Objectives:
- Evaluate the flexural strength of multiple conventional veneering porcelains used for zirconia based restorations.
- Evaluate the effect of revising the peak firing temperature of Lavaª Ceram (3M/ESPE) on its flexural strength.
Materials and methods:
- Five conventional veneering porcelains were used: VITA VM¨9 (Vita-Zahnfabrik), Noritake Cerabien ZR (Noritake), NobelRondoª Zirconia (Nobel Biocare), Lavaª Ceram (3M/ESPE), Revised firing chart for Lavaª Ceram.
- Fifty bars were fabricated from the veneering porcelains. Powder slurry mix was condensed and vibrated into a silicon mold with dimensions of 26x3x4 mm. Bars were then fired according to each manufacturer's recommendation except for the revised Lavaª Ceram firing chart. Specimens were then tested by Three-point bend test using a universal testing machine (Instron) with crosshead speed of 0.5 mm/min.
Statistical analysis was done with ANOVA and Tukey post hoc test at p= 0.05.
Results:
Flexural strength data for the veneering porcelains were: VM¨9, 83.4±10.4 MPa; Noritake CZR, 74.2±9.9 MPa; NobelRondoª, 68.88±15.3 MPa; Lavaª Ceram, 77.3±12.7 MPa; and revised Lavaª Ceram, 97.6±7.9 MPa.
Conclusions:
There are some significant differences in the flexural strength among the veneering porcelains. Increasing the firing temperature of Lavaª Ceram will significantly improve its flexural strength.