Objective: to investigate the effect of addition different concentration of TiO2  nanoparticles  on acrylic resin polymethyl methacrylate to improve the  anti-microbial properties of denture base material
Subjects and Methods: 24 completely edentulous patients were selected to be enrolled in of the following groups:  Group I: 8 patients were rehabilitated with complete  dentures had no nanoparticle (Control group),Group II: 8 patients were rehabilitated with complete dentures had a 1% concentration of titanium oxide nanoparticles and Group III: 8 patients were rehabilitated with complete dentures had a 3% concentration of titanium oxide nanoparticles . Microbiological evaluation was done from the fitting surface of dentures after one week, two weeks, and one month  of denture use.
Results: Regarding staphylococcus aureus and candida albicans colonization, the result revealed that between  one week, two weeks , and  one month  follow up periods  for each group and between different groups for each follow up period, there was a statistically significant difference between all groups. Regarding staphylococcus epidermis colonization , there was negative colonization of staphylococcus epidermis .
Conclusion: Addition of TiO2 nano particles with 1% and 3%  concentrations to  PMMA has a great anti-microbial effect with reduction of the colonization of S. aureus, S. epidermis and C. albicans than the conventional dentures