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 SiO₂-Al₂O₃-MgO-MgF₂-SrCO₃-CaCO₃-CaF₂-P₂O5 glass system. There were four mica-based glass-ceramics produced in this study according to the pigment added (CeO₂ or Pr-ZrSiO₄/Fe-ZrSiO₄) 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_IC) was determined using the fractographic analysis approach. The one-way ANOVA was used to analyze the significant differences among the obtained K_IC 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_IC of mica-based glass-ceramics ranged between 1.36 to 1.53 MPa•m^1/2 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.