It dawned on me today, maybe she is from a military family. I am not sure how the military treats missing dependents. Say somebody's child goes missing on a military base in Germany. That makes me think that on a base, missing children reports were handled differently than they would for a civilian living in the US.
We know that she probably did not receive any dental care based on the condition of her teeth. Now, in the Armed Services, your family receives full medical and dental care. However, back in the 60's and 70's that was not the case, the only dental care a child of a soldier could receive was emergency or if it was part of another medical procedure. The only time a dependent could receive routine dental care was when they were overseas or in some remote location of the U.S. (think some Island in Alaska) where dental care was not available.
It wasn't until 1986 that the military started to provide dental insurance to servicemen's families.
I got that information from this document:
http://www.cna.org/sites/default/files/research/d0000437.a3.pdf