| Project/Area Number |
11671902
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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 | Showa University |
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Principal Investigator |
KIMURA Yuichi Showa University School of Dentistry, Associate professor, 歯学部, 助教授 (60211877)
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| Co-Investigator(Kenkyū-buntansha) |
YONAGA Kazuo Showa University School of Dentistry, Instructor, 歯学部, 助手 (30343495)
MURAKAMI Yoshiko Showa University School of Dentistry, Assistant Professor, 歯学部, 講師 (10297038)
坂井 啓子 昭和大学, 歯学部, 助手 (40286852)
松岡 英美 昭和大学, 歯学部, 助手 (40286860)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 2001: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2000: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1999: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | Er:YAG laser / Er.Cr:YSGG laser / Root canal enlargement / Root canal preparation / Apical stop / Debris / Periodontal tissues / Thermal effects / Er : YAGレーザー / Er,Cr : YSGGレーザー / 動物実験 / Er:YAGレーザー / サーモグラフィー / ファイバースコープ / 微小漏洩 / スミアー層 |
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| Research Abstract |
Prior to the extraction of tooth, the experimental protocol was explained to the patients and their informed consent that extracted tooth would be used for experiments was obtained.
Extracted human teeth were irradiated by Er : YAG laser using three different sizes of fiber tips at the two different parameters (2 Hz and 136 - 184 mJ/pulse, 2 Hz and 170 - 230 mJ/pulse). After laser irradiation, the teeth were longitudinally bisected and observed by stereoscopy and scanning electron microscopy (SEM). Irradiated areas were found to be scale-like and clean, but rough by SEM. The statistical analysis revealed that the time required for preparation at high energies was significantly shorter compared to that at low energies (p < 0.01). The degree of apical leakage from the teeth prepared by laser after obturation was slightly, but not significantly less than that from control teeth (p > 0.01). Morphological findings by SEM showed that contact between the root canal walls and obturated material
… More
s was hermetic in both groups, but canal walls prepared, by laser were rough and irregular. The temperature on the root surface during laser irradiation increased by less than 6C at the apical area and by less than 3* at the central area. A morphological evaluation revealed no carbonization or melting. These results suggest that the thermal effect upon periodontal tissues during root canal preparation using an Er : YAG laser at less than 230 mJ/pulse for 1 minute is minimal. The thermal effects of Er : YAG laser irradiation on the periodontal region during root canal preparation were evaluated using rats. At 4 weeks after treatment, no inflammation or resorption was observed in any cases in the control or 34 mJ/pulse-irradiated groups. However, moderate to severe inflammation with resorption of root surface was observed in 9 of 10 cases (90%) in the 68 and 102 mJ/pulse-irradiated groups. These results suggest that thermal effects on periodontal tissues during root canal treatment by Er : YAG laser irradiation are minimal, if appropriate parameters are selected. Less
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