Abstract
STATEMENT OF PROBLEM: Nylon clip wear affects the retention of implant-retained overdenture. PURPOSE: The purpose of the present investigation was to determine the wear of nylon clips and patient satisfaction with either a cobalt-chromium (Co-Cr) metal bar or a milled polyether ether ketone (PEEK) bar in mandibular dentures supported by two implant-retained mandibular overdentures over a one-year clinical study. MATERIALS AND METHODS: Twenty edentulous patients were randomly divided into two groups ten patients in each group. Group I (Co-Cr metal bar with nylon clip) and Group II (PEEK bar with nylon clip). In both groups, two implants were placed in the canine–premolar region using a delayed loading protocol. The primary outcome was Nylon clip wear, it was evaluated using volumetric change and surface roughness assessment at insertion, three months, six months, nine months, and one year. Patient satisfaction was evaluated at six months and one year using a visual analog scale (VAS). Data were collected and statistically analyzed to compare the final outcomes between the two groups. RESULTS: The metal group showed significantly higher roughness and volumetric changes with volumetric changes reached 7.49 μm ± 0.47 after 12 months (P=.0001) compared to the PEEK group that reached 7.21 μm ± 0.43 with no difference was found between them at 12 months (P = .188). Patient satisfaction scores were significantly higher in the PEEK group, regarding retention, stability, comfort, and speaking at both 6 months and 1 year (P=.04). CONCLUSIONS: Nylon clips showed clinically acceptable wear performance with both PEEK and metal bars after 1 year, and the PEEK bar demonstrated superior surface properties and patient satisfaction, especially in the first 6 months of the study. TRIAL REGISTRATION: The study was approved by the Research Ethics Committee of the faculty of dentistry, Cairo University (No 94/23) and registered in the Clinical Trials.gov (NCT06909435). Trial Registration date is 27-03-2025. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12903-026-08020-3.