| Project/Area Number |
06454542
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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 |
Conservative dentistry
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
HAYASHI Yoahiko Fac. Dent., Dept. Conservat. Dent., Associate Prof., 歯学部, 助教授 (20150477)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥7,300,000 (Direct Cost: ¥7,300,000)
Fiscal Year 1995: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1994: ¥6,500,000 (Direct Cost: ¥6,500,000)
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| Keywords | caries prevention / occlusal fissure / mineral deposits / HREM / natural occlusion / bacterial mineralization / calcium phosphate crystal / エナメル質 / 裂溝 / ミネラル沈着 / 齲蝕 / 高分解能電子顕微鏡 |
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| Research Abstract |
The central parts of occlesal fissures occluded by macroscopically visible deposits were investigted using a high resolution electron microscope. The fissures were almost completely occleded by mineral deposits which revealed marked variation in shape and size of the crystals at low magnifications. The bottom third of the fissure was occupied by the large polygonal crystals. The middie third was occupied by the plate-like crystala. The coronal third was occupied by the mineralized bacteria filled with fine needle-like crystals. The large polygonal crystals at the bottom third of the fissure consisting of single crystals were mainly whitlockite. The contact between the large crystals was formed in some interfaces where the incoherent tilt boundary was formed. The plate-like crystals at the middle third of the fissure correponded with whitlockite and consisted of the aggregation of small crystallites positioned in different directions at the appositional levels, where the distortion of lattice fringes were formed. These findings suggest that two types of the large crystals provide a reasonable and favorable structure for a natural occlusion to occur at the intact fissure.
It is important to promote crystal growth for early occlusion of the fissure floor. Then, such medication as Ca and Pi ions are released by hydrolysis would have to be filled at the fissure floor. Furthermore, the periodical supplement of Ca and Pi ions is also necessary to prompt bacterial mineralization in the plaque.
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