Shear bond strength and ARI scores of metal brackets to glazed glass ceramics and zirconia: an in vitro study investigating surface treatment protocols.

OBJECTIVE

To evaluate the shear bond strength (SBS) and adhesive remnant index (ARI) scores of metal brackets to glazed lithium disilicate reinforced glass-ceramics and zirconia according to various surface treatment protocols.

METHODS

A total of 240 lithium disilicate ceramic (LD) and 240 zirconia (Zr) blocks were randomly divided according to sandblasting, hydrofluoric acid (HF) etching, universal primer use, and the adhesive system applied. A maxillary canine metal bracket was bonded to each sample with resin cement (Transbond XT, TXT). SBS tests and ARI score analysis were performed. Four-way ANOVA followed by Tukey's post hoc test was used for SBS differences, and Fisher's exact test was used for the ARI scores (p < 0.05).

RESULTS

All groups combining a universal primer with a universal adhesive with and without sandblasting provided satisfactory SBS values for both LD and Zr. Fractures of the samples were observed only for LD in the groups combining HF with universal primers and universal adhesives with and without sandblasting.

CONCLUSIONS

Combining a universal primer with a universal adhesive could be recommended for orthodontic bonding to both LD and Zr. Regarding their risks (i.e., damaging the restoration surface or burning the oral tissues), sandblasting or HF might not be necessary despite the presence of glaze covering the ceramic surface.