M.P.
First, this is not an impacted tooth unless the dentist says it is. I suggest you not borrow trouble. You have enough to deal with as it is.
Second, children with developmental delays tend to chew on things. It helps to keep them calm. I suggest you substitute soft toys for the hard cards. You can google stores for sensory issues and find specific items geared towards sensory issues.
My grandson chews gum, even at school, which is a help.
later BTW: Many sensory issues are not readily visible. Many of my grandson's issues were unknown until he was in occupational therapy.