Scanning Electron Microscopy and Energy-dispersive X-ray Spectroscopy in Determining the Metallic-shine-loss Causes of a Low Gold Content Conventional Alloy

摘要

The aim of this study is to determine the causes which lead to a significant colour change and loss of the metallic shine of a 4-element bridge made of a low-gold-content conventional alloy, only a few months after cementation. The authors used scanning electron microscopy (SEM) with retrodiffused electrons and energy-dispersive X-ray spectroscopy (EDX), applied to the restoration surface and in transversal section. The failure occurred due to the incorrect melting conditions of the alloy which leads to internal porosities and areas with very different superficial composition. On the other hand, the improper polishing of the surface led to diminished corrosion resistance and the degradation of the prosthetic piece only a few months after cementation in the mouth.