Things Luke says - teeth

Luke asked me about my mouth guard the other day and I explained it was because I clench my teeth at night and the guard props my mouth open a bit so I can't.  The dentist told me that Luke's front teeth are chipped from grinding so I asked him about it, how I know he used to do it when he first got his teeth but I haven't heard him do it since then.  His response, "back then I couldn't communicate and I was trying to figure out what they were for".