| Budget Amount *help |
¥5,200,000 (Direct Cost: ¥5,200,000)
Fiscal Year 1986: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1985: ¥3,400,000 (Direct Cost: ¥3,400,000)
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| Research Abstract |
The purpose of this study was to determine the actual situation of the unpolymerized layer in the surface area and make up some clinical counterplan for it. Therefore, Firstly, the study on the unpolymerized layer in the surface was conducted.
The following results were obtained. After initial setting of the resin, the degree of cure for the restoration continues to increase with time, but the unpolymerized layer continuously remaines at the surface of restoration, that might be the cause of surface degradation. Many clinical procedures ; using a matrix, prolonged irradiation time, using a white tip protector on the light unit end, and so on , which techniques were previously reported to improve the degree of cure on the surface of the restoration, were attempted. Unfortunately, the degree of cure at the surface area was remarkably improved but the apperance of the layer could not be prevented. It is the best way that the removal of layer by finishing and polishing procedures, at the pr
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esent moment. Therefore, in order to determine the actual range of the unpolymerized layer, the relatively properly cured area in the surface region of the commercial products has to be detected by means of the Knoop hardness measurement as a parameter. Because, the area where is unpolymerized or inadequately cured might be appeared at the surface layer. The Knoop hardness measurements were carried out from the area just below the irradiation surface to the depths along the irradiation direction, to obtain the hardness vs. depth curve. From the peak hardness on the curve, it is possible to determine the depth of resin products which must be removed by polishing.
The conclusions are as follows.
At first, the light activated composite resin should be overfilled ( approximately 0.5 mm ) in the cavity. After initial setting, the excess material must be removed by finishing or polishing procedure. Consequently, it is possible to expose the surface having the best surface texture on the restoration. Less
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