An invitro evaluation of the effect of zirconia surface treatment on shear bond strength to a resin cement

Developments in ceramic core materials such as lithium disilicate, aluminium oxide, and zirconium oxide have allowed more widespread application of all-ceramic restorations over the past 10 years. However, establishing a reliable bond of resin cement to zirconia based materials has been proven to be difficult, which is the major limitation against fabricating zirconia restoration, and there is no clear recommendation in the literature regarding surface treatment before bonding.

This study evaluated the effect of zirconia surface treatments namely Airborne Particle Abrasion, Hydrofluoric acid etching, Hydrofluoric acid etching followed by silanation and Primer application on shear bond strength to a self etch dual cure resin cement bonded to dentin specimens.

Twenty zirconia rods (3 x 2.5 mm) were prepared from zirconia blocks and assigned into 5 groups. Each group were subjected to the following surface treatments. (1) group I -Control (C) no treatment, (2) group II -airborne-particle abrasion (APA), (3) group III – hydrofluoric acid etching (HF), (4) group IV -hydrofluoric acid etching followed by silanation (HF/S), and (5) group V -application of zirconia primer (Z). Dentin specimens were prepared from extracted molars stored in 0.5% chloramine-T. Zirconia rods were bonded to dentin using a resin cement (Multilink Speed), then light polymerized. The specimens were loaded to failure with the notched shear bond test method in a universal loading apparatus. Results were analyzed using 1-way ANOVA (alpha=.05).

ANOVA showed significant differences in bond strength among the different surface treatments (p value 0.001). The highest values were obtained with group V (Z)(8.66 Mpa) followed bygroup II (APA) (6.71 Mpa), group IV (HF/S) (4.41 Mpa). The least values were obtained for group III (HF) (3.88 Mpa) and there were no significant difference (p value 0.53) between group III (HF) (3.88 Mpa) and group I (C) (3.70 Mpa).

The resin bond to Y-TZP was improved by surface treatment. Zirconia Primer application is practically a reliable surface treatment. Airborne Particle Abrasion, although not so reliable, is also an effective treatment while bonding zirconia to a resin cement.