Survival analysis of zirconia implant-supported, fixed complete dentures: A 5-year retrospective cohort study

Statement of problem: Existing data on the mid-term to long-term survival rates of zirconia implant-supported, fixed complete dentures (Zir-IFCDs) are lacking. Purpose: The purpose of this retrospective clinical study was to assess the prosthetic survival rate in patients treated with Zir-IFCDs. Material and methods: The patient record system at the Dental College of Georgia (DCG), Augusta University was searched to identify all patients treated with Zir-IFCDs from 2015 through 2022 by the DCG graduate prosthodontic, general practice residency, and Advanced Education in General Dentistry (AEGD) programs. Reasons for replacement were grouped as failure of veneering porcelain, framework fracture, implant loss, patient-driven concerns, excessive occlusal wear, and other. Results: A total of 67 arches were found that met the inclusion criteria, 46 maxillary and 21 mandibular. The median follow-up time was 8.5 months (interquartile range, 2.7 to 30.9 months). A total of 9 of the 67 arches were identified as having failed (4 maxillary, 5 mandibular), requiring replacement. Reasons for failure were as follows: 3 framework fractures, 2 implant losses, 2 patient-related concerns, 1 fracture of veneering porcelain, and 1 unknown. The combined survival rate (Kaplan-Meier, log-normal modeling) for Zir-IFCDs was 88.8% at 1 year and 72.5% at 5 years Conclusions: Based on the findings, the Zir-IFCDs investigated had a survival rate lower than that reported in similar studies, though higher than published results for metal-acrylic resin-IFCDs. The most common source of failure was fracture of the zirconia framework. Thickness of the zirconia framework, interocclusal space, cantilever length, occlusal force, and status of the opposing dentition may have been associated with framework failures and should be investigated further.