Tetrahydrofuran as alternative solvent in dental adhesive systems

Abstract Objective To evaluate the influence of tetrahydrofuran (THF) on the resin-to-dentin microtensile bond strength (μTBS) after water storage, for 24 h and 6 months, and to compare its behavior with that of traditional solvents. Methods Seven versions of monomer/solvent mixtures (primers) were prepared using the following solvent and water combinations: (1) THF, (2) acetone, (3) ethanol, (4) water, (5) THF/water, (6) acetone/water and (7) ethanol/water. An experimental adhesive resin was also synthesized to compare adhesive systems with the different primers. Forty-two bovine incisors, randomly separated into seven groups, had their superficial coronal dentin exposed. After acid-etching and rinsing, the excess water was removed from the surface with absorbent paper. Each experimental primer was applied with agitation (30 s) followed by a mild air stream (10 s). The experimental adhesive resin was applied and light-activated (20 s). Resin composite restorations were constructed incrementally. Restored teeth were stored in distilled water at 37 °C (24 h) and sectioned to obtain sticks with an area of 0.5 mm2 . Half the specimens were subjected to the μTBS test immediately after being cut and the other half were tested after 6 months of water storage. Data (MPa) were analyzed by two-way ANOVA (solvent type and storage time as factors) and Tukey–Kramer's test at α = 0.05. Results Factors and interaction showed a statistical effect. After 6 months storage, acetone groups and primers containing THF showed similar μTBS to initial means. Significance THF seems to be a promising solvent for use in dental adhesive systems, maintaining bond strength on dentin substrate after storage.