Effect of thickness of zirconia framework on fracture strength and fracture mode of ceria-stabilized tetragonal zirconia polycrystals/alumina ceramic restoration on resin tooth abutment

Vibul Paisankobrit, DDS, Satoshi Omori, DDS, PhD, Rie Fujita, DDS, PhD, Yoji Ueda, DDS, PhD, Reina Nemoto, DDS, PhD, and Hiroyuki Miura, DDS, PhD

Fixed Prosthodontics, Department of Restorative Sciences, Division of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan

Purpose: This study aimed to evaluate the fracture strength and fracture mode of ceria-stabilized tetragonal zirconia polycrystals/alumina (Al2O3) nanocomposites (Ce-TZP/A) and yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) ceramic restorations in different thicknesses of frameworks on resin tooth abutments and to assess the usability of Ce-TZP/A ceramic restoration with thin zirconia frameworks.
Materials and Methods: Artificial maxillary second premolars were prepared for all-ceramic and metal-ceramic restoration. Then resin tooth abutments were duplicated. Four groups of zirconia-ceramic restoration framework were fabricated (n = 10): standard 0.5 mm thickness frameworks (Y-TZPs, Ce-TZP/As) for all-ceramic restoration preparation, and modified 0.3 mm thickness with palatal support frameworks (Y-TZPm, Ce-TZP/Am) for metal-ceramic restoration preparation. Porcelains were pressed. The restorations were fixed to resin abutment teeth and loaded vertically until fracture. The maximum fracture loads were recorded as fracture strengths. One-way ANOVA and post hoc test (Tukey’s HSD) were performed. The fracture modes were observed and statistically analyzed with Fisher’s exact test. All tests were used at a significant level of 0.05.
Results: The fracture strength of Ce-TZP/Am (2,824.1 ± 320.8 N) was significantly higher than Y-TZPm (2,399.7 ± 188.8 N) but was not significantly different from Ce-TZP/As (3,056.4 ± 337.1 N). There was no significant difference in fracture mode between groups.
Conclusion: Within the limitations of this study, Ce-TZP/A can be use with the thin modified design framework. Ce-TZP/Am provided good fracture strength and sufficiency for clinical use.
(Asian Pac J Dent 2017; 17: 31-40.)
Key Words: Ce-TZP/A, fracture strength, framework thickness, zirconia-ceramic restoration