Mo. Rev. Stat. § 332.091

Any person "practices as a dental hygienist" within the meaning of this chapter who, under the supervision of a currently registered and licensed dentist, undertakes to or does remove hard and soft deposits from teeth, polishes natural and restored surfaces of teeth, polishes restorations of teeth, performs clinical examinations of teeth and surrounding tissues for diagnosis by a currently licensed and registered dentist, and who performs such other procedures as may be delegated by the supervising dentist under the degree of supervision set by and in accordance with rules and regulations promulgated by the board.