A stomatologist is a doctor who treats conditions of the teeth, gums and mouth. The astute reader may be thinking that there is another name for that, namely a dentist, but they would be somewhat incorrect.
The term stomatologist (and stomatology) is used in various senses, when it is used at all. Its use is also confined to other countries, and other times. One use, and one that is rarely used in the contemporary United States of America, is of a Medical Doctor who has taken up the care of teeth as a specialty, exactly as a dermatologist specializes in skin or a cardiologist specializes in the heart. A stomatologist would therefore be able to treat many of the conditions that are currently treated by dentists, but would still possess the complete medical background of an MD.
A stomatologist can also be a specialty of dentistry, in which case the stomatologist attended a school of dentistry and has a DDS degree. In dental parlance, a "stomatologist" signals a wider base of knowledge than a common dentist, since they are able to treat all of the tissues of the mouth, and not just the teeth. In some areas of Europe and the Former Soviet Union, stomatology seems to be a professional specialization parallel to, but separate from, dentistry.