The purpose of this study was to examine the effect of fluoride iontophoresis on fluoride uptake and retention on the bovine enamel surface.
Bovine enamel was treated with fluoride iontophoresis at 50, 100 and 200μA for two or four minutes. Enamel treated with fluoride alone without iontophoresis was used as a control. The treatment regiments were one time only, or once a day for three consecutive days. The treated enamel was soaked in artificial saliva for 30 minutes, 24 hours and 1 week, and in 1M KOH solution for 24 hours.
The results were as follows :
1. Iontophoresis significantly increased fluoride uptake in the surface enamel compared with the control.
2. Fluoride uptake increased significantly with an increase in electric current.
3. Iontophoresis significantly increased fluoride retention compared with the control.
4. There was no difference in fluoride uptake between the two- and four-minute treatments with iontophoresis. The two-minute treatment with iontophoresis showed significantly higher fluoride uptake than the four-minute treatment of the control.
5. The treatment with or without iontophoresis showed a greater increase in fluoride uptake and retention in the enamel treated once a day for three consecutive days than for treatment only once. The rate of increase in fluoride uptake and retention were greater with iontophoresis than with the control.
The results of this study suggest that iontophoresis enhances the activity of fluoride with respect to fluoride uptake and retention in the enamel surface.

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The effect of streptozotocin-induced diabetes on the structure of heparan sulfate (HS) prepared from rat liver glycosaminoglycans (GAG) was evaluated. GAG were isolated and purified from the livers of diabetic and age-matched control rats by standard procedures. The HS sample was prepared from GAG by digestion with chon-droitinase ABC and precipitation with cetylpyridinium chloride. The HS sample, including an unknown substance, was further purified by Sephadex G-100 chromatography. The HS fraction was confirmed to consist only of HS by electrophoresis on a cellulose acetate strip.
The amount of HS was decreased in the diabetic group. The Sephacryl S-300 HR column chromatogram of the HS from the control group indicated that the normal liver HS consisted of at least two kinds of HS, which probably originated from the cell surface HS proteoglycan (PG) and basement membrane HSPG. The former HS peak showed a decrease in height and heterogeneity with diabetes. The ratio of iduronic acid to glucuronic acid, which were clearly separated by HPLC, was higher in the diabetic liver HS than in the controls. The above information indicates that diabetes may influence the carbohydrate chain structure of HS in liver.
Quantitative and qualitative changes in the liver HS may contribute to the functional changes of HSPG in diabetic tissue.

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Dental school hospitals are expected to provide quality dental treatment while training dental students. This study examines the current status of radiographic examinations at teaching hospitals from the standpoint of radiation protection.
Detailed records of intraoral radiography conducted by undergraduate dental students have been collected over the past 8 years at the Department of Oral Radiology, Osaka Dental University. Of these records, those for the two-year period from 1985 to 1986 were selected for analysis of radiation exposure. Using a RANDO phantom, I estimated the mean X-ray dose per patient receiving intraoral radiography at this hospital.
The mean bone marrow dose per patient for whom intraoral radiography was performed by undergraduate dental students was 45.7μGy in 1985 and 42.4μGy in 1986. The effective dose was estimated at 52.1μGy in 1985 and 49.8μGy in 1986.

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Outer membrane proteins (OMP) of Bacteroides endodontalis HG 370 (=ATCC 35406) were prepared from the cell envelope fraction of the organism. The cell envelope that had been obtained by sonication of the whole cells for 20 minutes was extracted in lithium dodecyl sulfate, followed by partial purification by successive chromatography with Sephacryl S-200HR, and DEAE-Sepharose Fast Flow. On the other hand, B. endodontalis lipopolysaccharides (LPS) were prepared by hot phenol/water extraction. Two OMP fractions, OMP-I and OMP-II, were obtained, and their immunochemical properties and induction of specific antibodies were investigated :
1. The OMP-I preparation consisted mainly of a protein with an apparent molecular weight of 31,000 (31K), while the OMP-II preparation was composed of 15.5K, 27K and 44K proteins as revealed by SDS polyacrylamide gel electrophoretic analysis.
2. Immunodiffusion tests revealed that anti-OMP-I serum formed three precipitin bands against the homologous OMP-I and against OMP-II, respectively. One of the precipitin bands of the OMPs produced a fused precipitin band. On the other hand, anti-OMP-II serum formed two precipitin bands against OMP-II and only one precipitin band against OMP-I.
3. OMP-I was found to exhibit significant porin activity, i. e. the ability to form hydrophilic diffusion pores by incorporation into the artificial liposome membrane. However, the liposomes containing heat-denatured OMP-I were scarcely active.
4. Spontaneous and antigen-specific IgM, IgG, and IgA-secreting cells (SFC) enzymatically dissociated into single cell suspensions from chronically inflamed periapical tissues, and were enumerated by ELISPOT assay. In patients with radicular cysts or dental granulomas, the major isotype of spontaneous SFC was IgG. In radicular cysts, the OMP-II -specific IgG-SFC represented 0.006%〜0.03% of spontaneous IgG-SFC. No antigen-specific IgA- or IgM-SFC was observed. However, these mononuclear cells did not contain lymphoid cells producing antibody to antigen such as OMP-I or B. endodontalis LPS.

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Antimicrobial susceptibility and β-lactamase production was examined for streptococci and enterococci isolated from infectious oral lesions.
Morphological changes in CEX-susceptible and CEX-nonsusceptible enterococci were observed by transmission electron microscopy to ascertain the origin in these differences in susceptibility.
Seventeen strains of S. milleri, 10 of S. sanguis, 10 of S. morbillorum, 5 of S. mitior, 7 of S. sp., and 3 of S. faecalis were isolated. Streptococci were generally highly susceptible to EM, CLDM, JM, ABPC and PIPC. Enterococci indicated moderate susceptibility to ABPC, AMPC and EM, although virtually none of the strains were susceptible to other antibiotics. No strains producing β-lactamase were found in the streptococci or enterococci when nitrocefin was used.
Elongated cells were observed in the strain of CEX-nonsusceptible enterococci exposed to 1/2 MIC of CEX, while the cells of the CEX-susceptible strain collapsed without morphological changes. It is known that differences in the affinity for β-lactam antibiotics in the penicillin-binding proteins in the two strains of bacteria induce different morphological changes. Therefore it was thought that the differences in the MIC for the two enterococci resulted from differences in the affinity for CEX in the penicillin-binding proteins.
It was concluded that ABPC and CLDM were appropriate for oral infections caused by streptococci, enterococci, and other anaerobic bacteria. The lack of susceptibility of Enterococcus was most likely caused by a decrease in the affinity for CEX in the penicillin-binding protein.

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[in Japanese]

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