Fractographic Analysis of a Clinically Failed FPD After 10 Years in Service

This study retrieved and analyzed by scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) the failure of a single four-unit fixed partial denture (FPD). Low SEM magnifications revealed a smooth/featureless fracture surface, indicating brittle fracture. Higher magnifications revealed a small fatigue fracture region located on the inferior part of the connector. EDS analysis indicated that the FPD alloy was gold-based. Additionally, SEM showed segregation of small spherical particles at grain boundaries of the alloy, with high aluminum and oxygen content. The particles, most likely retained aluminum, possibly resulted from sandblasting procedures for a scrap metal alloy, which was then recast into a new FPD. It appears that the fracture was initiated in the oral cavity by fatigue crack formation, but the presence of Al₂O₃ particles facilitated alloy embrittlement and brittle fracture.