Zogheib, Lucas VillaçaDella Bona, AlvaroKimpara, Estevão Tomomitsu [UNESP]Mccabe, John F.2014-05-272014-05-272011-05-13Brazilian Dental Journal, v. 22, n. 1, p. 45-50, 2011.0103-64401806-4760http://hdl.handle.net/11449/72424The aim of this study was to examine the effect of different acid etching times on the surface roughness and flexural strength of a lithium disilicate-based glass ceramic. Ceramic bar-shaped specimens (16 mm x 2 mm x 2 mm) were produced from ceramic blocks. All specimens were polished and sonically cleaned in distilled water. Specimens were randomly divided into 5 groups (n=15). Group A (control) no treatment. Groups B-E were etched with 4.9% hydrofluoric acid (HF) for 4 different etching periods: 20 s, 60 s, 90 s and 180 s, respectively. Etched surfaces were observed under scanning electron microscopy. Surface profilometry was used to examine the roughness of the etched ceramic surfaces, and the specimens were loaded to failure using a 3-point bending test to determine the flexural strength. Data were analyzed using one-way ANOVA and Tukey's test (α=0.05). All etching periods produced significantly rougher surfaces than the control group (p<0.05). Roughness values increased with the increase of the etching time. The mean flexural strength values were (MPa): A=417 ± 55; B=367 ± 68; C=363 ± 84; D=329 ± 70; and E=314 ± 62. HF etching significantly reduced the mean flexural strength as the etching time increased (p=0.003). In conclusion, the findings of this study showed that the increase of HF etching time affected the surface roughness and the flexural strength of a lithium disilicate-based glass ceramic, confirming the study hypothesis.45-50engCAD/CAMFlexural strengthHydrofluoric acidLithium disilicate glass ceramicRoughnesshydrofluoric acidlithia disilicatechemistrydental acid etchingdental bondingdental carematerials testingmethodologypliabilityrandomizationscanning electron microscopysurface propertytimetooth prosthesisAcid Etching, DentalDental BondingDental PorcelainDental Stress AnalysisHydrofluoric AcidMaterials TestingMicroscopy, Electron, ScanningPliabilityRandom AllocationSurface PropertiesTime FactorsArtigo10.1590/S0103-64402011000100008S0103-64402011000100008Acesso aberto2-s2.0-799557562572-s2.0-79955756257.pdf09679163886657540000-0003-0586-4644