Abstract: Objective To investigate whether the acid etching has an influence on the surface morphology and internal microstructure of the machinable ceramic. Methods 32 resin infiltration ceramics and lithium disilicate glass ceramic specimens each having a size of 4 mm × 4 mm × 2 mm were prepared. After grinding and cleaning, they were randomly divided into 4 groups (n=8): (1) 4% hydrofluoric acid 20 s, (2) 9.5% hydrofluoric acid, 20 s, (3) MBEP all-ceramic treatment solution, 20 s, (4) control group. The surface roughness and three-dimensional shape of the test piece were measured by AFM, and the Si/C ratio of the resin-infiltrated ceramic and the Si/K ratio of the lithium disilicate glass ceramic were detected by EDS. Results The surface roughness parameters of the 4% and 9.5% hydrofluoric acid treated specimens of the two materials were higher than those of the control group. The Si/C ratio of the 4% and 9.5% hydrofluoric acid treated groups of the resin-infiltrated ceramics was lower than that of the control group. Scanning electron microscopy showed that the 9.5% hydrofluoric acid treatment group of both materials had a more aggressive surface etching pattern, and the all-ceramic treatment group produced a similar surface etching pattern to the control group. Conclusions Acid etching affects the surface topography and internal micro-structure of the two machinable ceramics. MBEP all-ceramic treatment liquid has a mild acid etching ability.

Key words: 【Key words】ceramics, hydrofluoric acid, all-ceramic treatment liquid, scanning electron microscope, energy spectrum analysis