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김부섭 ( ) - 지산전문대학 치기공과
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Abstract
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Various methods have been introduced for ring liners and treatment techniques of dental castings and are often derive from different cast result.
Reassessment of dental precision casting theory of expansion of phosphate investment appears to be required.
The present study examined preliminary linear expansion test and the dimensional accracy of full crown shaped casts with 4 different method, A = wet cellulose paper 1 sheet lining within metal ring, B : wet cellulose paper 2 sheets lining within metal ring, C : wet cellulose paper 1 sheet lining and 20 seconds water soaking, D = ringless technique.
Preliminary test mold was made with "⊂" shaped former(120mm X 20mm X 20mm, Fig. 1) and main investigation former was prepared with cylindrical metal die with cap(Fig. 2).
Patterns were prepared according to the conventional wax pressure method with metal die and cap. Mould prepared 4 different type were heated same conventional process. Ten castings were made for each method. A high prequency vacuum pressure casting machine(Globucast) was used and the the castings were cleaned with a sand blasting and electrical polishing. The casting accuracy was determined by measuring discrepancy for each set of a wax pattern and its casting with a thickness gauge.
Statistical significance (t-test) was set at p<0.05.
The result are as follows =
1. Leaner expansion comparative test of prliminary test were shown as order of
B>C>D>A.
2. An average discrepancy of A = 0.24mm, B : 0.09mm, C : 0.21mm, D : 0.50mm were obtained in main investigation when it gave a 4 different kinds of ring linings and method.
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KeyWords
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원문 및 링크아웃 정보
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등재저널 정보
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