Effect of antioxidants on push-out bond strength of hydrogen peroxide treated glass fiber posts bonded with two types of resin cement

OBJECTIVES: Hydrogen peroxide (H2O2) surface treatment of fiber posts has been reported to increase bond strength of fiber posts to resin cements. However, residual oxygen radicals might jeopardize the bonding procedure. This study examined the effect of three antioxidant agents on the bond strength of fiber posts to conventional and self-adhesive resin cements. MATERIALS AND METHODS: Post spaces were prepared in forty human maxillary second premolars. Posts were divided into five groups of 8 each: G1 (control), no pre-treatment; G2, 10% H2O2 pre-treatment; G3, G4 and G5. After H2O2 application, Hesperidin (HES), Sodium Ascorbate (SA) or Rosmarinic acid (RA) was applied on each group respectively. In each group four posts were cemented with Duo-Link conventional resin cement and the others with self-adhesive BisCem cement. Push-out test was performed and data were analyzed using 2-way ANOVA and tukey's post-hoc test (alpha = 0.05). RESULTS: There was a statistically significant interaction between the cement type and post surface treatment on push-out bond strength of fiber posts (p < 0.001, F = 16). Also it was shown that different posts' surface treatments significantly affect the push-out bond strength of fiber posts (p = 0.001). H2O2 treated posts (G2) and control posts (G1) cemented with Duo-link showed the highest (15.96 +/- 5.07MPa) and lowest bond strengths (6.79 +/- 3.94) respectively. CONCLUSIONS: It was concluded that H2O2 surface treatment might enhance the bond strength of fiber posts cemented with conventional resin cements. The effect of antioxidants as post's surface treatment agents depends on the characteristics of resin cements used for bonding procedure.

Assessment of microleakage of class V composite resin restoration following erbium-doped Yttrium Aluminum Garnet (Er:YAG) laser conditioning and acid etching with two different bonding systems

The use of laser for cavity preparation or conditioning of dentin and enamel surfaces as an alternative for dental tissue acid-etch have increased in recent years. The aim of this in vitro study was to compare microleakage at enamel-composite and dentincomposite interfaces following Erbium-Doped Yttrium Aluminum Garnet [Er:YAG] laser conditioning or acid-etching of enamel and dentin, hybridized with different bonding systems. Class V cavities were prepared on the lingual and buccal surfaces of 50 recently extracted intact human posterior teeth with occlusal margin in the enamel and gingival margin in the dentin. The cavities were randomly assigned to five groups: group1:conditioned with laser [Energy=120mJ, Frequency=10Hz, Pulse duration=100 micro s for Enamel and Energy=80mJ, Frequency=10Hz, Pulse duration=100 micro s for Dentin] + Optibond FL, group2:conditioned with laser + etching with 35% phosphoric acid + Optibond FL, group3:conditioned with laser + Clearfil SE Bond, group 4 [control]:acid etched with 35% phosphoric acid + Optibond FL, group 5 [control]: Clearfil SE Bond. All cavities were restored using Point 4 composite resin. All samples were stored in distilled water at 37°C for 24 h, then were thermocycled for 500 cycles and immersed in 50% silver nitrate solution for 24 h. The teeth were sectioned bucco-lingually to evaluate the dye penetration. Kruskal-Wallis and Mann-Whitney tests were used for statistical analysis. In occlusal margins, the least microleakage showed in groups 2, 4 and 5. The maximum microleakage was observed in group 3 [P=0.009]. In gingival margins, the least microleakage was recorded in group2, while the most microleakage was found in group 5 [P=0.001]. Differences between 5 study groups were statistically significant [P<0.05]. The microleakage scores were higher at the gingival margins. The use of the Er:YAG laser for conditioning with different dentin adhesive systems influenced the marginal sealing of composite resin restorations

[Microleakage study of simplified adhesive systems in class V cavities of primary teeth]

There is a high demand for tooth-colored restorations in pediatric dentistry. Since etch-and-rinse adhesive systems are time-consuming, there is a tendency to replace them with simplified adhesive systems. This study compared microleakage of class V composite resin restorations in primary teeth restored using simplified adhesive systems. In this in vitro study standard class V cavities were prepared in 60 primary canines with incisal margins in enamel and gingival margins in dentin. The samples were randomly divided into 4 groups and restored as follows: Group 1: Opti Bond Solo Plus [OBP]; Group 2: Clearfil SE Bond [SEB]; Group 3: Clearfil S[3] Bond [S[3]B]; Group 4: Xeno IV [XeIV]. The cavities were filled with Filtek Z250 composite resin and observed under a stereomicroscope at x 32 for microleakage scoring. The results were analyzed with Kruskal-Wallis test followed by Mann-Whitney and Wilcoxon Signed Rank tests using SPSS software. The results showed significant differences between groups 1 and 4 and group 3 in enamel leakage [p value = 0.005]. There was also a significant difference between group 1 and groups 2 and 4 in dentinal leakage [p value = 0.001]. The test showed that enamel leakage in groups 1 and 4 was significantly lower than dentinal leakage in these groups. The strong acidic adhesives in groups 1 and 4 were more effective in enamel leakage prevention. The mild self-etching adhesive in group 3 was effective in enamel and was the best in dentin leakage prevention