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Original Articles
- Influence of the curing time for the adhesive on the oxygen-inhibited layer thickness and the shear bond strength to dentin
- Yong-Hoon Choi, Ji-Hyun Bae, Ho-Hyun Son, In-Bog Lee, Chung-Moon Um, Seung-Ho Baek, Oh-Young Kim, Chang-Keun Kim, Byeong-Hoon Cho
- J Korean Acad Conserv Dent 2004;29(2):177-184. Published online January 14, 2004
- DOI: https://doi.org/10.5395/JKACD.2004.29.2.177
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Abstract
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ePub ABSTRACT Objectives: This study investigated the hypothesis that increasing light-curing time would leave the oxygen-inhibited layer (OIL) of the adhesive thinner, and in turn, result in lower shear bond strength (SBS) than those obtained by the routine curing procedures.
Methods: 120 human extracted posterior teeth were randomly divided into three groups for bonding with three adhesives: All Bond 2®, One Step®, and Adper Prompt®. They were subsequently divided into four subgourps with different light-curing time (10, 20, 30 and 60 s). The assigned adhesives were applied on superficial occlusal dentin according to the manufacturer’s instructions and cured with one of the four curing times. Composite resin cylinder, 2.35 mm in diameter, were built on the cured adhesive and light-cured for 40 s. SBS were measured after 24 h from the bonding using a universal testing machine (crosshead speed 1.0 mm/min). The relative thickness of the OIL and the degree of conversion (DC) were determined from the adhesive on a slide glass using FT-NIR in an absorbance mode. Data were analysed with One-way ANOVA and Duncan’s multiple test (p < 0.05).
Results: With increasing cure time, although there were no significant difference in th SBS of One-step and Adper Prompt (p > 0.05), those of All Bond 2 decreased significantly (p < 0.05). The relative thicknesses of the OIL on each adhesive were not affected by the cure time (p > 0.05). Although the DC of All-Bond 2 were statistically not different with increasing cure time (p > 0.05), those of One-Step and Adper Prompt showed an increasing trends with increasing cure time (p < 0.05).
Conclusions: Increasing light-curing time did not affect on the relative thickness of the OIL of the adhesives, and in turn, on the SBS to dentin.
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- Microleakage of microfill and flowable composite resins in class V cavity after load cycling
- Suk-Ho Kang, Oh-young Kim, Myung-Hwan Oh, Byeong-Hoon Cho, Chung-Moon Um, Hyuk-Choon Kwon, Ho-Hyun Son
- J Korean Acad Conserv Dent 2002;27(2):142-149. Published online March 31, 2002
- DOI: https://doi.org/10.5395/JKACD.2002.27.2.142
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Abstract
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Low-viscosity composite resins may produce better sealed margins than stiffer compositions (Kemp-Scholte and Davidson, 1988; Crim, 1989). Flowable composites have been recommended for use in Class V cavities but it is also controversial because of its high rates of shrinkage. On the other hand, in the study comparing elastic moduli and leakage, the microfill had the least leakage (Rundle et al. 1997). Furthermore, in the 1996 survey of the Reality Editorial Team, microfills were the clear choice for abfraction lesions.
The purpose of this study was to evaluate the microleakage of 6 compostite resins (2 hybrids, 2 microfills, and 2 flowable composites) with and without load cycling.
Notch-shaped Class V cavities were prepared on buccal surface of 180 extracted human upper premolars on cementum margin. The teeth were randomly divided into non-load cycling group (group 1) and load cycling group (group 2) of 90 teeth each. The experimental teeth of each group were randomly divided into 6 subgroups of 15 samples. All preparations were etched, and Single bond was applied. Preparations were restored with the following materials (n=15): hybrid composite resin [Z250(3M Dental Products Inc. St.Paul, USA), Denfil(Vericom, Ahnyang, Korea)], microfill [Heliomolar RO(Vivadent, Schaan, Liechtenstein), Micronew(Bisco Inc. Schaumburg, IL, USA)], and flowable composite [AeliteFlo(Bisco Inc. Schaumburg, IL, USA), Revolution(Kerr Corp. Orange, CA, USA)]. Teeth of group 2 were subjected to occlusal load (100N for 50,000 cycles) using chewing simulator(MTS 858 Mini Bionix II system, MTS Systems Corp., Minn. USA). All samples were coated with nail polish 1mm short of the restoration, placed in 2% methylene blue for 24 hours, and sectioned with a diamond wheel. Enamel and dentin/cementum margins were analyzed for microleakage on a sclale of 0 (no leakage) to 3 (3/3 of wall). Results were statistically analyzed by Kruscal-Wallis One way analysis, Mann-Whitney U-test, and Student-Newmann-Keuls method. (p=0.05)
Results 1. There was significantly less microleage in enamel margins than dentinal margins of all groups. (p<0.05)
2. There was no significant difference between six composite resin in enamel margin of group 1.
3. In dentin margin of group 1, flowable composite had more microleakage than others but not of significant differences.
4. There was no significant difference between six composite resin in enamel margin of group 2.
5. In dentin margin of group 2, the microleakage were R>A=H=M>D>Z. But there was no significant differences.
6. In enamel margins, load cycling did not affect the marginal microleakage in significant degree.
7. In dentin margins, load cycling did affect the marginal microleakage only in Revolution. (p<0.05)
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