The structure and microstructure of dental porcelain in relationship to the firing conditions.

A scanning electron microscope and heating microscope are used to visualize the microstructure of dental porcelain during fabrication and demonstrate the relationships of the porcelain firing conditions to the translucency and hue of the completed restoration. The firing cycle, temperature, rate of temperature rise, holding time, and cooling time influence the distribution of the sintering, glass, and crystal phases in the microstructure of the porcelain. Observing the changes of fritted porcelain and opacifiers as they progress through the firing cycle demonstrates how the quality of the final ceramic restoration is largely dependent on the firing conditions chosen.