|
Purpose: To evaluate the microtensile bond strength (µTBS) of eleven contemporary adhesives to dentin, including three one-step self-etch systems, four two-step self-etch systems, three two-step total-etch systems, and one three-step total-etch system. Materials and Methods: Resin composite (Z100) was bonded to flat, mid-coronal dentin from 33 extracted human third molars using the adhesives strictly according to the respective manufacturers instructions. After storage overnight in 37°C water, the bonded specimens were sectioned Into 3 to 6 slabs of approximately 1 mm thickness and 2.5 mm width. They were then trimmed into an hourglass shape resulting in an Interface area of approximately 1 mm˛, and subsequently subjected to µTBS testing with a crosshead speed of 1 mm/min. Results: The µTBS varied from 30.0 MPa for the one-step self-etch adhesive Prompt L-Pop 2 (ESPE) to 63.1 MPa for the three-step total-etch adhesive OptiBond FL (Kerr), the latter being the only one that significantly differed from all other µTBS values. Although not significantly different, one-step self-etch adhesives tended to have lower µTBS than two-step self-etch and two-step total-etch adhesives. Specimen failures during sample preparation occurred with Prompt L-Pop 2 (4 pretesting failures out of 17 specimens) and NRC/Prime&Bond NT (7 pretesting failures out of 14 specimens). Conclusion: Adhesives with simplified application procedures, either following a total-etch or self-etch approach, produced lower bond strengths to dentin than a conventional three-step total-etch adhesive. Some concern exists regarding the consistency in bonding effectiveness to dentin of some self-etch adhesives.
|