Background:The criteria of conventional curing of polymethyl methacrylate do not match the standard properties of the denture base materials.Objectives:This research was conducted to investigate the addition of TiO2 nano practical on impact strength, thermal conductivity and color stability of acrylic resin cured by microwave in comparison to the conventional cured of heat-polymerized acrylic resin.Materials and Methods:120 specimens made of high impact acrylic resin were divided into two main groups according to the type of curing (water bath, microwave), then each group was subdivided into two groups according to the addition of 3% TiO2 nano-fillers and control group (without the addition of TiO2 0%). Each group was subdivided according to the type of test into 3 groups with 10 specimens for each group. Data were statistically analyzed using Student t-test to detect the significant differences between tested and control groups at significance level (P<0.05).Results:According to curing type methods, the results showed that there was a significant decrease in impact strength of microwaved cured resin, but there was no significant difference in the thermal conductivity and color stability of resin. In addition, by using nanofiller, there was a significant increase in the impact strength and color stability with the addition of 3% TiO2 nanofillers, but no significant difference was found in the thermal conductivity of the acrylic resin.Conclusion:The microwave curing of acrylic resin had no change in the color stability and thermal conductivity in comparison to the water bath, but the impact strength was decreased. The addition of 3% TiO2 improved the impact and the color stability, but the thermal conductivity did not change.

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Background: Soft lining denture base materials have a key role in modern prosthodontics, but the major problem with soft linings is that they show change in the sorption and solubility after being used for a long period, which lead to dramatically effect on the dimensional stability and on the adhesion of soft lining acrylic denture base material. The purpose of this study was to investigate the effect of adding plant oil extracts on sorption and solubility of soft linings as well as the effect of different pH levels of artificial saliva at different times of immersion on sorption and solubility of soft linings. Materials and methods: 270 specimens were made from heat cured soft liner materials and divided into three groups (90 specimens in each group) according to the addition of ginger oil extracts. The first group was the control group made of soft liners only without adding ginger oil; we added 2% of ginger oil extract to the second group and 5% to the third group. Each group was divided into subgroups according to the immersion time of different pH artificial saliva levels (neutral, basic and acidic). There were three different periods of immersion: 1week, 3 weeks and 6 weeks. The sorption and solubility of each specimen were measured separately. Results:The results showed that there was no significant difference in the sorption and solubility of soft linings when adding plant oil extracts, but there was a highly significant difference when different pH levels of artificial saliva were used. The result also showed a highly significant difference when we used different times of immersion. Conclusion:The findings of the study concluded that there was no effect on the sorption and solubility of the soft liners when adding plant oil extracts and there was a highly significant difference on the sorption and solubility of soft lining materials when immersed in different pH levels of artificial saliva at different periods.

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