Effect of Variations in Post-set Temperature and Monomer Concentration on Self-cure Acrylic Surface Candidal Growth: An In-vitro Study

Abstract

Objectives: To identify the effect of variations in power-liquid ratio and post-set temperature on water absorption and residual monomer concentration on growth of Candida albicans on self-cure denture base resins. Methodology: 60 self-cured acrylic discs (39 x 4mm) were made and divided into 3 groups each having 20 specimens. Group 1 consisted of discs fabricated at a powder-liquid ratio of 5.1:2.8 as recommended by the manufacturer. Groups 2 and 3 constituted specimens with variations in post-set temperatures and powder-liquid ratios respectively. Specimens from group 2 were soaked in four water baths at temperatures of 37°C, 47°C, 57°C and 67°C for 24 hours. Specimens from the temperature-controlled group 3 were fabricated at four different powder-liquid ratios by increasing monomer liquid volume by 10%, 15%, 20% and 25%. The acrylic discs from control groups 1 and 3 were soaked at a constant temperature of 37°C for 24 hours. Residual monomer leeched out from disc into water was analyzed using Ultraviolet spectrophotometer. The variations in water absorption and Candidal growth were recorded. Results: Linear regression analysis was used to analyze the results. A moderately positive correlation was calculated for the association between powder-liquid ratio and Candidal growth (r = 0.67, p < 0.001) suggesting Candidal growth is higher at increased powder-liquid ratios having low monomer content. The correlation between the Candidal growth and the post-set temperatures was found to be moderately negative (r = -0.41 p < 0.001), indicating a decrease in Candidal cells on increasing post-set soaking temperatures. Conclusions: Candidal growth follows a positive linear relation with a decreasing powder-liquid ratio having cells increasing with an increase in liquid monomer content. Candidal growth follows a negative linear relation with post-set temperature soaking with cells decreasing with an increase in temperature.