Comparison of enamel-bracket bond strength using direct- and indirect-bonding techniques with a self-etching ion releasing S-PRG filler.

This in vitro study compared the shear bond strength (SBS) and adhesive remnant index (ARI) of two systems for bonding orthodontic brackets to enamel. The first system involved a self-etching primer (Beauty Ortho Bond, BO) containing surface pre-reacted glass filler. The second involved a primer applied with phosphoric acid etching (Transbond XT, TX). Ninety-six extracted human premolars were divided into eight groups: Group I (TX/direct bonding), Group II (TX/indirect bonding), Group III (BO/direct bonding), and Group IV (BO/indirect bonding). Groups V-VIII were identical to Groups I-IV, respectively, but were also subjected to 1,500 thermal cycles between 5 and 55°C. ARI was scored by binocular microscopy. SBS was analyzed by three-way ANOVA and the Bonferroni test. ARI was analyzed by the chi-squared test. The BO groups showed lower SBS and ARI results than the TX groups. SBS was significantly influenced by the primer material, bonding technique, and thermal cycling.