title: Surface-layer modification of hydroxyapatite ceramic with acid and heat treatments.
abstract: The purpose of this study was to examine or characterize the surface layer of a calcium phosphate ceramic with a gradual compositional change from alpha-tricalcium phosphate (alpha-TCP) on the surface to hydroxyapatite (HAP) on the inside. The surface of a dense HAP ceramic was acid-treated for 1 hour with orthophosphoric acid (H3PO4) solutions of several concentrations (0.5, 1.0 and 5.0 mol/L) or a buffered solution (pH 4.0) consisting of phosphate solutions. After acid treatment, specimens were heat-treated at 1,250 degrees C for 1 hour. X-ray photoelectron spectroscopy revealed that the compositional gradient layer could be modified on the surface of the HAP ceramic with all acid and heat treatments, and that 5.0 mol/L H3PO4 solution and heat treatments had a maximal thickness of approximately 2 microm for the surface-modified layer. It was confirmed that the outermost layer of HAP ceramics modified with the treatments, except 5.0 mol/L H3PO4 solution, showed a compound such alpha-TCP.
authors.affiliation: Department of Dental Engineering, School of Dentistry, Tokushima University, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kon
authors.forename: Luciana M
authors.initials: LM
authors.lastname: Hirakata
authors.forename: Youji
authors.initials: Y
authors.lastname: Miyamoto
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Kawano
authors.forename: Kenzo
authors.initials: K
authors.lastname: Asaoka
mesh_terms: D000143:Acids / Q000737:chemistry; D001672:Biocompatible Materials / Q000737:chemistry*; D002021:Buffers; D002118:Calcium / Q000737:chemistry; D002130:Calcium Phosphates / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry*; D004577:Electron Probe Microanalysis; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D010710:Phosphates / Q000737:chemistry; D010756:Phosphoric Acids / Q000737:chemistry; D010758:Phosphorus / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013997:Time Factors; D014961:X-Ray Diffraction
chemical_list: D000143:Acids; D001672:Biocompatible Materials; D002021:Buffers; D002130:Calcium Phosphates; D010710:Phosphates; D010756:Phosphoric Acids; D010758:Phosphorus; D017886:Durapatite; D002118:Calcium