Influence of chemical conditioning and micromechanical roughening on bond strength to zirconia ceramic

TL;DR

This study found that applying a primer significantly improves the bond strength to zirconia ceramic, regardless of other surface treatments.

Contribution

The study demonstrates that chemical conditioning with a primer is more effective than micromechanical treatments for enhancing bond strength to zirconia.

Findings

Primer application significantly increased tensile bond strength (TBS) to zirconia ceramic.

Micromechanical surface treatments did not significantly affect bond strength.

The highest bond strength was observed in airborne-particle abrasion with primer application.

Abstract

The objective of the present in-vitro study was to evaluate the effect of different surface treatment methods with and without chemical conditioning on bonding to zirconia ceramic.

A total of 64 disc-shaped specimens (3 mm in thickness and 8 mm in diameter) were fabricated and divided according to surface treatment into four main groups (n = 16): as milled by CAD CAM with no further treatment (control group) (CNT); airborne-particle abrasion with AL2O3, (APA); etched by ammonium hydrogen difluoride (ABF), etched by a zirconia etching system (ZES). Each main group was divided into two subgroups (n = 8) according to use of primer: Primer application (P) or no primer application (NP) to form a total of 8 test groups as follow; CNT-NP, CNT-P, APA-NP, APA-P, ABF-NP, ABF-P, ZES-NP and ZES-P. Transparent plastic tubes were filled with composite resin and bonded to zirconia discs using adhesive resin cement. All specimens were artificially aged. Hydrolytic ageing (5 months, 37 °C) and thermalcycling (x5000, 5–55 °C) were applied. Tensile bond strength (TBS) was recorded in MPa using a universal testing machine. Statistical analysis was performed using 2-way ANOVA to assess the effects of surface treatment and primer application on bond strength followed by serial 1-way (ANOVA)s test and post hoc (LSD) test for pairwise comparisons.

Chemical conditioning by primer application showed a significant effect on TBS measurements (P = 0.014), whereas micro-mechanical surface treatment did not show a significant difference (P = 0.47), and the interaction between the two factors was also not significant (P = 0.14). Group APA-P showed the highest mean TBS (7 ± 2.8, P < 0.05), while group CNT-NP showed the lowest mean TBS (3.4 ± 0.7, P > 0.05).

Primer application significantly improved bond strength to zirconia ceramic regardless of the different techniques used for micromechanical surface treatment.

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