Effects of ultrasonic instrumentation with different scaler-tip angulations on the shear bond strength and bond failure mode of metallic orthodontic brackets.

Objective: To evaluate the effects of ultrasonic instrumentation with different scaler-tip angulations on the shear bond strength (SBS) and bond failure mode of metallic orthodontic brackets.

Methods: Adhesive pre-coated metallic brackets were bonded to 72 extracted human premolars embedded in autopolymerizing acrylic resin. The teeth were randomly divided into 3 groups (n = 24 each) to undergo no treatment (control group) or ultrasonic instrumentation with a scaler-tip angulation of 45° (45°-angulation group) or 0° (0°-angulation group).