To compare the microtensile bond strength (µTBS) of five adhesives to human dentin prepared with 600-grit SiC abrasive paper (SiC), a diamond rotary instrument, or a carbide bur. The null hypothesis was that different cavity preparation instruments do not affect adhesion of resin adhesives. Human molars (n = 45) were randomly divided into three groups according to surface treatment. Each group was bonded using a total-etch adhesive (Single Bond, 3M ESPE), one of three self-etching primer systems (Clearfil SE Bond or ABF, Kuraray; Imperva Fluorobond, Shofu), or a self-etching adhesive (One-Up Bond F, Tokuyama). A 4-mm composite crown was built over the bonded surface. Specimens were stored in water for 24 h at 37°C. They were sectioned into 0.7-mm-thick slabs, trimmed to a cross-sectional area of 1 mm2, and loaded to failure at a crosshead speed of 1 mm/min using a tabletop tester (EZ-Test, Shimadzu). Microtensile bond strength data were analyzed using analysis of variance and Fisher's PLSD test. Surface preparation using a carbide bur generally yielded higher bond strengths than preparation using either a diamond rotary instrument or SiC abrasive paper. SE Bond had the highest mean µTBS of the five adhesives tested. Resin-dentin bond strengths can be affected by the type of instrument used to prepare the tooth. Specifically, higher bond strengths might be achieved by using carbide burs rather than diamond cutting instruments. Keywords: adhesion, dentin bonding, burs, self-etching primers, smear layer