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Volume 29 (1979 - 198･･･
- Issue 4 Pages 346-
- Issue 3 Pages 276-
- Issue 2 Pages 90-
- Issue 1 Pages 1-
Volume 29, Issue 2
Displaying 1-5 of 5 articles from this issue
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(II) Observations under Microradiogram and Scanning Electron MicroscopyTetsuo KODAKA, Tetsuko IMURA, Miyuki KOBAYASHI, Takeyuki NAKAGAWA, Sho ...1979 Volume 29 Issue 2 Pages 90-102
Published: 1979
Released on J-STAGE: July 27, 2010
JOURNAL FREE ACCESSHuman incisors, fixed in 10% formalin, were exposed to disinfected (Calpis) or live (Yakult) lactobacillus drink at 37°C and the structural changes of the natural surface and the outer enamel layer were observed.
The natural surfaces of the enamel exposed to the lactobacillus drinks became white and the degree of whitenss increased day by day. The changes however were not as distinct by scanning electron microscopy and electron probe X-ray microanalyser. It was found that the peripheries of the terminal enamel rods on the natural surfaces were dissolved by exposure to the disinfected lactobacillus drink for 10 days and by exposure to the live lactobacillus drink for 24 hours.
On the other hand, in the outer enamel layer the demineralized zone migrated to the subsurface enamel layer as days went by and the uppermost surface of the enamel was recognized as a highly mineralized zone, indicative of remineralization. On exposure to live lactobacillus drink for 10 days a highly mineralized zone was observed in the outer enamel layer and inside the mineralized zone a demineralized zone was found. By scanning electron microcopy the crystallites of the enamel rods were needle-like in structure and their arrangement was relatively sparse in the demineralized zone. The cores of the enamel rods were dissolved at the incremental lines of Retzius.
In the ground enamel and dentin exposed to the lactobacillus drinks demineralization occured from their surfaces and the highly mineralized zones as shown in the intact enamel were not observed.View full abstractDownload PDF (20531K) -
Part 3Masanori KOHARA, Makoto WADA, Michio MURAKMI, Yukio KAMONJI, Hitoshi T ...1979 Volume 29 Issue 2 Pages 103-111
Published: 1979
Released on J-STAGE: March 02, 2010
JOURNAL FREE ACCESSIn the present study, 12 dental students at Nihon University School of Dentistry were used. They were instructed to brush their maxillary and mandibular anteriors thoroughly for 10 minutes and, subseqently, their teeth remined unbrushed for 48 hours, in which time the formational processes of dental plaque were observed at 6 different intervals.
In the initial time interval, the individual differences were particularly noted with the rate of plaque formation being anywhere form 21 to 27% after 4 hours. After the passage of 48 hours, however, the rate of plaque formation was just 4 to 10%. In terms of different teeth and surfaces, the labial surface of maxillary lateral incisors was the soonent in plaque formation in 13 to 16 hours after the brushing. followed by that of mandibular lateral incisors in 15 to 17 hours. The lingual surface of maxillary central incisors was the latest in plaque formation with the time lapse of 24 hours.
Although there was no appreciable difference between the maxilla and mandible with regard to the labial surface, the mandible hed a tendency of a sooner plaque formation as regards the lingual surface.
Propagative processes were not directly connected with an inadequate toothbrushing, and, in many cases, the tips of propagative plaques presented round appearances.View full abstractDownload PDF (1276K) -
Kohei KATAYAMA, Yoshikazu TAKAHASHI1979 Volume 29 Issue 2 Pages 112-122
Published: 1979
Released on J-STAGE: March 02, 2010
JOURNAL FREE ACCESSTo elucidate precisely the sex differences in caries morbidity, they should be observed by post-eruptive tooth age on the individual kind of teeth under the constant sugar consumption per year per head after eruption (p) based on the epidemiological principles in dental caries attack. Authors analysed 983 boys and 778 girls who were longitudinally observed for 3 to 6 years from 1970, using the criteria on caries of WHO, the material collected by K. Katayama. The sugar consumption during the period under survey was in stable condition of about 27kg per year per head. Analytic methods were shown in detail in the previous paperaand followed by the same approach. Cumulative number of carious teeth up to the post-eruptive tooth age x per initial 100 teeth (ΣCx) is applyed for this study. The main results of the caries indices are shown in Table 1 and 2. Statistical test of sex differences in ΣCx by ordinary chronological age is resulted in Table 3, and results of same test by post-eruptive tooth age are shown in Table 4. Cochran's Criterion Method is applied to compare the overall difference in ΣCx of every kind of teeth between the sexes, and the results are shown in Table 5.
