Effect of thermocycling on some mechanical properties of polyamide hypoallergenic denture base material (comparative study)

Abstract

Background: Hypoallergenic denture base material became recently the most attractive option due to their use asalternative to poly methyl methacrylate in hypersensitive patients. The study of the effects of thermocycling on themechanical properties is very important, as it is beneficial for clinical purposes.Materials and methods: One hundred and sixty specimens were prepared according to manufacturer's instructionsand they were divided into two groups: Valplast and Vertex as a control group (eighty specimens for each), twentyspecimens from each material were used to test each of property. They were either thermocycled or notthermocycled (n = 10).Results: There was significant difference between polyamide and conventional heat cured acrylic in the four testedproperties. Furthermore, thermocycling significantly decreased the flexural strength of both polyamide and the heatcured acrylic and it significantly increased the tensile strength and hardness of both tested materials. Thermocyclingdid not significantly affect the impact strength of both materials.Conclusions: Vertex showed higher values of flexural strength than Valplast, flexural strength of both materialsdecreased post-thermocycling. Although the flexural strength of valplast was relatively low, it demonstrated greaterimpact strength than Vertex, impact strength of both tested materials was not affected by thermocycling. The tensilestrength of Vertex was more than Valplast, for both materials tensile strength increased after thermocycling. Thehardness of Vertex was higher than that of Valplast, both materials' hardness increased after thermocycling