The apical canal sealing ability of newly developed calcium phosphate cement (TDM-C), an equimolar mixture of tetracalcium and dicalcium phosphate dihydrate kneaded with Mcllvain's buffer solution containing sodium carboxymethyl cellulose, was evaluated in a relative comparison with several recognized available products. The latter included BONETRIX (α-tricalcium phosphate mixed with citric acid and tannic acid), ARS (α-tricalcium phosphate and hydroxyapatite mixed with polyacrylic acid), and zinc oxide eugenol sealer (ZOE). Canals of forty extracted human maxillary central incisors were prepared to the file size #70, divided into four groups, and obturated with each of the four above materials. Setting of all sealers took place either in 30% bovine serum solution or in phosphate buffered saline solution. Teeth were then decalcified and cleared to measure linear penetration of India ink from the apex into the canal. Results were statistically analyzed by Student's t-test. Surfaces of all materials, after setting, were also observed by scanning electron microscopy (SEM). We found that TDM-C, BONETRIX, and ZOE all showed excellent apical sealing ability whereas ARS was less effective in this regard. SEM analysis revealed micropores on the surface of every apatitic product, but ZOE was free of such porosity. It was concluded that TDM-C and BONETRIX may prove clinically useful as root canal sealant materials.
We developed a TMJ viscoelasticity analyzer for non-invasive evaluation of the soft tissues of the TMJ region. We used this device to measure the viscoelastic parameters, viscosity (c), elasticity (k) and mass (m), of the TMJ region for two volunteers. Experiments were performed to determine the optimum measurement conditions for the preload magnitude, head posture and clenching level. We determined measurement variability and carried out statistical analysis by analysis of variance (ANOVA). We found that the values for c and k varied significantly depending on preload magnitudes (p<0.001). In addition, all parameters varied significantly depending on head posture. However, clenching level did not significantly affect any of the parameters. Measurement variability was below 10% for all parameters. Examination of viscoelasticity of the TMJ region provides valuable information about functional and pathological changes in the soft tissues of this area. In this study, we were able to determine the fundamental characteristics of the TMJ viscoelasticity analyzer and develop methods for examining patients with temporomandibular disorders.
We investigated the biochemical characteristics of cell membrane-associated proteoglycans extracted from ascites Tawa sarcoma cells. Proteoglycans were extracted with 4M Gdn-HCI, and purified by DEAE-Sephacel. The extract sample was fractionated into two proteoglycan fractions, TC-I and TC-II, and eluted at salt concentrations of approximately 0.35M and 0.45M NaCl, respectively, by HPLC ion exchange chromatography using a Bio-Scale DEAE 5 column in 7M urea. After HPLC gel filtration using a TSK gel G 6000 PW column, the fractions were further analysed by hydrophobic interaction chromatography on Octyl-Sepharose in 4M Gdn-HCI. Since TC-I displayed hydrophobic properties while TC-II was non-hydrophobic, the former was regarded as the proteoglycan associated with the cell membrane. Cellulose acetate membrane electrophoresis confirmed that both TC-I and TC-II contained only heparan sulfate as a sugar chain, and that the degree of sulfation of TC-I and TC-II was lower than that for normal tissue. Immunoblotting with monoclonal antibody HepSS-1 showed that TC-I and TC-II contained two heparan sulfate proteoglycans with Mr of about 30 kDa and 45 kDa, respectively. These results indicate that the proteoglycan associated with the cell membrane of ascites Tawa sarcoma cells is a small and undersulfated-heparan sulfate proteoglycan.
Patterns of collateral vascularization were investigated by SEM evaluation of microvascular corrosion casts following either ligation or embolization of the external carotid artery in the rabbit. Results indicated that rich collateral channels were established soon after ligation of this artery, and blood supply to the lesional area was never cut off. In contrast, embolization effectively obstructed blood supply by reducing collateral branches. We concluded that for purposes of controlling blood loss, it is more helpful to employ external carotid embolization rather than ligation for oral maxillofacial lesions with a rich blood supply.
p53 expression in rat tongue epithelium was investigated immunohistochemically following experimental carcinogenic induction by 4-nitroquinoline 1-oxide (4NQO). p53 assays were performed using PAb240 anti-p53 monoclonal antibody during various stages of experimental carcinogenesis. I found that p53-positive epithelial cells increased in direct proportion to development of the tumor. Significant increases were observed during the periods from control to 4 weeks and from 8 to 12 weeks after 4NQO adiministration. Although no histological changes were observed in the earlier period, hyperplasia and dysplasia were observed in later stages. Mutant type p53 was detected by immunoprecipitation at 16 and 20 weeks after administration of 4NQO. Results suggested that epithelial p53 detected prior to onset of histological changes was wild-type, while that in the hyperplastic or dysplastic epithelium was mutant.