Please don't consider allowing untrained persons to scale teeth in a living person's mouth.  This is unsafe and quite scary.  I have a four year degree in dental hygiene, where two years were spent on scaling.  How much training does the dentist have scaling?  Practice in scaling?  Who's doing the training?  What background does the assistant have?  (Most have minimal training.)  What about the complete care of the patient (i.e. oral hygiene instructions, periodontal probing, head and neck exam..?)  The dentist doesn't have time for this nor time to train to someone to do this.  This is why we have trained dental hygienists.The argument that assistants already scale margins of crowns is invalid.  I've seen too much tissue trauma and cement left on these teeth.  Thank you.