Novel fabrication method for zirconia restorations: bonding strength of machinable ceramic to zirconia with resin cements

A novel method was developed to fabricate all-ceramic restorations which comprised CAD/CAM-fabricated machinable ceramic bonded to CAD/CAM-fabricated zirconia framework using resin cement. The feasibility of this fabrication method was assessed in this study by investigating the bonding strength of a machinable ceramic to zirconia. A machinable ceramic was bonded to a zirconia plate using three kinds of resin cements: ResiCem (RE), Panavia (PA), and Multilink (ML). Conventional porcelain-fused-to-zirconia specimens were also prepared to serve as control. Shear bond strength test (SBT) and Schwickerath crack initiation test (SCT) were carried out. SBT revealed that PA (40.42 MPa) yielded a significantly higher bonding strength than RE (28.01 MPa) and ML (18.89 MPa). SCT revealed that the bonding strengths of test groups using resin cement were significantly higher than those of Control. Notably, the bonding strengths of RE and ML were above 25 MPa even after 10,000 times of thermal cycling -adequately meeting the ISO 9693 standard for metal-ceramic restorations. These results affirmed the feasibility of the novel fabrication method, in that a CAD/CAM-fabricated machinable ceramic is bonded to a CAD/CAM-fabricated zirconia framework using a resin cement.     

Biochemical and serological studies on oral ureaplasma

This study was conducted to study chemically and serologically the characteristics of the Ureaplasmas isolated from the human oral cavity. Two hundred and fifty-one healthy and 12 periodontitis subjects were examined for the incidence of the isolation of Ureaplasmas from their oral cavity. A total of twenty-six strains was isolated from the healthy human saliva. But no strains could be isolated from a variety of clinical specimens obtained from the patients. The serological properties of the isolates were tested by the method of metabolism inhibition test (MI test). Seven out of 26 isolates were serologically identical with either one of the ATCC standard strains. However, the serological types of the other strains could not be demonstrated by the MI test. The biological characteristics of 4 isolates and ATCC strains were tested by the usual method. The isolates did not metabolize glucose and arginine, while all strains hydrolyzed urea. On the other hand, none of the isolates lysed skimmed milk and gelatin. The proteolytic activity of the isolates could be demonstrated by using casein and horse serum proteins as substrates. Zymogram patterns from one of the isolates and Streptococcus salivarius were obtained by polyacrylamide gel electrophoresis of the cells lysed with digitonin or cell protein extracts. On the basis of the gel electrophoresis patterns, it is clear that the urease of the Ureaplasma is different from that of the Streptococcus salivarius.     

Transplantation of cancerous cell sheets effectively generates tumour‐bearing model mice

Tumour‐bearing mice were created by transplanting cancerous cell sheets onto the subcutaneous tissue of the dorsal region, using luciferase gene‐transfected mammary gland adenocarcinoma cells, 4T1‐luc2, to investigate the tumourigenicity of the cell sheet relative to a conventional injection of cell suspension. Contiguous breast cancerous cell sheets were harvested from temperature‐responsive culture dishes by reducing the temperature from 37 °C to 20 °C; the sheets were then transplanted onto the dorsal side of the mouse subcutaneous tissue, using a chitin‐based supporting membrane. Cell suspensions obtained by trypsin digestion were subcutaneously injected into the dorsal region of mice. The tumour growth of the transplanted cancer cells was evaluated by the tumour volume and by the bioluminescence from luciferase‐gene transfected cancer cells, using an in vivo imaging system. The cell sheet method improved the 4 T1‐luc2 engraftment efficiency in living mouse tissues at the initial stage by 13‐fold compared with that from injecting cell suspensions. On day 14 after the transplantation, the tumour formation at the transplanted area of cell sheet‐transplanted mice also accelerated, and the mean tumour volume became 1116 mm³, which was 10 times larger than that in cell suspension‐transplanted mice. The cell sheets engrafted on the recipient tissues efficiently due to the preserved extracellular matrix on their basal sides, such that cancer cells were supplied with sufficient oxygen and nutrients from the host tissues to develop tumour tissues. Therefore, cancerous cell sheet‐based transplantation is a promising method for efficiently creating cancer‐bearing mice. Copyright © 2013 John Wiley & Sons, Ltd.     

Gross appearance of hepatocellular carcinoma reflects E-cadherin expression and risk of early recurrence after surgical treatment

BACKGROUND AND AIMS: Correlation between the gross classification of hepatocellular carcinoma (HCC) and its vascular invasion or intrahepatic metastasis has been reported previously. Because E-cadherin-mediated epithelial cell-to-cell adhesion is thought to suppress cancer cell invasion, the present study was performed to analyze the correlation between E-cadherin expression and the gross classification of HCC. METHODS: Thirty-six resected solitary HCC <6 cm in diameter were each classified as single nodular type (type 1), single nodular with extranodular growth type (type 2) or contiguous multinodular type (type 3), and the clinicopathological and prognostic differences between type 1 HCC and the other types were analyzed. The expression of E-cadherin in each tumor was examined by immunoblotting and immunohistochemical analysis. RESULTS: Vascular invasion and microscopic intrahepatic metastasis were observed more frequently in types 2 and 3 (61%) than in type 1 (13%) HCC. Immunoblot analysis indicated that the relative level of E-cadherin expression in cancerous tissue was significantly lower in type 2 and 3 (0.75 +/- 0.49) than in type 1 (1.46 +/- 0.79) HCC. Immunohistochemical examination revealed decreased and partially absent E-cadherin expression in the tumorous area of type 2 and 3 HCC. The recurrence-free survival rate was higher for patients with type 1 HCC than for those with the other types. CONCLUSIONS: Types 2 and 3 HCC have marked metastatic and invasive potential and reduced expression of E-cadherin, predicting a high risk of recurrence after surgical treatment.