A dental hygienist or oral hygienist is a licensed dental professional, registered with a dental association or regulatory body within their country of practice. Prior to completing clinical and written board examinations, registered dental hygienists must have either an associate's or bachelor's degree in dental hygiene from an accredited college or university. Once registered, hygienists are primary healthcare professionals who work independently of or alongside dentists and other dental professionals to provide full oral health care. They have the training and education that focus on and specialize in the prevention and treatment of many oral diseases.