Microwave radiation has been used for sterilization and disinfection of dental prosthesis which considered as an alternate method for chemical disinfectants.Aim: to evaluate the influence of microwave as a disinfection procedure on the colour ,the transverse strength and dimensional stability on the thermoplastic resin denture base and compare it with two types of conventional acrylic resin at different exposure times
Material and methods: 180 samples were made, 60 for each of the next tests (colour, transverse strength and dimensional stability) .The samples of each test, were subdivided into three groups each group has 20 samples according to the denture base material used (Breflex thermoplastic resin, heat cure and self cure). Each test were divided into four groups, one control and the other groups according to the time of microwave disinfection that were utilized (5,10,15 minutes) at 650 watt. Colour, transverse strength and dimensional stability parameters were measured with and without disinfection. Data were analyzed with ANOVA and Post-hoc Tukey's tests with statistically significant at p ≤ 0.05 .
Result: Microwave disinfection had no significant influence on the colour, the transverse strength beside the dimensional changes of all denture base materials at all the disinfection intervals, except it has a significant influence on the colour of heat cure for 15 minutes. Breflex showed a significantly increase in the flexural strength also, improvement in its fitness to the casts when compared with both heat and self cured resins after treated with microwave.
Conclusion: Microwave can be used safely for disinfection of all the denture base material except heat cure for 15 minutes. Breflex is the best due to it has no influence on its colour , increase the flexural strength, as well as dimensionally stable when compared with both heat and self cured acrylic resins