Streptococcus constellatus, a member of the anginosus group streptococci, is commonly associated with oral abscesses, bacteremia with subsequent septic shock, and brain abscesses. We isolated S. constellatus strain H39 from an apical abscess lesion. Scanning electron micrographs revealed that strain H39 had dense meshwork-like structures around the cells, which are a characteristic of biofilm-forming bacteria. In this study, we reported a draft genome sequencing of strain H39 which can be used for further genetic study on biofilm formation mechanisms. The genome sequencing was performed by pyrosequencing. The putative gaps between contigs were closed by sequencing of polymerase chain reaction amplicons over the gaps. A high-quality draft genome sequence indicated that strain H39 had 3 ribosomal RNA genes, 45 transfer RNA genes and 1,926 putative protein-coding genes. We also found that strain H39 possessed genes encoding exopolysaccharide biosynthesis proteins and ABC-type polysaccharide transport proteins. These genes might contribute to the biofilm formation of S. constellatus strain H39.

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We investigated the repeatability of contact area measurements using a tooth contact analyzing device which can quantitatively measure occlusal contact area and the number of contact points. A kneaded sample of silicon was weighted with a 1 kg steel ball fixed on a constant loader. We made seven silicon samples with steel balls of seven different sizes, and recorded the contact area of the samples at thicknesses of less than 4 μm, less than 9 μm and less than 29 μm using the BiteEye^® tooth contact analyzing device. The measurements were made twice on the same day. Two measurement values were assessed by the intraclass correlation coefficients (ICC), and the mean differences (MD) and 95% limits of agreement (95% LOA) were obtained by the Bland-Altman method. We then evaluated the repeatability of repeated measurements.
    The ICCs were greater than 0.9 for all of the repeated measurements for each thickness of silicon sample. The MDs were all essentially zero (-0.005 mm², -0.002 mm² and 0.011 mm² for the silicon thicknesses of less than 4μm, less than 9μm and less than 29μm, respectively). The 95% LOAs were -0.083 to 0.070 mm², -0.054 to 0.051 mm², and -0.082 to 0.105 mm² for the three thicknesses, respectively. We found that the repeatability of the measurements using the tooth contact analyzing device was very high.

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Recent studies have demonstrated that bacterial heat shock proteins (HSPs) play a role not only as intracellular molecular chaperons, but also as adhesion molecules and stimuli against the host immune system. We examined the effect of recombinant GroEL and DnaK proteins of Prevotella intermedia (P. intermedia) on the biofilm formation of this organism. The recombinant GroEL was also used as an immunogen to obtain rabbit antibodies against the wild-type GroEL of this organism. In addition to the biofilm assay, the genome sequence of P. intermedia strain 17-2 (which is a naturally occurring variant without biofilm-forming capacity) was obtained by using the 454 pyrosequencing technology and mapped on that of the biofilm-forming parent strain 17.
    The rabbit polyclonal antibodies recognized 60 kD proteins which had a molecular weight corresponding to that of the wild-type GroEL in the sonicate of strain 17 cells as well as in the culture supernatant. Although recombinant GroEL and DnaK in the culture media inhibited the biofilm formation of strain 17, it enhanced those of strain 17-2 and ATCC 25611 (a type strain for P. intermedia). The genome mapping of strain 17-2 on its parent strain genome revealed that a few genes of strain 17-2 contained extensive mutations. The data obtained in this study suggest that the extracellular GroEL and DnaK of P. intermedia both play a role in the biofilm formation of this organism, and may also suggest that genes highlighted in this study might be responsible for its biofilm formation.

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We attempted to clarify the plaque control efficacy of the short use of electric toothbrushes. Ten dental students and staff volunteers participated in this before-and-after study. First, the subjects used a manual toothbrush as usual for 2 min twice daily for one week. Then, following instruction in its use, they used an electric toothbrush under the same conditions for either one week or three months. Evaluations of plaque, gingivitis, bleeding and quantitative light fluorescence (QLF) were performed at the beginning and end of each experimental period. After using each brush for two weeks, the subjects were asked to complete a questionnaire that documented their attitude to and subjective opinion of the electric toothbrush, and a visual analogue scale (VAS) score was calculated.
     The adhesion of dental plaque, the grade of gingivitis, and the existence of bleeding were evaluated at one week and at three months. There was a tendency for improvement and the oral age decreased in many subjects. Results of the VAS score showed that the subjects had a high degree of satisfaction with the electric toothbrush.

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It is thought that elucidation of the proliferation potential of oral squamous cell carcinoma (OSCC) will contribute to progress in anticancer therapy. We investigated the proliferation potential of the OSCC cell lines HSC3 and HSC4. 5× 10³ cells per well were cultured on a nonadhesive 96-well plate at serum concentrations between 0% and 10%. HSC3 proliferated at a serum concentration of 5%, and showed low level proliferation at 1%. However, no proliferation was seen with a serum concentration of 0%. When HSC4 cells were cultured at concentrations between 1×10³ to 2×10⁴ cells per well under serum-free conditions, there was no proliferation at 1×10³ cells per well. However, the proliferation increased in a concentration dependent manner up to 2×10⁴ cells per well. Furthermore, when TAPI-2 (Sheddase inhibitor) and DAPT (γ-secretase inhibitor) were added in the HSC4 culture medium, proliferation was reduced only by TAPI-2. Moreover, proliferation was decreased when AG1478, which is an EGFR inhibitor, was added.
     These results suggest that HSC4 promotes autonomous proliferation in a serum-free culture based on the autocrine-loop mechanism of the EGFR ligand, which is the growth factor emitted by ectodomain shedding. However, HSC3 had no effect on this system.

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