• Restorative Dentistry and Endodontics
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• 제44권1호
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• pp.5.1-5.9
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• 2019

Objectives: The aim of this in vitro study was to evaluate the push-out bond strength of a novel calcium silicate-based root repair material-BIOfactor MTA to root canal dentin in comparison with white MTA-Angelus (Angelus) and Biodentine (Septodont). Materials and Methods: The coronal parts of 12 central incisors were removed and the roots were embedded in acrylic resin blocks. Midroot dentin of each sample was horizontally sectioned into 1.1 mm slices and 3 slices were obtained from each root. Three canal-like standardized holes having 1 mm in diameter were created parallel to the root canal on each dentin slice with a diamond bur. The holes were filled with MTA-Angelus, Biodentine, or BIOfactor MTA. Wet gauze was placed over the specimens and samples were stored in an incubator at $37^{\circ}C$ for 7 days to allow complete setting. Then samples were subjected to the push-out test method using a universal test machine with the loading speed of 1 mm/min. Data was statistically analyzed using Friedman test and post hoc Wilcoxon signed rank test with Bonferroni correction. Results: There were no significant differences among the push-out bond strength values of MTA-Angelus, Biodentine, and BIOfactor MTA (p > 0.017). Most of the specimens exhibited cohesive failure in all groups, with the highest rate found in Biodentine group. Conclusions: Based on the results of this study, MTA-Angelus, Biodentine, and BIOfactor MTA showed similar resistances to the push-out testing.

• Restorative Dentistry and Endodontics
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• 제44권1호
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• pp.3.1-3.10
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• 2019

Objectives: It was the aim of this study to evaluate the effect of cooling water temperature on the temperature changes in the pulp chamber and at the handpiece head during high-speed tooth preparation using an electric handpiece. Materials and Methods: Twenty-eight intact human molars received a standardized occlusal preparation for 60 seconds using a diamond bur in an electric handpiece, and one of four treatments were applied that varied in the temperature of cooling water applied (control, with no cooling water, $10^{\circ}C$, $23^{\circ}C$, and $35^{\circ}C$). The temperature changes in the pulp chamber and at the handpiece head were recorded using K-type thermocouples connected to a digital thermometer. Results: The average temperature changes within the pulp chamber and at the handpiece head during preparation increased substantially when no cooling water was applied ($6.8^{\circ}C$ and $11.0^{\circ}C$, respectively), but decreased significantly when cooling water was added. The most substantial drop in temperature occurred with $10^{\circ}C$ water ($-16.3^{\circ}C$ and $-10.2^{\circ}C$), but reductions were also seen at $23^{\circ}C$ ($-8.6^{\circ}C$ and $-4.9^{\circ}C$). With $35^{\circ}C$ cooling water, temperatures increased slightly, but still remained lower than the no cooling water group ($1.6^{\circ}C$ and $6.7^{\circ}C$). Conclusions: The temperature changes in the pulp chamber and at the handpiece head were above harmful thresholds when tooth preparation was performed without cooling water. However, cooling water of all temperatures prevented harmful critical temperature changes even though water at $35^{\circ}C$ raised temperatures slightly above baseline.

• 대한소아치과학회지
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• 제41권2호
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• pp.125-133
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• 2014

