Effect of thermocycling on surface roughness of commercially available heat cure denture base resin-an in vitro study

Abstract

Introduction: Heat-polymerized acrylic resin has been the most commonly used denture base material for over 60 years. In the oral environment, dentures are also subjected to thermal alterations through food intake, besides the unavoidable biofilm development and bacterial colonisation on the denture surface. The aim of this study is to evaluate the effect of thermocycling on the surface roughness of heat cure denture base resin. Materials and Methods: This is an in vitro study done at White lab, Material research centre, Saveetha Dental College, Chen-nai. Ten pellets of heat-cure (DPI) were prepared with circular disc, diameter and thickness (10 x 10 x 4 mm). Later, it was polished using poly buffs brushes and polishing paste followed by a wet rag wheel with a slurry of pumice. For thermocycling, TC 4 SD mechatronik thermocycler was used. The temperature for cold is 10° and for hot is 60° celsius. Number of cycles it undergoes is 1000 cycles which equates to 6 months in alternative hot and cold temperatures. The time taken to dwell is 30 seconds for each and to drain the time taken is 10 seconds each. A stylus profilometer was used to check the surface roughness. The values were collected and statistically analysed using SPSS software. Results: Ra value (Roughness average), the average value obtained prior to thermocycling for DPI resin samples was the same after subjecting to thermocycling. Rq value( Root mean square roughness ), the average value prior to thermocycling surface roughness of DPI resin samples was the same when compared to after subjecting to thermocycling. Rz value, the average value of pre thermocycling surface roughness for DPI was less when compared after subjecting to thermocycling. The P-value obtained by paired T-test for pre and post surface roughness was 0.168 (< 0.005; not statistically significant). Conclusion: Thermocycling has increased the surface roughness of DPI heat cure resin. From this study, it can be concluded that thermocycling affects the surface roughness of heat cure denture base resin.