My best friend is a dental hygienist and worked extremely hard to get there.  She spent several years as a dental assistant and did what "assistants" should do..."assisted."  A hygienist, on the other hand, is a trained professional who has the education/training necessary to properly clean teeth. From a patient's perspective, I would not want an assistant cleaning my teeth.  As it is, I am not satisfied with some of the care I've received from my hygienist.  I cannot imagine having an untrained dental assistant trying to clean my teeth.  Patients should be able  to trust their dentist.  He/she should ensure that the patient gets "professional" care.