Grant-in-Aid for General Scientific Research (B)
|Allocation Type||Single-year Grants |
|Research Institution||Kagoshima University |
INOUE Katsuichiro Kagoshima University, Dental School. Professor, 歯学部, 教授 (30047790)
KADOKAWA Akihiko Kagoshima University, Dental School. Assistant, 歯学部, 助手 (00169533)
ARIKAWA Hiroyuki Kagoshima University, Dental School. Assistant, 歯学部, 助手 (90128405)
FUJII Koichi Kagoshima University, Dental School. Assistant, 歯学部, 助手 (60156817)
JYOSHIN Kazuhiko Kagoshima University, Dental School. Assistant Professor, 歯学部, 助教授 (80028737)
|Project Period (FY)
1987 – 1989
Completed (Fiscal Year 1989)
|Budget Amount *help
¥7,700,000 (Direct Cost: ¥7,700,000)
Fiscal Year 1989: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1988: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1987: ¥5,700,000 (Direct Cost: ¥5,700,000)
|Keywords||Composite resin / Light-activated composite resin / Setting characteristic / Mechanical properties / Cytotoxicity / Human tooth / Viscoelastic properties / Unreacted substance / 未反応物 / 動的粘弾性 / 熱的性質 / 寸法安定性 / 疲労限界|
The present investigation is composed of the following four Parts.
1. Setting characteristics of UV and visible light-activated composite resins.
The setting times for specimens of maximum depths of cure recommend by the manufacturers were in the range 0, 9-2,5 min. These values varied with the thickness of the specimen, exposure time and distance from the fiber tip of light curing unit to the specimen.
The curing shrinkage in the direction of tooth axis for a 2.5m specimen was in the 1,5-2,8%.
2. Physical and mechanical properties of UV and visible light-activated composite resins.
Hardness of the material increased considerably after exposure to light and reached approximately constant values after 24 hours. Hardness and elastic modulus were strongly dependent upon the filler fraction.
There was no significant between filler fraction and compressive strength.
3. Cytotoxicity test to Mouse Fibroblasts in culture of UV and visible light-activated composite resins.
Agar overlay cytotoxicity tests of light activated composite resins were carried out, using L929 mouse fibroblasts in culture.
The injured area of L-cell was enlarged as the unreacted substances in the cured material increased.
4. Dynamic shear modulus in torsion of human dentin.
For enamel, the dynamic shear modulus and the loss tangent were markedly stable and independent of the temperature. The shear moduli at 37ﾟC ranged from 2,35X10^<11> to 4,48X10^<11> dyne/cm^2. For dentin, the shear modulus slightly increased for temperatures near 50 to 1OOﾟC, which was caused by a loss of water.
Enamel had a modulus which was approximately three to five times higher. There were no significant correlations between the values of the shear modulus and sex, age or tooth type.
It was found that the dimensional stability test is the most effective in the estimation of the functional limit in oral cavity of the restorative composite resins.