2 year old, face half swollen. does this mean she has dental issues?

Maybe: I would definitely rule out dental issues. It could also be parotid gland swelling, temporal tendonitis, or other.

Go to dentist: A simple visit to the dentist could answer your question very quickly, we can visually and radiographically if necessary detect if this is a dental issue....My guess would be probably not but go get it looked at!

Swollen: Probably yes. I would start with my pediatric dentist asap for an exam especially if the child is running a fever. As parents we need to clean our childrens teeth and keep the sugars down. Make brushing a fun experience by chasing the sugar bugs.