A dentist uses various materials in his everyday work. An important category of materials in dentistry is metals and alloys. They are used as construction materials in restorative and paediatric dentistry, orthodontics, prosthodontics and oral surgery. Furthermore, they are used in making of dental instruments and auxiliary tools. Dental metals and alloys have to have certain characteristics and the most important ones are biocompatibility, hardness and strength. Metals as separate elements do not satisfy the requirements of the demanding oral cavity environment (except for titan), hence the process of alloying which results in various alloys. Alloys are mixtures of a metal and another metal or non-metal in a solid solution with a purpose of acquiring better properties, with an emphasis on metallic properties. According to the components of the alloy, alloys are categorized into binary, ternary or multicomponent alloys. Metals which show mutual affinity in liquid and solid state blend together completely. Products of crystallization are solid solutions. In dentistry, only homogeneous alloys of identical crystals can be used because they are resistant to corosion. There are few systematizations which are usually based on the type and mass fraction of a certain component, most often noble metals. These systematizations make easier to choose the alloy and find its optimal purpose. Based on the mass fraction of the noble metal in the alloy, alloys can be noble or non-noble. Noble alloys are gold, silver-palladium and palladium alloys and non-noble alloys are nickel-chromium, cobalt-chromium, ferrous and titanium alloys and amalgam.