이 연구의 목적은 시효된 복합레진 수복물에 이산화탄소 레이저로 표면처리한 경우와 기존의 여러 가지 표면처리 방법에 따른 교정용 브라켓의 전단응력을 측정하여 비교하기 위함이다. 복합레진을 이용하여 직경 6 mm, 두께 5 mm의 시편을 96개 제작하였다. 제작된 시편을 인공타액에 침적시켜 $37^{\circ}C$의 온도로 2주 동안 시효처리 하였다. 그 후 96개의 시편을 무작위적으로 16개씩 6개의 군으로 나누었다. 1군은 표면처리를 하지 않았고, 2군은 37% 인산으로, 3군은 4% 불산으로, 4군은 입자 분사 연마로, 5군은 고속 다이아몬드 버로, 6군은 이산화탄소 레이저로 표면처리하였다. 만능 시험기를 이용하여 전단응력을 측정하였으며, 주사전자 현미경을 이용하여 표면처리 양상을 관찰하였다. 버를 사용한 5군이 가장 큰 전단응력 값을 보였으며, 이산화탄소 레이저를 사용한 6군이 그다음으로 큰 값을 보였다. 버를 사용한 5군과 이산화탄소 레이저를 사용한 6군은 나머지 표면처리 방법들보다 통계적으로 유의하게 높은 전단응력 값을 보여주었다(p < 0.05). 또한, 주사전자 현미경 사진을 통해 분석한 결과 레이저를 이용한 6군에서 표면이 가장 거칠었으며 불규칙한 요철구조가 형성되었다. 이산화탄소 레이저를 이용한 표면처리 방법은 브라켓 접착시 적절한 결합강도를 제공하므로, 시효된 레진 수복물에 교정용 브라켓을 접착하기 위한 유용한 방법이 될 수 있다.

• 한국잡초학회지
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• 제17권3호
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• pp.303-309
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• 1997

가막사리 50개 수집종을 대상으로 여러 가지 형태적(形態的), 생리적(生理的)특성의 변이를 조사하고, 초형(草形), 열엽편수(裂葉片數), 수과(瘦果)길이, 개화소요일수(開花所要日數)를 기준(基準)으로 Ward의 최소분산법(最小分散法)으로 군집분석(群集分析)을 한 결과는 다음과 같다. 가막사리 수집종은 초형, 경장, 개화소요일수, 엽장폭비, 열엽편수, 엽록소함량, 엽색, 경색, 수과색, 수과길이, 수과장폭비 에서 다양한 변이를 보였으며, 수집종에 따라 약간의 변이가 있으나 대부분 상당한 휴면성과 광발아성이 있었다. 초형은 직립형(I)에서 삼각형(V)까지 다양했는데, 마름모형(III)이 가장 많았고, 경장과는 5% 수준에서 부(負)의 상관관계가 있는 것으로 나타났다. 열엽편수는 3개인 것이 가장 많았고 그 다음은 5개의 순으로 나타났는데 열엽(裂葉)되지 않는 수집종도 있었다. 수과길이 및 엽록소함량과는 5% 수준에서 엽장폭비와는 1% 수준에서 부(負)의 상관관계가 있었다. 개화소요일수는 94-141 일 범위였다. 수과길이와는 1% 수준에서, 엽장폭비와는 5% 수준에서 정(正)의 상관관계, 그리고 수과색과는 1% 수준에서 부(負)의 상관관계를 보였다. 수과길이는 6.5-14.0mm의 범위로, 평균 10.0mm, 표준편차 1.7로 9.0-12.0mm 사이가 60%를 차지했다. 수과장폭비, 경장, 개화소요일수와는 1% 수준에서, 엽장폭비와는 5% 수준에서 정(正)의 상관관계를, 그리고 엽색, 경색, 수과색, 열엽편수와는 5% 수준에서 부(負)의 상관관계를 보였다. Ward의 최소분산법을 이용한 군집분석 결과 거리 0.06에서 식물학적으로 특성이 각기 다른 6개 군으로 분류할 수 있었다.

• Restorative Dentistry and Endodontics
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• 제24권1호
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• pp.156-165
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• 1999

