|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1993 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 1992 : ¥1,100,000 (Direct Cost : ¥1,100,000)
The purpose of this study was to investigate influence of irradiation conditions on the physical properties of a light cured glass ionomer cement.
As the results, the bond strengths after 24 hours increased with prolonged irradiation times in the case of no dentin surface treatment. The strength values fell into two separated groups : groups with irradiation times of 10, 20, 30, and 40 seconds were significantly stronger than O and 5seconds for Fuji II LC (GC). The failure mode was found to be adhesive. The bond strength improvement was most likely due to increased light activating. The bond stengths after 3 hours for various irradiation times increased with prolonged irradiation times, but 20 and 30 seconds groups were not signuficantly different. The bond strengths after 3 hours were almost half those after 24 hours. This means that the bond strengths increased with time, similar to the other physical properties. The interval between start of cement mixing and light irradiation also affected the bond strength. The bond strengths decreased with a longer interval. This means that light curing should be done soon after mixing the cement. The light intensity affected the bond strength. The light activating and sequence were very important factors influencing dentin bond strengths.
Also other physical properties were influenced with irradiation time, time interval, and the light intensity.
As the conclusion, the performance of this product is highly dependent upon proper light curing technique. This demands the operator's close attention to the cure times, light access to the materials, distance of the light from the materials, and light intensity.