• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.3
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• pp.159-167
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• 2013

The aim of this study was to evaluate changes in demineralization resistance and bonding strength of light cured glass ionomer after the addition of nano hydroxyapatite in various ratios. Fuji II LC GIC (GC Co., Japan) was used as the control group and also as a base material for experimental group. HA was mixed into the RMGIC at various ratio to create a HA-LC GIC mixture, preparing six experimental groups, i.e. 5%, 10%, 15%, 20%, 25%, 30% HA-LC GIC. According to the results, the bonding strength increased due to the addition of HA, showing the maximum value at the 15% nano HA group (p < 0.05). Under CLSM observation after 4 days of demineralization, the HA groups were more resistant to demineralization compared to the control group. No significant difference was observed between HA groups. In analysis through SEM, the HA groups showed attachment of granular materials and decreased demineralized tooth surfaces under influence of HA particles.

• Restorative Dentistry and Endodontics
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• v.30 no.3
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• pp.204-214
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• 2005

This study compared the microtensile bond strength (${\mu}$TBS) and microscopic change of two 2-step and two 1-step self-etching adhesives to dentin according to storage times in distilled water. Occlusal dentin was exposed in 48 human molars. They were divided to four groups by different adhesives: SE Bond group (Clearfil SE Bond), AdheSE group (AdheSE). Adper group (Adper Prompt L-Pop), and Xeno group (Xeno III) . Each group was stored in 37$^{\circ}C$ distilled water for 1, 15, and 30 days. Resin-bonded specimens were sectioned into beams and subjected to ${\mu}$TBS testing with a crosshead speed of 1 mm/minute. For SEM observation, one specimen was selected and sectioned in each group after each stroage time. Resin-dentin interface was observed under FE-SEM. In all storage times, mean ${\mu}$TBS of SE group was significantly higher than those of other groups (p < 0.05). There was no significant difference between mean ${\mu}$TBS of SE group and AdheSE group among all storage times, but significant difference between 1- and 30-day storage in mean y${\mu}$TBS of Adper group and Xeno group (p > 0.05). For 1-and 15-day storage, all groups showed the close adaptation between resin-dentin interfaces. For 30-day storage, resin-dentin interfaces showed wide gap in Adper group and separate pattern in Xeno III group.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.174-181
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• 2009

Statement of problem: There is a reduction of dentin bonding strength when the bonding procedure is carried out immediately after bleaching with peroxides. Purpose: The aim of this study is to evaluate a proper time interval for in-office bleaching technique using 35% hydrogen peroxide. Material and methods: Fifty extracted non-caries human third molars were used in this study. Buccal enamel of each tooth was removed and polished by 600 grits silicone carbide paper. They were randomly divided into five groups and bleached 35% hydrogen peroxide except control group. All groups were bonded with Single Bond/Z 350 after each time intervals ; Group-A: control, no bleaching treatment. Group-B: resin bonding immediately after bleaching. Group-C: resin bonding 1day after bleaching. Group-D: resin bonding 2 days after bleaching. Group-E: resin bonding 7days after bleaching. Shear bond strengths were measured with a cross-head speed of 1.0 mm/min using an Instron machine. The data of results were statistically analyzed by analysis of variance(ANOVA) and Tukey multiple comparison test.(P=.05) Results: There were significant decreases in mean shear strength in immediately bonding group after bleaching. The reduction of bond strengths was 78% compared with the group of no bleaching treatment. Group C showed the recovery of 51%, and Group D showed recovery of 63%. Both of them have no statistical difference with non-bleaching group. Group E showed no statistical difference with no bleaching treatment group. Conclusion: Dentin bonding strength is significantly reduced when bonding is performed immediately after bleaching for in-office bleaching regimens using 35% hydrogen peroxide, and increases as time goes by. One week of elapsed time between bleaching and resin bonding significantly increases bonding strengths for the in-office bleaching technique.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.1
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• pp.69-79
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• 2013

The aim of this study was to evaluate the effect of surface conditioning on the shear bond strength of zirconium-oxide ceramic to resin cement. A total of 120 disk-shaped zirconium-oxide ceramic blocks(3-TZP, Kyoritsu, Tokyo, Japan) were treated as follows: (1) no treatment; (2) sandblasting with 110 ${\mu}m$ aluminum-oxide(Al2O3); (3) particles tribochemical silica coating(RocatecTM, 3M ESPE). Then zirconium-oxide ceramic blocks were divided into six groups(10 for each group) and bonded with resin cement(Rely X U-200, 3M ESPE). (1) No treatment / No treatment (2) No treatment / Sandblasting with 110 ${\mu}m$ aluminum-oxide particles (3) No treatment / Silica coating (4) Sandblasting with 110 ${\mu}m$ aluminum-oxide particles / Sandblasting with 110 ${\mu}m$ aluminum-oxide particles (5) Sandblasting with 110 ${\mu}m$ aluminum-oxide particles / Silica coating (6) Silica coating / Silica coating. Each group was tested in shear bond strengths by UTM. Data analysis included one-way analysis of variance(ANOVA) and the Tukey Honestly Significant Difference test (P=0.05). Group that bonded two silica coated specimen showed a highest bond strength(P<0.05). Two silica coated surface conditioning group and air-abrasion and silica coated surface conditioning group showed significantly difference with other groups(P<0.05). Other groups had no significantly difference each other. Within the limitation of this study, Surface conditioning with Rocatec treatment to each side of specimen provided the highest bond strength.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.3
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• pp.253-265
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• 2011

