Host contributions to Ebola virus replication, transcription and translation:research advances / 军事医学

Ebola virus(EBOV) disease,the fatality rate of which is as high as 25％-90％,can be transmitted by contac t between human and non-human primates.Early studies of the virus focused on the functions of viral proteins.Recently,the focus of research of EBOV has been switched to the host interaction factors during the process of virus reproduction.In this review,advances in studies on host contributions to EBOV replication,transcription and translation are summarized in order to enhance our understanding of contributions of the host to the virus reproduction process and provide reference for research strategies and new antiviral drugs.

Effect of sandblasting particle sizes on bonding strength between porcelain and titanium fabricated by rapid laser forming / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the effect of sandblasting particle sizes of Al2O3 on the bonding strength between porcelain and titanium fabricated by laser rapid forming (LRF).</p><p><b>METHODS</b>The thermal expansion coefficient, roughness (Ra), contact angle, surface morphology of titanium surface and the bonding strength between titanium and porcelain were evaluated after the titanium surface being sandblasted using different sizes of Al2O3 (50 microm, 120 microm, 250 microm) at a pressure of 0.5 MPa. The cast titanium specimens were used as control, and were sandblasted with 50 microm Al2O3 at the same pressure.</p><p><b>RESULTS</b>The thermal expansion coefficient of cast titanium [(9.84 +/- 0.42) x 10(-6)/ degrees C] and LRF Ti [(9.79 +/- 0.31) x 10(-6)/ degrees C) matched that of Noritake Ti-22 dentin porcelain [(8.93 +/- 0.36) x 10(-6)/ degrees C). When larger size of Al2O3 was used, the value of Ra and contact angle increased as well. There was no significant difference in bonding strength between the LRF Ti-50 microm [(25.91 +/- 1.02) MPa] and cast titanium [(26.42 +/- 1.65) MPa]. Significantly lower bonding strength was found in LRF Ti-120 microm [(21.86 +/- 1.64) MPa] and LRF Ti-250 microm [(19.96 +/- 1.03) MPa].</p><p><b>CONCLUSIONS</b>The bond strength between LRF Ti and Noritake Ti-22 dentin porcelain was above the lower limit value in the ISO 9693 (25 MPa) after using 50 microm Al2O3 sandblasting in 0.5MPa air pressure.</p>

An 8-year follow-up study of Cerec2 computer aided design and computer aided manufacture of all-ceramic crowns / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the clinical performance of the crowns made by Cerec2 computer aided design and computer aided manufacture (CAD/CAM) system.</p><p><b>METHODS</b>Twenty four teeth were restored with Cerec2 CAD/CAM crowns. Eight years after delivery of the prostheses, the all-ceramic crowns were evaluated using modified standard of California Dental Association quality evaluation system. Patients filled out a satisfaction questionnaire at the same time. And Kaplan-Meier analysis was carried out.</p><p><b>RESULTS</b>Three out of 24 restorations were rated as failure. Kaplan-Meier analysis showed that the success rate of Cerec2 crowns eight year following delivery was 88%.</p><p><b>CONCLUSIONS</b>Crowns made by Cerec2 CAD/CAM system can survive in oral condition and function well for 8 years.</p>

