Nucleation efficacy and flexural strength of novel leucite glass-ceramics.

OBJECTIVES: To optimize the nucleation mechanism in leucite glass-ceramics to allow more efficacious glass-ceramic manufacture and improvements in microstructure and mechanical reliability. MATERIALS AND METHODS: An alumino-silicate glass was designed and synthesized using melt quench methods. The glass was crushed and milled using various milling times (48-93h) and spray drying. Nucleation and growth heat treatment schedules were applied to synthesize glass-ceramics. Glass/glass-ceramic powders and frit specimens were characterized using differential scanning calorimetry (DSC), transmission electron microscopy (TEM), energy-dispersive X-ray spectrometry (EDX), magic angle spinning nuclear magnetic resonance spectroscopy (MAS-NMR) and X-ray diffraction analyses (XRD). Glass-ceramic specimens were tested using the biaxial flexural strength test (BFS). RESULTS: Application of defined nucleation heat treatments resulted in the synthesis of Na/Ca titanates. NMR indicated changes to the (23)Na glass spectra in the nucleated glass and TEM/EDX the presence of Na/Ca/Ti domains ( 0.05). SIGNIFICANCE: Na/Ca titanates were synthesized in leucite glass-ceramics for the first time and associated with its nucleation and efficacious growth. This nucleation optimization provides opportunities for more efficient manufacturing and microstructural/mechanical reliability improvements. Improved synthesis of high strength/reliable leucite glass-ceramics is useful for construction of esthetic minimally invasive restorations.