• 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.27 no.3
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• pp.270-276
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• 2002

치근단 수술시 구동형 수술현미경과 미세수술기구들이 사용됨에 따라 치근단 절제술 후 역충전와동의 효과적인 형성 및 충전을 위해 새로운 초음파기구가 개발되었다 따라서 본 연구에서는 최근 상품화되어 사용되고 있는 초음파기구중 신속하게 역충전와동을 형성할 뿐아니라 충분한 깊이를 제공하여 역충전재료의 변연누출 감소에 효과적인 것으로 알려져 있는 3종의 초음파기구를 사용하여 역 충전와동을 형성 한 후 SuperEBA로 충전하여 그 변연누출을 비교하였다. 모두 56개의 근첨형성이 완료된 단근치를 선택하여 Profile .06를 사용하여 근관형성한 후 음성대조군 2개를 제외한 54개의 치아를 수직가압법으로 충전하였다. 근단부 3mm를 절제한 뒤 KaVo Isthmus, KaVo T-shape 그리고 KiS tip을 각각 18개의 치아에 사용하여 역충전와동을 형성하고 그중 각각 2개의 양성대조군 치아를 제외한 나머지 치아에 SuperEBA로 충전하였다. 각치아는 1% methylene blue dye에 침윤시켜 1주일 후 종절단하여 그 색소침투정도를 측정, 비교하였다. 실험결과 측정된 평균 변연누출은 KaVo Isthmus가 $1.5\pm$1.4mm, KaVo T-shape이 1.7$\pm$1.2mm이고 KiS tip은 1.1$\pm$0.7mm 이었으며, 통계적으로 유의할만한 차이는 없었다. 따라서 초음파기구를 사용한 역충전와동의 임상시술 성공여부는 술자의 편의도와 임상적 사용시 조작능력에 달려 있는 것으로 사료된다.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.515-524
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• 1998

The purposes of this study were to observe the cavity wall morphology and to evaluate the degree of cavity cleanliness when root-end retrograde cavity preparation was done with ultrasonic diamond instruments. To observe the morphology of retrocavity and to evaluate the degree of cavity cleanliness. root-end resections were done on 20 palatal roots of extracted maxillary first molars after canal filling with gutta-percha. Retrocavities were prepared using either ultrasonic diamond instruments or stainless steel ones of medium power setting of level 6 ($Miniendo^{TM}$, EIE, CA, U.S.A.). Morphology of the cavity. degrees of the remaining canal debris and smear layer were evaluated under the scanning electron microscope. The results were as follows: Cavities prepared with ultrasonic diamond instruments showed scratched appearance of wall, while ultrasonic stainless steel preparation showed hatcheted appearance. Ultrasonic diamond instruments induced more smear layer than stainless steel ones did (p<0.01) in the cavity. However, there was no significant difference in canal debris (p>0.05).

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.166-179
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• 1999

Apical sealing is essential for the success of surgical endodontic treatment. Root-end cavity is apt to be contaminated with moisture or blood, and is not always easy to be dried completely. The purpose of this study was to evaluate the influence of dry methods of retrocavity on the apical seal in endodontic surgery. Apical seal was investigated through the evaluation of apical leakage and adaptation of filling material over the cavity wall. To investigate the influence of various dry methods on the apical leakage, 125 palatal roots of extracted human maxillary molar teeth were used. The clinical crown of each tooth was removed at 10 mm from the root apex using a slow-speed diamond saw and water spray. Root canals of the all the specimens were prepared with step-back technique and filled with gutta-percha by lateral condensation method. After removing of the coronal 2 mm of filling material, the access cavities were closed with Cavit$^{(R)}$. Two coats of nail polish were applied to the external surface of each root. Apical three millimeters of each root was resected perpendicular to the long axis of the root with a diamond saw. Class I retrograde cavities were prepared with ultrasonic instruments. Retrocavities were washed with physiologic saline solution and dried with various methods or contaminated with human blood. Retrocavities were filled either with IRM, Super EBA or composite resin. All the specimens were immersed in 2% methylene blue solution for 7 days in an incubator at $37^{\circ}C$. The teeth were dissolved in 14 ml of 35% nitric acid solution and the dye present within the root canal system was returned to solution. The leakage of dye was quantitatively measured via spectrophotometric method. The obtained data were analysed statistically using one-way ANOVA and Duncan's Multiple Range Test. To evaluate the influence of various dry methods on the adaptation of filling material over the cavity wall, 12 palatal roots of extracted human maxillary molar teeth were used. After all the roots were prepared and filled, and retrograde cavities were made and filled as above, roots were sectioned longitudinally. Filling-dentin interface of cut surfaces were examined by scanning electron microscope. The results were as follows: 1. Cavities dried with paper point or compressed air showed less leakage than those dried with cotton pellet in Super EBA filled cavity (p<0.05). However, there was no difference between paper point- and compressed air-dried cavities. 2. When cavities were dried with compressed air, dentin-bonded composite resin-filled cavities showed less apical leakage than IRM- or Super EBA-filled ones (p<0.05). 3. Regardless of the filling material, cavities contaminated with human blood showed significantly more apical leakage than those dried with compressed air after saline irrigation (p<0.05). 4. Outer half of the cavity showed larger dentin-filling interface gap than inner half did when cavities were filled with IRM or Super EBA. 5. In all the filling material groups, cavities contaminated with blood or dried with cotton pellets only showed larger defects at the base of the cavity than ones dried with paper points or compressed air.

