This study compared the microshear bond strength (µSBS) of light-cured and dual-cured composites to enamel bonded with three self-etching adhesives. Crown segments of extracted human molars were cut mesiodistally, and 1 mm thickness of specimen was made. They were assigned to three groups by used adhesives: Xeno group (Xeno III), Adper group (Adper Prompt L-Pop), and AQ group (AQ Bond). Each adhesive was applied to cut enamel surface as per manufacturer's instruction. Light-cured (Filtek Z 250) or dual-cured composite (Luxacore) was bonded to enamel of each specimen using Tygon tube.

After storage in distilled water for 24 hours, the bonded specimens were subjected to µSBS testing with a crosshead speed of 1 mm/minute. The mean µSBS (n = 20 for each group) was statistically compared using two-way ANOVA, Tukey HSD, and t test at the 0.05 probability level. The results of this study were as follows;

1. The µSBS of light-cured composite was significantly higher than that of dual-cured composite when same adhesive was applied to enamel.

2. For Z 250, the µSBS of AQ group (9.95 ± 2.51 MPa) to enamel was significantly higher than that of Adper goup (6.74 ± 1.80 MPa), but not significantly different with Xeno group (7.73 ± 2.01 MPa).

3. For Luxacore, the µSBS of Xeno group (5.19 ± 1.32 MPa) to enamel was significantly higher than that of Adper goup (3.41 ± 1.19 MPa), but not significantly different with AQ group (4.50 ± 0.96 MPa).

In this study, the changes in the degree of conversion (DC) and the microtensile bond strength (MTBS) of self-etching adhesives to dentin was investigated according to the time after curing. The MTBS of Single Bond (SB, 3M ESPE, USA), Clearfil SE Bond (SE, Kuraray, Japan), Xeno-III (XIII, Dentsply, Germany), and Adper Prompt (AP, 3M ESPE, USA) were measured at 48h, at 1 week and after thermocycling for 5,000 cycles between 5℃ and 55℃. The DC of the adhesives were measured immediately, at 48h and at 7 days after curing using a Fourier Transform Infra-red Spectrometer. The fractured surfaces were also evaluated with scanning electron microscope. The MTBS and DC were significantly increased with time and there was an interaction between the variables of time and material (MTBS, 2-way ANOVA, p = 0.018; DC, Repeated Measures ANOVA, p < 0.001). The low DC was suggested as a cause of the low MTBS of self-etching adhesives, XIII and AP, but the increase in the MTBS of SE and AP after 48h could not be related with the changes in the DC. The microscopic maturation of the adhesive layer might be considered as the cause of increasing bond strength.

Recently, self-etching adhesive system has been introduced to simplify the clinical bonding procedures. It is less acidic compared to the phosphoric acid, thus there is doubt whether this system has enough bond strength to enamel. The purpose of this study was to investigate the influence of additional etching on the adhesion of resin composite to enamel.

Ninety extracted bovine permanent anterior teeth were used. The labial surfaces of the crown were ground with 600-grit abrasive paper under wet condition. The teeth were randomly divided into six groups of 15 teeth each. Clearfil SE Bond®, Adper™ Prompt L-Pop and Tyrian SPE™ were used as self-etching primers. Each self-etching primers were applied in both enamel specimens with and without additional etching. For additional etching groups, enamel surface was pretreated with 32% phosphoric acid (UNI-ETCH, Bisco, Inc., Schaumburg, IL, USA). Hybrid resin composite Clearfil AP-X, (Kuraray Co., Ltd., Osaka, Japan) was packed into the mold and light-cured for 40 seconds. Twenty-four hours after storage, the specimens were tested in shear bond strength. The data for each group were subjected to independent t - test at p < 0.01 to make comparisons among the groups.

In Clearfil SE Bond®, shear bond strength of additional etching group was higher than no additional etching group (p < 0.01). In Adper™ Prompt L-Pop and Tyrian SPE, there were no significant difference between additional etching and non-etching groups (p > 0.01).

In conclusion, self-etching adhesive system with weak acid seems to have higher bond strength to enamel with additional etching, while self-etching adhesive system with strong acid seems not.

This study investigated the hypothesis that the dentin bond strength of self-etching adhesive (SEA) might be improved by applying additional layer of bonding resin that might alleviate the pH difference between the SEA and the restorative composite resin. Two SEAs were used in this study; Experimental SEA (Exp, pH: 1.96) and Adper Prompt (AP, 3M ESPE, USA, pH: 1.0). In the control groups, they were applied with two sequential coats. In the experimental groups, after applying the first coat of assigned SEAs, the D/E bonding resin of All-Bond 2 (Bisco Inc., USA, pH: 6.9) was applied as the intermediate adhesive. Z-250 (3M ESPE, USA) composite resin was built-up in order to prepare hourglass-shaped specimens. The microtensile bond strength (MTBS) was measured and the effect of the intermediate layer on the bond strength was analyzed for each SEA using t-test. The fracture mode of each specimen was inspected using stereomicroscope and Field Emission Scanning Electron Microscope (FE-SEM). When D/E bonding resin was applied as the second coat, MTBS was significantly higher than that of the control groups. The incidence of the failure between the adhesive and the composite or between the adhesive and dentin decreased and that of the failure within the adhesive layer increased. According to the results, applying the bonding resin of neutral pH can increase the bond strength of SEAs by alleviating the difference in acidity between the SEA and restorative composite resin.

