the California Dental Association provides this free service using your zip code to locate a low cost provider in California. this is the page: http://www.mercyimagingcenters.com/clinics?action=search&zip=91504<o=25
And the result for Burbank is:
Kids Community Clinic of Burbank
Tel. (818)841-8010
For North Hollywood:
Valley Community Clinic
Tel. (818)763-8836