2014 Volume 57 Issue 6 Pages 555-562
Purpose: The purpose of this study was to examine the effect of warm air-drying on the surface free energy and enamel bond strength of a HEMA-free single-step self-etch adhesive.
Methods: As the HEMA-free self-etch adhesive system, BeautiBond Multi (Shofu) was employed. Bovine mandibular incisors were mounted in self-curing resin, and wet-ground with #600-grid SiC paper to expose the labial enamel. Adhesive was applied according to the manufacturer's instruction, followed by drying in a stream of warm air for 5 s at 37°C. Normal air-drying at 23°C served as a control. After light irradiation of the adhesive, the surface free energy was determined by measuring the contact angle of three test liquids placed on the cured adhesive. For the determination of enamel bond strength, the adhesive-applied surfaces were dried in a stream of warm air for 5, 10, and 15 s at 37°C, and normal air-drying at 23°C served as a control. Resin composites were condensed into a mold (ɸ4×2 mm) and polymerized. Ten samples per test group were stored in distilled water at 37°C for 24 h, and then shear-tested at a crosshead speed of 1.0 mm/min.
Results: For all surfaces, the value of the estimated surface-energy component γSLW was relatively constant within the range of 41.7-42.7 mN・m－1. The enamel bond strengths varied according to the air-drying time, and ranged from 17.4-18.2 MPa. Maximum bond strengths were achieved at air-drying times of 5 s. No significant differences in bond strength were observed with different air-drying times.
Conclusion: These data suggested that warm air-drying was not effective for increasing the enamel bond strength of the HEMA-free self-etch adhesive, although the Lewis base component decreased with warm air-drying.
