This study evaluated the effect of chlorhexidine (CLX) in cavities prepared with either ultrasound-mounted CVDentUS diamond tips or conventional diamond burs on dentin bond strength after 24 h and 180 days. Forty-eight dentin surfaces from sound third molars were flattened and divided into four groups (n = 12), according to the type of cavity preparation (CVDentUS ultrasound tip or conventional diamond) and with or without 2% CLX (Consepsis) treatment. After application of the adhesive system (Clearfil SE Bond), microhybrid composite resin blocks (Charisma) were made on the dentin surface in increments. After 24 h, the specimens were sectioned into stickshaped samples with an adhesive interface of approximately 1 mm(2). From each tooth, half of the sticks were evaluated after 24 h of storage in distilled water and the other half after 180 days, using a universal testing machine. Three-way analysis of variance showed no significant triple interactions (p = 0.722) or double interactions between factors. Higher bond strength values were observed with the use of ultrasonic tips (p = 0.019), irrespective of whether or not CLX was applied in either time period. No difference in bond strength values was observed in terms of CLX application (p = 0.581). No significant difference in bond strength values was shown after storage for 24 h or 180 days (p = 0.302). In conclusion, the ultrasonic tips promoted greater bond strength to dentin, irrespective of whether or not CLX was applied, and storage time.