| Project/Area Number |
05671700
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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 |
矯正・小児・社会系歯学
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
KOJIMA Hiroshi Hokkaido Univ. School of Dentistry Lecturer, 歯学部, 講師 (50186681)
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| Co-Investigator(Kenkyū-buntansha) |
TSUTSUMI Tomonori Hokkaido Univ. School of Dentistry Instructor, 歯学部, 助手 (50241344)
KAGA Masayuki Hokkaido Univ. Dental Hospital Lecturer, 歯学部附属病院, 講師 (70125300)
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| Project Period (FY) |
1993 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1995: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1994: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1993: ¥600,000 (Direct Cost: ¥600,000)
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| Keywords | Glass ionomer cement / Filling / Prognosis / Pits and fissure sealant / Scanning electron microscope / Toxicity / Enamel conditioning |
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| Research Abstract |
(1) TOXICITY TEST
The toxicity of light-activated glass ionomer cement (LCIII) was investigated in vivo (responses of human gingival fibraoblast). The results of these studies indicated that there was no toxic effect when LCIII was light illuminated more than 30 seconds prior to the implantation into rat subcutaneous tissue or cell culture.
(2) CONDITIONING OF ENAMEL SURFACE AND LEAKAGE TEST
LCIII was applied to the pits and fissures of extracted premolars which were pretreated with polyacrylic acid or citric acid, and the dye penetration between the enamel surface and LCIII was exmined after 4000 cycles of thermal stress. The results indicated that the leakage was significantly little in the citric acid-treated groups than in the polyacrylic acid-treated groups or no treatment group.
(3) CLINICAL EVALUATION
The retention and wear of LCIII used as a pits and fissure sealant material was evaluated clinically over a period of 2 years. A total of 65 first and second permanent molars of 42 children aged 5-12 years were selected. The clinical observation revealed good retention of LCIII for at least one year after the initial application. However, partial loss of LCIII was observed in some cases thereafter. At the recall visits between 496-765 days, more than 40% of the cases showed partial loss of LCIII.The examination of replicas under scanning electron microscope showed that the complete retention rate was approximately 50% in the examination period of 316-405,406-495,496-585 days, 0% in 586-675 days and 13% in 676-765 days. Complete loss of LCIII was not observed throughout the examination period. Five cases produced secondary caries subsequent to the partial loss LCIII after the obsevation period of more than 416 days.
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