• Restorative Dentistry and Endodontics
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• v.32 no.1
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• pp.9-18
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• 2007

The purposes of this study were to examine the variability of adhesive thickness on the different site of the cavity wall when used total-etch system without filler and simplified self-etch system with filler and to evaluate the relationship between variable adhesive thickness and microtensile bond strength to the cavity wall. A class I cavity in six human molars was prepared to expose all dentinal walls. Three teeth were bonded with a filled adhesive, $Clearfil^{TM}$ SE bond ana the other three teeth were bonded with unfilled adhesives, $Scotchbond^{TM}$ Multi Purpose. Morphology and thickness of adhesive layer were examined using fluorescence microscope. Bonding agent thickness was measured at three points along the axial cavity wall edge of cavity margin (rim). halfway down each cavity wall (h1f), internal angle of the cavity (ang). After reproducing the adhesive thickness at rim, h1f and ang, micro-tensile bond strength were evaluated. For both bonding agents, adhesive thickness of ang was significantly thicker than that of rim and h1f (P <0.05). As reproduced the adhesive thickness, microtensile bond strength was increased as adhesive thickness was increased in two bonding agents. Adhesive thickness of internal angle of the cavity was significantly thicker than that of the cavity margin and the halfway cavity wall for both bonding agents. Microtensile bond strength of the thick adhesive layer at the internal angle of the cavity was higher than that of the thin adhesive layer at 1,he cavity margin and the halfway cavity in the two bonding systems.

• Restorative Dentistry and Endodontics
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• v.32 no.5
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• pp.469-475
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• 2007

The purpose of this study was to evaluate the effect of a new resin monomer on the microleakage of composite resin restorations. By adding new methoxylated Bis-GMA (Bis-M-GMA, 2,2-bis[4-(2-methoxy-3-methacryloyloxy propoxy) phenyl] propane) having low viscosity, the content of TEGDMA which has adverse effects on polymerization shrinkage might be decreased. As a result, microleakage might be improved. $2\;mm\;{\times}\;2\;mm\;{\times}\;2\;mm$ cavities with occlusal margins in enamel and gingival margins in dentin were prepared on buccal and lingual surfaces of 40 extracted human premolars. Prepared teeth were randomly divided into four groups and restored with Clearfil SE bond (Kuraray, Japan) and one of experimental composite resins; EX1, Experimental composite resin1 (Bis-M-GMA/TEGDMA = 95/5 wt%, 40 mm nanofillers); EX2, Experimental composite resin2 (Bis-M-GMA/TEGDMA = 95/5 wt%, 20 mm nanofillers); EX3, Experimental composite resin3 (Bis-GMA/TEGDMA = 70/30 wt%, 40 nm nanofillers); and Filtek Z250 (3M ESPE, USA) was filed as a control group. The restored teeth were thermocycled, and immersed in 2% methylene blue solution for 24 hours. The teeth were sectioned buccolingually with a low speed diamond saw and evaluated for microleakage under stereomicroscope. The data were statistically analyzed by Pearson Chi-Square test and Fisher Exact test (p = 0.05). The microleakage scores seen at the enamel margin were significantly lower than those of dentin margin (p = 0.007). There were no significant differences among the composite resins in the microleakage scores within each margin (p > 0.05). Bis-M-GMA, a new resin monomer having low viscosity, might in part replace high viscous Bis-CMA and might improve the quality of composite resin.

• Restorative Dentistry and Endodontics
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• v.32 no.3
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• pp.198-207
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• 2007

The purpose of this study was to investigate the effect of calcium hydroxide on dentin bonding strength of various dentin bonding systems as a function of time in composite resin restoration. Dentin adhesives used in this study were Scotchbond Multipurpose, Single Bond, SE Bond and Prompt L-Pop. Flat dentin surfaces adjacent to pulp chamber were created, then $Ca(OH)_2$ and saline were mixed and applied on dentin surface of experimental group, then IRM was used to cover the mixture on dentin surface and the specimens were stored at $36.5^{\circ}C$ for experiment period (7 days, 30 days). After removing IRM and $Ca(OH)_2$, each dentin adhesives were treated on dentin surfaces. Composite resin (Z-250, 3M) was placed with S mm height and was light-cured for 20 seconds. After stored in distilled water for 24 hours, each dentin-composite bonded spicemen was embedded in epoxy resin and sectioned into $1.0\times1.0mm^2$ cross section composite-dentin beams. Specimen was mounted on zig of Universal testing machine and ${\mu}TBS$ test was performed. SEM analysis was performed to examine the fractured surfaces. The results suggested that applying calcium hydroxide did not show significant difference in dentin bonding strength.

