Josephine, M Russ
| Josephine, M Russ |
Josephine, M Russ1, Marina Kaizer2, Sonaj Vardhaman1
Yu Zhang1
1Preventive and Restorative Sciences, University of Pennsylvania, School of Dental Medicine; 2Restorative, Positivo University Brazil
Introduction
Modifying elastic gradient on the intaglio surface of ceramics can effectively increase occlusal load bearing capacity. The aim of the study was to compare the load bearing capacity of graded lithium disilicate (LiDi) and various zirconia compositions (3Y, 4Y, and 5Y-PSZ) to their monolithic counterparts.
Methods
The experimental group consisted of 1.00 mm thick samples (n = 10) of lithium disilicate (LiDi), 3Y-PSZ (3Y), 4Y-PSZ (4Y), and 5Y-PSZ (5Y) each. Zirconia samples were pre-sintered (1350°C for 1h) prior to glass-infiltration. An in-house glass was applied to the intaglio surface and a second round of sintering carried out (3Y at 1530°C for 2h, 4Y and 5Y at 1450°C for 2h). LiDi blue blocks were treated with two layers of e.max CAD Glaze Spray on the intaglio surface at 1 foot followed by crystallization per manufacturer’s recommendation. The control group included 1.00 mm samples (n = 10; ΙΈ12 × 1 mm) of each material without any glaze spray treatment. All samples were cemented to a dentin analog material (G10) and the ceramic/cement/dentin modeling system was subjected to Hertzian indentation testing. The plate on foundation theory was used to validate load bearing capacity analyses.
Results
Graded (G) ceramics bonded to a dentin-like substrate show an increase in load-bearing capacity as compared to the non-infiltrated monolithic counterparts as follows (N): G3Y=1768 (89); 3Y=1355 (149); G4Y=1559 (113); 4Y=1232 (120); G5Y=1249 (98); 5Y=970 (140); GLiDi=1136 (198); LiDi= 844 (84).
Conclusion
G4Y, G5Y, and GLiDi showed significant improvement (~30%) in load bearing capacity, and G3Y held the highest load bearing capacity.