• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.4
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• pp.498-508
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• 2002

The purpose of this study was to compare the amount of fluoride release and remineralizing effect of compomer with those of glass ionomer cement and composite resin. Composite resin($Z-100^{(R)}$) was used for negative control group(Group I), glass ionomer(Fuji II $LC^{(R)}$) for positive control group(Group IV), compomer(Dyract $AP^{(R)}$ and $F-2000^{(R)}$) for experimental group(Group II and Group III). The results obtained can be summarized as follows : 1. Glass ionomer showed the higher amount of fluoride release than compomer groups. Composite resin showed no fluoride release during test period. 2. Significant evidence of remineralization could be noticed in samples of all groups. The highest degree of remineralization was observed in glass ionomer group followed by compomer group. The least evidence of remineralization was observed in composite resin group. 3. Microhardness values of carious site was lower than control site, but Microhardness values of caries site at form away from filling materials in group II, III, IV was significantly higher than the other area. Based on the above results, compomer could be considered as one of the very attractive restorative materials in the field of pediatric dentistry.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.4
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• pp.529-538
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• 2002

There is no adverse opinion on the anticariogenic effect of fluoride, so glass ionomer restoration which release the fluoride is recommended fer child patient. To study the anticariogenic effect of initial carious lesion of fluoride released from adjacent glass ionomer restoration, the in situ model was constructed. A microhardness test, polarized scope investigation and electron probe microanalysis was done for analyzing the distribution of fluoride which was precipitated from glass ionomer restoration to the enamel caries lesion. Fuji IX, the conventional glass ionomer, was used for experimental group and Z-100, composite resin that fluoride was not contained, was used for control group. On the microhardness test, the remineralization was accelerated by fluoride. And on the polarized investigation, the size of caries lesion was reduced in the oral cavity and that phenomenon was accelerated by fluoride, too. Electron probe microanalysis shows that the remineralization was accelerated by fluoride and the fluoride concentration on subsurface area was increased. It maybe that the subsurface area was critical to anticariogenic effect. In summary of these result, initial caries lesion can be remineralized in the oral cavity and that phenomenon can be accelerated by fluoride. The subsurface area of caries lesion was a major part of defense to cariogenic invasion and to conserve the subsurface area, the surface of lesion body have to conserved.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.3
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• pp.168-176
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• 2013

The aim of this study was to evaluate the acid neutralizing capacity and to observe surface changes of giomer in comparison with composite resin, when it comes in contact with an acidic solution. A packable giomer(Beautifil II) and a flowable giomer(Beautifil Flow F02) were used as experimental groups, while a packable composite resin($Filtek^{TM}$ Z-250) was used as control group. pH values were measured after mixing the specimens of the disc and powder types with a pH 2.0 hydrochloric acid solution, respectively. Also, in the case of powder type giomers used in the earlier experiment, their pH values were measured again after mixing them with a fresh acid solution. Moreover, surface structure changes of disc type specimens were observed by using a scanning electron microscopy(SEM). In the disc type test, the pH values of packable giomer were significantly increased after 24 hours(p < 0.05). In contrast, in the powder type test, the pH values of packable and flowable giomers were dramatically increased within 30 minutes. The pH value of packable giomer, in particular, was higer than that of flowable giomer(p < 0.05). In the repeated neutralizing test, the degree of pH variation was lower than that of the previous neutralizing test(p < 0.05). Erosive changes on the surface of packable giomer were observed to be more than those on composite resin and flowable giomer as well. In conclusion, giomer has a acid neutralizing capacity, when it comes in contact with an acidic solution. Especially, packable giomer with high filler content has a greater acid neutralizing capacity than flowable giomer.

• Restorative Dentistry and Endodontics
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• v.35 no.3
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• pp.180-187
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• 2010

Since the introduction of restorative dental composites, their physical properties have been significantly improved. However, polymerization shrinkage is still a major drawback. Many efforts have been made to develop a low shrinking composite, and silorane-based composites have recently been introduced into the market. In addition, many different methods have been developed to measure the polymerization shrinkage. In this study, we developed a new method to measure the linear polymerization shrinkage of composites without direct contact to a specimen using a particle tracking method with computer vision. The shrinkage kinetics of a commercial silorane-based composite (P90) and two conventional methacrylate-based composites (Z250 and Z350) were investigated and compared. The results were as follows: 1. The linear shrinkage of composites was 0.33-1.41%. Shrinkage was lowest for the silorane-based (P90) composite, and highest for the flowable Z350 composite. 2. The new instrument was able to measure the true linear shrinkage of composites in real time without sensitivity to the specimen preparation and geometry.

• 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.

• Restorative Dentistry and Endodontics
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• v.31 no.5
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• pp.337-343
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• 2006

