Effect of the application time of phosphoric acid and self-etch adhesive systems to sclerotic dentin

OBJECTIVES: To evaluate the effect of application time on the resin-dentin bond strength (µTBS) and etching pattern of adhesive systems applied on sclerotic dentine. MATERIAL AND METHODS: A total of forty-two bovine incisors had their roots removed. The 1-step self-etch GO (SDI), the 2-step self-etch Adper SE Bond (3MESPE) and the 35% phosphoric acid (3MESPE) from the 2-step etch-and-rinse Adper Single Bond 2 (3MESPE) were applied on the bovine incisal surfaces according to the manufacturer's instructions or duplicating the recommended conditioning time. After adhesive application, thirty teeth were restored with composite resin, stored for 24 h in distilled water at 37º C, and sectioned into resin-dentin bonded sticks (0.8 mm(2)) and tested according to the µTBS at 0.5 mm/min. The etching pattern of the remaining twelve teeth (n=4 for each material) was examined under scanning electron microscopy. Each tooth was divided into a buccal-to-lingual direction into three thirds, and each third randomly assigned to the groups: control (no treatment), according to the manufacturers' instructions and duplicating the recommended application time. The µTBS and the relative percentage of the tubule area opening were evaluated by two-way repeated measures ANOVA and Tukey's tests (α=0.05). RESULTS: The duplication of the conditioning time favored only the GO adhesive (p<0.05). Both application methods significantly increased the tubule area opening (p<0.05) compared to the controls. CONCLUSIONS: The efficacy of duplicating the conditioning time was only effective for the 1-step self-etch adhesive system tested

Effect of residual water on dentin bond strength and hybridization of a one-bottle adhesive system

This research investigated the effects of wet and dry conditions of phosphoric acid etched dentin on resin bonding and determined the optimum moisture condition for resin bonding using an ethanol-based one-bottle adhesive system. Bovine dentin surfaces were etched with 35% phosphoric acid and rinsed with water. Under four wet and dry conditions (overwet, blot dry, one-second dry and desiccated), resin composite was bonded using Single Bond. Tensile bond strength was measured and the results analyzed by one-way ANOVA and Fisher's PLSD test at the 5% level. The resin-dentin interfaces of bonded specimens were observed with SEM. The bond strength of overwet, blot dry, one-second dry and desiccated groups were 5.2 MPa, 12.6 MPa, 11.9 MPa and 4.4 Mpa, respectively. The blot dry group and one-second dry groups revealed significantly higher bond strengths than the desiccated and overwet groups (p<0.05). The formation of hybrid layers approximately 5 μm thick (overwet and blot dry), 2 pm (one-second dry) and 3 μm (desiccated) were observed. The coefficient of variation in the blot dry group was very high, even though a higher mean was observed. In the one-second dry group, the moisture content of the collagen network was possibly too low, such that hybrid layer formation was not as good even though the bond strength was high.link_to_subscribed_fulltex

Effect of residual water on dentin bond strength and hybridization of a one-bottle adhesive system

This research investigated the effects of wet and dry conditions of phosphoric acid etched dentin on resin bonding and determined the optimum moisture condition for resin bonding using an ethanol-based one-bottle adhesive system. Bovine dentin surfaces were etched with 35% phosphoric acid and rinsed with water. Under four wet and dry conditions (overwet, blot dry, one-second dry and desiccated), resin composite was bonded using Single Bond. Tensile bond strength was measured and the results analyzed by one-way ANOVA and Fisher's PLSD test at the 5% level. The resin-dentin interfaces of bonded specimens were observed with SEM. The bond strength of overwet, blot dry, one-second dry and desiccated groups were 5.2 MPa, 12.6 MPa, 11.9 MPa and 4.4 Mpa, respectively. The blot dry group and one-second dry groups revealed significantly higher bond strengths than the desiccated and overwet groups (p<0.05). The formation of hybrid layers approximately 5 μm thick (overwet and blot dry), 2 pm (one-second dry) and 3 μm (desiccated) were observed. The coefficient of variation in the blot dry group was very high, even though a higher mean was observed. In the one-second dry group, the moisture content of the collagen network was possibly too low, such that hybrid layer formation was not as good even though the bond strength was high.link_to_subscribed_fulltex

Effect of light-curing method and irradiation time on marginal sealing and cavity wall adaptation of resin composite restorations.

PURPOSE: To evaluate the effect of irradiation time on two light-curing methods on the marginal sealing and cavity wall adaptation of resin-based composite restorations. METHODS: Cylindrical cavities, 1 mm deep and 3 mm in diameter (C-factor = 2.3) were prepared on flat superficial bovine dentin surfaces. The teeth were restored with Clearfil Photo Bond, Clearfil Liner Bond 2 or Super-Bond D-Liner adhesive systems followed by Photo Clearfil Bright resin-based composite. The resins were cured using a conventional method at an output of 600 mW/cm2 for 60 s, or 600 mW/cm2 for 30 s, or the slow-start curing method at an output of 270 mW/cm2 for 10 s + 5 s (interval) + 600 mW/cm2 for 50 s or 270 mW/cm2 for 10 s + 5 s (interval) + 600 mW/cm2 for 20 s. After thermocycling, a dye penetration test was carried out. The dye penetration length was calculated as a percentage of the total cavity wall length. RESULTS: Slow-start curing method; 270 mW/cm2 10 s + 5 s (interval) + 600 mW/cm2 for 50 s showed the best marginal sealing and cavity wall adaptation. A shorter irradiation time increased cavity wall adaptation when the conventional curing method was used. Super-Bond D-Liner showed good marginal sealing and resin composite adaptation to the cavity wall regardless of the light-curing method.link_to_subscribed_fulltex

Bond strength of two adhesive systems to primary and permanent enamel

The bonding performance of current adhesive systems to primary enamel has not been thoroughly researched. This study compared the micro-shear bond strength of two adhesive systems to primary and permanent tooth enamel. Two commercially available resin adhesives, a self-etching primer system (Clearfil SE Bond) and a single-bottle adhesive system (Single Bond) used with a total-etch wet bonding technique were tested. A micro-shear bond test was used to examine the adhesive systems on mid-coronal buccal enamel of extracted primary or permanent teeth. In addition, etched enamel surfaces and etched-bonded enamel interfaces were examined using scanning electron microscopy (SEM). No statistically significant differences of shear bond strength values were found between the primary and permanent enamel or the adhesive systems used (p>0.01). The SEM observations showed that both adhesive systems etched the primary enamel deeper than the permanent enamel, suggesting that the action of acid etch seemed to be more intense on primary enamel than on permanent enamel. Bonding of the adhesive systems to primary enamel was almost identical to permanent enamel. ©Operative Dentistry, 2002.link_to_subscribed_fulltex