Statement of problem: 3D printed denture base resin is needed to reinforce Purpose: To evaluate the effects of adding nano-ZrO2 and nano-TiO2 on microbial colonization and patient satisfaction with 3D-printed maxillary complete dentures.

Materials and Methods: Twenty-four patients who needed complete dentures were randomly distributed into three equal groups. Group I: Patients used maxillary complete dentures 3D printed without additives. Group II: Patients used maxillary complete dentures 3D after reinforcement by Nano-ZrO2 (0.4%) by Wt. Group III: Patients used maxillary complete dentures 3D printed after reinforcement by Nano-TiO2 (0.4%) by Wt. For microbial evaluation, a cotton swab was taken from the mucosa and the intaglio surface of maxillary dentures, and microbial colonization was evaluated by calculating the number of colony-forming units of S. aureus on mannitol salt agar plates and C. albicans on Sabouraud's dextrose agar plates after 48 hours of incubation at insertion, 6 months, 12 months and 18 months. Patient satisfaction was evaluated 15 days after insertion and at 6, 12, and 18 months. The values of microbial colonization and patient satisfaction were analyzed via repeated-measures ANOVA followed by Tukey's multiple comparison test.

This study aims to compare the effect of 3D printed denture base without nanoparticles and 3D printed denture base reinforced with ZrO2 and TiO2 nanoparticles on completely edentulous patients, as regards:

1. Microbial colonization.
2. Patient satisfaction.

The following steps will be carried out for all patients:

1. Conventional primary and final impressions will be made for each patient
2. Master casts (upper and lower) and occlusion blocks will be scanned by an extra-oral scanner.
3. Files in standard tessellation language (STL) format of master casts and jaw relation records will be imported to the software platform. The software will enable virtually simultaneous mounting and aligning. Each denture will have two STL files that will be printed separately: one for the denture base and one for the teeth, using a 3D printer.29
4. For Group Ι, the designed dentures STL files will be sent to the 3D printer software. Pink denture base resin will be used to print denture bases without nanoparticles.
5. For Group II, Pink denture base resin reinforced by Nanoparticles (ZrO2) will be used to print denture bases.
6. For Group Ш, Pink denture base resin reinforced by Nanoparticles (TiO2) will be used to print denture bases.
7. White teeth resin will be utilized for teeth printing for all groups. Finally, teeth will be attached to recessed pockets in the dentures bases via resin. Followed by finishing. Eventually, dentures will be placed in the post-curing unit.

All patients will be given similar post insertion instructions and a regular oral and denture hygiene protocol.

Inclusion Criteria:

• Completely edentulous patients with good local and systemic health.
• Patients' ages range from 50 to 70 years old.
• Must have adequate interarch space and class Ⅰ angle classification.
• Must have a reasonable neuromuscular control. Patient exclusion criteria
• Patients with any diseases that may affect denture construction
• Patients with oral parafunctional habits.
• Patients with tempromandibular disorders

According to the guidelines of human research adopted by the Research Ethics Committee, Faculty of Dentistry, Tanta University.