Effects of Surface Abrasion With Airborne-Particles and Surface Etching With Hydrofluoric Acid on Color Difference...

To evaluate the effects of alumina airborne-particle abrasion, glass-bead airborne-particle abrasion, and hydrofluoric acid etching of intaglio surfaces on the color difference and translucency of a nano-hybrid ceramic after cementation to resin abutment specimens, and to analyze the relationships between surface roughness and these parameters.

Thirty nano-hybrid ceramic discs were allocated to alumina airborne-particle abrasion (hereinafter called as AL), glass-bead abrasion (hereinafter called as GB), or 9.5% hydrofluoric acid etching (hereinafter called as ET) (n = 10, respectively). Surface roughness (Ra) was measured with a 3D confocal laser microscope. Treated specimens were cemented to 3D-printed resin abutment specimens with the same translucent resin cement, and CIELAB coordinates were recorded using a spectrophotometer with black and white backgrounds to calculate CIEDE2000 color difference (ΔE₀₀) and translucency parameter (TP₀₀). Surface microstructures and elemental compositions were assessed by field-emission scanning electron microscopy (hereinafter abbreviated as FE-SEM) and energy-dispersive x-ray spectroscopy (hereinafter abbreviated as EDS). Data were analyzed using one-way or Welch ANOVA with post hoc tests and Pearson correlation (α = 0.05).

Ra decreased in the order of AL>GB > ET (p < 0.001). ET (with the lowest Ra) showed greater ΔE₀₀ and lower TP₀₀ than AL and GB (p < 0.001), though no significant correlations between Ra and either ΔE₀₀ or TP₀₀ were found in it. However, in AL and GB, larger ΔE₀₀ and lower TP₀₀ correlated with higher Ra (p < 0.05). Etched (ET) surfaces showed distinct open micro-porosity and reduced Si with increased F and Na.

Hydrofluoric acid etching of the nano-hybrid ceramic intaglio surface resulted in greater color difference and lower translucency after cementation than alumina or glass-bead airborne-particle abrasion. Surface roughness was associated with ΔE₀₀ and TP₀₀ only in the airborne-particle abrasion groups.

For nano-hybrid ceramic restorations, the intaglio surface-conditioning method can influence post-cementation color difference and translucency. Under the present in vitro conditions, alumina and glass-bead airborne-particle abrasion produced smaller color differences and higher translucency than the evaluated hydrofluoric acid-etching protocol, suggesting that these treatments may be more favorable when shade matching and translucency preservation are clinically prioritized.