Sorption and Solubility of Self-etching Adhesives Immersed in Organic Acids Present in Oral Biofilm

Purpose: This study evaluated the sorption and solubility of self-etching adhesive systems after immersion in distilled water, lactic acid, and propionic acid. Materials and Methods: Specimens of 2 two-step (P90 System Adhesive [P90], Clearfil SE Bond [CSE]) and 1 single-step (Adper Easy One [AEO]) adhesive systems were prepared and divided into 4 groups: P90 primer ( P90-P), P90 bond (P90-B), AEO, and CSE bond (CSE-B). Specimens were placed in a desiccator and weighed daily until achieving a constant mass (m1). The specimens (n = 5) were then immersed in the respective media and weighed until a achieving a constant mass (m2). The specimens were again desiccated (m3). Sorption and solubility data were analyzed with two-way ANOVA and Turkey's test. Specimens were also observed using SEM without immersion, after 24 h, and at the end of the respective total time of immersion. Results: For all immersion media, the highest sorption values were obtained for AEO and P90-P, followed by CSE-B and P90-B, which presented the lowest sorption. The time required for adhesives to absorb the solutions was: 11 to 19 days for P90-P, 12 to 13 days for P90-B, 15 to 19 days for AEO, and 14 to 18 days for CSE-B. The highest values of solubility were shown for AEO and P90-P in all immersion media. In water and propionic acid, the adhesives with the lowest solubility values were CSE-B and P90-B. CSE-B had the lowest solubility in lactic acid. Conclusion: The greatest surface degradation was observed after each respective total time of immersion. AEO specimens presented more evident surface degradation and the highest sorption and solubility. Keywords: sorption, solubility, self-etching adhesives, organic acids, oral biofilm