Introduction
Dental alloys are the most widely used base material for prostheses. They beat resins and ceramics in several ways, but they also have weaknesses that limit where they can be used.
Advantages
- High mechanical properties: fixed prostheses can be very thin and fine, with minimal tooth preparation. Removable denture bases are strong at very low volume, which is comfortable for the patient.
- Fine detail by casting: castability is the ability of molten alloy to fill the smallest parts of the mold. It depends on viscosity, which falls with temperature, so the alloy is slightly overheated before casting.
Mechanical properties depend on the components of the alloy and the size of its crystal grains.
Disadvantages
- Corrosion: the main weakness. It changes color, reduces strength, and releases products that can cause local and general disease. Corrosion resistance decides how biocompatible an alloy is.
- Volume changes: shrinkage on cooling creates difficulties in casting.
- Thermal conductivity: hot and cold food can harm the pulp under fixed restorations. In removable dentures, however, it helps the patient sense food temperature.
- Electrical conductivity: this deepens corrosion, and some patients notice a metallic taste.
- Appearance: the metal color limits their use in visible areas.