Abstract
Aims: To evaluate the porosity that occur in the acrylic resin denture base polymerized by the microwave cycle and conventional water bath with two different thickness, relation between the thickness of specimen and its percentage of porosity. Material and methods: Forty rectangular resin specimens with the following dimensions (65×40×6mm), (65×40×3mm) were subdivided according to polymerization method into microwave cycle and conventional heat polymerization method to obtain 10 specimens with different polymerization method and thickness, for each one of 4 groups. Porosity was calculated by measure the specimen volume before and after its immersion in water, data were analyzed by student t–test analysis at ( p< 0.05). Results: Showed that specimens of (6mm) that cured by microwave polymerization method showed significantly higher percentage of porosity when compared to the same thickness of conventional water bath polymerized acrylic resin at (p<0.05), while no significant difference between the percentage porosity of the conventional and microwave heat cured acrylic resin of (3mm) thickness specimens. Also there is no significant difference between the thickness of specimen and the conventional water bath method of heat cured acrylic resin. While for microwave curing method of heat cured acrylic resin there is significant difference for increase of percentage of porosity with increase of thickness of specimens. Conclusions: The conventional acrylic resin of (≥3mm) specimens thickness can be polymerized with microwave curing method safely with less porosity , while for (≥ 6mm) specimens thickness is preferred to be polymerized by conventional water bath curing method
