The toxicity evaluation of sol-gel silica coating coagulated by NaHCO3 in vivo / 实用口腔医学杂志

Objective:To evaluate the toxicity of NaHCO3 coagulated silica gel for coating on the zirconia bonding surface in vivo. Methods:The silica gel was subjected to short term systemic toxicity test by delayed-type hypersensitivity test by oral route and oral mucosa irritation test according to the YY/T 0244-1 996 standards,T1 6886.1 0-2005 /ISO 1 0993-1 0:2002 standards and YY/T 01 27. 1 3-2009 standards respectively.Results:In the short term systemic acute toxicity tested mice there was no significant difference in the weekly food utilization rate and relative body weight growth rate between the experimental and control groups.No abnormality and path-ological change were observed.The delayed-type hypersensitivity test showed that no erythema and edema reaction presented in all the test cavies after 24 and 48 h of stimulation contact,and the sensitization rate was 0.There was no local or systemic pathological change in all the oral mucosa irritation test animals.Conclusion:NaHCO3 procoagulant silica gel has no in vivo toxicity.

Effects of different surface treatments on shear bond strength of diatomite-based dental ceramic / 国际生物医学工程杂志

Objective To investigate the effects of different surface treatments on shear bond strength between diatomite-based dental ceramic and IPS e.max veneering ceramic.Methods Diatomite-based dental ceramic was randomly divided into acid-etched group,sandblasting group and untreated group,and then sintered with IPS e.max veneering ceramic,respectively.Shear bond strength were detected,and the interface microstructures and elemental distribution were observed by scanning electron microscope-energy dispersive spectrometer (SEM-EDS).Results Shear bond strength of acid-etched group was significantly higher than that of untreated group (P＜0.01).SEM observation results showed that the interface of acid-etched group bonded closely.There was no statistical difference of the shear bond strength between the sandblasting group and untreated group (P＞0.05).Conclusions Acid-etched treatment can significantly enhance the bond strength of diatomite-based dental ceramic and IPS e.max veneering ceramic.

Effects of a zirconia primer and a self-adhesive resin cement on zirconia bonding / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the effects of a zirconia primer and a self-adhesive resin cement on the resin bonding zirconia.</p><p><b>METHODS</b>Eighty zirconia blocks were manufactured, alumina-sandblasted, and randomly divided into five groups that received surface-treatments using different resin cements: group C, treated with a conventional bisphenol-A diglycidyl dimethacrylate (Bis-GMA)-based resin cement; group R, treated with a self-adhesive resin cement; group S, silica-coated via a Sol-gel process, conditioned with silane, and then treated with the Bis-GMA-based resin cement; group ZC, conditioned with a zirconia primer (Z-Prime Plus) and subsequently treated with the Bis-GMA-based resin cement; group ZR, conditioned with the zirconia primer and treated with the self-adhesive resin cement. Light-cured composite resin cylinders were prepared and bonded on the prepared zirconia blocks. Half of the specimens in each group were water-stored for 24 hours, whereas the remaining specimens were aged by thermocycling. All specimens were then subjected to shear bond strength (SBS) testing. Fourier transmission infrared (FT-IR) spectroscopy and gas chromatography-mass spectrometry (MS) were performed to characterize the zirconia primer.</p><p><b>RESULTS</b>Group C presented the lowest SBS, whereas groups R, ZC, and ZR presented the highest values. Thermocycling had no effect on SBS. FT-IR results showed that Z-Prime Plus contained a benzene ring and a carbonyl group. MS analysis showed that Z-Prime Plus contained 2-hydroxyethyl methacrylate, triethylamine.</p><p><b>CONCLUSION</b>Zirconia primer and self-adhesive resin cement increase the resin bonding of zirconia.</p>

Finite element stress analysis of all-ceramic crown of the upper central incisor in differential thickness / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the stress distributions under load in an all-ceramic crown of the upper central incisor in differential thickness.</p><p><b>METHODS</b>The 3-dimensional finite element model of all-ceramic crown of the upper central incisor in differential thickness was applied with differential loads (100, 150, 200 N). The stress values and distributions of all-ceramic crown were calculated and expressed.</p><p><b>RESULTS</b>The tendency of stress distributions in all-ceramic crown of differential thickness and loads was similar. The maximal stress intensity value was located in the loading site and the cervical region. As the thickness of all-ceramic crown increased, the stress concentration reduced. When the load increased, the stress values increased, especially in the loading site and the cervical region.</p><p><b>CONCLUSION</b>The increasing of the thickness of all-ceramic crown will decrease stress concentration. Because stress concentration is mainly in cervical region and loading site, these regions should be cared in fabrication of all-ceramic crown.</p>

Preparation of diatomite based nano-composite dental ceramic powders by layer-by-layer technique / 国际生物医学工程杂志

