Purpose: This study examined the color analysis of 3% hydrogen peroxide on organic and inorganic chromogen sources in bovine dentin. Materials and Methods: 21 bovine dentin samples with a thickness of 0.5mm were prepared. Samples were divided into 7 groups discolored by organic chromogen sources (Maillard reaction using a glucose; GL solution), inorganic chromogen sources (trace metal elements; Ni, Cu, Fe) and by mixture of both the Maillard reaction and trace metal elements. Spectrophotometric measurements were taken before the samples were subjected to 3% hydrogen peroxide and throughout the bleaching process at 10 seconds intervals (total 120 seconds). Color changes on dentin samples of 7 groups were analyzed for color difference ⊿E, L*, a* and b* values. Results: Samples discolored via the Maillard reaction responded best by increasing their ⊿E values while decreasing the b* values. In contrast, samples discolored by trace metal elements of Cu were not responsive, and samples discolored by Fe were darkened greatly. Ni indicated a slightly positive response. Conclusion: Hydrogen peroxide was effective in bleaching samples discolored by Glucose and Ni. However, the peroxide bleaching decreased the value of L*, and worsened the effect for samples discolored by Fe. This study suggests that the type of chromogen that discolors teeth has a great role in determining the efficacy in peroxide bleaching.
I had to grasp of color studies and an Optical observation of silicone resin and the color which were maxillofacial epitase materials precisely and examined it. I chose transparent silicone resin and five colors pigments (brown, white, yellow, blue, red) as maxillofacial epitase materials. I produced five colors of monotone color samples on three kinds of thicknesses: 1.0, 2.0, 3.0 mm. White and brack background were used as a measurement for colors. With a spectrophotometer, I calculated the dispersion coefficient (K) and the absorption coefficient (S) based on the Kubelka-Munk theory. I produced a two-colors compound color sample with thicknesses of 1.0, 2.0, 3.0 mm and measured them. A color of a compound color material used a dispersion coefficient and the absorption coefficient that I calculated from a sample of three kinds of thicknesses based on a formula of Duncan and predicted it. I compared the actual survey value with the prediction value of each compound color material and calculated a color-fixer. The average dE value was 6.77, between a prediction value and actual survey values with monotone color samples of thickness of 1.0mm were 11.95, greatest color-fixer minimum color-fixers was 4.25. Tolerance level of a color-fixer to be able to put in the mouth is reported as 3.7-3.8. Besides, it faces each other in the gloomy mouth, and a color-fixer at the sensitive face skin surface and maxillofacial epitase interval of a color must lowered it more.
The expression of intercellular adhesion molecules and the cell proliferative activity were analyzed in metastatic focus of lymph node and compared with those in primary oral squamous cell carcinomas in the present study. Immunohistochemistry was performed for E-cadherin, α-catenin and β-catenin in the primary lesions of 11 oral squamous cell carcinomas, and 36 tissues of 18 metastatic foci. The PCNA (proliferative cell nuclear antigen) labeling index was calculated as the percent of immunostain-positive cells to anti-PCNA antibody. Immunostaining of adhesion molecules was categorized as one of three types: preserved, reduced, and lost compared with that in normal oral epithelium. These three adhesion molecules were clearly expressed in the cell-cell contact sites of normal oral epithelium. In the expression of E-cadherin, 8 primary tumors showed reduced type (72.7%), which was the highest ratio. In contrast, in metastatic foci, 25 tumors showed lost-type as the highest (69.4%). Furthermore, in metastatic focus, the expression of E-cadherin was significantly (ANOVA, p<0.05) decreased, and that of β-catenin was also decreased as the tumor expanded in the lymph node. However, the expression of α-catenin did not change with tumor progression. Although the PCNA labeling index in metastatic foci was significantly lower than that in primary tumors (Student t-test, p<0.01), it increased as the tumor advanced in the lymph node. In metastatic foci, as the expression of E-cadherin reduced, the PCNA labeling index was increased conversely. In conclusion, in metastatic oral squamous cell carcinoma of the lymph node, reduction of E-cadherin was involved in the growth and migration of oral squamous cell carcinoma.
Psychosedation, as used in the field of dentistry, is intended to provide trouble-free dental care while maintaining a proper level of sedation. One drug used in psychosedation is midazolam, which is known to have a strong amnestic effect. In the current research, I sought to clarify whether the bispectral index (BIS) using EEC analysis can be used for assessment of optimal sedation in psychosedation, and what effects midazolam has on the cerebrum's mechanism of memory. The subjects were 17 healthy adult volunteers. Intravenous sedation involved a single administration of 0.06mg/kg midazolam, or 6mg/kg/h propofol, administered for 5 minutes and then continuously administered for 25 minutes at 3mg/kg/h. For nitrous oxide inhalation sedation, 10-30% nitrous oxide was used. Clinical sedation and the BIS were measured in a variety of circumstances. To examine the effects of midazolam on the central nervous system, changes in brain oxygen consumption in visual memory tasks were assessed through observing changes in areas of brain activation using 3 T fMRI. With intravenous sedation using midazolam or propofol, the BIS decreased immediately after drug administration, and the BIS at which optimal sedation was clinically determined was about 65. In contrast, no decrease in the BIS was noted with nitrous oxide inhalation sedation. In observing areas of brain activation by fMRI, the oxygen consumption mainly of visual cortices in the occipital lobe increased as a result of stimulation by visual memory tasks. Regardless of the amnestic effect midazolam produced in subjects, it did not suppress activation of the visual cortices in the occipital lobe. In intravenous sedation using midazolam or propofol, the BIS is effective in determining optimal sedation, and appropriate perioperative management can be performed using the BIS. However, in nitrous oxide inhalation sedation it appears that the BIS cannot be used to monitor levels of sedation. Amnestic action by midazolam is assumed to occur not through inhibition of pathways from visual cells to visual cortices, but through inhibition of the higher central nervous system.