title: Machinable glass-ceramics forming as a restorative dental material.
abstract: MgO, SiO(2), Al(2)O(3), MgF(2), CaF(2), CaCO(3), SrCO(3), and P(2)O(5) were used to prepare glass-ceramics for restorative dental materials. Thermal properties, phases, microstructures and hardness were characterized by DTA, XRD, SEM and Vickers microhardness. Three-point bending strength and fracture toughness were applied by UTM according to ISO 6872: 1997(E). XRD showed that the glass crystallized at 892°C (second crystallization temperature+20°C) for 3 hrs consisted mainly of calcium-mica and fluorapatite crystalline phases. Average hardness (3.70 GPa) closely matched human enamel (3.20 GPa). The higher fracture toughness (2.04 MPa√m) combined with the hardness to give a lower brittleness index (1.81 µm(-1/2)) which indicates that they have exceptional machinability. Bending strength results (176.61 MPa) were analyzed by Weibull analysis to determine modulus value (m=17.80). Machinability of the calcium mica-fluorapatite glass-ceramic was demonstrated by fabricating with CAD/CAM.
authors: Department of Materials Engineering, Kasetsart University, Bangkok, 10900 Thailand. fengddc@ku.ac.th
authors: Duangrudee
authors: D
authors: Chaysuwan
authors: Krongkarn
authors: K
authors: Sirinukunwattana
authors: Kanchana
authors: K
authors: Kanchanatawewat
authors: Greg
authors: G
authors: Heness
authors: Kimihiro
authors: K
authors: Yamashita