0.05).Conclusion:It suggests that HPDLFs exposured to static magnetic field produced by magnetic attachment have little mutagenic effects on chromosomes and DNA.

Objective To explore the relationship between the maxi ll ofacial complexion and age-sex in Han nationality. Methods The maxillofacial skin chroma L*, a* and b* were measured a nd compared in 1462 people aged from 18 to 85 years old in Han nationality, incl uding 682 men and 780 women, by means of Minolta Chroma Meter CR-100. Results Male had the lower L* and b* value and the hig her a* value than those in female. The maxillofacial chroma L* and a* were related to age negatively, and b* was related to age positiv ely. Conclusion The effect of sex and age on color of the maxillofacial skin should be considered while matching colors in construction o f maxillofacial defect.

0.05).Conclusion: Modified RPI clasp with clinically acceptable retentive force and better cosmetic effcts is feasible for clinical application.

?Objective: To study the preparation method of nanometer powder of zirconia, which was used to toughen dental alumina ceramics. Methods: The inorganic precursors at the concentrations of 0.0155 , 0.03, 0.05, 0.1 and 0.28 mol/L were used to prepare zirconia powder via precipitation method. Ammonia water was added into the said solutions to control the pH value at 7.0, 8.5 and 9. The dried precipitation product was then calcined. The prepared zirconia powder were studied by using X ray diffraction (XRD) and scanning electron microscope (SEM). Results: The zirconia powder prepared under the condition of 0.03 0.05 mol/L concentration of inorganic precursors, pH = 8.5, and calcined at 700 ℃ for 2 h was even in size,well dispersed and well micronized. The diameter of the final powder was about 100 nm. Conclusion: With proper preparation condition, weakly agglomerated powder of zirconia in nanometer size can be obtained.

0.05). The maximum color differences ( ?E) in the selected firing cycles were 2.279 8 and 1.389 4 for GI Ⅱand Vita In Ceram Alumina groups respectively, the maximum ?E between the two groups was 2.295 6, which fell into the clinically acceptable threshold for color differences. Conclusion: Color stability of all ceramic restorations with GI Ⅱand Vita In Ceram Alumina as substructure can be guaranteed after repeated firing of veneering porcelain up to 10 times.

OBJECTIVEThis study aims to evaluate the optical data of the different sites of the cobalt-chrome (Co-Cr) alloy abutments covered by four different all-ceramic crowns and the color difference between the crowns and target tab using a digital dental spectrophotometer.

METHODSTen Co-Cr alloy abutments were made and tried in four different groups of all-ceramic crowns, namely, Procera aluminia, Procera zirconia, Lava zirconia (Lava-Zir), and IPS E.max glass-ceramic lithium disilicate-reinforced monolithic. The color data of the cervical, body, and incisal sites of the samples were recorded and analyzed by dental spectrophotometer. The CIE L*, a*, b* values were again measured after veneering. The color difference between the abutments covered by all-ceramic crowns and A2 dentine shade tab was evaluated.

RESULTSThe L* and b* values of the abutments can be increased by all of the four groups of all-ceramic copings, but a* values were decreased in most groups. A statistical difference was observed among four groups. After being veneered, the L* values of all the copings declined slightly, and the values of a*, b* increased significantly. When compared with A2 dentine shade tab, the ΔE of the crowns was below 4.

CONCLUSIONFour ceramic copings were demonstrated to promote the lightness and hue of the alloy abutments effecttively. Though the colorimetric baseline of these copings was uneven, veneer porcelain can efficiently decrease the color difference between the samples and thee target.

Ceramics ; Chromium Alloys ; Cobalt ; Color ; Colorimetry ; Crowns ; Dental Materials ; Dental Porcelain ; Dental Prosthesis Design ; Humans ; Metal Ceramic Alloys ; Titanium ; Zirconium

0.05 ). And the fitness values(?m) of the crown of DA9-4 alloy were:the margin gap of the crown 71.3 ?8.34, the shoulder gap 53.4?4.83, the axial wall gap 41.85?8.08, the occlusal lift amount 55.2?9.21.Conclusion:DA9-4 alloy has good fitness and can meet the require of clinic.

