Clinical and Prosthetic Outcomes of Titanium Zirconium Versus <scp>PEEK</scp> Composite Maxillary Fixed Prostheses Opposing Distal Extension Partial Dentures: Comparative Clinical Study

OBJECTIVES: Titanium and zirconia are commonly used materials for implant frameworks. The selection of prosthetic material influences the load-bearing capacity of fixed dental prostheses and plays a critical role in the longevity of implant-supported fixed dental prostheses (ISFDPs) by affecting stress transmission during the chewing cycle. PURPOSE: To evaluate clinical results, prosthetic results, and patient satisfaction associated with fixed prostheses fabricated from polyetheretherketone and titanium-zirconia, supported by six maxillary implants and opposed by mandibular distal extension removable partial dentures. MATERIALS AND METHODS: Thirty patients with an edentulous maxilla and mandibular distal-extension ridges received six implants in the maxillary regions of 12, 14, 16, 22, 24, and 26, with lengths of 10-14 mm and diameters of 3.6-4.5 mm. Patients were randomly classified into two equal groups: (G1) PEEK composite frameworks, and (G2) titanium-zirconia frameworks. Plaque score, gingival score, pocket depth, implant mobility, and vertical bone loss (VBL) were assessed at the time of fixed complete-arch implant prosthesis placement (T0), and at six (T6) and twelve (T12) months after delivery. Patient satisfaction (VAS) and prosthetic complications were evaluated after 1 year. RESULTS: G2 showed significantly higher plaque scores, pocket depth, and VBL than G1 at 6 and 12 months. G2 revealed a significantly higher patient satisfaction with maxillary prostheses compared to natural teeth and appearance than G1. Compared to G2, G1 showed noticeably greater patient satisfaction with relation to cleaning and ease of chewing than G2. G2 revealed a significantly higher incidence of prosthetic complications regarding veneer fracture or separation and prosthetic screw loosening than G1. CONCLUSIONS: PEEK composite and titanium zirconia fixed implant restorations for an edentulous maxilla opposed by distal extension mandibular ridges can be effectively used to rehabilitate patients using the maxillary All-on-Six concept. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT06111391.