Prosthetic complications and survival rates of metal-acrylic implant fixed complete dental prostheses: A retrospective study up to 10 years

Statement of problem: Long-term data are sparse on the use of metal-acrylic resin implant-supported fixed complete dentures. Purpose: The purpose of this retrospective clinical study was to assess the prosthetic survival and complication rate in patients treated with metal-acrylic resin implant-supported fixed complete dentures (ma-IFCDs). Materials and methods: The patient record system at the Dental College of Georgia was searched from 2006 to 2020 to identify all patients treated with ma-IFCDs by the graduate prosthodontic and general practice residents during this time. Variables collected were date of delivery of the prosthesis, arch treated (maxilla, mandible), date of the last visit, status of the opposing arch (complete arch fixed implant-supported prosthesis, complete denture, removable implant-supported overdenture, teeth and removable partial denture, teeth and implants, teeth only), date of replacement, and reason for replacement. Reasons for replacement were grouped as fracture of the framework, implant loss, patient-related concerns, catastrophic acrylic resin fracture (judged to be beyond predictable repair by the clinician), and extensive occlusal wear (judged to have worn to the point of requiring replacement). Results: A total of 84 arches in 55 patients who met the inclusion criteria were identified from the electronic health review. Of the 84 complete arch prostheses, 43 were maxillary and 41 were mandibular. The median follow-up time was 2.8 years (interquartile range [IQR] 0.95, 4.65). A total of 31 of the 84 arches were identified as having failed, requiring replacement. The most frequent reason for replacement was catastrophic fracture of the acrylic resin (61%), followed by excessive occlusal wear (19%). It was found that 13% of the failures were associated with patient-related concerns, and 7% with the loss of an implant. Survival rates were analyzed based on the opposing arch. The combined survival rate (Kaplan-Meier, log-normal modeling) for ma-IFCDs was 54% at 5 years (95% confidence interval [CI] 42%, 66%) and 32% at 10 years (95% CI 20%, 47%). Conclusions: Mid- to long-term survival rates for ma-IFCDs are concerningly low. The findings suggest that the status of the opposing arch plays a role in the survival rate of ma-IFCDs. The most common complication was catastrophic fracture of the acrylic resin superstructure, followed by wear of the acrylic resin denture teeth.