• Restorative Dentistry and Endodontics
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• v.23 no.2
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• pp.537-549
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• 1998

The purpose of this study was to evaluate the influence of root resection and retrograde cavity preparation methods on the apical leakage in endodontic surgery. To investigate the effect of various root resection and retrograde cavity preparation methods on the apical leakage, 71 roots of extracted human maxillary anterior teeth and 44 mesiobuccal roots of extracted human maxillary first molars were used. Root canals of the all the specimens were prepared with step-back technique and filled with gutta-percha by lateral condensation method. Three millimeters of each root was resected at a 45 degree angle or perpendicular to the long axis of the tooth according to the groups. Retrograde cavities were prepared with ultrasonic instruments or a slow-speed round bur, and occlusal access cavities were filled with zinc oxide eugenol cement. Three coats of clear nail polish were placed on the lateral and coronal surfaces of the specimens except the apical cut one millimeter. All the specimens were immerged in 2% methylene blue solution for 7 days in an incubator at $37^{\circ}C$. The teeth were dissolved in 14 ml of 35% nitric acid solution and the dye present within the root canal system was returned to solution. The leakage of dye was quantitatively measured via spectrophotometric method. The obtained data were analysed statistically using two-way ANOVA and Duncans Multiple Range Test. The results were as follows: 1. No statistically significant difference was observed between ultrasonic retrograde cavity preparation method and slow-speed round bur technique, without apical bevel (p>0.05). 2. Ultrasonic retrograde preparation method showed significantly less apical leakage than slow-speed round bur technique, with bevel (p<0.0001). 3. No statistically significant difference was found between beveled resected root surface and non-beveled resected root surface, with ultrasonic technique (p>0.05). 4. Non-beveled resected root surface showed significantly less apical leakage than beveled resected root surface, with slow-speed round bur technique (p<0.0001). 5. No statistically significant difference in apical leakage was found between the group of retrograde cavity prepared parallel to the long axis of the tooth and the group of one prepared perpendicular to the long axis of the tooth (p>0.05). 6. Regarding isthmus preparation, ultrasonic retrograde preparation method showed significantly less apical leakage than slow-speed round bur technique, in the mesiobuccal root of maxillary molar, without bevel (p<0.0001).

• Restorative Dentistry and Endodontics
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• v.34 no.4
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• pp.371-376
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• 2009

We evaluated in vitro microleakage of Mineral Trioxide Aggregate (MTA) powder with 4-methacryloxyethyl trimellitate anhydride (4-META) / methyl methacrylate (MMA) & tri-n-butylborane (TBB) resin as a retrograde filling material by using methylene blue dye method. Fifty-two single rooted, extracted teeth were instrumented and obturated with gutta percha and AH plus sealer. The apical 3mm of each root was resected and 3mm deep ultrasonic root end preparation was done. External surface of roots was coated with nail varnish. Prepared teeth were randomly divided into five groups; Negative control: completely covered with nail varnish; Positive control: coated with nail varnish except for apical foramen; Group 1 (retrofilled with Portland cement); Group 2 (retrofilled with MTA); Group 3 (retrofilled with MTA powder mixed with 4-META/MMA & TBB resin). Immediately after completion of root-end filling, all specimens were submerged in methylene blue dye for 72 hours in $37^{\circ}C$incubator. The roots were longitudinally sectioned and measured for extent of dye penetration by three different examiners under microscope (${\times}$10). The results were statistically analyzed using one way ANOVA and Turkey's HSD test. No leakage was evident in negative control and complete leakage in positive control group. Group 3 showed significantly less leakage than group 1 and 2 (p < 0.01). There was no significant difference between group 1 and 2 (p > 0.01). It was concluded that MTA powder with 4-META/MMA & TBB resin was excellent in reducing initial apical microleakage.

