For that matter there are very probably ways for dentists to detect a child having been physically abused."Hummm...the textbooks say that the only possible explanation for this kid's teeth looking like this is if he had been repeatedly punched in the mouth".And in such a case that must be stopped.
But failure to appear for a cleaning? Yikes!!!!
When I grew up you never heard of teeth cleaning.
I took my athlete son to a specialist to have his hurt arm examined. It turned out to be a spiral fracture. We explained what happened and my son told the doc how his coach had said (in heavy accent) you break your arm you keep doing it that way. I found out later that orthopedics are supposed to report limb spiral fractures of children because it is a sign of abuse. But my boy was so muscular and mentioned his coach as a witness, the doc clearly saw how it happened and believed us.