• The Journal of Advanced Prosthodontics
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• 제5권4호
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• pp.479-484
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• 2013

PURPOSE. The aim of this study was to evaluate the effects of additional acid etching and curing mechanism (light-curing or self-curing) of a composite resin on the dentin bond strength and compatibility of one-step self-etching adhesives. MATERIALS AND METHODS. Sixteen human permanent molars were randomly divided into eight groups according to the adhesives used (All-Bond Universal: ABU, Clearfil S3 Bond: CS3), additional acid etching (additional acid etching performed: EO, no additional acid etching performed: EX), and composite resins (Filtek Z-250: Z250, Clearfil FII New Bond: CFNB). Group 1: ABU-EO-Z250, Group 2: ABU-EO-CFNB, Group 3: ABU-EX-Z250, Group 4: ABU-EX-CFNB, Group 5: CS3-EO-Z250, Group 6: CS3-EO-CFNB, Group 7: CS3-EX-Z250, Group 8: CS3-EX-CFNB. After bonding procedures, composite resins were built up on dentin surfaces. After 24-hour water storage, the teeth were sectioned to make 10 specimens for each group. The microtensile bond strength test was performed using a microtensile testing machine. The failure mode of the fractured specimens was examined by means of an optical microscope at ${\times}20$ magnification. The data was analyzed using a one-way ANOVA and Scheffe's post-hoc test (${\alpha}$=.05). RESULTS. Additional etching groups showed significantly higher values than the no additional etching group when using All-Bond Universal. The light-cured composite resin groups showed significantly higher values than the self-cured composite resin groups in the Clearfil S3 Bond. CONCLUSION. The additional acid etching is beneficial for the dentin bond strength when using low acidic one-step self-etch adhesives, and low acidic one-step self-etch adhesives are compatible with self-cured composite resin. The acidity of the one-step self-etch adhesives is an influencing factor in terms of the dentin bonding strength and incompatibility with a self-cured composite resin.

• 대한치과기공학회지
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• 제39권2호
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• pp.75-82
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• 2017

Purpose: This study provided the basic data for selection the zirconia block and CAM by means of marginal fitness observations, flexural strength test and hardness test. Methods: Three dental zirconia blocks(ABCera, NaturaZ, ST98) and two dental milling machines(CAD/CAM MS, DWX-50) were used in this study. Metal abutment(diameter 10 mm, height 5 mm, inclined angle $3^{\circ}$ taper, 1 mm chamfer margin) was fabricated by Ti customized abutment, and then zirconia copings were fabricated for each ten specimens. Silicone replica technique was used to observe the marginal fitness of cross-sections with a stereomicroscope at ${\times}50$ magnification. The dental zirconia blocks was cut into 10 pieces each having a size of $25mm{\times}5mm{\times}1mm$, and fabricated according to the manufacturer's instructions, and flexural strength was measured using a universal testing machine. For hardness test, a micro Vickers hardness tester was used as it was in the flexural strength test. Statistical analysis was performed by one way ANOVA and post-test was performed by Scheffe test. Results: For marginal fitness of bucco-lingual axial, ZU group($59.7{\pm}10.3{\mu}m$) was the lowest, followed by RA, ZA, ZD, RD, RU. For marginal fitness of mesio-distal axial, ZU group($59.3{\pm}10.2{\mu}m$) was the lowest, followed by RA, ZA, RD, ZD, RU. One-way ANOVA showed statistically significant difference between groups(p<0.05). For flexural strength, ABCera block($718.0{\pm}57.2MPa$) was the highest, followed by NaturaZ, ST98. For hardness, ABCera block($1550.3{\pm}19.8Hv$) was the highest, followed by ST98, NaturaZ. There was no significant difference in flexural strength and hardness between blocks(p>0.05). Conclusion: Based on the results of this study, the type of dental zirconia block did influence the marginal fitness, and all dental zirconia blocks are expected to be suitable for clinical application. The highest flexural strength and hardness were ABCera block, and no statistically significant difference was observed.

