Adhesion of streptococci to saliva-coated and uncoated composite-based resins

This study was designed to evaluate the bacterial adhesion to five types of experimental composite-based resins and a commercial composite resin used as a control. Physicochemical surface characteristics of composite resins with and without an artificial saliva coating were measured. The relationship between the numbers of adhering cells (Streptococcus sanguis, S. mutans and S. sobrinus) and surface characteristics was analysed. The values of contact angles and the number of adhering cells were small with saliva coating. S. sanguis ATCC 10557 showed a positive correlation (r=0.835, p<0.05) with the contact angles of uncoated resins, whereas no relationship was observed for saliva-coated resins. With S. mutans Ingbritt the cell numbers adhering to resins correlated strongly (p<0.01) with the values of zeta potential of resins for either saliva coated or uncoated. Electrical repulsion forces had a strong contribution to adherence of cells such as S. mutans and S. sobrinus which show a high absolute zeta potential.     

The morphology of α′ martensite in a two-phase (α+γ) Fe-Cr-Ni stainless steel

Both lath-shaped and martensites are induced by tensile deformation within of a two-phase ( + ) Fe-Cr-Ni stainless steel, forms from the through the at an intersection of two crystals. These are observed both when is surrounded by and when borders . The amount of strain at which both and nucleate, increases with test temperatures in the range –196 to 50° C. Adjacent laths are either twin-related, or 5, 9, 15 or 19° off the twin relationship, as found by analysing electron diffraction patterns.     

Effect of tannic acid solution on collagen structures for dental restoration

This study examined the effect of tannic acid solution on dissolution of dentine collagen and morphological aspects of tendon collagen. Using root dentine, which was cut off from bovine anterior tooth, dentine powders were obtained by the pulverization and lyophilization. They were subject to an application of 1, 3, 5 or 10% tannic acid (TA) solution for 1, 3, 6, 12 or 24 h. TA-treated dentine powders were treated with 40% phosphoric acid (PA) for 30 s at 20 °C and additionally with trypsin. Released hydroxyproline in Woessner's assay after a hydrolysis in 6 N HCl at 110 °C for 20 h was assumed to be dissolved dentine collagen. Released hydroxyproline in a control sample without acid treatment decreased from 100 to about 60% with increased TA concentration of 1 to 10%, and decreased with increased incubation times of 1 to 24 h when applied by 5% TA solution. Scanning electron microscopy results established the morphological effect of their surface characteristics due to such treatments as 40% PA for 30 s and 5% TA for 6 h, or 40% PA after 5% TA treatment, yielding collagen structures protected by TA to attack from phosphoric acid.     

Tensile behaviour in 30Ni-30Cu-40Mn-based alloys for a dental application

It was possible to examine the tensile behaviour in experimental 30Ni-30Cu-40Mn-based alloys which were modified by alloying additions of aluminium, indium and tin. Namely, the experimental alloys were developed on the basis of crack formation in a commercial nickel-based alloy and microstructural features in nickel-based alloys investigated. The addition was done by substituting only the manganese content (40 wt%) to 35 and 40 wt%. The results indicated that both changes of tensile strength and elongation were obtained with castability values above 94%. Comparison of tensile properties in experimental Ni-Cu-Mn-based alloys studied here showed that the addition of aluminium to the alloys was appropriate to obtain results similar to those for commercial alloys, indicating that the refining of dendrite arm spacing was obtained by aluminium addition.     

Denture base materials reinforced with glass fibres

Glass fibres for industrial use were laid on denture base materials such as self-curing and heat-curing resins to reinforce them. The use of heat-curing rather than self-curing resin as a base resin indicated a superior effect on bending properties.     

