A dental hygienist is a licensed dental professional who specializes in preventive care and professional cleaning.

Careful and frequent tooth-brushing and flossing help to prevent the build-up of plaque and calculus (tartar), which may lead to cavities. A dental hygienist can instruct people on, and demonstrate, proper techniques.

Regular tooth cleaning by the dental hygienist is important for removing plaque that may develop even with careful brushing and flossing, especially in areas that are difficult for a person to reach on her/his own, at home. Professional cleaning includes tooth scaling and tooth polishing and debridement (a medical term referring to the removal of dead, damaged, or infected tissue - to improve the healing potential of the remaining healthy tissue) if too much tartar has accumulated. This involves the use of various instruments or devices to loosen and remove deposits from the teeth.

Plaque is a soft deposit of bacteria that grows on teeth. This can be removed easily by brushing, though within hours it may have re-gathered itself.

Tartar is plaque that has calcified (hardened). It occurs within a few days in plaque that remains undisturbed by brushing (usually in the hard-to-reach areas of the mouth) - and this has to be scrapped off by a professional.