• Restorative Dentistry and Endodontics
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• v.27 no.2
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• pp.158-174
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• 2002

The aim of this study was to investigate the effect of light irradiation modes on polymerization shrinkage, degree of cure and microleakage of a composite resin. VIP$^{TM}$ (Bisco Dental Products, Schaumburg, IL, USA) and Optilux 501$^{TM}$ (Demetron/Kerr, Danbury, CT, USA) were used for curing Filtek$^{TM}$ Z-250 (3M Dental Products, St. Paul., MN, USA) composite resin using following irradiation modes: VIP$^{TM}$ (Bisco) 200mW/$\textrm{cm}^2$ (V2), 400mW/$\textrm{cm}^2$ (V4), 600mW/$\textrm{cm}^2$ (V6), Pulse-delay (200 mW/$\textrm{cm}^2$ 3 seconds, 5 minutes wait, 600mW/$\textrm{cm}^2$ 30seconds, VPD) and Optilux 501$^{TM}$ (Demetron/Kerr) C-mode (OC), R-mode (OR). Linear polymerization shrinkage of the composite specimens were measured using Linometer (R&B, Daejeon, Korea) for 90 seconds for V2, V4, V6, OC, OR groups and for up to 363 seconds for VPD group (n=10, each). Degree of conversion was measured using FTIR spectrometer (IFS 120 HR, Bruker Karlsruhe, Germany) at the bottom surface of 2 mm thick composite specimens V2, Y4, V6, OC groups were measured separately at five irradiation times (5, 10, 20, 40, 60 seconds) and OR, VPD groups were measured in the above mentioned irradiation modes (n=5 each). Microhardness was measured using Digital microhardness tester (FM7, Future-Tech Co., Tokyo, Japan) at the top and bottom surfaces of 2mm thick composite specimens after exposure to the same irradiation modes as the test of degree of conversion(n=3, each). For the microleakage test, class V cavities were prepared on the distal surface of the ninety extracted human third molars. The cavities were restored with one of the following irradiation modes : V2/60 seconds, V4/40 seconds, V6/30 seconds, VPD , OC and OR. Microleakage was assessed by dye penetration along enamel and dentin margins of cavities. Mean polymerization shrinkage, mean degree of conversion and mean microhardness values for all groups at each time were analyzed using one-way ANOVA and Duncan's multiple range test, and using chi-square test far microleakage values. The results were as follows : . Polymerization shrinkage was increased with higher light intensity in groups using VIP$^{TM}$ (Bisco) : the highest with 600mW/$\textrm{cm}^2$, followed by Pulse-delay, 400mW/$\textrm{cm}^2$ and 200mW/$\textrm{cm}^2$ groups, The degree of polymerization shrinkage was higher with Continuous mode than with Ramp mode in groups using Optilux 501$^{TM}$ (Demetron/Kerr). . Degree of conversion and microhardness values were higher with higher light intensity. The final degree of conversion was in the range of 44.7 to 54.98% and the final microhardness value in the range of 34.10 to 56.30. . Microleakage was greater in dentin margin than in enamel margin. Higher light intensity showed more microleakage in dentin margin in groups using VIP$^{TM}$ (Bisco). The microleakage was the lowest with Continuous mode in enamel margin and with Ramp mode in dentin margin when Optilux 501$^{TM}$ (Demetron/Kerr) was used.

• Restorative Dentistry and Endodontics
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• v.27 no.5
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• pp.479-487
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• 2002

