1992 Fiscal Year Final Research Report Summary
Studies of Hydoroxyapatite Crystal Formation in Rat Enamel
| Project/Area Number |
03454439
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Functional basic dentistry
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| Research Institution | TSURUMI UNIVERSITY |
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Principal Investigator |
SHIMIZU Masaharu Tsurumi Univ., Sch. of Dent. Med., Professor, 歯学部, 教授 (40064357)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAKOSHI Yasuo Tsurumi Univ., Sch. of Dent. Med., Assistant, 歯学部, 助手 (20182470)
KAWAMOTO Tadafumi Tsurumi Univ., Sch. of Dent. Med., Assistant, 歯学部, 助手 (60148046)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Hydroxyapatite / Calcium-Transport / DCPD / OCP / ACP / カルシウム輸送 |
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| Research Abstract |
The distribution of calcein, ^<45>Ca and ^<32>PO_4 in the freeze-dried sections of lower incisor of 9 day old rats was examined. Also, several regions of enamel in the secretory and the maturation stages were examined by energy dispersive X-ray analysis, X-ray diffraction, resolution-enhanced Fourier transform infrared spectroscopy and GBHA staining.
The results would indicate the followings: (1) in the secretory stage most of calcium and phosphate ions are transported into the enamel intercellulary, and the secretory ameloblasts extrude calcium to the capillary side to maintain the enamel at a low level of calcification, whereas in the maturation stage the ameloblasts control the entry of calcium ions into the enamel by changing the tightness of intercellular junction and/or their activities for ion transport. (2) in the mineralization processes of enamel the calcium phosphate is first deposited in the phosphate rich media as a precipitate with a lower Ca/P ratio similar to amorphous calcium phosphate, octacalcium phosphate and dicalcium phosphate dihydrate than the ratio of hydroxyapatite. This precipitate may then transform to hydroxyapatite by a preferential supply of calcium ions by the ruffle-ended ameloblasts.
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