Effect of microwave polymerisation on indentation creep, recovery and hardness of acrylic denture base materials.

With the advent of newer methods of activation of the polymerisation of denture base resins, there is a need to compare their physical properties using various modes of activation. Indentation creep, recovery and hardness of denture base resins polymerised either by microwave irradiation or heat were compared. A microwave curing cycle of 3 minutes at 500W was used. The Wallace microhardness tester and an indentation creep test were employed in order to evaluate the denture base resins. Under the experimental conditions of the study the results indicated that indentation creep, recovery and cyclic loading-deloading were similar in the resins polymerised by the two methods. Hardness was either similar or a softer produce was produced by microwave irradiation for two of the resins used. Hardness seems to be more sensitive to residual monomer levels, and for this reason a suitable microwave curing cycle should be employed to optimise all the physical properties.