Strain changes of acrylic resin specimens cured by three curing cycles

Kang, In Ho; Kim, Yung Soo; Kim, Chang Whe

Abstract

The acrylic resin was first introduced as denture base materials in 1937 and it is commonly used for denture base fabrication nowadays. Three different curing cycles (Conventional curing cycle, short curing cycle and long curing cycle) and three commercially available heat-activated acrylic resins (Vertex RS, Lucitone 199 and ProBase Hot) were investigated to find the curing cycle and ma-terial that showed the minimum shrinkage of the resin during polymerization process. A brass master mold was fabricated and duplicated by additional silicone impression material. Stone molds were made by pouring of type III dental stone (SILKY-ROCK YELLOW, Whip-Mix, Louisville, Kentucky). It was embedded in the flask. Strain gauge and thermocouple were embedded in the specimen. Strain gauge and thermocouple were connected to signal conditioning amplifier and data was recorded by pre-programmed software. The parameters ESmax (Maximum ex-pansion strain), Sb (Strain measured just before deflasking procedure), Sa (Strain measured just af-ter deflasking procedure) and Sf (Strain measured at the end of the experiment) were measured delta S was calculated from Sb and Sa (delta S=Sb-Sa). In the experiment concerned about materials, the pa-rameters 90-ESmax (Maximum expansion strain measured during early 90 minutes of curing procedure), 180-ESmax (Maximum expansion strain measured from 90 minutes to 180 minutes), Sb, Sa, delta S and Sf were measured and the following conclusions were made. 1. The ESmax value of conventional curing cycle showed the largest value and the 180-ESmax val-ue of Lucitone 199 showed the smallest value. 90-ESmax values showed no significant difference (p<0.05). 2. delta S values of conventional curing cycle showed the positive values. delta S values of short curing cycle and long curing cycle showed the negative values. All three materials cured by conventional curing cycle showed the positive values. 3. The Sf values of long curing cycle and ProBase Hot (cured by conventional curing cycle)showed the smallest values.