복합레진의 중합시 발생하는 수축과 응력은 와동의 형태에 의하여 영향을 받으며 이는 수복재는 물론 접착계면의 물성을 결정하는 요인이 된다. 본 연구는 다양한 C-factor를 갖는 와동에 상아질 접착제 Clearfil SE Bond(Kuraray)를 도포하고 혼합형 복합레진인 Clearfil AP-X(Kuraray)와 미세혼합형의 Esthet-X(Dentsply)를 충전하여 미세인장강도 및 변연누출을 측정 평가함으로써 중합수축이 수복물과 치아계면에 미치는 영향을 평가하고자 시행하였다. 98개의 Bovine 하악전치를 이용하여 표면의 상아질을 #600 SiC paper로 연마한 대조군 및 와동의 넓이를 조절하여 C-factor 2.3, 3.0, 3.7이 되도록 제작한 실험군 와동에 복합레진을 충전한 후 37의 증류수에 24시간 보관하였다. 저속 diamond saw(Buehler)를 이용하여 1mm 두께로 수직절단 후 고속 diamond point(#104 Shofu)를 이용하여 단면적 1mm$^2$가 되도록 hour-glass모양으로 형성하여 시편을 제작하였고, Universal testing machine(EZ-Test; Shimadzu, Japan)에 시편을 부착하고 cross head speed 1mm/min으로 인장력을 가하여 미세인장 결합강도를 측정하였다. 각 C-factor에 따른 변연누출실험을 위하여 복합레진이 수복된 치아를 37$^{\circ}C$의 증류수에 24시간 보관한 후 와동을 제외한 부위에 nail varnish를 도포하고 3mol/L silver nitrate용액에 24시간 암보관한 다음 수세하여 현상액에 24시간 경과시킨 후 치아의 장축에 따라 절단하여 침투된 색소의 정도를 광학현미경상에서 40배로 관찰하였다. 각각의 실험결과는 ANOVA/Tukey's test 및 Kruskal-Wallis non-parametric independent analysis와 Mann-Whitney U test에 의하여 통계 분석하여 다음과 같은 결론을 얻었다. 1. 대조군에 있어서 혼합형 복합레진의 미세인장 결합강도는 미세혼합형에 비하여 높았으며, 실험군 사이에는 유의차를 보이지 않았다. 2.모든 복합레진의 미세인장 결합강도는 와동의 C-factor증가에 따라 감소하는 경향을 나타내었고, 혼합형 복합레진의 실험군은 대조군에 비하여 낮게 나타났으며, 미세혼합형 복합레진에서는 유의차를 보이지 않았다. 3. 절단측 및 치은측 변연부의 미세누출정도는 혼합형 복합레진이 미세혼합형에 비하여 대체로 높게 나타났다. 4. 모든 실험군에서 미세누출은 C-factor증가에 따라 증가하였고 절단측에 비하여 치은측 변연이 높게 나타났으나 통계학적 유의차는 보이지 않았다. C-factor의 변화에 대하여 필러함량과 탄성계수가 높은 혼합형 복합레진이 미세혼합형에 비하여 더 민감한 결과를 보인다. 이는 복합레진 수복시 재료의 선택과 중합수축의 적절한 조절이 중요한 요소임을 시사한다.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.3
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• pp.456-468
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• 2008

This study was performed to evaluate the quality of newly offered dentin bonding system($AdheSE^{(R)}$ One) by comparing the degree of microleakage measured with those of several conventional adhesive materials(AQ Bond Plus and $Adper^{TM}$ Single Bond 2). The quality of hybrid layer and resin tags was analyzed by observing restoration/ tooth interface under SEM. All-in-one system is in the limelight for having advantage of reducing chair time of children with difficult behavior pattern. Therefore the possibility of clinical application of All-in-one system was evaluated. The results obtained are as follows; 1. At the enamel margin, group II(AQ Bond Plus) showed the highest value of microleakage, and the other groups showed decreased value in order of group III($AdheSE^{(R)}$ One) and I($Adper^{TM}$ Single Bond 2). There was statistically significant difference between group II and the others(p<0.05), and no statistical difference was found between group I and III. 2. At the dentin margin, microleakage value was increased in order of group II, I, III and significant difference between all groups(p<0.05). 3. In group I and III, microleakage value measured at the enamel margin was significantly lower than that seen at the dentin margin(p<0.05), and there was no statistical difference in group II. 4. Resin tags observed under SEM were very weak and tangled in group II and III while the strong and thick tags were observed in group I. In conclusion, careful case selection and accurate clinical application is recommended in using AQ Bond Plus and $AdheSE^{(R)}$ One, giving consideration of the results showing its higher microleakage and weaker strength than $Adper^{TM}$ Single Bond 2.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.3
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• pp.479-485
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• 1999

Materials for posterior teeth includes amalgam, gold inlay and composite resin inlay. Amalgam and gold inlay have unsatisfyine esthetics. And because they simply obturate the cavity preparation, they do not strengthen the remaining tooth structure. Posterior composite resin has become established in recent years. However, its polymerization shrinkage and insufficient wear resistance were the most undesirable characteristic. The physical and mechanical properties of the composite resin inlay are further improved through heat treatment in an oven. The major part of polymerization contraction of the resin inlay takes place be fore cementation, and possible gap formation is only due to shrinkage of the thin layer of resin cement. With the semidirect technique, the inlay material is placed directly in the prepared tooth, and the primary polymerization is made by light activation with a handhold curing unit. Additional curing may take place extraorally with use of different curing ovens. It provides the patient with the benefits of luted restorations without the procedure of indirect lab-made inlay. I report three successfully treated cases by semidirect resin inlay technique. Entire clinical steps are described in detail with some discussions on the outcome.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.1
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• pp.30-37
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• 2002

