| Project/Area Number |
06671880
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
病態科学系歯学(含放射線系歯学)
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| Research Institution | Osaka University |
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Principal Investigator |
FURUKAWA Souhei Osaka University, Faculty of Dentistry, Assistant Professor, 歯学部, 講師 (80173524)
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| Co-Investigator(Kenkyū-buntansha) |
FUCHIHATA Hajime Osaka University, Faculty of Dentistry, Professor, 歯学部, 教授 (70028728)
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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 |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1995: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1994: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Injurious Effects / 後障害 / 頭頸部癌 / 頭頚部癌 |
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| Research Abstract |
It is well known that hyposalivation caused by irradiation of salivary glands in humans results in a dramatic increase in the incidence of dental caries. The purpose of the present study is to examine the effects of irradiation-induced hyposalivation on the dental caries in SPF rats infected with mutans streptococci.
SPF Sprague-Dawley rats infected with S.mutans MT8148R and given caries-inducing diet 2000 received irradiation under pentobarbital anesthesia on a neck region including parotid, submandibular and sublingual glands. Hyposalivation was induced by 20Gy of irradiation and enhancement of caries incidence was recognized in rats receiving 35Gy. 5OGY of radiation administered by fractionated irradiation method, induced heavy accumulation of dental plaque and severe dental caries. There was a statistically significant correlation between caries scores and flow rates of saliva in hyposalivated rats.
SPF SD rats, infected with S.mutans MT8148R and fed diet 2000, were either completely
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or partially surgically hyposalivated. Complete removal of the major salivary glands led to the greatest increase in the caries incidence. Partial removal of either the parotid or submandibular and sublingual glands reduced the flow rate of whole saliva and enhanced the caries incidence. A significant correlation was also observed between caries score and flow rate of whole saliva in partially hyposalivated rats. However, the recovery of inoculated streptococci from hyposalivated rats was not always high. SPF SD rats, fed diet 2000, and receiving surgery for complete hyposalivation without inoculation of mutans streptococci manifested severe dental caries, while sham-operated rats were caries free.
Bacteriological examination demonstrated that the total number of lactobacilli increased significantly, while total cultivatable microorganisms and total streptococci stayd relatively constant. These results indicated that saliva flow exerts a significant influence in dental caries incidence and microorganisms other than mutans streptococci may play some role in promoting dental caries in hyposalivated rats.16FA01 : Radiation Therapy Less
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