I have a sister that's going to school to be a dental hygenist. The amount of material they have to study is phenomenal, and I don't feel that a dental assistant could be adequately trained to scale teeth in a short period of time. We trust dentists and dental hygenists to work on our teeth because of their extensive schooling, and giving a dental assistant the same abilities in a few short training sessions would undermine that schooling; it would also decrease the quality of care.