As a Dental Hygienist and a former Dental Assistant I do NOT believe an assistant should be allowed to do any scaling. I know that assistants are a very important part of the dental team and their training is to be an assistant, not a hygienist. If they want to increase their duties, then they should go back to school and become a licensed dental hygienist. Obtaining proper education through years of training to provide the best possible care for the patients, not a scaling coarse.  Please consider the harmful effects this will have on your patients overall oral health.