One thing would be they cannot clean teeth. That is the job of a dental hygienist. Another thing a dental assistant cannot do is take x-rays without an x-ray license.
It is possible if the assistant is within contact with blood from an individual who is infected. This is why great precautionary training is critical, and this is why eye protection, masks, and...
It is actually the choice of being a certified dental assistant or a REGISTERED dental assistant. The difference in the two, is that if you are a CDA you have taken an exam administered by the DANB...