Three-dimensional finite element analysis of weakened roots restored with different cements in combination with titanium alloy posts / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>It is very difficult and relatively unpredictable to preserve and restore severely weakened pulpless roots. To provide much needed benefit basis for clinical practice, this study was carried out to analyze the stress distribution in weakened roots restored with different cements in combination with titanium alloy posts. Finite element analysis (FEA) was employed in the study.</p><p><b>METHODS</b>A pseudo three-dimensional model of a maxillary central incisor with flared root canal, theoretically restored with titanium alloy posts in combination with different cements, was established. The analysis was performed by use of ANSYS software. The tooth was assumed to be isotropic, homogenous and elastic. A load of 100 N at an angle of 45 degrees to the longitudinal axis was applied at the palatal surface of the crown. The distributions of stresses in weakened roots filled with cements of different elastic modulus were analyzed by the three-dimensional FEA model.</p><p><b>RESULTS</b>Several stress trends were observed when the stress cloud atlas obtained in the study was analyzed. With the increase of the elastic modulus of cements from 1.8 GPa to 22.4 GPa, the stress values in dentin decreased from 39.58 MPa to 31.43 MPa and from 24.51 MPa to 20.76 MPa (respectively, for maximum principle stress values and Von Mises stress values). When Panavia F and zinc phosphate cement were used, the stress peak values in dentin were very small with no significant difference observed, and the Von Mises stress values were 20.87 MPa and 20.76 MPa respectively. On the other hand, maximum principle stress value and Von Mises stress value in cement layer increased with the increase of the elastic modulus of cements.</p><p><b>CONCLUSIONS</b>The result of this study demonstrated that elastic modulus was indeed one of the important parameters to evaluate property of the cements. Our three-dimensional FEA model study also found that the cement with elastic modulus similar to that of dentin could reinforce weakened root and reduce the stress in dentin. Thus, it may be a better choice for the restoration of weakened roots in clinical practice.</p>

Effects of laser welding on bond of porcelain fused cast pure titanium / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the influence of the laser welding on bond of porcelain fused to cast pure titanium.</p><p><b>METHODS</b>Twenty cast titanium plates were divided into two groups: laser welded group and control group. The low-fusing porcelain was fused to the laser welded cast pure titanium plates at fusion zone. The bond strength of the porcelain to laser welded cast pure titanium was measured by the three-point bending test. The interface of titanium and porcelain was investigated by scanning electron microscopy (SEM) and energy depressive X-ray detector (EDX). The non-welded titanium plates were used as comparison.</p><p><b>RESULTS</b>No significant difference of the bond strength was found between laser-welded samples [(46.85 +/- 0.76) MPa] and the controls [(41.71 +/- 0.55) MPa] (P > 0.05). The SEM displayed the interface presented similar irregularities with a predominance. The titanium diffused to low-fusing porcelain, while silicon and aluminum diffused to titanium basement.</p><p><b>CONCLUSIONS</b>Laser welding does not affect low-fusing porcelain fused to pure titanium.</p>

Structural characteristics of laser-welded cast pure titanium joints by different gap distance / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To measure the microstructure of laser-welded cast pure titanium by different gap distance.</p><p><b>METHODS</b>Forty specimens were sectioned and welded at four gaps (0.00 mm, 0.25 mm, 0.50 mm and 1.00 mm). Took microhardness test and metallographic examination of welded zone surface.</p><p><b>RESULTS</b>There were no difference in microhardness value and metallographic observation between welded specimens. The width of heat-effected zone was different. The smaller grains and needle-like alphamartensitic structure were found in the heat-affected zone.</p><p><b>CONCLUSION</b>The effects of the joint gap were not significant.</p>

The study on fabrication of dental restoration using PMMA-ZrO2 composites via CAD/CAM / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To obtain dental restorations by machining PMMA-ZrO2 organic-inorganic composites with the dental CAD/CAM system.</p><p><b>METHODS</b>Partially sintered Zirconia compacts (PSZC) were prepared via isostatic pressing and partially sintering, with Zirconia nanopowder as raw materials. PMMA-Zirconia organic-inorganic composites were prepared by vacuum infiltrating the prepolymerized MMA into the PSZC, followed by in-situ polymerization. The mechanical properties and machinability of composites were studied. The composites were machined on the dental CAD/CAM system to obtain dental restoration.</p><p><b>RESULTS</b>At 71.44% TD of PSZC, the composite had a 3-point bending strength of (202.56 +/- 3.09) MPa, fracture toughness of (4.30 +/- 0.16) MPa.m(1/2), elasticity modulus of (58.71 +/- 1.98) GPa, and Vickers hardness of (3.82 +/- 0.34) GPa, respectively. A premolar crown was fabricated by CAD/CAM system in 16 mins, and was verisimilitude, without any cracks.</p><p><b>CONCLUSIONS</b>The composite at 71.44% TD of PSZC has good mechanical properties and dental restorations can be manufactured by PMMA-Zirconia composites via dental CAD/CAM system.</p>

