Optical effects of a novel opaque liquid on the masking capacity and color stability of high-translucency pre-colored zirconia

This study aimed to develop and assess a novel opaque liquid for high-translucency pre-colored zirconia (HT-Zr) that enhances shade masking while maintaining the frame original shade and optical performance. Plate-shaped (8 × 8 × 1 mm) and crown-shaped A2-shaded HT-Zr specimens were prepared. Plates were assigned to seven groups: 3 opaque liquids with 2 numbers of applications conditions (single or triple) and one no-opaque control (n = 10 per group). Following application and sintering, light transmittance, penetration depth (PD), and penetration rate (PR) were evaluated. Color over different underlying substrates (white, A2, and metal) was measured; CIE L*a*b* and CIEDE2000 (ΔE 00 ) values were calculated using a transparent‑plate reference and interpreted using acceptability thresholds. The novel opaque liquid exhibited 13.94–21.28 % transmittance and the lowest PD (