• 치과방사선
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• 제28권2호
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• pp.471-489
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• 1998

For the successful endodontic treatment, root canal should be cleaned thoroughly by accurate mechanical and chemical canal preparation and sealed completely with canal filling material without damaging the periapical tissues. The accuracy of the root canal length measurement is a prerequisite for the success of the endodontic treatment, and the root canal length is often determined by the standard periapical radiographs and digital tactile sense. In this study, the accuracy and the clinical usefulness of Digora/sup (R)/, an intraoral digital imaging processor and the conventional standard radiographs were compared by measuring the length from the top of the file to the root apex. 30 single rooted premolars were invested in a uniformly sized blocks and No.25 K-file was inserted into and fixed in each canal. Each block was placed in equal distance and position to satisfy the principle of the bisecting angle and paralleling techniques and Digora/sup (R)/ system's image and standard periapical radiographs were taken. Each radiograph was examined by 3 different observers by measuring the length from top of the file to the root apex and each data was compared and analyzed. The results were as follows; 1. In the bisecting angle technique, the average difference between the Digora/sup (R)/ system and standard periapical radiograph was 0.002 mm and the standard deviation was 0.341 mm which showed no statistically significant difference between the two systems(p>0.05). Also, in the paralleling technique, the average difference between these two system was 0.007 mm and the standard deviation was 0.323 mm which showed no statistically significant difference between the two systems(p>0.05). 2. In Digora/sup (R)/ system, the average difference between the bisecting angle and paralleling technique was -0.336 mm and the standard deviation was 0.472 mm which showed a statistically significant difference between the two techniques(p<0.05). Also, in the standard periapical radiographs, the average difference between the bisecting angle and paralleling technique was 0.328 mm and the standard deviation was 0.517 mm which showed a statistically significant difference between these two techniques(p<0.05). 3. In Digora/sup (R)/ system and the standard periapical radiographs. there was a statistically significant difference between the measurement using the bisecting angle technique and the actual length(p<0.05), But there was no statistically significant difference between the measurement using the paralleling technique and the actuallength(p>0.05). In conclusion. the determination of the root canal length by using the Digora/sup (R)/ system can give us as good an image as the standard periapical radiograph and using the paralleling technique instead of the bisecting angle technique can give a measurement closer to the actual canal length. thereby contributing to a successful result. Also. considering the advantages of the digital imaging processor such as decreasing the amount of exposure to the patient. immediate use of the image. magnification of image size. control of the contrast and brightness and the ability of storing the image can give us good reason to replace the standard periapical radiographs.

• 대한치과보철학회지
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• 제32권1호
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• pp.23-36
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• 1994

Most investigators recommended that porcelain surface should be roughened with abrasives and/or be etched with acid in repairing the fractured porcelain with composite resin. This study was designed to evaluate the effect of porcelain surface treatments on the bond strength between porcelain and composite resin by measuring the shear bond strength and observing the porcelain surface with SEM. 48 porcelain disc were fabricated with Vintage porcelain and embedded in epoxy resin with the test surface exposed. The specimens were divided four groups at random and the test surfaces of the four groups were prepared as follows : Group 1 : Porcelain surface was roughened with a fine diamond and treated with 32% phosphoric acid gel for 10 seconds. Group 2 : Porcelain surface was roughened with a fine diamond and etched with 8% hydrofluoric acid gel for 5 minutes. Group 3 : Porcelain surface was roughened with a coarse diamond and treated with 32% phosphoric acid gel for 10 seconds. Group 4 : Porcelain surface was roughened with a coarse diamond and etched with 8% hydrofluoric acid gel for 5 minutes. All specimens were washed for 30 seconds. A representative specimen of each group was selected and the porcelain surface was observed with SEM at 1000 magnification. Remaining specimens were silanated, bonded with composite resin, thermocycled, and shear-tested on specially designed zig connected to Instron machine. The results were as follows : 1. The shear bond strength of the group etched with hydrofluoric acid was significantly higher than that of group treated with phosphoric acid(p<0.01). 2. The shear bond strength of the group roughened with a fine diamond was not significantly different from that of the group roughened with a coarse diamond(p>0.01). 3. SEM examination of prepared porcelain surfaces revealed that the surface etched with hydrofluoric acid showed numerous microporosities, undercut, and rougher surface than the surface treated with phosphoric acid. 4. All specimens etched with hydrofluoric acid showed cohesive failure within porcelain, but specimens treated with phosphoric acid mainly showed adhesive failure between porcelain and composite resin.

• 대한치과보철학회지
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• 제52권2호
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• pp.90-96
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• 2014

