Using glass-graded zirconia to increase delamination growth resistance in porcelain/zirconia dental structures

• Published in: Dental materials 2018-01, Vol.34 (1), p.e8-e14
• Main Authors: Chai, Herzl, Mieleszko, Adam J., Chu, Stephen J., Zhang, Yu
• Format: Article
• Language: English
• Subjects: All-ceramic dental restorations; Aluminum Silicates - chemistry; Dental Materials - chemistry; Dental Porcelain - chemistry; Dental Prosthesis Design; Dental Restoration Failure; Dental Stress Analysis; Dental Veneers; Hardness; Interfacial fracture energy; Materials Testing; Porcelain fused to zirconia; Porcelain-veneered graded zirconia; Potassium Compounds - chemistry; Surface Properties; Zirconium - chemistry
• ISSN: 0109-5641; 1879-0097
• DOI: 10.1016/j.dental.2017.11.004

Porcelain fused to zirconia (PFZ) restorations are widely used in prosthetic dentistry. However, their tendency to delaminate along the P/Z interface remains a practical problem so that assessing and improving the interfacial strength are important design aspects. This work examines the effect of modifying the zirconia veneering surface with an in-house felspathic glass on the interfacial fracture resistance of fused P/Z. Three material systems are studied: porcelain fused to zirconia (control) and porcelain fused to glass-graded zirconia with and without the presence of a glass interlayer. The specimens were loaded in a four-point-bend fixture with the porcelain veneer in tension. The evolution of damage is followed with the aid of a video camera. The interfacial fracture energy GC was determined with the aid of a FEA, taking into account the stress shielding effects due to the presence of adjacent channel cracks. Similarly to a previous study on PFZ specimens, the fracture sequence consisted of unstable growth of channel cracks in the veneer followed by stable cracking along the P/Z interface. However, the value of GC for the graded zirconia was approximately 3 times that of the control zirconia, which is due to the good adhesion between porcelain and the glass network structure on the zirconia surface. Combined with its improved bonding to resin-based cements, increased resistance to surface damage and good esthetic quality, graded zirconia emerges as a viable material concept for dental restorations.