Quantitative monomolecular coverage of barium glass by the silane coupling agent gamma-methacryloxypropyltrimethoxysilane / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To study the monomolecular coverage of the silane coupling agent gamma-methacryloxypropyltrimethoxysilane (gamma-MPS) on the barium glass filler surface.</p><p><b>METHODS</b>Kubelka-Munk (K-M) function values of the isolated OH-groups on the barium glass filler surface, which were based on the change of gamma-MPS concentrations, were measured using the quantitative analysis of the diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. When all of the isolated OH-groups on the filler surface disappeared (where the K-M function values was zero), the monomolecular coverage of the gamma-MPS molecules on the filler surface was indicated by the linear regression analysis.</p><p><b>RESULTS</b>The relationship tallied with negative linear correlation between the K-M function values of the isolated OH-groups on the barium glass surface and the concentrations of gamma-MPS. Each gamma-MPS molecule occupied 0.21 nm(2) when the monomolecular coverage was formed on the barium glass surface.</p><p><b>CONCLUSIONS</b>The result of this study indicated the optimal amount of silane coupling agent on silanated barium glass filler during the production of resin composite.</p>

Rheological properties of photo-polymerized composite resin reinforced with retentive filler / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To determine the rheological properties of the photo-polymerized composite resin reinforced with retentive filler (RF) and its rheological difference with normal filler (NF) composite resin.</p><p><b>METHODS</b>Rheological properties of the composite resins, such as viscosity, shear stress and creep compliance, were measured with dynamic stress rheometer at room temperature (25 degrees C).</p><p><b>RESULTS</b>The viscosity of the composite resin reinforced with RF is higher than that of NF composite resin (P < 0.01); at the beginning, the viscosity of the former has little change with the rising of shear stress and the latter decreases, then the viscosities of the two composite resins increase with the rising of shear stress as soon as over 203.18 Pa of shear stress; the creep compliance of the composite resin reinforced with RF is significant smaller than that of NF composite resin (P < 0.01).</p><p><b>CONCLUSIONS</b>The rheological properties of the two composite resins have significant difference, so they have different clinical using properties.</p>

Effect of particle size distribution of dental poly (methyl methacrylate) beads on the microstructure of denture / 中华口腔医学杂志

<p><b>OBJECTIVES</b>To investigate the effect of particle size distribution (PSD) of dental poly (methyl methacrylate) (PMMA) beads on the microstructure of denture.</p><p><b>METHODS</b>It was compared and analyzed that the porosity of three groups of spherical specimens which were made of PMMA beads with different PSD at proper polymer/monomer ratios. And the final microstructure of each group was investigated using Digital High Definition Microscope.</p><p><b>RESULTS</b>With proper polymer/monomer ratio increasing, the occurrence of porosity tended to decrease. The final microstructure of denture varied with PSD of PMMA beads.</p><p><b>CONCLUSION</b>By means of optimizing PSD of beads, the microstructure of denture could be improved, and the occurrence of porosity could be reduced.</p>