연구 목적: 이 연구의 목적은 열가압성형기법이 금속도재관의 치경부 변연적합도에 미치는 영향을 확인하는 것이다. 연구 재료 및 방법: 실험에 앞서, 4개의 금속 주모형을 형성하였다. 각 모형은 각각chamfer, heavy chamfer, shoulder with bevel, shoulder (collarless)변연을 형성하였다. 각 변연당 10개씩의 금관을 제작하여, 총 40개를 제작하였다. Coping 단계에서, 그리고 금속도재관 완성 단계에서 주모형과 금관 사이의 변연간극은 100배율의 광학현미경 관찰을 통하여 측정되었다. Data분석은 paired t-test along with one-way ANOVA와 Duncan multiple comparison test를 이용하여 이루어졌다. 결과: 변연간극의 평균과 표준편차를 분석한 결과, 금속 코핑과 그 후 완성된 금속도재관, 모든 경우에서 변연부 간격은 임상적 허용범위 안에 있었다. Chamfer 변연 실험군의 경우 Heavy chamfer 변연 실험군에 비하여 금속도재관 완성 후 변연부 간격의 유의한 증가가 있었다. 그리고Shoulder 변연 실험군에서 도재로 처리된 변연이 Chamfer와 Shoulder변연 실험군의 금속변연에 비하여 변연부 간격이 유의하게 작게 나타났다. 결론: 열가압성형기법을 통하여 제작한 금속도재수복물의 변연적합도는 전통적인 방법으로 제작한 금속도재수복물의 변연적합도와 유의한 차이점이 없었다. 제작과정의 효율성으로, 열가압성형기법은 임상에서의 효과적인 사용법으로 고려될 수 있다.

• Journal of Radiation Protection and Research
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• 제4권1호
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• pp.14-20
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• 1979

고(高)에너지 방사선(放射線) 치료(治療)에 있어서 정상조직(正常組織)의 완전차폐(完全遮蔽)를 위하여 $5{\sim}8cm$ 납두께의 부정형(不定形) 차폐(遮蔽)벽돌을 제작(製作)해야하는 난점(難點)이 있었다. 저자(著者)들은 납 30.0%, 주석 11.5% 비스므스 48.5%, 카드미늄 10.0%를 사중(四重) 공정결합(共晶結合)시켜 밀도(密度)가 $9.8g/cm^3$ 용융온도(熔融溫度)가 $68^{\circ}C$인 저용융(低熔融) 차폐물질(遮蔽物質)을 개발(開發)하여 이를 Lead Y라고 명명(名命)하였다. 제작(製作)된 Lead Y Block을 $68^{\circ}C$에서 용융(熔融)시켜 보호(保護)해야할 중요(重要)한 장기(臟器)의 형태(形態)대로 제작(製作)된 styrofoam 음형(陰形)에 부어서 차폐효과(遮蔽效果)가 큰 차폐(遮蔽)벽돌을 쉽고 안전(安全)하게 제작(製作)할 수 있었고 납보다 더 단단하고 재현성(再現性)이 크며 저렴(低廉)한 가격(價格)으로 구입(購入)이 가능(可能)하므로 방사선(放射線) 치료효과(治療效果)에 큰 도움을 줄 수 있었다.

• 한국식품조리과학회지
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• 제22권4호통권94호
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• pp.419-427
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• 2006

The purpose of this study is to promote the substitution of rice flour for wheat flour in making bread and thus the consumption of rice by examining the effect of particle size of rice flour on leavening rice bread. For this purpose, several experiments were carried out. With regard to particle size distribution, 59.45% of wheat flour had passed 200 mesh and 3 kinds of rice flour milled to penetrate into 20, 35, and 45 mesh (S1, S2 and S3) had passed 21.88%, 33.1% and 36.38% of those for 200 mesh, respectively. To leaven the rice flour dough to bread, 25% of vital gluten was needed. To determine the optimal water quantity for rice bread dough, the hardness of wheat and rice flour dough was measured by rheometer. The appropriate water quantity for S1, S2 and S3 was set at 285 ml , 295 ml and 335${\sim}$340m1, respectively. The loaf volume index of the wheat flour bread was 6.24, while that of and rice flour bread S1, S2 and S3 was 5.38, 5.50 and 5.75, respectively. These results indicated that the loaf volume index of rice flour bread is lower than that of wheat flour bread, but that the volume of rice flour bread was increased with fuel particle size of rice flour. Scanning electron microscopy (SEM), image of the wheat bread tissue at a magnification of 35 times showed long, large, oval-shaped, air cells and thin cell membrane, as well as small air cells, whereas the images of rice flour showed angular, circular, air cells and rough and thick cell membrane. The size and number of air cells in the rice bread were larger in S2 and S3 with fuel particle flours than in S1. In particular, the bread made with S3 contained many air cells that were as large as those in the wheat bread were. In addition, when the inner cell wall was magnified 1500 times, almost no small air cell was observed in C and S3, whereas many fine air cells were observed in the cell wall of S1 and S2.

