Machinable glass-ceramics forming as a restorative dental material

Abstract

MgO, SiO2, Al2O3, MgF2, CaF2, CaCO3, SrCO3, and P2O5 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 micafluorapatite glass-ceramic was demonstrated by fabricating with CAD/CAM.

Optical and Mechanical Properties of Newly Developed Monolithic Multilayer Zirconia

“…For each specimen, the brittleness index (B) was given by the ratio of hardness (Hv) to fracture toughness K Ic as follows: …”

A systematic review of CAD/CAM fit restoration evaluations

“…The analysis of the results of the studies included in this review shows that the marginal fit ranges from 39Á1 to 201 lm and the internal fit varies from 23 to 230 lm (157)(158)(159)(160)(161)(162)(163)(164)(165)(166)(167)(168). Two studies used the Cerec 3D system to evaluate the cervical adaptation of laminates.…”

Two-body wear rate of CAD/CAM resin blocks and their enamel antagonists

“…Furthermore, it was reported that polymeric CAD/CAM resins exhibited similar color stability to glass-ceramic. 5 The mechanical properties, such as flexural strength of glass-ceramic, 6 are comparable to resins, 7 but the hardness values of glass-ceramic 8 are higher than those of resins. 7 An advantage of all resin-based materials is their plastic deformability, which could prevent the spontaneous fracture of the restoration.…”