Studies on the saliva adsorption and the salivary film property on the hydroxyapatite surface / 中华口腔医学杂志

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSIONS</b>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.</p>

Adsorption kinetic study of the interaction between human salivary alpha-amylase and the polyphenoles from the black/green tea / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To explore the driving force of the oral astringency produced by the interaction of theaflavin (TF) and epigallocatechin-3-gallate (EGCG) to human salivary a-amylase(HSA).</p><p><b>METHODS</b>The constants of the rate, equilibrium of reaction (k(a), k(d), K(A), and K(D)) and Langmuir, Freundlich adsorption isotherm (K(L), K(f), and Mm) were determined by surface plasmon resonance (SPR) technique and adsorption kinetics.</p><p><b>RESULTS</b>Both of Langmuir and Freundlich models could be used for describing the binding processes of TF and EGCG onto HSA surfaces, and there were no significant differences of the correlation coefficient of determination between these two models (P > 0.05). The constants of adsorption isotherm, the rate and equilibrium constants of the association for TF were higher than those of EGCG (P < 0.05). The rate and equilibrium constants of the dissociation for TF were lower than those of EGCG (P < 0.05). The affinity of TF to HSA was higher than that of EGCG.</p><p><b>CONCLUSION</b>The sorely oral astringency is much easily produced by TF from the black tea rather than EGCG from the green tea. The driving force of the oral astringency is attributed to the hydrogen bonds of hydroxyl groups and hydrophobic interaction of galloyl groups in polyphenolic structures.</p>

Influence of deposition time on chromatics during nitrogen-doped diamond like carbon coating on pure titanium / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The aim of this study was to observed the influence of deposition time on chromatics during nitrogen-doped diamond like carbon coating (N-DLC) on pure titanium by multi impulse are plasma plating machine.</p><p><b>METHODS</b>Applying multi impulse are plasma plating machine to produce TiN coatings on pure titanium in nitrogen atmosphere, then filming with nitrogen-doped DLC on TiN in methane (10-80 min in every 5 min). The colors of N-DLC were evaluated in the CIE1976 L*a*b* uniform color scale and Mussell notation. The surface morphology of every specimen was analyzed using scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS).</p><p><b>RESULTS</b>When changing the time of N-DLC coating deposition, N-DLC surface showed different color. Golden yellow was presented when deposition time was 30 min. SEM showed that crystallization was found in N-DLC coatings, the structure changed from stable to clutter by varying the deposition time.</p><p><b>CONCLUSION</b>The chromatics of N-DLC coatings on pure titanium could get golden yellow when deposition time was 30 min, then the crystallized structure was stable.</p>

Study of nitrogen silicon zirconium-hydroxylapatite as a coating on pure titanium implantation / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To compare the osseointegration and corrosion of different kind of coatings on pure titanium.</p><p><b>METHODS</b>By plasma spraying technology, nitrogen silicon zirconium-hydroxylapatite (ZrSiN-HA) compound coating was prepared on the surface of pure titanium and the pure titanium was implanted with the mandible of the experimental animal. The superficial appearance of the compound coating was observed and analyzed by scanning electron microscope (SEM). The ZrSiN-HA, nitrogen silicon zirconium (ZrSiN), hydroxylapatite (HA) and pure titanium were compared and examined. In the four groups, the bone binding force of coatings were detected, and the superficial appearance of the break regions were observed by the electronic multipurpose material testing aircraft. In the four groups, the anticorrosive of coatings were compared and examined on the electrochemistry corrosion testing system.</p><p><b>RESULTS</b>Experimental results indicated that the implant surface sprayed with the ZrSiN-HA was more compact than that sprayed with HA. The crystallization was obvious. Compared with the other coatings, the bone binding force of the ZrSiN-HA coating was the highest, and its anticorrosive performance was the strongest.</p><p><b>CONCLUSION</b>The application of ZrSiN-HA coating is advantageous to the long-term retention of implant, and it has huge latent application value to dental dummy.</p>

