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.

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.

OBJECTIVETo evaluate the effects of a zirconia primer and a self-adhesive resin cement on the resin bonding zirconia.

METHODSEighty 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.

RESULTSGroup 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.

CONCLUSIONZirconia primer and self-adhesive resin cement increase the resin bonding of zirconia.

Adhesives ; Aluminum Oxide ; Benzhydryl Compounds ; Bisphenol A-Glycidyl Methacrylate ; Composite Resins ; Dental Bonding ; Dental Cements ; Humans ; Methacrylates ; Resin Cements ; Shear Strength ; Silanes ; Spectroscopy, Fourier Transform Infrared ; Zirconium

Objective To analyze the risk factors for complications in elderly patients with cardiac surgery under cardiopulmonary bypass.Methods From July 2004 to June 2012,64 patients aged ≥ 60 years undergoing cardiac operations were selected.Clinical data were collected.The complications after cardiac operation and the risk factors were evaluated by single factor analysis and multivariate Logistic regression analysis with SPSS software.Results The postoperative complication rate in all patients was 34.4％ (22/64).The complications occurred in 42 subjects and operative mortality was 6.3％ (4/64).The single factor analysis showed that chronic obstructive pulmonary disease combined before operation (P=0.001),diabetes combined before operation (P=0.009),cardiopulmonary bypass time ≥2 h (P=0.000),aortic cross clamping time ≥90min (P=0.001),and blood transfusion volume ≥2000 ml (P =0.000) were the important risk factors for postoperative complications.Multivariate Logistic regression analysis revealed that chronic obstructive pulmonary disease (P=0.007) and diabetes combined before operation (P=0.028),cardiopulmonary bypass time ≥2 h (P=0.003),and blood transfusion volume ≥2000 ml (P=0.030) were the significant independent predictive risk factors for postoperative complications.Conclusions Chronic obstructive pulmonary disease,diabetes,cardiopulmonary bypass time ≥2 h,aortic cross clamping time ≥90 min,and blood transfusion volume ≥2000 ml are the independent predictive risk factors for postoperative complications in elderly patients with cardiac surgery under cardiopulmonary bypass.

Objective This study aims to evaluate the influence of hot chemical etching on short- and long-term shear bond strength (SBS) of zirconia to resin. Methods Eighty zirconia ceramic slices were obtained and randomly divided into five groups based on the surface treatment to be applied-group A: H2SO4/(NH4)2SO4 hot solution etching + application of Clearfil; group B: HF/HNO3 hot solution etching + application of Clearfil; group C: H2SO4/HF/HNO3 hot solution etching + Clearfil; group D: alumina sandblasting + application of Clearfil; group E: tribochemical silica coating + application of silane coupling agent. Eighty composite cylinders were bonded to pretreated ceramic slices using a bis-GMA-based resin cement. Specimens in each group were divided into two fractions: the first half received 24 h water storage, and the second half re-ceived 40 d water storage. Then, SBS tests were conducted. Morphological analysis of sandblasted alumina and hot chemical-etched zirconia surfaces were performed by scanning electron microscopy(SEM). Results Group E displayed the highest SBS before artificial aging, and no statistical difference was found among the other groups. After 40 d water storage, groups A, B, and E showed significantly higher SBS than groups C and D. SBS increased significantly after artificial aging in groups A and B. No significant variations were found before and after artificial aging in the other groups. Conclusion The experi-mental hot chemical etching solution provides enhanced bonding for zirconia than sandblasting, and the bond strengths remain stable after artificial aging.

OBJECTIVETo investigate the stress distributions under load in an all-ceramic crown of the upper central incisor in differential thickness.

METHODSThe 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.

RESULTSThe 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.

CONCLUSIONThe 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.

Ceramics ; Crowns ; Dental Porcelain ; Dental Stress Analysis ; Finite Element Analysis ; Humans ; Incisor ; Tensile Strength

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.

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.
Composite Resins ; chemistry ; Dental Materials ; chemistry ; Humans ; Nanotubes, Carbon ; chemistry ; Resin Cements ; chemistry ; Silicon Dioxide ; chemistry ; Surface Properties ; Tensile Strength

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.

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.