1999 Fiscal Year Final Research Report Summary
A study on tissue irritation of sodium hypochlorite paste
| Project/Area Number |
10671804
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Conservative dentistry
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| Research Institution | The The Nippon Dental University, School of Dentistry at Tokyo |
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Principal Investigator |
KATSUUMI Ichiroh The Nippon Dental University, School of Dentistry at Tokyo, Professor, 歯学部, 教授 (50120639)
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| Co-Investigator(Kenkyū-buntansha) |
KOUSHI Rentaroh The Nippon Dental University, School of Dentistry at Tokyo, Assistant, 歯学部, 助手 (80225367)
MAEDA Munehiro The Nippon Dental University, School of Dentistry at Tokyo, Lecture, 歯学部, 講師 (10219280)
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| Project Period (FY) |
1998 – 1999
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| Keywords | sodium hypochlorite / paste / oganic substance dissolving agent / tissue irritation / chemical cleaning of root canal / root canal preparation |
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| Research Abstract |
The purpose of the present study was to evaluate how the paste 10% NaCl (produced by adding an inorganic compound thickener, montmorillonite, on an experimental basis) gives irritation on oral mucosa and lower incisor pulp of rat. The evaluation was performed through the measurement of the level of histamine determined by fluorometric method and histological observation.
When 10% NaOCl paste or 10% NaOCl liquid is given to rat oral mucosa to expert action for 30 minutes, exposure, vacuolation and hypertrophy of lamina propria were noted from one hour after the procedure, and this tendency persisted up to 48 hours thereafter. Also, appearance of inflammatory cells and dilation of blood vessel were found. There was no difference in the degree of histological changes between the paste and the liquid. In the paste group, the histamine level showed the maximum value one hour after the procedure, and the level decreased over time up to 48 hours after. There was almost no difference between the paste and liquid.
On lower incisor of rat, a cavity of 5 mm in depth was formed under high-speed cutting and cooling. For 30 minutes, the 10% NaOCl paste and the 10% NaOCl liquid were kept into contact with the cavity, which reached dental pulp. Immediately after this procedure to 48 hours after the procedure, pathohistological examination of dental pulp and measurement of histamine level were performed. On dental pulp, vascular dilation and appearance of inflammatory cells were recongnized from immediately after the procedure. There was no distinct difference due to the action between the paste and the liquid. However, the histamine level in the pulp of the paste group increased immediately after the procedure and reached the maximum value. Also the liquid group showed the maximum value after the procedure. In both groups, a tendency to decrease was observed thereafter.
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