Aims: The aims were to evaluate mandibular residual ridge resorption for patients wearing lower complete dentures made of heat curing acrylic resin lined with acrylic soft liner and compare it with patients wearing conventional heat curing dentures and compare patients satisfaction with dentures for both groups. Materials and Methods: Residual ridge resorption was evaluated in 35 male patients through a period of 6 months by means of digital panoramic radiographs, the patients divided into three groups, first group 5 patients not used prostheses, the second group 15 patients worn conventional heat curing dentures and the third group 15 patients worn dentures lined with acrylic based soft liner, the patients also surveyed about their satisfaction with dentures. Results: The results indicated insignificant difference in the rate of residual ridge resorption between the three tested groups in 6 months period. Conclusions: There is no significant difference between conventional heat curing dentures and dentures lined with acrylic based soft lining material regarding the rate of residual ridge resorption. Regarding denture satisfaction, most patients seem to have more comfortable denture and better chewing ability by using soft liners.

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Aims: This study aims to evaluate the effect of (MRI) on physical, and mechanical properties of acrylic resin denture base materials. Materials and Methods: one hundred and ten samples were the total no. of samples, samples were divided into two groups each group contain two fifty five, the 1st sample group pink and 2nd groups clear heat cured acrylic resin, then the two groups is divided into four subgroups , follow that the samples were exposed to magnetic resonance image at three different periods of time (5, 15, 30) minutes within control group respectively and samples tested for indentation hardness, tensile strength. Results: the results obtained to show that there was a change in the physical properties "heat cured" acrylic resin weather it is "Pink" or "Clear" after exposure to (MRI) and this change happened at different levels and variable degree, also it has shown that there was a slight tendency to change order of a arrangement of atoms within each molecules with no well and clear evidence of altering of the main material itself, at least at circumstances of experiment. Conclusion: Exposure to (MRI) at different periods of time lead to altering of physical properties and at different levels of significant.

Aims:To study the effect of metal oxide nanoparticles (MgO, ZrO2, ZnO) on acrylic based soft liner surface properties and FTIR. Materials and Methods: Acrylic-based softliner specimens were prepared by adding three different concentrations (0.5, 1, and 2) %wt of metal oxide nanoparticles (MgO, ZrO2, ZnO). A disk-shaped specimens with 30mm diameter and 3mm thickness were prepared for shore (A) hardness test to evaluate the surface hardness of modified soft liner. The surface roughness of soft-liner samples (10X10X2mm) was tested by a profilometer. FTIR analysis was conducted to evaluate chemical reaction that may occur between acrylic-based soft liner and nanoparticles. Results: there were no chemical reaction carried out between soft liner and metal oxide nanoparticles at different concentration-surface hardness (shore A) was increased as nanoparticles concentration increased in modified resin. Nanoparticles with 1 and 2% concentration incorporated in soft liner had lower surface roughness value. Conclusions: Metal oxide nanoparticles have improved the surface texture of acrylic-based soft liner, while the hardness of modified soft liner was increased with nanoparticles concentration increases.

Aims: To investigate the effect of different concentrations of ZnO nanoparticles on the compressive strength of type IV dental stone. Materials and methods: Total specimens of this research was 66 specimens, it was divided into 3 groups, the first one for wet strength , second group for dry strength and third groups for scanning electron microscope analysis. 0.2%, 0.5% , 1.0% ,1.5% and 2.0% weight of ZnO were incorporated into type IV dental stone. The study evaluated both wet and dry compressive strength and compared them with the control specimen and investigate it under SEM. The results of the study were analyzed statistically by (Mean ± standard deviation, ANOVA and Duncan's multiple range test) and the results were considered significant at p ≤ 0.05. Results: The compressive strength decreased in comparison to control specimens. This drop in strength value is not significant in wet strength, while significant in dry strength. SEM image exhibited the morphology of both stone crystals and zinc oxide NPs and exhibited the distribution of NPs inside the specimens Conclusions: The study showed that incorporation of zinc oxide nanoparticles into dental stone reduced the compressive strength property of dental stone and NPs evenly distributed into dental stone.