title: Surface degradation of lithium disilicate ceramic after immersion in acid and fluoride solutions.
abstract: OBJECTIVE
  To analyze whether immersion in sodium fluoride (NaF) solutions and/or common acidic beverages (test solutions) would affect the surface roughness or topography of lithium disilicate ceramic.
  
  
  METHODS
  220 ceramic discs were divided into four groups, each of which was subdivided into five subgroups (n = 11). Control group discs were immersed in one of four test beverages for 4 hours daily or in artificial saliva for 21 days. Discs in the experimental groups were continuously immersed in 0.05% NaF, 0.2% NaF, or 1.23% acidulated phosphate fluoride (APF) gel for 12, 73, and 48 hours, respectively, followed by immersion in one of the four test beverages or artificial saliva. Vickers microhardness, surface roughness, scanning electron microscopy (SEM) associated with energy dispersive spectroscopy, and atomic force microscopy (AFM) assessments were made. Data were analyzed by nested analysis of variance (ANOVA) and Tukey's test (α = 0.05).
  
  
  RESULTS
  Immersion in the test solutions diminished the microhardness and increased the surface roughness of the discs. The test beverages promoted a significant reduction in the Vickers microhardness in the 0.05% and 0.2% NaF groups. The highest surface roughness results were observed in the 0.2% NaF and 1.23% APF groups, with similar findings by SEM and AFM. Acidic beverages affected the surface topography of lithium disilicate ceramic. Fluoride treatments may render the ceramic surface more susceptible to the chelating effect of acidic solutions.
authors.forename: Aljomar José
authors.initials: AJ
authors.lastname: Vechiato-Filho
authors.forename: Daniela Micheline
authors.initials: DM
authors.lastname: Dos Santos
authors.forename: Marcelo Coelho
authors.initials: MC
authors.lastname: Goiato
authors.forename: Amália
authors.initials: A
authors.lastname: Moreno
authors.forename: Rodrigo Antonio
authors.initials: RA
authors.lastname: De Medeiros
authors.forename: Sidney
authors.initials: S
authors.lastname: Kina
authors.forename: Elidiane Cipriano
authors.initials: EC
authors.lastname: Rangel
authors.forename: Nilson Cristino
authors.initials: NC
authors.lastname: Da Cruz
mesh_terms: D000149:Acidulated Phosphate Fluoride / Q000737:chemistry; D001628:Beverages; D002253:Carbonated Beverages; D002327:Cariostatic Agents / Q000737:chemistry*; D032084:Citrus sinensis; D003069:Coffee; D003776:Dental Porcelain / Q000737:chemistry*; D004577:Electron Probe Microanalysis; D005459:Fluorides / Q000737:chemistry*; D005638:Fruit; D006244:Hardness; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D012464:Saliva, Artificial / Q000737:chemistry; D012969:Sodium Fluoride / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors; D014920:Wine
chemical_list: D002327:Cariostatic Agents; D003069:Coffee; D012464:Saliva, Artificial; C493120:lithia disilicate; D003776:Dental Porcelain; D000149:Acidulated Phosphate Fluoride; D012969:Sodium Fluoride; D005459:Fluorides