Shear Bond Strength of Metallic and Ceramic Brackets Bonded with Two-step and Three-step Light Cure Adhesives

The bonding process is highly important in orthodontic treatment for its fast speed. The purpose of this study was to compare the shear bond strength of ceramic and metallic brackets between three stage (transbondTM XT) and two stage (GC ortho connectTM) light cure composites.

In this experimental study, 80 maxillary and mandibular first and second premolar teeth, extracted for the purpose of orthodontic treatment, were randomly divided into four groups (n=20 per group). All teeth were etched using 35% phosphoric acid. They were then bonded with metallic brackets with GC ortho connectTM composite (group I), and TransbondTM XT composite (group II), and ceramic brackets with GC ortho connectTM composite (group III) and TransbondTM XT composite (group IV). The shear bond strength of the brackets was measured by universal testing machine 24 hours after thermocycling and mounting procedures. The amount of resin remained on the tooth surface was determined by stereomicroscope. Data were analyzed by SPSS V22 applying Kruskal–Wallis one-way analysis of variance.

The average shear bond strength in groups I, II, III, and IV were 18.71±1.99, 19.82±8.75, 18.4±5.78, and 18.5±52.42 MPa, indicating no significant differences between the groups studied (P> 0.05). Also, we found no significant differences in adhesive remnant index (ARI) between all groups (P=0.641).

The shear bond strength of GC ortho connectTM composite was similar to that of the TransbondTM XT composite in both metallic and ceramic brackets. Therefore, GC ortho connectTM can serve as a substitute for TransbondTM XT.