Effect of different power settings of Er,Cr:YSGG laser before or after tribosilicatization on the microshear bond strength between zirconia and two types of cements.

The aim of this study was to evaluate the effect of different output powers of Er,Cr:YSGG laser and the association with tribochemical silica coating on the bond strength between zirconia ceramic and two resin cements. One hundred ninety-two zirconia ceramic bars (IPS e-max ZirCAD Ivoclar Vivadent-) were sectioned (6 × 6 × 4 mm), sintered, and randomly divided into 12 groups for each cement system according to the surface treatment (n = 8): C-without treatment (control); R-tribochemical coating + resin cement (control); 2L-laser (2.0 W) + resin cement; 2LR-laser (2.0 W) + tribochemical coating + resin cement; R2L-tribochemical coating + laser (2.0 W) + resin cement; 2.5L-laser (2.5 W) + resin cement; 2.5LR-laser (2.5 W) + tribochemical coating + resin cement; R2.5L-tribochemical coating + laser (2.5 W) + resin cement; 3L-laser (3.0 W) + resin cement; 3LR-laser (3.0 W) + tribochemical coating + resin cement, R3L-tribochemical coating + laser (3.0 W) + resin cement; and RPHO-tribochemical + resin cement + photoactivation (control). After the surface treatment, the respective primers were applied, and resin cements, Multilink N, Ivoclar Vivadent (M), and Panavia F 2.0, Kuraray Medical Inc. (P), were inserted into Tygon molds which were bonded to the zirconia bars. Each specimen received two cements bars. After 24 h of storage in a relative humidity (100%) at 37 °C, they were evaluated by the microshear test speed of 1 mm/min. The microshear values were analyzed by one-way ANOVA and Tukey's test (α = 0.05). ANOVA showed statistically significant differences among the evaluated groups. The highest bond strength was observed in RPHO, which statistically differed from all groups. The lowest bond strength was observed in M2.5L (Multilink N) and in P3LR (Panavia F 2.0). It can be concluded that the lowest power output tested was suitable and showed bond strength values similar to tribochemical silica deposition. The light curing is important to adhesion and the tribosilicatizated surface achieves similar microshear values to untreated surface in absence of light.

Antibacterial activity of various self-etching adhesive systems against oral streptococci.

The antibacterial properties of self-etching adhesive systems constitute an important issue in operative dentistry, since viable bacteria can still be present after cavity preparation. The current study evaluated the antibacterial activity of five one-step self-etching adhesives (SEAs) and four self-etching primers (SEPs) against oral streptococci. Clearfil S3 (S3), One-Up Bond F Plus (OU), Futurabond NR (FB), GBond (GB), Xeno IV (X4), Clearfil SE Bond (SE), Clearfil Protect Bond (PB), Adper SE Plus (AS) and AdheSE (AD) were tested for antibacterial activity against five streptococci species: S oralis, S sanguinis, S cricetus, S mutans and S sobrinus. Chlorhexidine (0.12%) and phosphoric acid (37%) gel were used as control. The agar diffusion test method was used. Plates containing BHI agar and 300 uL of bacterial cell suspension (0.5 MacFarland) were prepared. Holes 6 mm in diameter were made and partially filled with bacteriological agar. Then, 10 uL of each SEA or SEP was dropped and the plates were incubated under microaerophilic atmosphere at 37 degrees C for 48 hours and the diameter of each halo was registered. The results were analyzed by two-way ANOVA and Tukey test. PB exhibited the most effective antibacterial activity against oral streptococci. The performances of SE and FB were similar or better than chlorhexidine for all bacteria. S3, X4, AS, AD, OU and GB showed significantly lower inhibition values. Among the species tested, S oralis was the most sensitive to all self-etching adhesive systems; on the other hand, S cricetus, S mutans and S sobrinus were more resistant. Among the self-etching adhesive systems evaluated, Clearfil Protect Bond exhibited the most effective antibacterial activity against oral streptococci.