Experimental study of periosteal osteoblasts adhesion to artificial bone scaffolds based on rapid prototype / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study the biocompatibility of bone engineering scaffolds designed and fabricated by CAD and Rapid Prototyping techniques.</p><p><b>METHODS</b>Infant rat calvarias osteoblasts were isolated and expanded in vitro and the cells (2nd passage) were seeded onto scaffolds with porosity 80%, 90%, 95% at a density of 2.06 x 10(9)/L. Cell adhesion number and morphology were measured with SEM after 4 days, 10 days co-culture.</p><p><b>RESULTS</b>(1) The osteoblasts' adhesion amounts increased with culture time in three porosity group (P < 0.05), but the increase were different among three groups, 80% group was 0.35 x 10(5), 90% group was 2.84 x 10(5); (2) Through SEM observations, it showed that osteoblasts adhered to all scaffolds well.</p><p><b>CONCLUSION</b>The scaffolds designed and fabricated by CAD and rapid prototyping own a good cellular biocompatibility. The results suggest the feasibility of using such scaffold fabricating method for bone tissue engineering research and clinical therapy.</p>

Influence of eugenol-containing temporary cement on efficacy of dentin-bonding systems / 中华口腔医学杂志

<p><b>OBJECTIVE</b>This study investigated the influence of eugenol-containing temporary cement on the efficacy of two relatively new dentin-bonding systems.</p><p><b>METHODS</b>Thirty-two freshly extracted bovine central incisors were randomly divided into four groups. Dentin was exposed and polished with 320#, 400#, and 600# sand papers. After embedded, Group 3 and 4 specimens were covered with ZOE. Specimens in Group 1 and 2 were served as control. All specimens were stored for 1 week in distilled water at 37 degrees C. Then, the ZOE was mechanically removed. The dentin surfaces of Group 1 and 3 were treated with Prime & Bond NT bonding system and the dentin surfaces of Group 2 and 4 were treated with GLUMA adhesive system according to manufacturer's instructions. Thereafter composite resin columns (6 mm diameter, 2 mm high) were applied. After specimens stored in distilled water at 37 degrees C for 24 hours, the shear bond testing was carried out using a SHIMADZU universal testing machine with a cross-head speed of 0.5 mm/minute. The mode of failure was examined using SEM. The data were analyzed using ANOVA test at a significance level of 0.05.</p><p><b>RESULTS</b>The medians of shear bond strength for each group were as follows: Group 1 (Prime & Bond NT) 9.57 MPa, Group 3 (Prime & Bond NT + ZOE) 10.72 MPa, Group 2 (GLUMA) 16.89 MPa, Group 4 (GLUMA + ZOE) 16.78 MPa. Group 1 and 3 had significantly lower bonding strength than did Groups 2 and 4. But no significant difference was found between the control groups and the groups treated with ZOE temporary cement.</p><p><b>CONCLUSION</b>Pretreatment of the dentin with ZOE temporary cement has no adverse influence on the efficacy of two relatively new dentin-bonding systems.</p>

Coloration of mica glass ceramic for use in dental CAD/CAM system / 中华口腔医学杂志

<p><b>OBJECTIVE</b>An intrinsically colored machinable glass-ceramic containing tetrasilicic fluormica as the predominant crystal phase was studied, which was used in molar crown in dental CAD/CAM system.</p><p><b>METHODS</b>Orthogonal design analysis was used to select appropriate base formula, coloration and heat treatment process.</p><p><b>RESULTS</b>Factors influencing the color appearance of mica glass ceramic were nucleation agent and the ratio of Mg(2+) to K(+) in base formula; Cerium oxide (CeO(2)) was used as the main coloration; The preferred heat treatment was 650 degrees C for 1 h and 1,000 degrees C or 1,050 degrees C for 3 h - 4 h.</p><p><b>CONCLUSIONS</b>This mica glass-ceramic could provide 4 to 5 color appearance for dental use, it showed excellent machinability which was eminently suitable for use in dental CAD/CAM system.</p>