Objective To prepare a novel bioactive and degradable scaffold with mineralized collagenpolyose based composite by biomimetic synthesis for bone tissue engineering and explore the compatibility of osteoblast culturing on the scaffold. Methods Two kinds of polyelectrolyte were assembled on the surface of diatomite particles in order to adsorbe on nano-zirconia through opposite charges. Zeta potential,particle size and size distribution were compared before and after the modification of diatomite; IR was used to analysis molecular structure of functional group changes on the surface of diatomite particles, nano-composite powder morphology was observed by SEM. Results Two kinds of the polyelectrolyte were successfully assembled on the surface of diatomite powders. Particle size and size distribution were significantly reduced, d (0.5) reduce from 16.421 μm to 0.420 μm. SEM showed the dispersion of the modified diatomite was improved and had a good adsorption with nano-zirconia. Conclusion Layer-by-layer technique could enhance the dispersion of diatomite-based dental ceramic powders as well as a good adsorption of nano-composite ceramic powder.

Progress in carbon nanotube based dental ceramic material / 国际生物医学工程杂志

Carbon nantubes composites draws more and more attention these days. Its application provides new potential for the reinforcement and toughness of dental ceramic. In this paper, the properties of carbon nanotube, carbon nanotube based ceramic composites and its mechanics of toughness, and the future trend of carbon nanotube in dental ceramic material, have been reviewed.

Progress on adhesion behavior between composite resin cement and ceramics / 国际生物医学工程杂志

Full ceramic restorations become more and more popular for their excellent properties. Bond strength between ceramic and composite resin cement is the key factor to success in clinical use. This paper illuminated the importance of ceramic surface treatments and reviewed recent progresses on ceramic surface treatments. The difference of bond strength caused by different dental materials was discussed too.

Surface modification and microstructure of single-walled carbon nanotubes for dental composite resin / 生物医学工程学杂志

In order to improve its dispersion condition in dental composite resin and enhance its interaction with the matrix, single-walled carbon nanotubes(SWNTs) were refluxed and oxidized, then treated by APTE. Their outer surface were coated by nano-SiO2 particles using sol-gel process, then further treated by organosilanes ATES. IR and TEM were used to analyze modification results. TEM pictures showed nano-particles were on the surface of SWNTs; IR showed characteristic adsorbing bands of SiO2. Composite resin specimen with modified SWNTs was prepared and examined by TEM. SWNTs were detected in composite resin matrix among other inorganic fillers.

Study on color masking ability of restoration material Vita Mark II / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The purpose of this study was to evaluate the color masking ability of Computer Aided Design/Computer Aided Manufacture(CAD/CAM) machining ceramic Vita Mark II, this ability was affected by thickness and shade.</p><p><b>METHODS</b>Each of 5 specimens of 0.5 mm, 1.0 mm and 1.5 mm Vita Mark II A3C/18 and A2C/18 were prepared and the color change was measured after the substrate simulating stained teeth was covered with the specimen.</p><p><b>RESULTS</b>Statistically significant differences (P < 0.01) were recorded in the substrates covered with different thickness and shade of Vita Mark II. The color changes (delta E) were 15.181, 17.691, 19.667 and 15.653, 16.880, 18.002 after the substrates were covered with 0.5 mm, 1.0 mm and 1.5 mm Vita Mark II A3C/18 and A2C/18.</p><p><b>CONCLUSION</b>As a dental material, CAD/CAM Vita Mark II has high quality to mask the underlying color. Being a veneer, the masking ability with A2C/18 is better than that with A3C/18, but being an inlay, the result is reverse.</p>

Effect of layering feldspathic porcelain on resulting veneer color with aluminum oxide core / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the resulting color of veneers affected by adding a layer of veneering porcelain on Procera aluminium oxide core.</p><p><b>METHODS</b>Fifteen aluminium oxide disks were randomized into three groups. Each of five disks was veneered with porcelain of the Vita shade Al, A2 and B4 respectively. The color of the substrate covered with non-veneered disks and the veneered disks was measured separately and the color differences were calculated.</p><p><b>RESULTS</b>Statistically significant differences (P < 0.01) in color coordinates of dark substrate were recorded between the substrate covered by an aluminium oxide disks and the addition of veneering porcelain to aluminium oxide disks. Mean coordinates color difference (DeltaE, DeltaL *, Deltaa *, Deltab *) after adding the three shades of veneering porcelain showed increase from Al (2.311) to A2 (4.313) to B4 (8.778) in DeltaE, decrease from Al (-1.530) to A2 (-3.369) and B4 (-3.358) in DeltaL *, and increase from Al (-1.440) to A2 (2.198) to B4 (7.955) in Deltab *. The direction of the color modification correlated with values obtained from the liberation. The resulting color was also affected by the color of the underlying structure.</p><p><b>CONCLUSION</b>This study illustrates that color of aluminium oxide shell could be modified with feldspathic veneering porcelain, which may be used by practitioners to alter the esthetic outcome of porcelain veneers.</p>