Shear Bond Strength of Orthodontic Brackets Bonded using Conventional vs One and Two Step Self-etching/adhesive Systems

OBJECTIVE: To assess and compare the effects of one- and two-step self-etching primer and adhesive with conventional acid-etching and bonding system on the shear bond strength of orthodontic brackets. MATERIALS AND METHODS: The one-step self-etching primer and adhesive used was Clearfil tri-S bond, the two-step fluoride-releasing antibacterial self-etching primer and adhesive was Clearfil Protect Bond, and the fluoride-releasing conventional acid-etching and bonding system was Kurasper F Bond. Brackets were bonded to defect-free human premolars (n = 14 per group) according to each manufacturer's recommendations by using light-cured bracket adhesive Kurasper F Paste with a light-emitting diode of a light-curing unit. The specimens were stored in deionized water at 37 degrees C for 48 hours and then tested in shear with a universal testing machine at a crosshead speed of 5 mm/min until the brackets debonded. The mode of failure of the brackets was determined by a modified adhesive remnant index. RESULTS: Mean shear bond strength values were 9.00 MPa for Kurasper F Bond, 9.55 MPa for Clearfil Protect Bond, and 9.48 MPa for Clearfil tri-S Bond. One-way analysis of variance detected no statistically significant difference among groups (P = .98, P > .05). The predominant failure for the three groups was at the bracket-adhesive interface leaving less than 25% of the adhesive on the bracket base. CONCLUSIONS: One-step self-etching adhesive and two-step fluoride-releasing antibacterial self-etching adhesive have sufficient mechanical properties for the bonding of orthodontic brackets.