Tetrahydrofuran as alternative solvent in dental adhesive systems

Objective. To evaluate the influence of tetrahydrofuran (THF) on the resin-to-dentin microtensile bond strength (mu TBS) after water storage, for 24h 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 degrees C (24 h) and sectioned to obtain sticks with an area of 0.5 mm(2). Half the specimens were subjected to the mu TBS 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 alpha = 0.05. Results. Factors and interaction showed a statistical effect. After 6 months storage, acetone groups and primers containing THF showed similar mu TBS 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. (C) 2009 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.