Fracture toughness of experimental mica-based glass-ceramics and four commercial glass-ceramics restorative dental materials.

The mica-based glass-ceramics were prepared in the SiO-AlO-MgO-MgF-SrCO-CaCO-CaF-PO glass system. There were four mica-based glass-ceramics produced in this study according to the pigment added (CeO or Pr-ZrSiO/Fe-ZrSiO) and crystallization time (5-35 min). Four dental glass-ceramics, which were leucite-based, lithium disilicate-based and two zirconia reinforced lithium silicate ceramics, were also tested. The phase identification of mica-based glass-ceramics was performed using an X-ray diffractometer. The fracture toughness (K) was determined using the fractographic analysis approach. The one-way ANOVA was used to analyze the significant differences among the obtained K values at a=0.05. The results from the phase analysis showed that the mica glassceramics consisted of calcium-mica, fluorapatite and strontiumapatite. The K of mica-based glass-ceramics ranged between 1.36 to 1.53 MPa•m which were superior to only that of a leucite-based glass-ceramic. The shade and translucency of mica-based glassceramics appeared to be acceptable for dental application when compared with other dental glass-ceramics.