# 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.

## Key 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.