HYDROFLUORIC ACID ETCHING PATTERNS AND SURFACE MORPHOLOGY OF THREE SILICA-BASED CERAMIC MATERIALS

Abstract

Purpose: This study investigates the hydrofluoric acid etching patterns and the surface morphology of three types of glass-ceramic materials. Materials and methods: Hydrofluoric acid etching patterns and surface morphology changes of three silica-based ceramics - EX-3, E.max press, and Heraceram press were studied. Fourteen rectangular experimental bodies with a cross-section of 2x2mm and a length of 5-7 mm were divided into two groups(n=7): polished (control group) and etched (5% hydrofluoric acid). Etching time was 120s in EX-3 (EXHF) and Heraceram press (HHF) groups and 20s in E.max press group (EHF). Surface morphology was observed under a scanning electron microscope at magnifications ranging from x50 to x2700. Results: The presence of numerous pores and channels as a result of the etching procedure was observed in all ceramic materials. In the EXHF group, irregularly shaped structures and canals with a width of 10-20µm characterize the ceramic surface. At higher magnifications, microwells with a size of 1-2 µm and channels with a length of 5-10 µm were observed. In the EHF group, lithium disilicate crystals with different orientations and the glassy phase dissolved between them can be seen. Channels with a wavy course and a length of about 5 µm are also observed. In the HHF group, 5-20µm cavernous-like formations surrounded by partially dissolved channels can be seen. Conclusions: Each ceramic material showed different etching patterns due to the material's composition and the distribution of the crystalline and vitreous phases.