The purpose of this study was to evaluate the effect of surface treatments on the shear bond strength between new and old composites. Circular cavities prepared on the center of acrylic resin mold and the prepared cavities were filled with composite resin. They randomly assigned into control group and 8 groups according to the difference in surface treatments of old composites; Control group: no surface treatment, Group 1: surface treated with #120 SiC paper & bonding agent, Group 2: surface treated with #400 SiC paper & bonding agent, Group 3: surface treated with #120 SiC paper, 32% $H_3PO_4$ & bonding agent, Group 4: surface treated with #400 SiC paper, 32% $H_3PO_4$ & bonding agent, Group 5: surface treated with #120 SiC paper, primer & bonding agent, Group 6: surface treated with #400 SiC paper, primer & bonding agent, Group 7: surface treated with #120 SiC paper, 32% $H_3PO_4$, primer & bonding agent, Group 8: surface treated with #400 SiC paper, 32% $H_3PO_4$, primer & bonding agent. New composites were applicated on the old composites of experimental groups. The shear bond strengths for the experimental specimen were measured and the results were analyzed by using one way ANOVA. The observations of surface morphology after SiC paper roughening and debonded surface morphology after shear bond strength test were done by SEM. The results were as follows; 1. Shear bond strengths for specimens roughened with #120 SiC paper matching with the particle size of coarse diamond bur were significantly higher than those for the specimens with #400 SiC paper(P<0.05). By SEM, the surface of the specimens roughened with #120 SiC paper was more irregular than the specimens with #400 SiC paper. 2. Shear bond strengths for specimens treated with 32% $H_3PO_4$ etchant, primer, bonding resin were significantly higher than those for specimens treated with 32% $H_3PO_4$ and bonding resin(P<0.05). 3. Shear bond strengths for the specimens treated with 32% $H_3PO_4$ etchant and bonding resin were significantly higher than those for specimens treated with only bonding resin(P<0.05). There was no remarkable change of surface morphology after 32% $H_3PO_4$ etching. 4. It was possible to observe mixed fracture patterns (the cohesive fracture of old composite and the adhesive fracture between old and new composite) in the specimens roughened with #120 SiC paper, but almost adhesive fracture in the specimens roughened with #400 SiC paper.

• Restorative Dentistry and Endodontics
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• 제22권1호
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• pp.267-277
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• 1997

The purpose of this study was to evaluate the shear bond strength of light-cured glass ionomer cements to dentin surface according to curing time induced by argon laser. In this study, 160 extracted human molars with sound crown were used. The dentin surface of these teeth were exposed with high speed diamond bur under water spray and polished with 120, 320, 400, 800, 1200 grits sand paper. 160 extracted human molars were randomly assigned into four groups (control, experimental 1, 2 & 3) with 40 teeth each. Control group used a visible light curing unit, XL 1000(3M Co., U.S.A) and experimental groups used argon laser($SPECTRUM^{TM}$). And then each group subdivided into two groups (A, B) according to filling materials. Subdivided A group used Fuji II LC(GC Co., Japan), B group used Vitremer(3M Co., U.S.A). The curing units and curing time of each group were as follows : Control group : visible light, 40 seconds Experimental group 1 Experimental group 2 Experimental group 3 : argon laser, 10 seconds : argon laser, 20 seconds : argon laser, 30 seconds The glass ionomer cements were bonded to dentin surface of each specimen. The specimens were stored in 100% relative humidity at 37"c for 7days. And then, the shear bond strength were measured by universal testing machine(Shimatzu Co. Japan) at crosshead speed of 5mm/min and 100kg in full scale and analyzed statistically. The following results were obtained : 1. Experimental group 2-A showed the highest shear bond strength with $9.87{\pm}1.24$ kgf and control group B showed the lowest shear bond strength with $4.08{\pm}0.78$ kgf(P<0.01). 2. The Fuji II LC showed higher shear bond strength with $9.49{\pm}1.24$ kgf than that of the Vitremer with $4.23{\pm}1.24$ kgf. There was significant difference between Fuji II LC and Vitremer(p<0.01). 3. There was no significant differences among experimental groups according to curing time induced by argon laser. 4. There was no significant differences between control group and experimental groups according to curing units.

