Shear bond strength of three self-adhesive resin cements to dentin.

Context: The result of the studies concerning the bonding of self-adhesive resin cements to dentin is controversial. Aims: To assess in vitro shear bond strength (SBS) of three self-adhesive dual-cured resin cements to dentin compared to a currently used dual-cured resin cement, using SBS test. Settings and Design: The extant study is an experimental in vitro one on extracted human third molars dentin. Material and Methods: 40 intact human third molars were selected and randomly divided into 4 groups of 10. Buccal dentin surfaces were exposed perpendicular to the long axis and prepared with SiC papers. A translucent plastic ring, was placed over the dentin surfaces. Group I (Control group): After 15 s of etching and application of Excite DSC Bond (Ex), Variolink II (Var II) resin cement was injected into the plastic ring and was light cured for 40 s. Group II: RelyX Unicem (RX) was injected into the plastic ring and after 30 s, was light cured for 40 s. Group III: Maxcem (Mc) was injected into the plastic ring and after 30 s, was light cured for 40 s. Group IV: Multilink Sprint (MS) was injected into the plastic ring and after 30 s, was light cured for 40 s. After thermal cycling, SBS were measured with a universal testing machine. Statistical Analysis Used: Statistical computations were conducted according to Student's t-test. Results: The mean SBS and standard deviations (in parentheses) for groups I, II, III, and IV were 12.95 (2.64), 6.73 (0.79), 3.01 (0.90), 4.60 (0.75) MPa, respectively. Statistical analysis, revealed that: (1) the mean SBS of Var II were significantly higher than the other groups (P<0.05). (2) The mean SBS of Mc and MS were significantly lower than RX (P<0.05). (3) The mean SBS of Mc and MS did not show significant difference (P>0.05). Conclusion: Bond strength of three self-adhesive resin cements was significantly lower than the conventional total-etch resin cement. RX significantly performed better SBS than Mc and MS to dentin.

[Microleakage of wetbond self adhesive composite in class V cavities]

The self adhesive composite has been introduced for reducing the process of using composite. The new composites can chemically and micromechanily attach to tooth without using bonding. There are no studies that show the traits of these composites. The purpose of this study was to compare the microleakage of new self-adhesive flowable composite with usual bonding [excite], Tetric Flow composite. In this in vitro experimental Study, 30 freshly extracted caries _free human molars were used. The teeth were randomly divided into four groups of 15 cavities [two cavities in each tooth]. Two modified class V cavities [3mm diameter, 2mm depth] were prepared using a round diamond bur [Swiss Tec [806 314]] on the cementoenamel junction of each tooth. The cavities were filled following the order: Group A: Etching/Excite Bonding/ Tetric Flow composite, Group B: WetBond composite, GroupC: Etching/Wetbond composite, Group D: Etching/Excite Bonding/WetBond composite. All samples were then subjected to thermocycling at temperature between 5 and 55[degree sign]C. 1000 cycles were performed. Next, the specimens were immersed in 2% aqueous solution of basic Fuchsine dye. After that, the teeth were embedded in acrylic resin. Finally, the teeth were sectioned buccolingually in the middle and were evaluated by two independent examiners on a stereomicroscope at 40x magnification to verify the dye penetration. The data analyzed by Kruskall Wallis [P<0.02] and Mann-Whitney test [P<0.05]. The least microleakage in occlusal region was found in group A and then in group D. The greatest microleakage was in groups B and C. The least microleakage in gingival margin was found in groups D and B and the greatest microleakage in groups A and C. According to this study, use of WetBond Self Adhesive Composite in class V cavities alone is not suggested and using etching and bonding prior to it could reduce the microleakage