Got one swollen lymph node (mild) on the right side of my neck. Got a dental abcess but on the left side can that be the causes or is it something else?

Separate conditions. They are two separate conditions. One thing they have in common, however, is that they can both be a product of infection and the visit to your dentist is warranted.
Maybe another abcess. If you have an abcess on one side you may have one you're not aware of on the other...or other source of infection on that side. Get it checked out.