Dental application of the 30Ni-30Cu-40Mn ternary alloy system

Experimental nickel-based alloys for dental application were made on the basis of the measurement of dissolved oxygen in the liquid state of the alloys. The improved Ni-Cu-Mn-based alloys were examined for hardness, microstructures and dimensional change. The alloys had a low concentration of dissolved oxygen, and each experimental Ni-Cu-Mn-based alloy containing a single additive element (either aluminium or tin) and complex additive elements (aluminium and tin, aluminium and indium, and aluminium, indium and tin) was constituted mainly by dendrite structure, but the aluminium, indium and tin-containing ones had a smaller amount of dendrite structure than the others, representing a fineness of dendrite structure. In addition, the metal crowns of the improved Ni-Cu-Mn-based alloys showed a better fit than that of the original Ni-Cu-Mn ternary alloy.     

Thermoanalytical characteristics of powders in dental cast investment

The present study examined the thermal properties of phosphate-bonded investments, a gypsum-bonded investment and an experimental investment powder when the basic powders were heated to high temperatures by simultaneous differential thermal analysis (DTA) and thermogravimetry (TG). The phosphate-bonded investments showed values of about 59 kcal mol^–1 (247 kJ mol^–1) (thermal decomposition of NH₄H₂PO₄) and about 11 kcal mol^–1 (46 kJ mol^–1) (formation of NH₄MgPO₄). Thermal reactions occurred clearly on the DTA-TG curves for the investment powders, using powders of NH₄H₂PO₄, and MgO with NH₄H₂PO₄/MgO = 1 as main components in the investment.     

Effect of TEGDMA content on staining of experimental bis-GMA-based resins

This study was to examine water uptake, contact angle and colour change vector in relation to the staining on the optically smooth surface in five experimental visible light-cured (VLC) bis-GMA-based resins. They were formulated from bis-GMA-based resins including 25 to 45 wt% TEGDMA which were accelerated by CQ/DMAEMA/BHT = 0.5/2/0.05 (wt%) to bis-GMA/TEGDMA resin matrix. Of the set resins including more than 25 wt% of TEGDMA, the resins including 30 to 45 wt% had less than 1.0% as bis-GMA residual monomer. Water uptake and solubility in bis-GMA-based resins including 35 wt% TEGDMA were the minimum of the resins tested. Contact angle decreased with increasing time over 70 days, from 67 to 62 degrees. Using the hydrophilic staining solution (food red 3), the values of colour change vector were 6 to 9 after immersing them for 70 days at 37 °C, whereas hydrophobic oil orange staining test had a range of 12 to 19. The change of water uptake with time of immersion correlated with that of the colour change vector. With the accelerated test, the minimum value was 4.55 in 65/35 (bis-GMA/TEGDMA) resin. Of the bis-GMA-based resins (25 to 45 wt% fraction of TEGDMA) the minimum value of water uptake and contact angle were obtained.     

Differences of resected hepatocellular carcinoma with hepatitis B or C virus

BACKGROUND/AIMS: The purpose of this study was to clarify the clinicopathologic differences of hepatocellular carcinoma associated with the hepatitis B versus the hepatitis C virus. METHODOLOGY: One hundred and sixty-eight patients with resected hepatocellular carcinoma were tested for viral hepatitis. Ten (6%) had both the hepatitis B surface antigen and antibodies to the hepatitis C virus. Thirty-three (20%) had neither marker. Sixteen (9%) had only the hepatitis B surface antigen (group B), and 109 (65%) had only antibodies to the hepatitis C virus (group C). We compared groups B and C clinicopathologically. RESULTS: The mean tumor diameter was larger in group B than in group C (6.3 cm vs 3.4 cm), while group B patients were younger than group C (48 yrs vs 62 yrs, p<0.0001). Poor liver function, histologic cirrhosis and chronic active hepatitis were frequently found in group C. The 1- and 2-year tumor-free survival rates following surgery in group B were 67% and 33%, and those in group C were 73% and 49%. The 1-, 2-, and 3-year survival rates following surgery in group B were 78%, 68%, and 0%, while those in group C were 92%, 83%, and 76% (p=0.0189). CONCLUSIONS: Hepatocellular carcinoma with concomitant hepatitis B viral infection was found to present as larger tumors in younger patients with less severe liver dysfunction. Hepatocellular carcinoma with concomitant hepatitis C viral infection was often detected in follow-up studies when it was small.