Bacterial microleakage around restorations is considered the principal cause of pulpal inflammation associated with restorations. The rationale for using cavity disinfectant is based on its antimicrobial properties but the cavity disinfectant may leave debris on dentin surfaces. The purpose of this study was to evaluate the effect of 2% chlorhexidine on shear bond strength and microleakage of adhesive restoration. 45 sound bovine teeth were used for the shear bond strength test and 30 for the micorleakage. For the experimental groups, 2% chlorhexidine was applied before the restorations, and was not for the control groups. The result from the this study can be summarized as follows; 1. No significant difference could be found in shear bond strength of each group. 2. No significant difference could be found in microleakage of each group.

• Restorative Dentistry and Endodontics
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• v.14 no.2
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• pp.20-29
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• 1989

The purpose of the study is to evaluate the degree of the marginal leakage of class V cavities with 4 brands of esthetic filling materials by means of the dye penetration at the enamel & dentinal margins. 160 cavities of class V were prepared on the buccal & lingual surfaces of 80 extracted premolar teeth, which divided into 4 groups. The four groups of cavities were filled with Durafill$^{(R)}$-Durafill bond$^{(R)}$(KuIzer & Co GmbH), Bisfil M$^{(R)}$-Resin bond$^{(R)}$(BISCO Inc.), Silux$^{(R)}$-Scotchbond$^{(R)}$(3M Co.) and Fuji ionomer$^{(R)}$(type II, G-C Co.) each. All specimens were immersed in 2% methylene blue dye solution for 24 hours at $37^{\circ}C$ after a 30-second thermocycling at $4^{\circ}C$ and $60^{\circ}C$ and longitudinally sectioned with diamond disk into two parts. The results were as follows : 1. At enamel margins, the group filled with Durafill$^{(R)}$-Durafill bond$^{(R)}$, Bisfil M$^{(R)}$-Resin bond$^{(R)}$ and Silux$^{(R)}$-Scotchbond$^{(R)}$ show no significant difference each other(p>0.05), and the above groups show less marginal leakage comparing with the group filled with Fuji ionomer$^{(R)}$(p<0.01). 2. At dentinal margins, the group filled with Silux$^{(R)}$-Scotchbond$^{(R)}$ or Fuji ionomer$^{(R)}$ show less marginal leakage than that with Durafill$^{(R)}$-Durafill bond$^{(R)}$ or Bisfil M$^{(R)}$-Resin bond$^{(R)}$(p<0.01). 3. The enamel margins show less marginal leakage than dentinal margins in all the class V cavities(p<0.01).

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.1
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• pp.32-44
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• 2001

The purpose of this study was to investigate the effects of Er : YAG laser on cutting efficacy and temperature changes of dentin. We used the dentin specimens of human premolars and molars which contain the physiologic saline and maintain the pulpal pressure in dentinal tubules. Each specimen was exposed to Er : YAG laser with non-contact handpiece type delivery system under different treatment condition of irradiation energy, pulse repetition rate, and exposure time. Two procedures were conducted by the presence of water flow during lasing. The specimens were grouped by thickness of dentin. We investigated the cavity pattern, volume, and temperature change of dentin specimen to determine the cutting efficacy and temperature rise of Er : YAG laser, and obtained following results. 1. Cutting volume of dentin was increased by increasing the irradiation energy, pulse repetition rate, and exposure time(P<0.05). 2. Margins of abulated cavities were sharp and clean and floors of cavities were conical in shape and showing smooth surfaces. Upper diameter of abulated cavities were increasing as laser parameter of irradiation energy, pulse repetition rate, and exposure time were increased. A few cracks were observed on abulated surfaces under treatment condition of laser parameter with 150mJ, 5Hz, and 5sec. 3. Temperature was increased as laser parameter of irradiation energy, pulse repetition rate, and exposure time were increased, and temperature rise was decreased as dentin thickness was increased(P<0.05). 4. Temperature rise was decreased under water flow compared with no water flow during laser exposure(P<0.05). From these results, we think that the method of using a Er:YAG laser would be effective and safe in cutting dentin for clinical application.