INFLUENCE OF THE CHEMICAL AND MECHANICAL TREATMENT OF ZIRCONIUM OXIDE AND LITHIUM DISILICATE CERAMICS ON MICRO-ROUGHNESS AND BOND STRENGTH TO PINK PORCELAIN

Fifty-four ceramic discs (N = 54, 27 each for ZrO₂ and LDS) underwent treatments in-cluding sandblasting (SB), liner applications (ZirLiner for ZrO2, wash-firing for LDS), and dentin powder sprinkling. Six groups were formed: Zr-SB (control), Zr-Z (SB + ZirLiner), Zr-S (SB + ZirLiner + dentin powder), LDS-SB (control), LDS-WF (SB + wash-firing), LDS-S (SB + wash-firing + dentin powder). The surface roughness (Ra), SBS with pink porcelain, and failure modes were evaluated for 48 samples (eight per group), while the surface morphology was assessed using scanning electron microscopy (SEM) for six samples per group. For the ZrO₂ samples, the greatest surface irregularities were seen after the liner application (Zr-Z); for the LDS, they were seen for the dentin powder sprinkled samples (LDS-S). Zr-Z showed the highest Ra among the ZrO₂ groups, while LDS-S exhibited the highest Ra among the LDS groups. The highest SBS was observed in the Zr-S and LDS-WF groups for ZrO₂ and LDS, respectively. Adhesive and mixed failures occurred between the ceramic and porcelain for both the ZrO₂ and LDS groups. The dentin powder sprinkling post-SB and liner application improved the ZrO₂-porcelain bond strength while the wash-firing enhanced the LDS-porcelain bond strength significantly. The long-term effectiveness requires further investigation into the mechanical and chemical surface modifications and the reasons behind the veneering ceramic delamination.