Effect of sintering temperature on crystal structure, optical and thermal properties, and surface roughness and topography of nanolithium disilicate and zirconia-reinforced nanolithium silicate ceramics.

Purpose: This study evaluated the effects of sintering temperature on the crystal structure, optical and thermal properties, and surface roughness and topography of nanolithium disilicate ceramics (NLDS) and zirconia-reinforced nanolithium silicate ceramics (ZNLS).

Methods: One hundred and twenty specimens of each ceramics were prepared and divided into 4 groups on the basis of sintering temperature. The specimens were then subjected to X-ray diffraction (XRD), spectrophotometric analysis of optical properties, differential thermal analysis (DTA), thermal gravimetrical analysis (TGA), roughness analysis, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) spectrometry. The data were analyzed using one-way analysis of variance followed by Tukey's test (α = 0.05)Results: XRD confirmed the presence of lithium disilicate, lithium phosphate, lithium metasilicate, and quartz in NLDS and ZNLS specimens. TGA, DTA, and average roughness did not significantly differ between groups (P < 0.05). Among NLDS groups, NLDS4 had ∆E values that significantly differed from those of the other groups (P < 0.05). EDX showed that NLDS2 had the highest Si value (25.3 ± 0.1 wt%) followed by NLDS4 (24.8 ± 0.1 wt%). Among ZNLS groups, ZNLS2-4 had a clinically acceptable ∆E. EDX analysis showed no significant difference for any group.

Conclusion: Sintering temperature did not affect the evaluated properties of NLDS. However, sintering ZNLS at different temperatures might affect the tested properties.