Effect of Storage Media on the Flexural Strength of Heat and Self Cure Denture Base Acrylic Resins – An Invitro Study

Abstract

Various dental prostheses and appliances show failure due to fatigue that is inherited as a result of decreased flexural strength. They need to function in wet environments like saliva and during non function, they need to be stored in water. This study was aimed to assess the influence of water sorption on flexural strength of two heat and self cure denture resins and to evaluate any difference between storage in artificial saliva and water on its flexural strength. A digitally designed stainless steel die was used to fabricate molds for making samples from heat cure (Trevalon HI, Colto Cure H) and self cure (Colto Cure C,Dentsply RR) denture base acrylic resins. Samples were tested immediately after processing (Group (GP) A – control), immersed in water (GP B) and artificial saliva (GP C). After storage of samples at four different time intervals (1 day, 1 week, 2 months, 4months), flexure test was performed on a universal testing machine. Various levels of variables were tested using  Kruskal -Wallis H test (p<0.001) while differences between groups was tested using Mann Whitney test (p<0.05). Trevalon demonstrated highest dry strength. All samples demonstrated decline in flexural strength with heat cure showing less than self cure denture base resins. Reduction of flexural strength observed at 2 and 4 month time, showed a statistical difference between groups. Reduction of flexural strength was also significant when self cure  resins were stored in artificial saliva. Flexural strength tends to decrease as water sorption within the denture polymer increases. Both saliva and water show pronounced effect on flexural strength.