Porosity of different thickness of acrylic polymerized by different methods.


Aims: To evaluate the porosity that occur in the acrylic resin denture base polymerized by themicrowave cycle and conventional water bath with two different thickness, relation between thethickness of specimen and its percentage of porosity. Material and methods: Forty rectangular resinspecimens with the following dimensions (65×40×6mm), (65×40×3mm) were subdivided according topolymerization method into microwave cycle and conventional heat polymerization method to obtain10 specimens with different polymerization method and thickness, for each one of 4 groups. Porositywas calculated by measure the specimen volume before and after its immersion in water, data wereanalyzed by student t–test analysis at ( p< 0.05). Results: Showed that specimens of (6mm) that curedby microwave polymerization method showed significantly higher percentage of porosity whencompared to the same thickness of conventional water bath polymerized acrylic resin at (p<0.05), whileno significant difference between the percentage porosity of the conventional and microwave heatcured acrylic resin of (3mm) thickness specimens. Also there is no significant difference between thethickness of specimen and the conventional water bath method of heat cured acrylic resin. While formicrowave curing method of heat cured acrylic resin there is significant difference for increase ofpercentage of porosity with increase of thickness of specimens. Conclusions: The conventional acrylicresin of (≥3mm) specimens thickness can be polymerized with microwave curing method safely withless porosity , while for (≥ 6mm) specimens thickness is preferred to be polymerized by conventionalwater bath curing method