The purpose of this study was to estimate the relation between techniques used for microleakage from dye penetration and for marginal adaptation from SEM evaluation of the restoration. Using high speed #330 bur class V cavities ($4{\times}3{\times}1.5 mm$ around CEJ) were prepared on the buccal surface of 20 extracted human molars. Six dimples as reference points for SEM and dye penetration evaluation were made with 1/2 round bur. Cavity was bulk filled with microhybrid composite resin (Esthet X) and all-in-one adhesive (Xeno III). Teeth were stored in saline solution for one day, after then, they were finished and polished using Sof-Lex system. Fifty percent silver nitrate dye solution was used for the evaluation of microleakage and resin replica was used for marginal adaptation. All of these were done after 1000 times thermocycling between 5 and $55^{\circ}C$. Vertical sections were made through three dimples of restoration to obtain samples for the evaluation of dye penetration and inner marginal adaptation. Outer adaptational estimation was done with an intact restoration before sectioning. Dye penetration was determined in three degrees and percentage of outer and inner leaky margin was estimated from SEM image The data were analysed statistically: Spearman's rho test were used to check relationships between two methods. The result were as follows : 1. There were significant relationships between degree of dye penetration and inner and outer marginal adaptations each (p < 0.01). 2. However, there was no significant relationship between the results or inner and outer marginal adaptation. Within the results of this study, relationship between the percentage of marginal adaptation and microleakage shows significant relationship. However, inner and outer marginal adaptation did not show any significant relationship mutually.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.1
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• pp.19-29
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• 2002

The purpose of this study was to compare the polymerization shrinkage and the compressive strength of composite and compomer cured with two different light sources ; conventional halogen-light curing unit and recently-developed plasma arc curing unit. The 'strain gauge method' was used for determination of polymerization shrinkage and the compressive strength was measured by universal testing machine. The results of the present study can be summarized as follows: 1. Filling materials in polyethylene molds showed the initial expansion in the early phase of polymerization. This was followed by the rapid contraction in volume during the first 60 seconds and gradually diminished as curing process continued. 2. The polymerization shrinkage in tooth samples was generally lower than in the mold samples. 3. The generally lower amount of linear polymerization shrinkage was observed in compomer and plasma arc curing unit group when compared to composite and conventional curing unit. 4. The higher compressive strength values was found in composite groups regardless curing methods. The results of this study strongly support the application of plasma arc system and fluoride-containing compomer in the field of clinical pediatric dentistry claiming its effectiveness in curing the esthetic dental materials and the anticariogenic capacity.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.1
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• pp.1-10
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• 2002

The purpose of this study was to evaluate the fluoride release and anticariogenic effect of two compomers which is known to have been developed to improve the weak properties of glass ionomer cement and composite resin. Z-100 as composite resin(Group I), Dyract AP(Group II) and F-2000(Group III) as compomer, and Fuji II LC as glass ionomer cement(Group IV) were used as test materials and evaluations were peformed by pH/ISE meter far analyses of fluoride and polarizing microscope for analyses of anticariogenicity. The results can be summarized as follows: 1. The amount of fluoride release in compoite resin and compomer groups showed general pattern of decline during test period. Z-100 showed no fluoride release during test period. Fuji II LC showed the highest fluoride release among test groups and then F-2000 were followed. 2. The least resistance to dimineralization was observed microscopically in Z-100 group which has no fluoride in it. The best resistance to dimineralization was observed microscopically in Fuji II LC group and then compomer groups were followed. 3. Significant difference in lesion area was found between Fuji II LC group and another groups. Significant difference in lesion area was found between compomer groups and Z-100 group. No significant difference in lesion area was found between Dyract AP group and F-2000 cup. 4. Two compomers showed continual fluoride release and anticariogenic effect around filling materials. therefore, compomer was evaluated very attractive restorative material in pediatric dentistry.

• Journal of Adhesion and Interface
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• v.17 no.2
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• pp.49-55
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• 2016

In this study, we designed an environment friendly, water-based adhesive using the acrylic emulsion method as a replacement for solvent-based adhesives, which are most commonly used in layered laminates for flexible food packaging. We designed adhesives with different combinations of anionic, non-ionic, and phosphoric ester surfactants, and with different concentrations of chain transfer agent (CTA). We also examined the effect of the degree of cross-linking by synthesizing and comparing 8 test group adhesives with different types of functional monomers. Additionally, we synthesized 2 other test group pressure-sensitive adhesives (PSA) using styrene/alpha-methyl styrene/acrylic acid (SAA) semipolymer dispersing agents (with molecular weights of 13,000 g/mol and 8,600 g/mol, respectively) to replace the conventional surfactants. We evaluated whether the 10 test group pressure-sensitive adhesives met the basic physical property criteria required for flexible food packaging by carrying out a physical analysis of their glass transition temperature (Tg), particle size, adhesion, and molecular weight. In our test, 2 test group adhesives manufactured with the combination of anionic and non-ionic surfactants, CTA concentration of 0.2%, and functional monomers of hydroxyethyl acrylate (HEA) and glycidyl methacrylate (GMA) demonstrated molecular weight and flexibility suitable for flexible packaging, with low adhesiveness and small particle size.

• Journal of Korean Home Economics Education Association
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• v.21 no.1
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• pp.35-49
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• 2009

The purpose of this study was to examine the effect of instruction for the development of analytical rubrics based on teacher-student compromise, which would be applied to performance assessment about the ninth-grade housing unit of the 7th national curriculum. In order to find out the influence of the rubric development instruction on learning motivation, two different third-year classes in a middle school were selected respectively as an experimental group and a control group. The way of presenting the rubrics and learning motivation were respectively selected as independent and dependent variables. Both groups took two lessons and a pretest-posttest on learning motivation. As for the analytic rubric for the individual task performance in the housing unit, three evaluation items were selected. As a result, the instruction for the learner-involved development of analytical rubrics for the housing segment had a positive effect on the confidence and satisfaction of the middle schoolers, which were two out of four sub-factors of learning motivation. Open-ended questions showed that the instruction got to build confidence in the course of being aware of the evaluation criteria and fulfilling the given tasks.