This study compared the microtensile bond strength (μTBS) 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℃ distilled water for 1, 15, and 30 days.

Resin-bonded specimens were sectioned into beams and subjected to μTBS 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 μTBS of SE group was significantly higher than those of other groups (p < 0.05). There was no significant difference between mean μTBS of SE group and AdheSE group among all storage times, but significant difference between 1- and 30-day storage in mean μTBS 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 purpose of this study was to compare shear bond strength and interfacial pattern of composite bonded to dentin using self-etching adhesive systems.

Sixty extracted human molars with exposed occlusal dentin were divided into four groups and bonded with four adhesives and composites: Single Bond/Filtek Z 250(SB), Tyrian SPE-One-Step Plus/Aelitefil(TY), Prompt L-Pop/Filtek Z 250(LP), and One-Up Bond F/Palfique Toughwell(OU).

The results of this study were as follows;

Shear bond strength for OU was significantly lower than that of other groups(p<0.05). No significant difference was founded among SB, TY, and LP.

The purpose of this study was to compare in vitro interfacial relationship of restorations bonded with three self-etching primer adhesives and one self-etching adhesive.

Class I cavity preparations were prepared on twenty extracted human molars. Prepared teeth were divided into four groups and restored with four adhesives and composites: Clearfil SE Bond/Clearfil™ AP-X (SE), UniFil Bond/UniFil® F (UF), FL Bond/Filtek™ Z 250 (FL) and Prompt L-Pop/Filtek™ Z 250 (LP)

After storing in distilled water of room temperature for 24 hours, the specimens were vertically sectioned and decalcified. Morphological patterns between the enamel/dentin and adhesives were observed under SEM.

The results of this study were as follows;

1. They showed close adaptation between enamel and SE, UF and FL except for LP.

2. The hybrid layer in dentin was 2 µm thick in SE, 1.5 µm thick in UF, and 0.4 µm in both FL and LP. So, the hybrid layers of SE and UF were slightly thicker than that of FL and LP.

3. The lengths and diameters of resin tags in UF and FL were similar, but those of LP were slightly shorter and slenderer than those of SE.

4. The resin tags were long rod shape in SE, and funnel shape in other groups.

Within the limitations of this study, it was concluded that self-etching primer adhesives showed close adaptation on enamel. In addition, the thickness of hybrid layer ranged from 0.4-1.5 µm between adhesives and dentin. The resin tags were long rod or funnel shape, and dimension of them was similar or different among adhesives.

This study evaluated the microleakage performance of four self-etcing primer adhesives(Clearfil SE Bond, Clearfil Liner Bond 2, UniFil Bond, and FL Bond) and one self-etching adhesive(Prompt L-Pop). Class V cavity preparations with occlusal margins in enamel and gingival margins in dentin were prepared on both buccal and lingual surfaces of 50 extracted human molar teeth. Prepared teeth were randomly divided into five groups and restored using one of five adhesives and composite resins: Prompt L-Pop/Filtek Z 250(Group 1), Clearfil SE Bond/Clearfil AP-X(Group 2), Clearfil Liner Bond 2/Clearfil AP-X(Group 3), UniFil Bond/UniFil F(Group 4), and FL Bond/Filtek Z 250(Group 5).

Following one day storage in room temperature water, the restored teeth were thermocycled for 500 cycles between 5℃ and 55℃. Marginal microleakage was assessed by dye penetration using 2% methylene blue dye. After 24 hours, the teeth were sectioned longitudinally and evaluated for microleakage under steromicroscope. The data were statistically analysed by Kruskal-Wallis Test, Mann-Whitney and Wilcoxon signed ranked tests.

The results of this study were as follows;

1. The microleakges at both enamel and dentinal margins were the lowest in group 4, increasing among groups in the following order: group 2, follwed by group 5, follwed by group 1, and the highest in group 3.

2. At the enamel margins, the microleakage of group 3 was significantly higher than those of groups 2, 4 and 5(p<0.05), and also the microleakage of group 1 was statistically higher than those of groups 2 and 5(p<0.05).

3. At the dentinal margins, microleakage of group 3 was significantly higher than microleakages of groups 1, 2, 4 and 5(p<0.05).

4. Compared with microleakages between the enamel and dentinal margins of each group, groups 1, 4 and 5 at enamel margin and group 2 and group 3 at dentinal margin were higher microleakage. But there was no significant difference between enamel and dentinal microleakages of each group(p>0.05).