Effects of Ion-Releasing Tooth-Coating Material on Demineralization of Bovine Tooth Enamel

We compared the effect of a novel ion-releasing tooth-coating material that contained S-PRG (surface-reaction type prereacted glass-ionomer) filler to that of non-S-PRG filler and nail varnish on the demineralization of bovine enamel subsurface lesions. The demineralization process of bovine enamel was examined using quantitative light-induced fluorescence (QLF) and electron probe microanalyzer (EPMA) measurement. Ion concentrations in demineralizing solution were measured using inductively coupled plasma atomic (ICP) emission spectrometry and an ion electrode. The nail varnish group and the non-S-PRG filler group showed linear demineralization. Although the nail varnish group and the non-S-PRG filler group showed linear demineralization, the S-PRG filler group did not. Further, plane-scanning by EPMA analysis in the S-PRG filler group showed no changes in Ca ion distribution, and F ions showed peak levels on the surface of enamel specimens. Most ions in the demineralizing solution were present at higher concentrations in the S-PRG filler group than in the other two groups. In conclusion, only the S-PRG filler-containing tooth-coating material released ions and inhibited demineralization around the coating.

Optical and Electrical Characterizations of AlxGa1−xSb

ABSTRACTThe LPE grown AlxGa1−xSb was investigated by means of TEM, a carrier profiler and PL. The TEM image showed the dissociated 60° dislocations and Lomer-Cottrell sessile dislocation formed by the reaction of two dissociated 60° dislocations on different {111} planes. The EPMA measurement showed that Sb concentrations at the dislocation were lower than the stoichiometric composition. The epi-layer grown at 400°C had a relatively uniform carrier concentration of ∼7×1016cm−3. The PL spectra showed five emission peaks in 0≦×≦0.29. One shallow acceptor level and two native defect levels were introduced to interpret these PL emissions. The shallow acceptor level of Ev+∼30meV may be due to the defect of VGaGaSb. The native defects introduce two levels of EΓ1 - ∼90meV and EL1 - ∼160meV. The defect levels may be related to the complex defect of the Sb vacancy.