Dentin bonding tends to degrade with time in clinical use. Investigating the mechanical properties of bonds to dental hard tissues is important in restorative dentistry. Shear stress tests have been used extensively in dental research to evaluate the bond strengths of dental materials to human enamel and dentin. Objective: To determine the effects of four different storage solutions on shear bond strength of two bonding agents to human dentin over 1-90 days. Methods: Human dentin specimens (192) were prepared and bonded with Clearfil™ SE Bond and 3M/ESPE Adper™ Single Bond Plus using 3M Z250 composite. Samples were shear tested following immersion in Hank's Balanced Salt Solution (HBBS), 0.12% chlorhexidine, proteinase inhibitor, and 2% sodium hypochlorite at 37 degrees C for 1 day, 4 day, 20 day, and 90 day storage periods. Shear bond strengths were measured using a universal testing machine (Instron 1122) at a crosshead speed of 5 mm/min (n = 6). Results were evaluated statistically using 3 Way ANOVA and multiple comparisons (p<0.05). Results: A material*storage*time statistical interaction led to further analyses. For SE, the bond strength values decreased at the 90 day time period, with NaOCl storage giving significantly lower values than chlorhexidine or proteinase inhibitor. For SB, a significant decreased in bond strength was found for long term storage in NaOCl. Conclusion: Degradation of bonds generally increases with time, but the results depend upon the system and storage solutions used. Supported by NIH/NIDCR Grants T32-DE07326 and P01DE09859.

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