AnáLisis FESEM de Porosidades Superficiales y Patrón Grabado con HF de ceráMica de Vidrio de Disilicato de Litio Avanzada (CEREC-Tessera)

Objectives: To compare surface treatments with hydrofluoric acid (HF) on advanced lithium disilicate glass-ceramic (LD). Also, to characterize LD surface porosities.
Methods: Two specimens (1mm X 1mm X 12mm) were cut from 2 advanced LD blocks (CEREC Tessera, Dentsply Sirona, Hanau-Wolfgang, Germany) using a diamond-coated saw in a precision cutting machine (Isomet 1000, Buehler) under water cooling. Specimens were polished up to 2400-grit SiC paper. Then, fired in a furnace (Programat, Ivoclar Vivadent) following manufacturers’ recommended firing time. Specimens were divided into 3 parts according to surface treatment: Group 1 = None surface treatment (control); Group 2 = 4.5% HF (Ivoclar Vivadent) for 30 sec; and, Group 3 = 10% HF (Dentsply) for 30 sec. Then, specimens were cleaned ultrasonically, air-dried, left in vacuum desiccator for 24h, mounted in stubs, sput-coated, and observed under field-emission scanning electron microscope (JEOL) at magnifications of 5,000X to 40,000X.
Results: Control group showed smooth surface without retentive features for bonding perspective; also, ≈2 by ≈10µm-wide elliptic microporosites were depicted. LD/4.5%HF resulted in the most consistent ceramic etching pattern with an array of exposed crystals without over-etched areas. LD/10%HF specimens displayed the most pronounced etching pattern with over-etched areas and unsupported crystals. LD crystals rectangular size ranged from ≈100 by ≈500nm to ≈300 by ≈500nm.
Conclusions: Conclusion: CEREC Tessera surface 4.5% HF-etched results in a retentive pattern without areas of over-etching. 10%HF should be avoided, as it results in over-etching ceramic surface.