Clinical Adjustment of Zirconia-Reinforced Lithium Silicate and Lithium Disilicate Restorations Should Be Performed Before Crystallization

The objective of this study was to evaluate the biaxial flexural strength of zirconia-reinforced lithium silicate (ZLS, Suprinity, Vita Zahnfabrik, Bad Säckingen, Germany) and lithium disilicate (LDS, IPS e.max CAD, Ivoclar Vivadent, Schaan, Liechtenstein) discs after abrasion with a diamond tip, before or after crystallization of the ceramic. Discs of 1.2 × 15 mm dimensions were fabricated. The samples were separated into two groups: AC—abrasion with a diamond tip before material crystallization, and CA—material crystallization and subsequent abrasion with a diamond tip (n = 15). The initial roughness was measured before abrasion/crystallization, and final measurement was performed after abrasion/crystallization/polishing. The abraded surface was placed downward during the biaxial flexural strength test, and the data were recorded. The final roughness was significantly higher compared to the initial roughness in all groups. The ZLS-AC and LDS-AC groups (both materials with abrasion prior to material crystallization) showed higher biaxial flexural strength values than groups that underwent abrasion before crystallization. This study concluded that the clinical adjustment performed by abrasion with the diamond tip of glass ceramics lithium disilicate and zirconia-reinforced lithium silicate carried out prior to crystallization favored the resistance of the ceramics.