Some metal alloy-based prosthetic and dental materials, such as dentures, crowns, bridges, orthodontic appliances and implants, as well as separated endodontic instruments present in the patient’s oral cavity, present absolute or relative contraindications for diagnostic radiology (magnetic resonance imaging and X-ray diagnostics, including computed tomography). The aim of this study is to focus on prosthetic restorations that may cause artifacts, damage dentures, or threaten patients’ health during diagnostic imaging, and to discuss safe solutions. Ferromagnetic materials, e.g. nickel, cobalt and chromium, often cause flashes and shadows in the image, and are susceptible to damage, deformation or translocation. Prosthetic restorations made of bioceramics, titanium, zirconium, gold, aluminum and polymers are considered safe in diagnostic radiology. Veneering porcelain on a metal framework is a means to obtain biocompatible and durable prosthetic materials that do not interfere with radiological imaging. Dentists, aware of the difficulties in diagnostic radiology caused by prosthetic restorations, can increase patient safety and reduce imaging artifacts, thus improving diagnostic reliability.