I agree with Kestrel it does depend. For us we've had no cavities, not parent history of issues. No xrays with any concerns. DS2 did fall and hit his mouth very hard and we took him in (loads of blood - loose baby tooth) and we agreed an x-ray was good to do. Also DS2 had brain surgery as a child and MANY MRIs and so I am extra cautious of more radiation for him.