| Budget Amount *help |
¥3,730,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥330,000)
Fiscal Year 2007: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2006: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2005: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
In the in vitro experiment, 20% hydrochloric acid efficiently decalcified the mot canal dentin and the stress against files seemed to decrease. Especially, in nickel-titanium rotary preparation, chances of file breakage may be decreased by this decalcifying effect of 20% hydrochloric acid. Also, in very difficult cases, we could penetrate very narrow constricted canals and sometimes could make a bypass neighboring the broken file by the use of this solution. Although, the decalcified depth of the mot canal dentin by this solution has not yet been known, further investigation is needed for the safety.
The strains of the root canal dentin during root canal preparation, root canal filling, and hydration were investigated using strain gauges. As results, following knowledge were obtained :
1. Since the root canal dentin has a property of viscoelasticity, it expands very slowly then contracts very slowly.
2. By this viscoelasticity, accumulation of the strain was observed.
3. The observed maximum magnitudes of the strain were 2,000 micro strains for root canal preparation, 3,000 micro strains for root canal filling, and 8,000 micro strains for hydration, respectively.
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