Effect of PEG-based binder concentration on the mechanical properties of lithium disilicate glass-ceramics prepared by low-pressure injection moulding

Abstract

Lithium disilicate (LD) glass-ceramics are extensively employed in restorative dentistry because their superior aesthetic properties and hardness are similar to natural teeth. The aim of this work is to investigate the mechanical properties and chemical solubility of lithium disilicate glass-ceramics prepared by the low-pressure injection moulding using the PEG-based binder. The glass-to-binder ratio was varied as 60:40, 55:45, 50:50 and 45:55 vol.%. The sintering conditions of 800°C with 2 h dwell time were selected according to thermal analysis. Phase formation, microstructure and mechanical properties of the prepared samples were characterized by XRD, SEM, microhardness and three-point bending test, respectively. Besides, the chemical solubility of the system was investigated by the immersion test in acetic acid solution. XRD analyses of the sintered sample confirmed the presence of only one prominent crystalline phase of LD. SEM result showed that the porosity increased with decreasing glass powder content. The mechanical properties of the LD glass-ceramic samples tended to decrease when the proportion of the glass powder decreased, while the chemical solubility tended to increase. The mechanical properties of the glass-ceramics, i.e. the highest density value, Vickers hardness and flexural strength were 2.55 g/cm3, 6.80GPa, and 176MPa, respectively. These results could be useful in developing these LD glass-ceramics for their optimal use in dental applications.

Keywords

• lithium disilicate
• injection moulding
• mechanical properties
• dental materials