title: [Studies on the saliva adsorption and the salivary film property on the hydroxyapatite surface].
abstract: OBJECTIVE
  To evaluate the thickness and viscoelasticity of whole saliva (WS), parotid saliva (PS) and submandibular/sublingual gland saliva (SMSLS) film adsorption on the hydroxyapatite (HA) surface.
  
  
  METHODS
  Ultra-thin layer of HA nanocrystals was coated on the dissipation TiO(2) sensor of gold quartz crystal microbalance using electrophoretic deposition technique. The thickness of the HA layer was measured by the ellipsometer, and element analysis was conducted using X-ray photoelectron spectroscopy. Atomic force microscopy and scanning electron microscope were used to observe its morphology. The in-situ adsorption thickness, the shear elastic modulus and the shear viscosity of salivary layers (WS, PS and SMSLS) on HA surfaces were investigated. The statistical data were analysed by an one-way ANOVA analysis followed by a SNK-q test.
  
  
  RESULTS
  The results show that the HA layer was a plate-like morphology with 1.53 ± 0.12 in Ca/P molar ratio, (19.1 ± 0.9) nm in the thickness and (6.5 ± 1.6) nm in the roughness. The thickness of salivary film was SMSLS [(21.84 ± 1.25) nm] > WS[(17.91 ± 1.35) nm] > PS [(14.30 ± 1.03 nm) (P < 0.05). The shear elastic modulus of salivary film was PS [(0.61 ± 0.01) MPa] > SMSLS [(0.31 ± 0.09) MPa] and WS [(0.25 ± 0.03) MPa] (P < 0.05). The trend of the shear viscosity was opposite to one of thickness.
  
  
  CONCLUSIONS
  The characteristics of saliva adsorption on HA surface suggest that the thicker, softer and more hydrated properties for the SMSLS and WS films are likely to afford a stronger lubrication to protect oral surfaces from wear and dehydration. The viscoelasticity of the PS film is probably related to the retention covering the oral cavity.
authors.affiliation: Department of Prosthodontics, Xiamen Dental Hospital, School of Stomatology, Fujian Medical University, Xiamen Fujian 361001, China. dentyjw@126.com
authors.forename: Jiang-wu
authors.initials: JW
authors.lastname: Yao
authors.forename: Guo-yang
authors.initials: GY
authors.lastname: Chen
authors.forename: Feng
authors.initials: F
authors.lastname: Lin
authors.forename: Chang-jian
authors.initials: CJ
authors.lastname: Lin
authors.forename: Tao
authors.initials: T
authors.lastname: Tao
mesh_terms: D000327:Adsorption; D000328:Adult; D017886:Durapatite / Q000737:chemistry*; D005260:Female; D006801:Humans; D008297:Male; D018625:Microscopy, Atomic Force; D010306:Parotid Gland / Q000378:metabolism*; D056951:Photoelectron Spectroscopy; D058525:Quartz Crystal Microbalance Techniques; D012463:Saliva / Q000737:chemistry*; D013361:Sublingual Gland / Q000378:metabolism*; D013363:Submandibular Gland / Q000378:metabolism*; D013499:Surface Properties; D014783:Viscosity; D055815:Young Adult
chemical_list: D017886:Durapatite