title: Does acid etching morphologically and chemically affect lithium disilicate glass ceramic surfaces?
abstract: BACKGROUND
  This study evaluated the surface morphology, chemical composition and adhesiveness of lithium disilicate glass ceramic after acid etching with hydrofluoric acid or phosphoric acid.
  
  
  METHODS
  Lithium disilicate glass ceramic specimens polished by 600-grit silicon carbide paper were subjected to one or a combination of these surface treatments: airborne particle abrasion with 50-μm alumina (AA), etching with 5% hydrofluoric acid (HF) or 36% phosphoric acid (Phos), and application of silane coupling agent (Si). Stainless steel rods of 3.6-mm diameter and 2.0-mm height were cemented onto treated ceramic surfaces with a self-adhesive resin cement (Clearfil SA Cement). Shear bond strengths between ceramic and cement were measured after 24-hour storage in 37°C distilled water.
  
  
  RESULTS
  SEM images of AA revealed the formation of conventional microretentive grooves, but acid etching with HF or Phos produced a porous surface. Bond strengths of AA+HF+Si (28.1 ± 6.0 MPa), AA+Phos+Si (17.5 ± 4.1 MPa) and HF+Si (21.0 ± 3.0 MPa) were significantly greater than those of non-pretreated controls with Si (9.7 ± 3.7 MPa) and without Si (4.1 ± 2.4 MPa) (p&lt;0.05). In addition, HF etching alone (26.2 ± 7.5 MPa) had significantly higher bond strength than AA alone (11.5 ± 4.0 MPa) (p&lt;0.05). AA+HF, AA+Phos and HF showed cohesive failures.
  
  
  CONCLUSIONS
  Etching with HF or Phos yielded higher bond strength between lithium disilicate glass ceramic and self-adhesive resin cement without microcrack formation.
authors.affiliation: Occlusion and Removable Prosthodontics, Okayama University, Okayama - Japan.
authors.forename: Yukinori
authors.initials: Y
authors.lastname: Maruo
authors.affiliation: Occlusion and Removable Prosthodontics, Okayama University, Okayama - Japan.
authors.forename: Goro
authors.initials: G
authors.lastname: Nishigawa
authors.affiliation: Department of Biomaterials, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama - Japan.
authors.forename: Masao
authors.initials: M
authors.lastname: Irie
authors.affiliation: Center for Innovative Clinical Medicine, Okayama University, Okayama - Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Yoshihara
authors.affiliation: Department of Biomaterials, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama - Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Matsumoto
authors.affiliation: Department of Occlusal and Oral Functional Rehabilitation, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama - Japan.
authors.forename: Shogo
authors.initials: S
authors.lastname: Minagi
mesh_terms: D003776:Dental Porcelain / Q000737:chemistry*; D005898:Glass / Q000737:chemistry*; D006851:Hydrochloric Acid / Q000737:chemistry*; D010756:Phosphoric Acids / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D010756:Phosphoric Acids; C493120:lithia disilicate; D003776:Dental Porcelain; C030242:phosphoric acid; D006851:Hydrochloric Acid