Microstructure of dental porcelains in a laser-assisted rapid prototyping process.

Objectives: The goals of this study were to investigate the phase transformation and microstructure of dental porcelain bodies densified via a moving laser beam and to develop an understanding of how the microstructure of the dental porcelain varies with the laser processing condition and the position relative to the center of the laser beam.

Methods: A moving laser beam was used to scan and densify a commercial dental porcelain powder bed. The porcelain powder compact was also sintered using a furnace at different temperatures. The phase transformation and microstructure of these dental porcelain bodies were compared and investigated using a host of analytical instruments including scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, and quantitative image analysis.

Results: Based on the temperature dependence of the leucite content in the dental porcelain derived from the furnace-sintered samples, the temperature distribution in the dental porcelain body during laser densification was established. The microstructure of the laser-densified porcelain body was found to be dependent of the location relative to the center of the laser beam and the average laser densification temperature.

Significance: The understanding of how the microstructure of dental porcelain bodies varies with the laser processing condition and the location with respect to the center of the laser beam was developed. Based on this understanding, the laser processing condition has been optimized to achieve the desired microstructure and densification of dental porcelain bodies simultaneously.