• Vending industry
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• v.1 no.2 s.2
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• pp.46-53
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• 2001

지난 연말부터 충전자판기 시장이 급속도로 커지고 있다. 단기간 안에 2,800만의 인구로 급성장한 휴대폰 시장을 근저로 한 휴대폰충전자판기 시장은 현재까지 보급대수가 9,000여대에 육박한 것으로 추정될 만큼 급신장하고 있고, 이를 둘러싼 업체들의 시장경쟁도 거세지고 있다. 일단 `뜬 시장`임에는 분명한 시장.하지만 이 시장이 앞으로도 지속적인 고속성장을 해 나가기 위해서는 시장과제 역시도 산적해 있다. 향후 충전자판기 시장이 지속적으로 `발전`을 급속 충전해 나갈수 있을지, 아니면 반짝 시장으로 쉽게 `방전`되 버리는 시장으로 급락할지 금호 기획특집에서 집중 진단해 보았다.

• Restorative Dentistry and Endodontics
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• v.35 no.6
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• pp.445-452
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• 2010

Objectives: The aim of this study was to compare apical sealing ability and physical properties of MTA, MTA - AH-plus mixture (AMTA) and experimental Portland cement - Epoxy resin mixture (EPPC) for a development of a novel retro-filling material. Materials and Methods: Forty-nine extracted roots were instrumented and filled with gutta-percha. Apical root was resected at 3 mm and the retro-filling cavity was prepared for 3 mm depth. Roots were randomly divided into 3 groups of 15 roots each. The retro-filling was done using MTA, AMTA, and EPPC as the groups divided. Four roots were used as control groups. After setting in humid condition for 24 hours, the roots were immersed in 1% methylene blue dye solution for 72 hours to test the apical leakage. After immersion, the roots were vertically sectioned and photos were taken to evaluate microleakage. Setting times were measured with Vicat apparatus and digital radiographs were taken to evaluate aluminum equivalent thickness using aluminum step wedge. The results of microleakage and setting time were compared between groups using one-way ANOVA and Scheffe's post-hoc comparison at the significance level of 95%. Results: AMTA and EPPC showed less microleakage than MTA group (p < 0.05). AMTA showed the highest radio-opacity than other groups and the novel EPPC showed 5 mm aluminum thickness radio-opacity. EPPC showed the shortest initial and final setting times than other groups while the MTA showed the longest (p < 0.05). Conclusions: Under the condition of this study, the novel composite using Portland cement-Epoxy resin mixture may useful for retro-filling with the properties of favorable leakage resistance, radio-opacity and short setting time.

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.546-559
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• 1997

The purposes of this study were to evaluate the efficiency of cavity preparation and to determine the incidence of tooth crack when root-end retrograde cavity preparation was done with ultrasonics. 91 distobuccal root-ends of extracted human maxillary first molars were cut by 3 mm perpendicularly to the long axis of tooth using a slow speed diamond saw, retrocavities were prepared using a slow-speed no. 2 round bur as controls, and stainless steel ultrasonic tips of power settings of 1 through 10 as experimentals. Time consumed and the number of strokes used for the cavity preparation were measured and evaluated, and the incidence of tooth cracks was observed under a stereomicroscope. The results were as follows : For the retrograde cavity preparation, time and number of strokes used were decreased as the ultrasonic power setting increased (p<0.001). High power setting of ultrasonics induced significantly more tooth cracks than did the slow-speed bur or low- and medium power setting of ultrasonics (p<0.05). Teeth with previous crack induced significantly more tooth cracks than those without previous one when high power setting of ultrasonics were used for the retrograde cavity preparation (p<0.001). Teeth with initial apical canal size of no. 10 induced significantly more crack than did those with size of no. 15 when low power setting of ultrasonics were used for the retrograde cavity preparation (p<0.05).

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1358-1359
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• 2011

연축전지는 충전과 방전을 반복함에 따라 그 용량이 감소하는 특성을 보인다. 연축전지의 이러한 특성은 충전/방전 과정에서 전지의 극판에서 일어나는 화학반응 중 충전/방전에 관여하지 않는 비가역적인 반응이 발생하여 극판의 활물질의 감소를 가져오기 때문이다. 본 논문에서는 이러한 비가역적인 반응을 감소시키고 비가역 반응에 의해 생성된 화합물을 분해해 극판의 활물질로 되돌릴 수 있는 shark pulse 파형을 이용한 충전 방법을 제안한다. 제안된 충전방법으로 각기 열화정도가 다른 골프카트용 12V 연축전지를 대상으로 충전실험을 하였고, 방전실험을 통해 그 용량을 측정하였다. 그 결과 실험 대상 축전지는 SoH(State of Health)가 각각 7%와 27% 만큼 개선됨을 확인하였다.