In the Wild, where Rhinos mostly live, mirrors are in short supply. So Moms often have to supply information as best they can. For some reason, RhinoTots find mouths endlessly fascinating, so these familial exams are not uncommon.
The casual Reader may better understand the situation if you try to look into your own mouth without mechanical aid. See? Or rather, don’t See, right?
Rhino Education, cutting edge, every time.