Bond Strength Durability of Different Adhesives to Dentin After Aging in Two Different Solutions

Purpose: To determine the influence of aging in artificial saliva compared to distilled water on the dentin microtensile bond strength (μTBS) of different adhesive systems. Materials and Methods: Occlusal enamel and superficial dentin of 42 teeth were removed and roots were sectioned to expose the pulp chamber for connecting the tooth segments to an intrapulpal pressure assembly. According to the tested adhesives, tooth segments were allocated to three groups (n = 14): an etch-and-rinse adhesive (Adper Scotchbond Multi-Purpose, SBMP), a two-step self-etching adhesive (Clearfil SE Bond, CSE), and a singlestep self-etching adhesive (Clearfil S3 Bond, S3). Each adhesive system was applied to the dentin surface according to its manufacturer's instructions, while intrapulpal pressure was simulated. Resin composite (3M ESPE) was built up in two increments of 2 mm each. Each bonded specimen was sectioned to obtain eight sticks (0.8 ± 0.01 mm2). Sticks of each group were divided equally (n = 56) according to the storage solution, either distilled water or artificial saliva. For each storage solution, half of the sticks of each subgroup (n = 28) was stored for 24 h at 37°C and the other half was thermocycled for 10,000 cycles between 5°C and 55°C. Sticks were then subjected to μTBS testing. Data were statistically analyzed using multifactor ANOVA with repeated measures and Bonferroni's post-hoc test (p 0.05). Student's t-test was used for pairwise comparison. Failure modes were determined for all tested sticks using scanning electron microscopy. Results: The decrease in bond strength of the three adhesives was significantly higher in distilled water than in artificial saliva. The predominant failure modes were adhesive and mixed. Conclusion: The decrease in bond strength was more pronounced for specimens stored in distilled water than in artificial saliva. Keywords: distilled water, artificial saliva, adhesives, dentin bonding, bond strength, storage, microtensile bond strength