Journal of Clinical Medicine Article Hybrid Polyetheretherketone (PEEK)–Acrylic Resin Prostheses and the All-on-4 Concept: A Full-Arch Implant-Supported Fixed Solution with 3 Years of Follow-Up Miguel de Araújo Nobre 1,* , Carlos Moura Guedes 2, Ricardo Almeida 2, António Silva 3 and Nuno...