As I dental hygienist, I am professionally trained to removed calculus deposits from teeth.  To receive the qualifications and licensure to perform these duties, I graduated college, took both National and Regional Board Exams and applied for licensure in the state of VIrginia.  For any dentist to consider allowing DA's to perform the same functions as a RDH is purely negligent.  Patients deserve quality care, and should be free from potential harm that could be caused by lesser trained individuals.  If you were in the patient chair, who would you want using sharp instruments in your mouth?