Compatibility Evaluation of Ce-TZP/Al₂O₃ Nanocomposite and Porcelain for Zirconia

Objectives: The aim of the study is to evaluate the compatibility between Ce-TZP/Al₂O₃ Nanocomposite and a porcelain for zirconia core. Methods: (1) Ce-TZP/Al₂O₃ Nanocomposite (MACZ-100, Matsushita Electric Works, Ltd.) and porcelain for zirconia Vintage ZR (VZR, Shofu, Inc.) were measured for their thermal expansion coefficients (TEC) at 25 - 500°C. (2) A plate of MACZ-100 was sandblasted with alumina, rinsed with water, and heat-treated. Then an opaque liner porcelain of VZR was applied at the center of the MACZ-100 plate. After firing, the plate was built up with a body porcelain, and fired again. After shaping and self-glazing, the plate was used as a test specimen. Shear bond strength (SBS) was measured using a universal testing machine at a crosshead speed of 1mm/min. (3) A posterior 3-unit bridge fabricated using MACZ-100 was built up with VZR and its compatibility for use was evaluated. (4) Single-crown copings fabricated using MACZ-100 were built up with VZR (A2, A3, A3.5). Shades of the crowns were visually compared with the shade guides. Results: (1) TEC of MACZ-100 and VZR were 10.1 x 10^-6K^-1 and 9.4 x 10^-6K^-1, respectively. (2) SBS between MACZ-100 and VZR was 27.1 MPa (SD=5.7). For comparison, SBS between a metal and a porcelain was measured in the similar manner, which resulted in 22.8 MPa (SD=2.8). No significant difference in SBS was observed between the MACZ-100/VZR and the metal/porcelain specimens (Tukey test, p>0.05). (3) VZR applied on a clinical model had no problem for use, without any cracks after self-grazing. (4) The shades of the fabricated single crowns favorably matched the shade guides with visual comparison. Conclusion: The results above suggested that VZR, a porcelain for zirconia, has potential for clinical application in combination with ceramic frameworks fabricated with Ce-TZP/Al₂O₃ Nanocomposite.