• Restorative Dentistry and Endodontics
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• 제22권1호
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• pp.479-489
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• 1997

The purpose of this study was to evaluate the effect of the Nd : YAG laser on the tooth hypersensitivity by the observation of the morphological changes of the dentinal surface irradiated with Nd : YAG laser by use of SEM. In 40 mandibular and maxillary molars without any carious lesion or restoration, severe attrition and abrasion, Enamel was removed with fine grit diamond bur and exposed dentinal surfaces were polished with Soflex discs. In control group (10 teeth), exposed dentinal surfaces were acid-etched with 10 % Maleic acid for 15 seconds. In the experimental group 1 (10 teeth), acid-etched dentinal surfaces with 10% Maleic acid were prepared by Nd : YAG laser (6 watts power, 1 psi water, 18 psi air) for 2 minutes. In the experimental group 2 (10 teeth), exposed dentinal surfaces were irradiated with Nd: YAG laser (10 watts power, 3 psi water, 10 psi air) until the painted black stains on the dentinal surfaces were completely removed. In the experimental group 3 (10 teeth). dentinal surfaces were prepared with Nd : YAG laser (6 watts power, 1 psi water, 18 psi air) until the painted black stanins on them were completely removed and then the irradiated dentinal surfaces were acid-etched with 10 % Maleic acid for 15 seconds. The specimens were routinely processed and observed with scanning electron microscope. The results were as follows : 1. In the irradiated dentinal surfaces, the characteristics of the melting and recrystalization on the dentinal surfaces were observed. Compared with the results in the control group, we could observe that in the irradiated dentinal surfaces, the aperture of the dentinal tubules were reduced and there were more debris obstructing the dentinal tubules. 2. In the irradiated dentinal surfaces, crater structures were commonly present and in the crater bottoms, there were a lot of bead like melted dentin structures, which had the ruptured opening in the center of them. 3. The melted dentins and cracks in the smear layer were less frequently observed in the irradiated dentinal surfaces using copious cooling water than in the irradiated dentinal surfaces using scare cooling water.

• 대한치과의사협회지
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• 제48권6호
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• pp.469-477
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• 2010

The purpose of this study was to evaluate the effect of two dentin desensitizers and Er,Cr:YSGG laser for dentinal tubule occlusion. Twenty recently extracted single-rooted human teeth were used to obtain root dentinal fragments. The crowns were cut approximately 1mm below the cementum enamel junction(CEJ). A second cut was used to remove the apex of the root. Subsequently, a longitudinal cut was made in order to obtain 2 fragments from each root sample. The cementum from the cervical portion was removed using a high-speed diamond-coated bur in order to expose the dentin. To open dentinal tubules, forty samples were treated with 50% citric acid for 2 min and then rinsed under distilled water for 1 min. These were divided into four groups of ten samples each. The first group served as a control group. In group 2, the samples were irradiated with the Er,Cr:YSGG laser(Waterlase MD, Biolase, USA). In group 3, the samples were treated with Bisblock and ONE-STEP PLUS(Bisco, USA). In group 4, the samples were treated with Gluma comfort bond & Desensitizer(Heraeus Kulzer, Germany). All the samples were examined using Scanning electron microscopy(Hitachi, S-4700, Japan) with two different magnifications(X2000, X5000). These images were assessed by one examiner who was blind to the experimental procedure, using the index of smear layer removal. The distribution of smear layer removal grades was tested using Fisher's exact test. On the order hand, in order to evaluate the occluding effect of two dentin desensitizers and Er,Cr:YSGG laser, the number of exposed dentinal tubules was counted in each group. These were evaluated using the Kruskal-Wallis test with significance predetermined $\alpha$=0.05. There were statistically significant differences between the three groups(Er,Cr:YSGG laser, Bisblock+ONE-STEP PLUS, Gluma comfort bond & Desensitizer) and control group.

