effect of p2os on crystallization behavior and chemical resistance of dental glasses in the li20-si02-zr02 system

Commercial dental lithium disilicate based glass-ceramics containing various amounts of p2o5 were synthesized. regarding the crystallization behavior and physico-chemical properties of the glasses, the optimum percent of pfo$ was determined as 8 %wt.crystallization behavior of the glasses was investigated by x-ray diffraction (xrd) and differential thermal analysis (dta). the micro-hardness and chemical resistance of both glass and glass-ceramic searies were also determined. according to our results, lithium phosphate was precipitated prior to crystallization of the main phases, i.e lithium meta silicate and lithium disilicate. this early precipitation led to evacuation of residual glass phase from lithium ions, which caused increasing the viscosity of glass and so shifting of crystallization to higher temperatures.in addition, increasing in p2o5 amounts and consequently increasing in li3po4, led to significant decrease in the crystallite size and aspect ratio of crystals.furthermore, while the chemical resistance of the glasses was decreased with pfo^, it was increased with pfo^ after heat treatment process. the chemical solubility of the glass-ceramics was between 2080 and 1188 pg/cm^2.