Comparison of two resilient attachment systems for implant-/mucosa-supported overdentures with a PEKK framework: a clinical pilot study

OBJECTIVES: The aim of the study was to determine differences between Locator and CM LOC attachment systems regarding patient satisfaction and wear of the abutments and their inserts. Plaque accumulation onto the polyetherketoneketone (PEKK) framework and polymethylmethacrylate (PMMA) was investigated for the implant-supported overdentures. METHODS: Seventeen edentulous patients were randomised to receive either Locator or CM LOC system for the first year. The total number of implants was 53. After the randomisation, 25 implants received Locator system, and 28 implants received CM LOC system in the first year. After a period of 12 months, the attachment system was exchanged from either Locator to CM LOC or vice versa. Oral Health Impact Profile (OHIP-14) questionnaires were used to evaluate patient satisfaction, chewing comfort, and pressure lesions. Prosthesis hygiene on the PMMA and PEKK surfaces was evaluated by using Stark plaque index. After the exchange of the abutments, they were stored until the end of the 24 months, and the surface wear of the abutments was analysed using a scanning electron microscope. RESULTS: Three patients (10 implants) died shortly before the end of the first year. Two patients (7 implants) received only Locator system since CM LOC was not indictable for their implant system. Patient’s satisfaction was increased when the attachment system was changed from Locator to CM LOC after 12 months of wearing time. Chewing ability and comfort were increased when the attachment system was changed from CM LOC to Locator after 12-month wearing time. There was no influence of the change of the attachment system on pressure lesions. The observed plaque accumulation was higher on the PMMA than on the PEKK surface. For the 8 investigated Locator abutments, the wear was within low and middle level. For the 28 investigated CM LOC abutments, the wear was within middle and high level for the terminal implants and between low and middle for the central implants (for patients who received 4 implants). CONCLUSIONS: Patient’s satisfaction and wearing comfort can be improved with implant-supported overdentures with CM LOC abutments in comparison to Locator. There was no clear difference between both attachment systems concerning the chewing ability of the patients. Plaque accumulation was observed on both attachment systems in different areas. Plaque accumulation on PEKK surface was less than on PMMA surface. CLINICAL RELEVANCE: The CM LOC attachment system offers stable and comfortable wearing conditions for implant-supported overdentures. The use of PEKK as a framework material could reduce the incidence of pressure lesions.