title: Surface characterization of lithium disilicate ceramic after nonthermal plasma treatment.
abstract: BACKGROUND
  Surface transformation with nonthermal plasma may be a suitable treatment for dental ceramics, because it does not affect the physical properties of the ceramic material.
  
  
  OBJECTIVE
  The purpose of this study was to characterize the chemical composition of lithium disilicate ceramic and evaluate the surface of this material after nonthermal plasma treatment.
  
  
  METHODS
  A total of 21 specimens of lithium disilicate (10 mm in diameter and 3 mm thick) were fabricated and randomly divided into 3 groups (n=7) according to surface treatment. The control group was not subjected to any treatment except surface polishing with abrasive paper. In the hydrofluoric acid group, the specimens were subjected to hydrofluoric acid gel before silane application. Specimens in the nonthermal plasma group were subjected to the nonthermal plasma treatment. The contact angle was measured to calculate surface energy. In addition, superficial roughness was measured and was examined with scanning electron microscopy, and the chemical composition was characterized with energy-dispersive spectroscopy analysis. The results were analyzed with ANOVA and the Tukey honestly significant difference test (α=.05).
  
  
  RESULTS
  The water contact angle was decreased to 0 degrees after nonthermal plasma treatment. No significant difference in surface roughness was observed between the control and nonthermal plasma groups. Scanning electron microscopy and energy-dispersive spectroscopy images indicated higher amounts of oxygen (O) and silicon (Si) and a considerable reduction in carbon (C) in the specimens after nonthermal plasma treatment.
  
  
  CONCLUSIONS
  Nonthermal plasma treatment can transform the characteristics of a ceramic surface without affecting its surface roughness. A reduction in C levels and an increase in O and Si levels were observed with the energy-dispersive spectroscopy analysis, indicating that the deposition of the thin silica film was efficient.
authors.affiliation: Graduate student, Graduate Program in Dentistry, Department of Dental Materials and Prosthodontics, Araçatuba Dental School, São Paulo State University (UNESP), Araçatuba, São Paulo, Brazil.
authors.forename: Aljomar José
authors.initials: AJ
authors.lastname: Vechiato Filho
authors.affiliation: Professor, Department of Dental Materials and Prosthodontics, Araçatuba Dental School, São Paulo State University (UNESP), Araçatuba, São Paulo, Brazil. Electronic address: danielamicheline@foa.unesp.br.
authors.forename: Daniela Micheline
authors.initials: DM
authors.lastname: dos Santos
authors.affiliation: Professor, Department of Dental Materials and Prosthodontics, Araçatuba Dental School, São Paulo State University (UNESP), Araçatuba, São Paulo, Brazil.
authors.forename: Marcelo Coelho
authors.initials: MC
authors.lastname: Goiato
authors.affiliation: Graduate student, Graduate Program in Dentistry, Department of Dental Materials and Prosthodontics, Araçatuba Dental School, São Paulo State University (UNESP), Araçatuba, São Paulo, Brazil.
authors.forename: Rodrigo Antonio
authors.initials: RA
authors.lastname: de Medeiros
authors.affiliation: Graduate student, Graduate Program in Dentistry, Department of Dental Materials and Prosthodontics, Araçatuba Dental School, São Paulo State University (UNESP), Araçatuba, São Paulo, Brazil.
authors.forename: Amália
authors.initials: A
authors.lastname: Moreno
authors.affiliation: Graduate student, Graduate Program in Dentistry, Department of Dental Materials and Prosthodontics, Araçatuba Dental School, São Paulo State University (UNESP), Araçatuba, São Paulo, Brazil.
authors.forename: Liliane da Rocha
authors.initials: Lda R
authors.lastname: Bonatto
authors.affiliation: Professor, Laboratory of Technological Plasmas, Engineering College, São Paulo State University (UNESP), Sorocaba, São Paulo, Brazil.
authors.forename: Elidiane Cipriano
authors.initials: EC
authors.lastname: Rangel
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D001128:Argon / Q000737:chemistry; D002244:Carbon / Q000032:analysis; D002516:Ceramics / Q000737:chemistry*; D003775:Dental Polishing / Q000295:instrumentation; D003776:Dental Porcelain / Q000737:chemistry*; D006358:Hot Temperature; D006801:Humans; D006858:Hydrofluoric Acid / Q000737:chemistry; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010100:Oxygen / Q000032:analysis; D058626:Plasma Gases / Q000737:chemistry*; D011897:Random Allocation; D012821:Silanes / Q000737:chemistry; D012825:Silicon / Q000032:analysis; D012822:Silicon Dioxide / Q000737:chemistry; D012833:Siloxanes / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties; D013500:Surface Tension; D013997:Time Factors; D017155:Wettability
chemical_list: C508050:IPS e.max Press; D058626:Plasma Gases; D012821:Silanes; D012833:Siloxanes; C493120:lithia disilicate; D003776:Dental Porcelain; D001128:Argon; D002244:Carbon; D012822:Silicon Dioxide; C015917:hexamethyldisiloxane; D006858:Hydrofluoric Acid; D010100:Oxygen; D012825:Silicon