Evaluation of three transmission parameters of dental opal porcelains and the correlations among parameters / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To measure the translucency parameter (TP), masking effect (ME), and contrast ratio (CR) of opal porcelain of Ceramco, Shofu, Noritake, and Vita, and to compare the correlations among the three transmission parameters, in order to provide reference for selecting opal porcelain correctly.</p><p><b>METHODS</b>The color of specimens was measured according to CIE L*a*b* under different background and reflectance mode with a Color-Eye 7000A spectrophotometer. The color difference, TP, and ME value were calculated. Within 400-750 nm spectra, the ratio of light reflectance was measured, and CR was also calculated. The data was compared by ANOVA and SNK-q test (alpha=0.05). The correlation and multiple linear regression between TP, CR, and ME were analyzed (alpha=0.05).</p><p><b>RESULTS</b>There were statistical difference with different shade of the same brands (P<0.05). The correlations between ME and TP, TP and CR, ME and CR were existed (P<0.05). TP was correlated not only with ME but also with CR based on multiple regression analysis (P<0.05). The partial correlation coefficients were statistically significant (P<0.05). CR was the main devotion to translucency parameter on multiple regressions.</p><p><b>CONCLUSION</b>It is recommended to select opal porcelains based on transmission parameters. CR value has an inner significance of opaque property of opal porcelain and can express opacity property of opal porcelain more appropriately than ME.</p>

The influence of accelerated aging on color and microstructure of light-curing composite resin / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The aim of this investigation was to examine the changes of the color stability, surface microstructure and chemical constitution of light-curing composite resin after accelerated aging, and the relations between them.</p><p><b>METHODS</b>Four light-curing composite resin were aged in an accelerated aging instrument. The color was measured by CIE L*a*b* with a spectrophotometer after treatment for 24 h and 96 h. And the color differences were calculated. Environmental scanning electron microscopy (ESEM) and Fourier transform infrared spectroscopy (FTIR) spectrometer were used to examine the microstructure and chemical composition of the specimens before and after accelerated aging. The color differences were analyzed statistically by repeated-measures two-way analysis of variance and t-test after aging for 24 h and 96 h. The level of significance was defined as alpha=0.05.</p><p><b>RESULTS</b>The materials demonstrated statistically significant differences in color after aging between the 24 h and 96 h (P<0.05). There were significant influences on the microstructure and the chemical composition after aging. The matrix appeared some concaves and pores, the filler particles exposed after aging. The energy of chemical bonds were weaken or broken under the aging, and the unsaturated polymer reacted again.</p><p><b>CONCLUSION</b>The color differences of the composite resin increase with the aging time and irradiation dose. The hybrid filled composites have the best color stability.</p>

Study on the matching of the shade between beverage and modifying porcelain shade guide / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the matching of the shade between beverage and modifying porcelain shade guide according to Munsell color order system, thus to provide the reference basis for selecting modifying porcelain to mimic the stain of natural tooth by technician.</p><p><b>METHODS</b>The shade of Vita Akzent, Vita Interno, Shofu Vintage & Unibond and Noritake Super Porcelain EX-3 shade tabs as well as 15 kinds of beverage were measured according to Munsell color order system on Color-Eye 7000A spectrophotometer. The difference of the frequency of approximate hue, value, and chroma between shade tabs and beverage were compared by calculating the Fisher exact probabilities.</p><p><b>RESULTS</b>The frequency of approximate hue between 4 kinds of shade tabs and 15 kinds of bev-erage was significant different (P<0.05), while the frequency of approximate value, and chroma was not significant different (P>0.05).</p><p><b>CONCLUSION</b>Except the hue, the color distribution of 4 kinds of shade tabs was similar to that of 15 kinds of beverage. But the color of beverage also can be approximately matched by any kind of modifying porcelain by mixing porcelain powder of appropriate hue, value, and chroma.</p>