• 비파괴검사학회지
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• 제35권2호
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• pp.141-149
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• 2015

전자제품에 필수적으로 사용되는 전자회로의 제작 시, 반도체 위에 증착하는 박막의 산화를 방지하기 위하여 molybdenum을 증착한다. Molybdenum 박막 증착 시 표면의 particle 또는 dust의 존재는 밀착력 감소 및 성능 저하, 수명 단축, 안전도 저하를 유발한다. 본 논문에서는 particle의 유무에 따른 molybdenum 박막 증착부의 변화를 보기 위하여, 두 가지 glass substrate를 대상으로 손상 측정 실험을 하였다. Sputtering 증착 기법으로 molybdenum이 glass substrate에 직접 코팅이 되는 clean과 dirty 두 종류의 molybdenum 박막을 제작하고, 손상 측정을 위해 반사형 디지털 홀로그래피를 구성하였다. 반사형 디지털 홀로그래피는 간섭계의 구성이 손쉽고 다양한 배율렌즈를 적용하여 측정영역에 다양성을 줄 수 있으며, 측정시간이 타 기법에 비해 짧다는 장점을 가진다. 실험 결과로부터 반사형 디지털 홀로그래피가 박막의 손상 및 결함 측정에 유용한 기술임을 확인하였다.

• Parasites, Hosts and Diseases
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• 제36권4호
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• pp.227-234
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• 1998

쥐와포자충의 운동에 관여하는 구조에 대하여 다른 구충류에서와 마찬가지로 알려진 바가 없다. 이 연구에서는 쥐와포자충에서 microfilament와 그 결합단백질의 분포를 관찰하여 이 기생충의 운동기전에 대한 이해를 돕고자 하였다. Actin의 분포를 보기 위해 두 종류의 actin, 즉 닭 골격근과 평활근의 actin에 대한 항체를 사용하였고, tropomyosin의 관찰을 위해서는 닭 골격근의 tropomyosin에 대한 항체를 이용하여 면역황금표지법으로 관찰하였다. 관찰된 모든 발육단계의 쥐와포자충이 actin과 tropomyosin을 가지고 있었는데 두 종류의 actin은 서로 다른 부위에서 관찰되었다. 즉, 골격근에 대한 항체는 주로 세포질과 세포막 구조에 표지되었고, 평활근에 대한 항체는 feeder organelle과 숙주세포 사이의 섬유질 구조 (filamentous cytoplasm)에 주로 표지되어 서로 다른 actin이 상이하게 분포하고 있음을 알 수 있었다. 분포 위치로 미루어 볼 때 골격근형 actin은 기생충의 세포질 내 여러 가지 현상에, 평활근형 actin은 쥐와포자충과 숙주세포 부착을 유지시키는데 주요 역할을 할 것으로 생각된다. Tropomyosin은 쥐와포자충 모든 발육단계에서 관찰되었는데 세포막에 주로 분포하였고 세포질 내의 소공포 (vacuole) 막 주위 및 핵 주위에서도 관찰되었다. Tropomyosin은 쥐와포자충의 발육단계가 변함에 따라 끊임없이 분포를 달리하는 것으로 생각되며 특히 막구조에 다수 분포하므로 항원으로서 숙주세포를 자극할 가능성이 있는 것으로 보인다.

• 대한수의학회지
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• 제28권2호
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• pp.379-385
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• 1988

포유류(哺乳類)의 주요(主要) 기생원충(寄生原蟲)인 Toxoplasma gondii와 Sarcocystis species의 증식형(增殖型)에 대(對)한 표면미세구조(表面微細構造)를 비교(比較)하기 위하여 주사전자현미경(走査電子顯微鏡)으로 관찰(觀察)하였다. 동(同) 시료(試料)는 인공감염(人工感染)된 마우스로부터 분리(分離)된 T gondii와 자연감염(自然感染)된 도축우(屠畜牛)로부터 분리(分離)된 Sarcocystis species의 증식형(增殖型)이었다. 관찰결과(觀察結果) 마우스 복강(腹腔)으로부터 채취(採取)된 T gondii의 증식형(增殖型)인 tachyzoites는 초승달모양(crescent-like feature)을 나타냈고, 계측결과(計測結果) 길이 $5.57{\mu}m$, 폭 $2.33{\mu}m$이었으며 도축우(屠畜牛)의 심근(心筋)에서 채취(採取)된 Sarcocystis species의 증식형(增殖型)인 bradyzoites는 바나나모양으로 길이 $14.18{\mu}m$, 폭 $2.85{\mu}m$이었다. 특(待)히 Sarcocystis species 증식형(增殖型)의 표면관찰(表面觀察)에 있어서 높은 확대배율(擴大倍率)(60,000X)의 관찰계측(觀察計測) 결과(結果), 길이 $0.35{\mu}m$, 폭 $0.18{\mu}m$의 미세공(微細孔)(micropore)이 확인(確認)되었다.