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Volume 10 (1960)
- Issue 4 Pages 197-
- Issue 3 Pages 152-
- Issue 2 Pages 65-
- Issue 1 Pages 1-
Volume 10, Issue 3
Displaying 1-4 of 4 articles from this issue
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Hajime SATO1960 Volume 10 Issue 3 Pages 152-172
Published: 1960
Released on J-STAGE: March 02, 2010
JOURNAL FREE ACCESSExtracted human teeth which were caries-free and with normal appearance were used for the studies. 92 teeth were made up to the specimens. They were cut by means of a high speed carborundum wheel, so to obtain suitable surfaces for investigations. The cut surfaces were bisected through the long axis either in the bucco-lingual or labio-longual plane. The surface of the enamel and dentin of every specimen was artificially ground and polished to the greatest smoothness. The sutdies were conducted by using the Vickers microhardness tester. For the front teeth five places were measured which were cirvical region (both of labial and lingual side) ridge (or cusp), labial and lingual surface. For the posterior teeth 8 places were measured. They are cirvical region, cusps, buccal and lingual surface, bucco-occlusal and lingo-occlusal surface. Many impression points were made to the surface of every specimen from the enamel to the predentin at the places mentioned above with a known load, and so the hardness were determined by measuring those impression points.
As to the enamel region, from the dentino-enamel junction to the enamel surface it was divided into many parts with every width of 300μ. made a layer, b layer etc. the highest was up to 8 layers. As to dentin 5 layers were divided (a-e), at each of that layers the hardness was reseached.
The results are as follows;
1. The hardness of the enamel shows the average 360, the hardness of the dentin fell to the range nearly 60.
2. It was found that the enamel of the anterior teeth have the most hardness at cutting edge, near the neck teil of the tooth have a very low value. The middle value is the portion at the center parts of the labial and lingual surfaces. In the posterior teeth the hardness of enamel have a wide variation of the upper, lower or kinds of teeth.
3. A survey of the results revealed a wide variation in the hardness of the enamel but the hardness of the dentin shows a nearly same value.
4. There was a slight increase in hardness from the predentin near the amelo-dentinal junction towards the outer enamel layer.
5. The sexual difference was found out nothing by the hardness measuring of the enamel and dentin.View full abstractDownload PDF (2500K) -
Motoo KANEDA, Kunio MURAYAMA, Chaoshun RIN, Shuichiro ANDOW1960 Volume 10 Issue 3 Pages 173-179
Published: 1960
Released on J-STAGE: March 02, 2010
JOURNAL FREE ACCESSHigh incidence of mottled teeth is present all over the regions centering around Shippo and Kamimori villages of Aichi prefecture. Geologically, the above regions are of diluvial formation of soils carried by the river Kiso and the river Shonai. The incidence of mottled teeth is considered by some workers to be probably due to the effect of the underground water coming from fluorine-containing are of the upper reaches of the river Kiso.
If this interpretation be right, there should be more regions of mottled teeh in the basin of the river Kiso. At several regions of Gifu prefecture which are opposite to Shippo village acrosss the river, we carried out examinations of drinking water for fluorine, phosphoric acid, Ca, pH, etc., as well as investigations into the incidence of mottled teeth and dental caries, in order to gain knowlege on the factors responsible for the occurrence of mottled teeth. The main data obtained from the studies are given hereunder:
1) Of the Gifu prefectural side of the basin of the river Kiso, the incidence of mottled teeth in the 1st to 6th graders of primary schools of Maemiya village of Inaba-county and that in the 4th to 6th graders of primary schools of Hashima city of Hashima county, was 3.9%, and 39, 6%, respectively.
2) The enamel hypoplasia at the above places according to the classification of the Medical Affairs Bureau of Ministry of Welfare, shows the highest incidence in M1, followed by M±, M2, and M3, in that order, while B is quite negligible.
3) The incidence of the so-called mottled teeth in Maemiya village shows no difference from area, while the incidence in Hashima city differs from area to area, ranging from 26.0 to 54.1%.
4) Sex difference in the incidence of mottled teeth is not of statistical significance. The incidence according to primary-school grades declines in higher grades declines in higer graders at Maemiya village, but rises, on the contray, in Hashima city of Hashima city of Hashima county.
5) Our investigations indicate that so-called mottled teeth do not produce such immunization against dental caries as do mottled teeth due to fluorine.
6) Water examinations resulted in the detection of only a slight content of F; the Ca and PO4 levels as the PH of the water within the usual range.
The above studies point to that the enamel hypolasia in the regions in question is due to some other factor or factors than fluorine. Full clarification of the etiology requires further studies.View full abstractDownload PDF (1492K) -
Shizuko OBARA1960 Volume 10 Issue 3 Pages 180-183
Published: 1960
Released on J-STAGE: March 02, 2010
JOURNAL FREE ACCESSUrea, ammonium phosphide, sodium citrate and sodium phosphide were made into 5% solutions, and -after gargling with these, the patients were examined as to changes in the pH value of their saliva.
Of these four chemicals, sodium citrate was found to be the best with regard to pH rises and the duration of effect.
Sodium citrate is free from the danger of impairing the enamel of teeth.
When injected into the veins of rabbits, it hardly affect their carotid pressure.
On exposed rabbit intestines, it works stimulatively in a medium dose and restrictively in a large dose.
The effect of ammonium phosphide usually contained in tooth paste or powder has much stronger effect than sodium citrate on the carotid pressure of rabbits and the motion of their exposed intestines.View full abstractDownload PDF (517K) -
Yoshiaki TANAKA1960 Volume 10 Issue 3 Pages 184-195
Published: 1960
Released on J-STAGE: March 02, 2010
JOURNAL FREE ACCESSThe administration of aminoacetonitrile to rats is very effective to produce mesenchymal lesions characteristic for lathyrism. With the exception of enamel, dental tissues are of mesodermal origin.
Since aminoacetonitrile is known to exert profound effects upon connective tissues, further knowledge of its effects, if any, upon these types of mesodermal tissue would be mostly expected.
It is very interesting for us to investigate these problems, because we have elucidated pathologic responses of paradental tissue by many stressors.
Parotin, found by Prof. T. Ogata, is an extract of parotid glands of cow. Parotin, is said, stimulates the vitality of the all mesenchymal tissues. T. Ogata and his collaborators also found the fact that parotid glands of rabbits or rats became hypertrophic and increased their function after the extirpation of their submaxillar glands by compensaton.
The author found a characteristic change of Lathyrism in the paradental tissue and jowl of rats after administration, of aminoacetonitril. A continuous administration of parotin as well as an extirpation of submaxillary glands were effective to suppress the developments of Lathyrism in the paradental tissue and jowl bone of rats.
These changes were more remarkabl in the weanling rats. Prof. H. Selye reported the lathyrismic change in rats was aggravated by the injection of somatotrophic hormone.
Pror. Tasaka and Shibata published a paper that a long-term administration of parotin followed atrophy of parotid glands and decrease of the secretion of hypophyseal hormones. In this connection, the author's finding would be discussed. Male rats of Wistar strain, weighing about 100g were used and the histological preparations were made by Hematoxilin-Eosin or Mallory dyeing.View full abstractDownload PDF (7292K)
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