Shear bond strength of a RMGIC for orthodontic bracket bonding to enamel

To evaluate the shear bond strength (SBS) of a restorative resin-modified glass ionomer cement (RMGIC) for orthodontic bracket bonding.

One hundred twenty-one human teeth were randomly divided into 11 groups (n = 11) according to the surface treatment applied (H₃PO₄ ± Transbond Plus (TSEP) or Scotchbond Universal (SU)), and the adhesive used (Riva LC HV (RIVA), Fuji Ortho (FUJI), and Transbond XT (TXT)). For each sample, a metal button was bonded. SBS tests were performed at 1 week and debonded specimens were observed for failure modes determination. One-way ANOVA followed by Tukey’s post hoc test was used to compare SBS differences and Fisher’s exact test to analyze the failure modes (p < 0.05).

TSEP + FUJI and H₃PO₄ + SU + TXT showed the highest SBS values while H₃PO₄ + TSEP + RIVA showed the lowest value. Cohesive failure and mixed failure were found in the groups with SU and TXT and adhesive failure in the other groups.

The bonding of orthodontic attachments to enamel could be performed with any of the three materials studied. The use of a universal adhesive in the bonding protocol could optimize the adhesion values. Clinical studies would be needed to confirm the results obtained.