When restoring endodontically treated teeth is the mismatch between fiber post size and post space diameter, the resin cement layer is excessively thick in post space and voids are likely to form in it, thus predisposing to de-bonding. The method to overcome this problem is to reline the fiber post with composite resin. This individual anatomic post improves the adaptation of post to root walls and decreases the resin cement thickness. The purpose of this in vivo study was to evaluate the push-out bond strength of fiber post according to relining procedure and luting agents type used for simplicity of clinical procedure. Forty-two extracted teeth were divides into six groups.(n=7) A1: relined fiber post cemented with Luxacore/all-bons 2, A2: non-relined fiber post cemented with Luxacore/all-bond2, B1: relinind fiber post cemented with Calibra/XP-bond, B2: non-relined fiber post cemented with Calibra/XP-bond, C1: relined fiber post cemented with RelyX Unicem, C2: non-relined fiber post cemented with RelyX Unicem Push-out bond strength was affected by interaction between relining procedure and luting agent type. Relined fiber post presented higher push-out bond strength value than non-relined fiber post and statically significant differences(p<0.05) Cementation with RelyX Unicem showed significantly higher bond strength than other luting agents(p<0.05).

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.2
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• pp.112-120
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• 2014

Purpose: This study compared the shear bond strength of heat pressed and feldspathic porcelain to metal. Through thermocycling, the clinical aspect of heat pressed porcelain fused metal was estimated. Materials and Methods: 90 non-precious metal specimens were made ($4{\times}4{\times}8 mm$) and divided to three groups. All spicimens were treated and built-up with the porcelain ($4{\times}4{\times}3 mm$) by 2 different methods according to group: Group I: $Inspiration^{(R)}$, Group II: Ivoclar, IPS $Inline^{(R)}PoM$, Group III: GC Initial IQ-One $Body^{(R)}PoM$. The half of each group's specimens were thermocycled. All specimens' shear bond strength were measured by Instron universal testing machine. Exact measuring point was far 1 mm from porcelain/metal interface to the porcelain side. For the statistical analysis, 2-way ANOVA was used. Results: In no-thermocycling specimens, the shear bond strength showed no statistical significance between each group (P > 0.05). In comparison between nothermocycling and thermocycling specimens in each group, the shear bond strength was decreased according to thermocycling, but there was no statistical significance (P > 0.05). In thermocycling specimens, there was no statistical significance between each group (P > 0.05). Conclusion: In feldspathic porcelain and other two types heat pressed porcelain, there was no statistical difference in the shear bond strength of porcelain to metal. The heat pressed porcelain seems to be clinically useful for the aspect of the shear bond strength.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.199-205
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• 2009

Purpose: The purpose of this research was to evaluate the shear bond strength between zirconia core and veneer ceramic after surface treatment. Material and methods: Zirconia cores(N=40, n=10, $10mm{\times}10mm{\times}3mm$) were fabricated according to the manufacturers' instructions and ultrasonically cleaned. The veneering ceramics(thickness 3 mm) were built and fired onto the zirconia core materials. Four groups of specimens with different surface treatment were prepared. Group I: without any pre-treatment, Group II: treated with sandblasting, Group III: treated with liner, Group IV: treated with sandblasting and liner. The shear bond strength was tested in a universal testing machine. Data were compared with an ANOVA and $Scheff{\acute{e}}$ post hoc test(P=.05). Results: The shear bond strength of group VI was significantly higher than the other groups. Conclusion: Both mechanically and chemically treated simultaneously on zirconia core surface influenced the shear bond strength between the core and veneering ceramic in all-ceramic systems.

