2004 Fiscal Year Final Research Report Summary
In vitro bonding properties of resin reinforced glass ionomer cement reflecting clinical situations
| Project/Area Number |
13672173
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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 |
矯正・小児・社会系歯学
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| Research Institution | The Nippon Dental University |
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Principal Investigator |
KOMORI Akira The Nippon Dental University, School of Dentistry, Assistant Professor, 歯学部, 講師 (90267229)
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| Co-Investigator(Kenkyū-buntansha) |
KOJIMA Iori The Nippon Dental University, School of Dentistry, Assistant, 歯学部, 助手 (80267286)
ANDO Fumihito The Nippon Dental University, School of Dentistry, Assistant, 歯学部, 助手 (90318543)
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| Project Period (FY) |
2001 – 2004
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| Keywords | Resin-reinforced glass ionomer cement / Orthodontic bracket / high intensity blue light-emitting-diode / Plasma arc curing unit / Tungsten-quartz halogen curing unit / LED curing unit / Tensile bond strength / Shear bond strength |
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| Research Abstract |
The clinical situations, such as light exposure time, light intensity, and the intervals between material mixing and light exposure during bracket bonding using light cured resin-reinforced glass ionomer cement. (LCGIC) may vary for each individual bracket. This study evaluated the bond strength of LCGIC reflecting clinical situations.
The enamel surface temperature was measured to define the conditions under which the bond testing study was carried out. The over-all mean temperature as measured using a noncontact act infrared thermometer was 32℃. The tensile and shear bond strengths of LCGIC subjected to immediate and delayed light exposure were assessed. LCGIC was then compared to light cured composite resin (LCR). Mean bond strengths of LCR decreased with the time. Tensile and shear bond strengths of LCR indicated high statistical significance within groups across time. It could therefore be concluded that the bond strength of LCGIC was not affected by the timing of visible light exposure ; whereas, the bond strength of LCR decreased as time intervals increased. Further studies were carried out to evaluate the light intensity of various light curing units and to determine the effect of distance of the light guide. Validity of a tapered light guide was also assessed. Three types of light curing units were used : high intensity blue light-emitting-diode curing units (LED), and tungsten-quartz halogen curing units (TQH), and a plasma arc curing unit (PAC). A tapered light guide was also evaluated. The spectral output of each unit was measured from 300nm to 600nm with a spectroradiometer. The light intensities at distances of 0mm to 20mm were determined with the radiometer. The peak value of LED closely approximated that of PAC. The light intensity significantly decreased with distance. A tapered light guide enhanced light intensity at 0mm distance, but a reduction of light intensity by a tapered light guide was seen at 5 to 29mm distance.
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