Objective To investigate the differences and harmonization of immunoassay systems in detecting CA19-9 and to assess the possibility of mutual recognition in different laboratories.Methods Data were collected and analyzed from External Quality Assessments (EQA) of NCCL(Lots:200811-201215) and ZJCCL(Lots:080309-120211).120 fresh serum with different concentrations of CA19-9 were collected.The CA19-9 results of healthy people were also collected from September 2010 to March 2012.Four kinds of stable immunoassay systems were involved in our research,including Abbott Architect i2000,Beckman UniCel DxI 800,Roche E170 and Siemens ADVIA Centaur XP.The differences among four system groups were calculated with the EQA data.The fresh serum comparisons were also performed following the guideline of CLSI EP9-A2 The 95％ confidence interval of each immunoassay system was calculated.Comparisons were made by scatter diagrams and weighted regression.Results Both EQA of NCCL and ZJCCL showed better correlation coefficients and larger bias (bw ranged from 1.340 to 4.683) than in fresh serum comparisons.Although the correlation coefficients were all unsatisfactory,the bw were all close to 1 in fresh serum comparisons.When the recommended serum concentration of 27 U/ml was used,the biases were Abbott-Roche-6.41％,Beckman-Roche-5.07％,Siemens-Roche 13.15％,Beckman-Abbott 2.46％,Siemens-Abbott 22.52％ and Siemens-Beckman 39.66％,respectively.Differences of 95％ confidence intervals were statistically significant among parts of the immunoassay systems.Conclusions Only in the lower concentration can CA19-9 results be mutual recognized among four different immunoassay systems,there will be larger differences and risks in the higher concentration.

OBJECTIVEThe purposes of this study were to determine the spectral transmittance of GI-II glass/alumina composites and to explore the effects of different specimen thickness and fining arts of glass infiltration on the transmittance. Data were compared with those of Vita In-Ceram Alumina materials.

METHODSPlate-shaped specimens 12.5 mm in diameter, with 3 thickness (0.5, 1.0, 1.5 mm), 6 color groups for GI-II and 4 color groups for Vita In-Ceram Alumina were fabricated. Specimens of color AL2 for In-Ceram and IG2 for GI-II were selected in the study of relationship between different infiltration arts and transmittance. Five infiltration time duration and three temperatures were studied. A spectrophotometer with standard A light source paralleled light beam 5 mm in diameter and spectra range 380-780 nm was employed to measure the spectral transmittance.

RESULTSThe range of spectral transmittance were 2.7%-4.5% for GI-II and 2.4%-5.2% for Vita In-Ceram Alumina. Transmittance decreased with specimen thickness, but they were not linearly related. Transmittance of GI-II tended to increase and that of Vita In-Ceram Alumina decreased as the infiltration temperature elevated. The transmittance increased with infiltration time less than 4 hours and reduced with prolonged time over 6 hours for both materials.

CONCLUSIONGI-II glass/alumina composite has comparatively lower translucency. Influences of factors as color, thickness and infiltration arts on translucency of restorations should be considered in the clinical selection of the all-ceramic materials.

Aluminum Oxide ; chemistry ; Ceramics ; chemistry ; Dental Materials ; Dental Porcelain ; chemistry ; Glass ; chemistry ; Light ; Spectrophotometry ; Temperature ; Tensile Strength ; Transition Temperature

OBJECTIVEThe purpose of this study was to determine the thermal, mechanical properties and density of the composite infiltrated with GI-II tinted infiltration glass.

METHODSThe bar-shaped aluminum oxide and glass/alumina composite specimens with the size of 20 mm x 5 mm x 5 mm were prepared, with two free-end surfaces perpendicular to the long axis of the specimens and parallel to each other. The thermal expansion curves were obtained on a TMA2940 thermal analyzer with heating rate of 5 degrees C/min and temperature range of 25 degrees C to 1000 degrees C. The bar-shaped specimens with the size of 25 mm x 5 mm x 2 mm were fabricated and employed to test the density using Archmede's method. The flexural strength, elastic modulus were measured by means of 3-point bending test with the same specimens. The fractured specimens were indented with Vicker's diamond pyramid under load of 49 N for 15 seconds to determine the hardness and indentation fracture toughness.

RESULTSThe thermal expansion coefficient of the glass/alumina composite was 7.620 x 10(-6) degrees C-1 (25-500 degrees C), which was higher than that of Vitadur alpha veneering porcelain. The 3-poit flexural strength, elastic modulus, Vicker's hardness, indentation fracture toughness and density were 389.6 MPa, 92 GPa, 9.409 GPa, 3.2425 MNm-3/2 and 3.662 g/cm3 respectively.

CONCLUSIONThe thermal expansion of the GI-II glass/alumina composite is compatible with that of Vitadur alpha veneering porcelain, and the material could meet the strength demands for clinical use.

Aluminum Oxide ; chemistry ; Ceramics ; Dental Materials ; Dental Porcelain ; chemistry ; Glass ; chemistry ; Tensile Strength ; Transition Temperature