• The Journal of Korean Academy of Prosthodontics
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• v.25 no.1
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• pp.363-378
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• 1987

도재소부전장관에서 금속이 노출되지 않고 도재만이 파절시, 구강내에서 직접 행할 수 있는 심미적 수복 방법으로서 복합성 수지를 이용한 수복 방법이 널리 이용되고 있는데 본실험의 목적은 도재와 광중합성 수지간의 접합강도를 비교 측정코저 함에 있다. 본 실험에서는 주사전자 현미경을 사용하여 도재의 부식액 (5% 불화수소산용액, Excelco's porcelain etching gel) 및 부식 시간(2.5분, 5분, 10분, 20분)에 따른 부식양상을 먼저 관찰하였다. 그다음 각기 다른 시간에서 부식 처리된 도재와 대조군으로서 미부식 처리된 도재에 광중합성 수지를 부착시킬시, 첫째 Silane coupling agent(Scotch-Prime)도포후 광중합성 수지를 결합 시켰고 둘째 bonding agent(Scotch bond)도포후 광중합성 수지를 결합시켰으며 셋째 Silane coupling agent(Scotch-Prime)에 bonding agent(Scotch bond)를 도포후 광중합성 수지로 결합 시킨후, 인장강도 측정기 (Shimadzu universal testing machine)를 사용하여 결합력을 측정한 결과 다음과 같은 결론을 얻었다. 1. 부식처리된 도재가 미부식 처리된 도재 보다 결합력이 높았다. (p<0.05, P<0.001) 2. 부식 처리된 도재나 미부식 처리된 도재에 있어서 silane coupling agent 도포후 bonding agent로 처치한 경우 가장 결합력이 높았으며 그다음 silane coupling agent로 처치한 경우, bonding agent로 처치한 경우의 순이었다. 3. 도재부식 시간의 증가에 따른 결합력의 차이는 5% HF용액으로 부식 처리된 도재와 Excelco로 부식 처리된 도재에 있어서 5분 정도 까지는 결합력의 증가를 보였으나 그 후에는 결합력에 있어서 거의 증가하지 않는 양상을 보였다. 4. Excelco로 부식 처리된 도재와 5% HF 용액으로 부식처리된 도재간의 결합력 차이에 있어서 bonding agent만으로 처치한 경우에는 두결합력 사이에 서로 유의한 차이를 보이지 않았으나 (P>0.5) silane coupling agent만으로 처치한 경우와 silane coupling agent 도포후 bonding agent로 처치한 경우에는 두결합력 사이에 서로 유의한 차이를 보였다. (P<0.05, P<0.001) 5. Excelco로 부식처리된 도재가 5% HF 용액으로 부식처리된 도재보다 부식정도가 더 현저하였다.

• Journal of the Korea Concrete Institute
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• v.25 no.4
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• pp.411-418
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• 2013

Recently, in order to reduce a damage of chloride attack and hydration heat in marine concrete structures, blended cement in mixing the marine concrete is widely used. Long term strength development is distinct in concrete with blended cement and it also has excellent resistance to chloride attack and reduction of hydration heat. However, blended cement has a characteristic of relatively low compressive strength in early age of 28 days. On the other hand, a high level of compressive strength is required in the Standard Specification for marine concrete mix design. Such concrete mix design satisfying Standard Specification is effective to chloride attack but disadvantageous for hydration heat reduction due to large quantity of binder. In this study, the material properties of marine concrete considering water-binder ratio and binder type are experimentally investigated. Through the research results, compressive strength in blended cement at the age of 56 days is similar although it has smaller compressive strength at the age of 28 days compared with result of OPC (ordinary portland cement). Even though blended cement has a large water-binder ratio and small unit of binder content, chloride ion diffusion coefficient is still small and hydration heat is also found to be reduced. For meeting the required compressive strength in Standard Specification for marine concrete at 28 days, the increased unit content of binder is needed but the increased hydration heat is also expected.

• Restorative Dentistry and Endodontics
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• v.33 no.2
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• pp.125-132
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• 2008

The purpose of this study is to compare the shear bond strength of repaired composite resin with different bonding agents and evaluate the effect of bonding agents on composite repair strength. Forty composite specimens (Z-250) were prepared and aged for 1 week by thermo cycling between 5 and $55^{\circ}C$ with a dwell time of 30s. After air abrasion with $50\;{\mu}m$ aluminum oxide, following different bonding agents were applied (n = 10); SB group: Scotchbond multipurpose adhesive (3 step Total-Etch system); XE group: Clearfil SE bond (2 step Self-Etch system); XP group: XP bond (2 step Total-Etch system); XE group: Xeno III (1 step Self-Etch system). After bonding procedure was completed, new composite resin (Z-250) was applied to the mold and cured. For control group. 10 specimens were prepared. Seven days after repair, shear bond strength was measured. Data was statistically analyzed using one-way ANOVA and Tukey's test (p<0.05). The means and standard deviations of shear bond strength (MPa ${\pm}$ S.D.) per group were as follows: SB group: 17.06; SE group: 19.10; XP group: 14.44; XE group: 13.57; Control Group: 19.40. No significant difference found in each group. Within the limit of this study, it was concluded that the different type of bonding system was not affect on the shear bond strength of repaired composite resin.