With reference to frequently used caries indices, children of Group A are analysed, as shown in Table 6. Among the higher risk group of teeth in caries attack, females show higher risk than males during the early post-eruptive tooth ages and then the differences narrow in advanced ages. Two ΣCx curves of male and female in this paper show the same pattern as those of low and high risk groups in caries attack, derived from epidemiological principles advocated by M. Takeuchi. It gives the fact that the difference in sex of caries morbidity is existed, but it lies within a minor magnitude.
aKatayama K.: Caries incidence pattern by post-eruptive tooth age in permanent teeth, J. Dent. Hlth, 28; 220-243, 1978View full abstractDownload PDF (1561K) -
Toshiko ATSUMI1979 Volume 29 Issue 2 Pages 123-133
Published: 1979
Released on J-STAGE: March 02, 2010
JOURNAL FREE ACCESSIt is well known that nitrite is one of the precursors of potential carcingenic nitroso compounds. The presence of nitrite in human saliva has been also reported by some workers, but the mechanism of nitrite production in the saliva is not yet clear. The purpose of this study is made to determine how nitrite is produced in the saliva in vivo and in vitro.
The concentrations of nitrite and nitrate were estimated in the mixed and the parotid saliva, the gargle water, blood and urine in human under several conditions.
The results obtained were as follows.
1) After oral administation of sodim nitrate, large amounts of nitrite were detected in the mixed saliva, but it was not contained in the parotid saliva, the blood and the urine at all. On the other hand, nitrate concentration was increased in the mixed saliva, the parotid saliva and the urine. However nitate concentration in the blood did not change and showed constant level after the administration of sodium nitrate.
2) When sodium nitrate was kept in the oral cavity in a few minutes, the decrease in nitrate and the increase in nitrite were observed in the gargle water.
3) Nitrite was produced in parallel with the amounts of salivaly sediment in vitro. Activity of nitrate reduction of salivary sediment disappeared by both heating and filtration. It was also decreased to 20% by sonication at 10 _??_ KC for 10 mins.
4) Number of Veillonella, habitual oral microorganism, had correlation with the ratio of nitrite to nitrate in the gargle water.
From these results, it might be concluded that nitrite in the mixed saliva was not derived derectly from the blood, but it was formed from nitrate, which was concentrated in the salivary gland, and reduced by the oral microorganisms, mainly Veillonella.View full abstractDownload PDF (1728K) -
Kenshi SHINKAI1979 Volume 29 Issue 2 Pages 134-144
Published: 1979
Released on J-STAGE: March 02, 2010
JOURNAL FREE ACCESSThe purpose of this study was to examine the effects of fluoride varnish on the dentin. Experiments were made in vitro of applications of fluoride varnish with the intact dentin as material. Fluoride varnishes contained 5% and 2% NaF were used, and non-fluoride varnish as control. The fluoride content in succesive layers of dentin was determined by chemical analysis, using an ORION ion meter (model 801) and fluoride ion electrodes. The calcium content was determined by Yanagisawa's method, using plasmocorinth B.
The distributions of fluorine, calcium and phosphorus in the dentin treated with fluoride varnish have been studied by means of electron probe microanalysis.
An acid solubility test was made to determine the released calcium content from dentin treated with varnishes into a 0.4M acetate-sodiumacetate buffer (pH 4.0) during three hours in every thirty minutes.
In the experiments of applications of fluoride varnish on the dentin, the fluoride content of the dentin was increased, especially the outer surface layer of dentin contained greater amounts of fluoride. The distribution of fluoride was about 70-100 μm from the outer surface layer of dentin. An acid solubility test proved that the acid resistance was increased as 2-6 times much in the fluoride varnish treated dentin as the control varnish.View full abstractDownload PDF (4021K)
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