Investigating Correlations Between Translucency And Surface Hardness In Lithium Alumina-silicate (LAS) Dental Glass-Ceramics

Abstract

Lithium aluminum silicate (LAS) glass-ceramics materials are promising or under investigation in the field of dental restorations, but are not currently the most widely used due to their aesthetic performance. However, their materials often exhibit lower hardness under intensive contact conditions compared to alternative prosthetic crown systems. This study aims to determine an optimal temperature–time schedule for the nucleation and crystallization processes of Li–Al–Si glass, as well as clarify the correlation between translucency and surface hardness .The heat treatment protocol was designed based on differential thermal analysis (DTA) results and established thermal protocols.  Nucleation was performed at a fixed temperature of 520°C for durations ranging from 0 to 60 minutes. Crystallization stages were conducted at 750°C and 900°C to evaluate the impact of crystal density (nucleation) and crystal growth (crystallization) on the materials properties. Vickers hardness (HV) was measured, with the highest value (~7.66 GPa) observed in samples treated at 750°C. The results indicate that optimal translucency (HTP) is achieved through a fine, homogeneously distributed crystalline phase, whereas uncontrolled crystal growth at higher temperatures leads to a decrease in the translucency parameter (TP), increasing opacity.