• Restorative Dentistry and Endodontics
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• 제26권1호
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• pp.16-22
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• 2001

The purpose of this study was to evaluate the marginal microleakage of condensable composite resin restorations according to flowable resin lining of internal cavity wall. The eighty extracted human molar teeth without caries and/or restorations are used The experimental teeth were randomly assigned into four groups of ten teeth each. Eighty caries-free extracted human molars were used in this study. The conventional class II cavities (box-shaped on mesial and distal surface, faciolingual width : 3mm, gingival wall depth : 1.5mm) were prepared 1mm below cementoenamel junction with a # 701 carbide bur. The teeth were divided into four groups, and then each group were subdivided into A & B group according to flowable resin & compomer lining ; Group 1-A : Tetric Ceram filling, Group 1-B : Tetric Flow lining and Tetric Ceram filling, Group 2-A Ariston pHc filling, Group 2-B : Tetric Flow lining and Ariston pHc filing, Group 3-A SureFil filling, Group 3-B : Dyract Flow lining and SureFil filling, Group 4-A : Pyramid filling, Group 4-B : Aeliteflo lining and Pyramid filling. To simulate as closely as possible the clinical situation during retoration placement, a "restoration template" was fabricated, and the condensable resin was filled using a three-sited light-curing incremental technique. All the materials used were applied according to the manufacturers' instructions. The specimens were stored in the 100% humidity for 7 days prior to thermocycling (100 thermal cycles of 5~55$^{\circ}C$ water with a 30-second dwell time) The specimens were immersed in 2% metyleneblue dye for 24 hours, and then embedded in transparent acrylic resin and sectioned mesiodistally with diamond wheel saw. The degree of marginal leakage was scored under stereomicroscope ($\times$20) and the data were analyzed by Kruskal-Wallis test and Wilcoxon signed ranks test. The results were as follows : 1. In the gingival margins of all the group, microleakage of subgroup B was less than subgroup A. 2. In the group 1, 2, 4, there was significant differences between subgroup A and B (p<0.05), but in the group 3, there was not significant different between group 3-A (SureFil) and group 3-B (Dyract flow/SureFil) (p>0.05). 3. In the subgroup A and B, there was significant different between all group except group 4 of subgroup A. From the results above, it was suggested that the cavity lining of flowable resin and flowable compomer in condensable resin restoration decrease microleakage at gingival margin, and does improve their ability to seal the gingival margin of class II preparation.

• Restorative Dentistry and Endodontics
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• 제26권4호
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• pp.263-272
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• 2001

저광도 중합법, 펄스 지연 중합법, 초고광도 중합법 등의 광조사 방식이 광중합형 복합레진 수복물에서의 중합수축 응력에 미치는 영향을 알아보기 위해 in vitro에서 미세 누출 실험을 하였다. 80개의 발거된 소구치의 협측면에 5급 와동을 형성하고, 600mW/$cm^2$로 30초간 광조사하는 보통 광도 중합군, 300mW/$cm^2$로 60초간 광조사하는 저광도 중합군, 400mW/$cm^2$로 2초간 광조사하고 5분간 기다린 후 800mW/$cm^2$로 10초간 최종 중합시키는 펄스-지연 중합군, 그리고 1930mW/$cm^2$의 광도로 3초간 광조사하는 초고광도 중합군 등의 4개의 군으로 나누어 hybrid 형의 광중합복합레진을 충전하고 각 군의 방법대로 중합한 후, 변연의 0.5mm 외부에 nail varnish를 도포하고 37$^{\circ}C$, 2% metylene blue 용액에 24시간 동안 침적시켰다. 시편을 아크릴릭 레진에 매몰한 후 수복물의 중앙에서 종절단하여 입체현미경하에서 그 단면을 관찰한 후 법랑질과 상아질 변연으로 나누어 색소의 침투도를 측정하여 다음과 같은 결과를 얻었다. 1. 펄스 지연 중합군의 색소 침투도는 법랑질과 상아질 변연 모두에서 보통광도, 저광도 및 초고광도 중합군과 유의한 차이를 보이지 않았다(p>0.05). 2. 상아질 변연에서 초고광도 중합군은 보통광도 중합군과 저광도 중합군에 비해 유의하게 높은 색소 침투도를 보였다(p<0.05). 3. 법랑질 변연에서의 4개 군의 색소 침투도는 서로 유의한 차이를 보이지 않았다(p>0.05). 4. 모든 군에서 상아질 변연에서의 색소 침투도는 법랑질군에서의 색소 침투도에 비해 유의하게 높았다(p<0.05).