Purpose: this study was to evaluate the Retention of high-arched maxillary dentures constructed from conventional, thermoformed, and milled CAD/CAM resins.
Materials and Methods: An edentulous patient with high -arched palate was selected from the outpatient clinic, Department of Prosthetic Dentistry, Faculty of Dentistry, Minia University. The patient was seeking complete denture treatment. Using the master cast of this case; thirty stone casts were duplicated, numbered, and randomly allocated to one of three study groups 10 casts each. Thirty denture bases were constructed from the following materials to be as identical as possible 10 of each of the following material: conventional heat cure resin, thermoformed resin, and milling resin by CAD/CAM. The retention of the produced denture bases was tested using a universal testing machine .Results: The thermoformed group displayed the highest numeric retention mean (5.576 N) followed by CAD/CAM (4.888 N) and conventional method (3.232 N). There were statistically significant differences between all groups. Conclusions: within the limitations of this in vitro study, it may be concluded that: The thermoformed resin may be the most suitable material for high arched palate followed by CAD CAM materials. The conventional technique in this case is less recommended.