This study showed that salivary occurrence of periodontopathic bacteria in young individuals was related to the length of time the parents had lived in the United States, education level of the mother, length of time since last dental visit, and gender, but apparently not to ethnicity per se.

We studied the cause of high TC of superconducting boron-doped diamond (111) when compared with that of (001) even at the same boron concentration. The atomic stereophotograph revealed that a disproportionate boron concentration is located at one of the two sites in (111). The distinction of the dopant site exists only in (111) surface and does not exist in (001) surface. Furthermore, there is a theoretical prediction of high density of state at Fermi level in ordered dopant diamonds. Therefore, this configuration should be the origin of the higher TC of (111) as compared with that of (001).

We used a polymicrobial (PM) biofilm model to examine associations of bacterial adhesiveness with surface characteristics of various dental materials. Four types of dental materials (apatite pellet, zirconia, ceramic, and composite resin) with rough and mirror surfaces were used. Surface roughness, surface free energy, zeta potential, and colony-forming units (CFUs) of the biofilm formations were measured. Biofilms were cultured for 24 h under anaerobic conditions, plated onto blood agar medium, and anaerobically cultured for 4 days. After culturing, CFU per mm 2 was calculated, and samples were observed under a scanning electron microscope. Means and standard deviations of the experimental data were estimated, and one-way ANOVA and Tukey multiple comparison assays were performed. Pearson correlation coefficients were obtained for the CFU and surface characteristics. Surface roughness and surface free energy appeared to affect generation of PM biofilms on oral materials, and zeta potential was involved in generation of PM biofilms on mirrorground oral materials.

We have developed a new Wide Acceptance Angle Electrostatic Lens (WAAEL) and applied that as display-type electron energy analyser. Our present lens achieves ±60°(1p sr) acceptance angle and has a good focusing capability with 5-times mag-niˆcations. The relative energy resolution is typically from 2 to 5×10-3 and depends on the emission area on the sample, as well as, on the diameter of exit aperture. Some preliminary results and discussions related to its energy resolution are shown.

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