Chiral a-amino-d-keto esters are important precursors of organocatalysts, pharmaceuticals, and biochemically interesting molecules. The organocatalytic asymmetric umpolung reaction of imines has been developed to obtain chiral amines in a highly enantioselective manner. Herein, we report the organocatalytic asymmetric umpolung synthesis of a-amino-d-keto esters in high yield (up to 95% ee, > 20/1 r.r.).

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This study evaluated shear bond strengths of two gingiva-colored layering resin composites to zirconia frameworks coated with feldspathic porcelain. Airborne-particle abraded porcelain-coated zirconia disks were treated with one of the following primers: Clearfil Photo Bond, Clearfil Photo Bond with Clearfil Porcelain Bond Activator (CPB+Activator), Estenia Opaque Primer, Porcelain Liner M Liquid B (PLB), or no primer. A light-polymerizing (CER) or a photo/heat-polymerizing gingiva-colored indirect resin composite (EST) was bonded to the porcelain-coated zirconia disks in each group (n=11). Shear bond strength was measured. For both CER and EST specimens, bond strengths in CPB+Act group were significantly higher than those in the other groups. In all priming groups, bond strength was significantly higher for EST specimens than for CER specimens. Combined application of a phosphate monomer and silane enhanced initial bond strength of light-polymerized and photo/heat-polymerized gingiva-colored layering resin composites to porcelain-coated zirconia ceramics.

The purpose of this study was to evaluate the e#ect of yellow He-Ne laser irradiation in the presence of crystal violet (CV) solution on dental plaque formation in the human mouth. Four enamel specimens were fixed on a retainer, one of which was placed on both maxillary buccal sites of four subjects. The retainers were assigned randomly to 3-or 7-day experimental periods and the right or left buccal sites for the evaluation of plaque formation on the specimens. Then, the specimens were assigned randomly to four treatments as follows: A, laser irradiation; B, CV application; C, CV application and laser irradiation and D, no treatment (control). At three and seven days after the treatments, the inhibitory e#ects of plaque formation on the specimens were evaluated by measuring the thickness of the plaque on each section. Analysis of the plaque formation scores revealed that treatment C had a significantly greater inhibitory e#ect on plaque formation than treatment A, B and D after 3 days, however there were no significant di#erences among the plaque formation scores of the four treatment groups after 7 days. Analysis of the plaque thickness revealed that at both 3 and 7 days after treatment, the plaque layers after treatment C were significantly thinner than those after treatments A, B and D. These results indicated that yellow He-Ne laser irradiation in the presence of CV had an inhibitory e#ect of plaque formation in human mouth.

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