aim of the study : This study was designed to set up proper laser parameters including laser type, power intensity and time of application for glazing of a particular glass-ceramic.
The effect of laser glazing of the glass-ceramics on structural and roughness was investigated, evaluated and compared with the recommended glazing technique.
material and methods :The materials used in this study were two commercially available lithium disilicate ceramics, fabricated by two different techniques: conventional lost wax (Injectable heat – pressed) and machinable Computer Aided Design / Computer Aided Manufacturing (CAD/ CAM) techniques. A total of 50 ceramic samples in the form of discs (5mm diameter and 2 mm thickness). For CAD/ CAM samples, a total of 50 discs were done sequentiallyin the Cerec 3 CPUacquisition unit. Two glazing techniques were adopted to the studied ceramic samples namely; conventional glazing and laser glazing. For each material subjected to the different glazing protocols structural Analysis, Surface Roughness was measured before and after glazing using white light Profilometry.
results: Results of surface roughness (Ra) of the two investigated materials; IPS E-max press and IPS E-max CAD using two different surface treatments; conventional glazing and laser glazing in comparison to the control group are presented. For of M1; IPS E-max press material ANOVA results showed that the control group had the significantly highest surface roughness followed by laser glazing, while the conventional glazing showed the significantly lowest mean surface roughness (p <0.001). Regarding M2; IPS E-max CAD material no significantly difference was found between conventional glazing and laser glazing.
conclusions:Within the limitations of the current study, the following conclusions were drawn:
1. Conventional glazing can be considered as the most reliable glazing technique as regard surface roughness. 2. Laser glazing with high power density increased the surface roughness of lithium silicate based ceramics.