Scanning electron microscope (SEM) connected with X-ray microanalysis (EDX) was used to study surface alterations of gold-coated brass dental pins (Dentatus), taken out after some years from restored teeth due to necessity for repeating a restorative therapy. The study method led to establish that: --the gold coating of the base material, constituted of copper alloy, absolutely insufficient to prevent corrosion attack; --the observed morphological alterations are the consequence of a localized corrosion attack, produced by anaerobic bacteria, which origin is confirmed by the presence of S on the most attacked points; --finally the corrosive phenomenon does not cause a periapical pathology, but the process is contrary, or rather, it is the pathology that leads to the favourable conditions to create corrosion.