レジン床義歯の加熱重合法に関する臨床的研究 : 混和法の検討および重合方法の相違が義歯床の各部位における残留モノマー量におよぼす影響について
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Much, so far, has been reported on the amount of residual monomer in heat curing acrylic resin denture bases, which has supposedly undesirable influence on oral mucosa or on the physical properties of a denture base aftercuring. These reports, however, mostly have dealt with standardized models and few reported on the basis of casts clinically applicable. Further, in these reports, the methods of conducting examinations usually very in each student : ie. the methods of mixing and curing of monomer and polymer. Most of such models have simplified features, which, unfortunately, makes it impossible to make investigation of the difference in the heat emitted from resin, and also of the influence of different heat thus emitted, on the amount of residual monomer. The present author examined the mixing methods of monomer and polymer by the use of generally employed eduntlos practice casts, which had been completed : from the arrangement of artificial teeth to flasking. This process was for the purpose of obtaining the same condition of the casts which had undergone identical process from mixing to filling of dough-stage resin. The amount of residual monomer and heat inside an acrylic resin denture base was measured on each cast by different curing methods and the following results .were obtained : 1. The distribution of polymer size was examined among three kinds of resin : Acorn, L-resin, and Hircoe : and a fact was obtained that the area of their distribution was less than 130μ. Acron had its most distributed area in from 60 μ to less than 70 μ, L-resin in from 20 μ to less than 50 μ, and Hircoe in from 50 μ to less than 60 μ. 2. After surveying monomer and polymer mixing methods of the three cases above mentioned, a tendency was observed that, in order to mix polymer more efficiently, mixing time should be 60 seconds rather than 30 seconds, and that in case of employing vibrators the amount of mixed polymer increased in proportion to the degree of vibration. 3. Most efficient mixing ratio of polymer and monomer (P/L ratio) varied from 2 : 1 to 2.5 : 1 in Acron and L-resin, and from 2.5 : 1 to 3 : 1 in Flircoe. 4. Time duration necessary for reaching dough-like stage was about 20 minutes for Acron, about 15 minutes for L-resin, and about 8 minutes for Hircoe. Time duration after reaching dough-like stage was longest in L-resin, and next came Acron, Hircoe being shortest. 5. The author examined the changes in temperature of resin in curing process. With the flask submerged in the water 70℃ or 6O℃, the temperature of upper and lower dentume bases of the three kinds of resin tended to rise, first at the labial side of anterior area, next the buccal side of posterior area, and then at the lingual side of posterior area showed rise in temperature. 6. In the curing process of the upper and lower denture bases of the three kinds of resin, the elapsed time for the temperature inside the flask to reach curing temperature : 70℃ or 60℃ : tended to be shortest in the labial side of anterior area, next the buccal side of posterior are, and then the lingual side of posterior area reached the temperature necessary for curing. 7. He next measured the residual monomer in the denture bases which had been completed according to two curing methods, one method being to submerge flask in the water 70℃ in temperature for 90 minutes and then into boiling water for 30 minutes (70℃ Curing Method hence), and the other to submerge flask in the water 60℃ in temperature for 9 hours and then into boiling water for 30 minutes (60℃ Curing Method hence). By 70℃ Curing Method the amount of residual monomer showed in Acron to be between 0.44 and 0.46%, in L-resin between 0.35 and 0.36%, in Hircoe 0.73 and 0.86% ; by 60℃ Curing Method, the amount was in Acron between 0.26 and 0.30%, in L-resin between 0.23 and 0.27%, in Hircoe between 0.52 and 0.60%. 8. He compared values obtained by measuring the amount of residual monomer on three predetermined points in upper and lower denture bases of the three kinds of resin and detected no meaningful difference in its amount. He also compared 70℃ Curing Method and 60℃ Caring Method and observed a tendency that by the former method the amount of residual monomer tends to be slightly greater than by the latter.
- 社団法人日本補綴歯科学会の論文
- 1978-05-25