Dentistry is the branch of medicine that is involved in the study, diagnosis, prevention, and treatment of diseases, disorders and conditions of the oral cavity, the maxillofacial area and the adjacent and associated structures, and their impact on the human body. To the layman, dentistry tends to be perceived as being focused primarily on human teeth, though it is not limited strictly to this. Dentistry is widely considered necessary for complete overall health. Doctors who practice dentistry are known as dentists. The dentist's supporting team – which includes dental assistants, dental hygienists, dental technicians, and dental therapists – aids in providing oral health services.
Orthodontics, formerly orthodontia (from Greek orthos "straight or proper or perfect"; and odous "tooth") is the first specialty of dentistry that is concerned with the study and treatment of malocclusions (improper bites), which may be a result of tooth irregularity, disproportionate jaw relationships, or both. Orthodontic treatment can focus on dental displacement only, or can deal with the control and modification of facial growth. In the latter case it is better defined as "dentofacial orthopaedics". Orthodontic treatment can be carried out for purely aesthetic reasons with regards to improving the general appearance of patients' teeth. However, there are orthodontists who work on reconstructing the entire face rather than focusing exclusively on teeth.