were determined by X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), Fourier transform infrared (FT-IR), Zeta-potential, and contact angle measurements. The results indicated that oxygen plasma treatment led to a large amount of reactive functional groups onto the fiber surface, and these groups can form together as physical intermolecular bonding to improve the surface wettability with a hydrophilic polymer matrix.

• 상하수도학회지
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• 제14권3호
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• pp.231-239
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• 2000

Water treatment processes produce sludges resulting from water clarification. Sludge production amount increases each year and its treatment and disposal is growing to social problems according to water demand increase. Water treatment plant sludges can be modified to soil cover in sanitary landfill site through the lime treatment. Compression strength of $1.0kg/cm^2$ or more is recommended for soil cover material in municipal landfilling site. Compression and shear strength properties of modified sludges showed material property improvement applicable for soil cover alternatives. Solidification effect of the modified sludge was observed through the scanning electron microscope. Extraction tests for hazardous components in sludges revealed that extraction levels of cadmium, copper, and lead were below the regulated criteria. When adding 10% calcium hydroxide to water treatment plant sludges, the modified sludges can reach material properties for cover soil after 28 days solidification reaction.

• Corrosion Science and Technology
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• 제21권6호
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• pp.495-502
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• 2022

Anodization is a representative electrochemical surface treatment method that can improve both heat resistance and corrosion resistance by forming an anodization film on the surface of the aluminum. However, these properties can be changed after an additional heat treatment process. In this study, Al 6061 was subjected to an anodization process at 60 V for 1 hour, 5 hours, or 9 hours. An additional heat treatment process was performed at 500 ℃ for 30 minutes. Field emission scanning electron microscopy (FE-SEM) analysis revealed that the thickness of the anodized film was increased in proportion to the anodization time. Both pore size and pore diameter of the anodized film was also increased after anodization. After an additional heat treatment process, there were no significant changes in the thickness, pore size, or pore diameter of the anodized film. Heat resistance was confirmed through thermal analysis and chemical resistance was evaluated with a potentiodynamic polarization test.