IADR Abstract Archives
Selective Etching Improves Dentin Bonding Efficacy of a Universal Adhesive
Objectives: To evaluate the effect of partial dentin demineralization using various etching times on microtensile bond strength and hybrid layer (HL) quality of a universal adhesive system.
Methods: Extracted sound human molars were flattened with 320 grit SiC paper to expose medium dentin and etched with 37% phosphoric acid for 3, 5, 10 or 15 sec. After etching, a universal bonding agent (Scotchbond Universal, 3M ESPE: SU) was applied, light cured for 10 sec, and restored with composite resin incrementally to a height of 4mm. SU in self-etch mode with no acid-etching served as control. Additionally, a three step etch-and-rinse system (Scotchbond Multi-purpose 3M ESPE: SBMP) was also used as an isolated control group. After storage in 37°C water for 24h, the specimens were sectioned into composite-dentin beams (0.9X0.9mm) and water-stored for 24h. The microtensile bond strength testing (µTBS) was carried out at a crosshead speed of 0.5mm/min. Three beams per tooth were submitted to qualitative nanoleakage evaluation using SEM. The data were analyzed using ANOVA and Tukey’s test (α=0.05).
Results: Etching time significantly affected dentin bond strength (p<0.0001) of SU. No significant differences in bond strengths were observed between SBMP and SU used in self-etch mode or after 15s etching. In general, etching time reduction increased dentin bond strength. Dentin etching for 3s produced significantly higher bond strengths (p<0.05) compared to SBMP and SU used in self-etch mode and after 15s etching. Nanoleakage extension along the HL was similar for SBMP and SU after 15 and 10s etching, presenting mostly a scattered reticular pattern. Lower etching times, 3 and 5s produced mainly fine spotted silver deposits along the HL.
Conclusions: Dentin etching with 37% phosphoric acid for short periods improves dentin bonding of universal adhesives without compromising HL integrity.
Methods: Extracted sound human molars were flattened with 320 grit SiC paper to expose medium dentin and etched with 37% phosphoric acid for 3, 5, 10 or 15 sec. After etching, a universal bonding agent (Scotchbond Universal, 3M ESPE: SU) was applied, light cured for 10 sec, and restored with composite resin incrementally to a height of 4mm. SU in self-etch mode with no acid-etching served as control. Additionally, a three step etch-and-rinse system (Scotchbond Multi-purpose 3M ESPE: SBMP) was also used as an isolated control group. After storage in 37°C water for 24h, the specimens were sectioned into composite-dentin beams (0.9X0.9mm) and water-stored for 24h. The microtensile bond strength testing (µTBS) was carried out at a crosshead speed of 0.5mm/min. Three beams per tooth were submitted to qualitative nanoleakage evaluation using SEM. The data were analyzed using ANOVA and Tukey’s test (α=0.05).
Results: Etching time significantly affected dentin bond strength (p<0.0001) of SU. No significant differences in bond strengths were observed between SBMP and SU used in self-etch mode or after 15s etching. In general, etching time reduction increased dentin bond strength. Dentin etching for 3s produced significantly higher bond strengths (p<0.05) compared to SBMP and SU used in self-etch mode and after 15s etching. Nanoleakage extension along the HL was similar for SBMP and SU after 15 and 10s etching, presenting mostly a scattered reticular pattern. Lower etching times, 3 and 5s produced mainly fine spotted silver deposits along the HL.
Conclusions: Dentin etching with 37% phosphoric acid for short periods improves dentin bonding of universal adhesives without compromising HL integrity.