Loading Protocols for Dental Implants Placed in Healed Fully Edentulous Maxilla

The goal of this clinical trial is to compare immediate versus early loading protocols for complete implant-supported fixed dental prostheses in healed edentulous maxillae. The main questions it aims to answer are: * How does the timing of delivery of the prosthesis affect the stability of the implant and the surrounding soft and bone tissue? * Does prosthesis delivery time affect quality of life and patient satisfaction? Researchers will compare immediate and early (6 weeks after implant placement) loading protocols in rehabilitation of fully edentulous upper jaw. Participants will: * Receive 6 dental implants in the edentulous upper jaw and after that complete fixed dental prostheses will be delivered immediately or 6 weeks after implant placement. * Visit the clinic at the scheduled time for checkups and tests