Cross over design the investigator divide participants to two groups group (A) will receive rapid heat cured denture base material and group (b) will receive the acrylic denture modified by titanium dioxide nanoparticles and after washout period alternatively group (a) will receive the acrylic denture modified by titanium dioxide nanoparticles AND group (b) will receive rapid heat cured denture base material the investigator will take swaps from dentures to count the anaerobic bacteria.

First the investigator will take primary impression, and pour it obtain primary cast, then will fabricate special tray an take secondary impression and obtain master cast after that duplication of master cast will be done the investigator will make cross over design.and divide participants to two groups group (A) will receive rapid heat cured denture base material and group (b) will receive the acrylic denture modified by titanium dioxide nanoparticle and after washout period alternatively group (a) will receive the acrylic denture modified by titanium dioxide nanoparticle AND group (b) will receive rapid heat cured denture base material the investigator will take swaps from the different dentures to count the anaerobic bacteria by (CFU).

Inclusion Criteria:

1. Completely edentulous maxillary arch and partially dentate mandibular arch with adequate interarch space.
2. The edentulous ridges should be covered by firm healthy mucosa. 3-Angle class I maxillomandibular relation. 4-Healthy and cooperative patient

Exclusion Criteria:

1. Patients with bad habits as severe clenching or bruxism, drug or alcohol addiction, moderate or heavy smoking (greater than 10 cigarettes per day).
2. Previous history of radiotherapy or chemotherapy.
3. Any skeletal problem dictates surgical intervention