sounds like obsessive-compulsive disorder. probably more people have it, than don't. it's an anxiety problem. try focusing his attention completely on something else for 15 or 20 minutes. that will give his brain a chance to cool down, and the grinding should stop. if you can't stop it, or if he's still doing it in his sleep, there is an appliance that a dentist can fit him with, to prevent tooth damage. good luck with him.
I believe it is the age. He has teeth and kids do that. My daughter wil be 2 in April and she has done it off and on. The more attention you pay to it, the more they will keep it up. I can't stand that more than anything, so it is difficult for me to not say anything. I try to quickly divert her attention to something else and she stops. She doesn't do it a lot though, only once in a great while. I have a sister who is quite a bit younger than myself and she also did it around that age too.
If it not just a habit and ignoring it doesn't work, he may just have a need to do it. I know that sounds weird, but some kids have some oral sensory issues and have a craving for that type of pressure in their mouths. Does he chew on toys or sippy cups?
What may help is getting that need filled in a less irritating way. when he does start you can just hand him a bagel, gummy bears or anything else you can think of that he may like that is hard to chew. See if that helps and he grinds less. If he continues to do it I would ask you dr or dentist what you can do because he can actually wear the enamel off his teeth and cause chipping or cavities.
My little girl is 21 months old and does this to it makes my teeth ache when I hear it, its like nails on a chalk board if I draw attention to it she does it more I Think they just noticed that they have teeth in there and what they can do with them.
At age two there is not any type of appliance that can be put in his mouth to help with the grinding. Number one he is two years old and is not going to be compliant to a splint in his mouth and there is no way to keep it in while he is sleeping, which is when most grinding occurs. Grinding is normal for children. It is the way they come in to their bite. It frequently goes away once they begin to get adult dentition, around age 6 or 7. It is not stress related, it is growth related, and you can't stop that. My 4 year old has no cusp tips on his posterior teeth and has chipped several front teeth. Nothing you can do but wait it out. I wouldn't offer food to chew on because that is giving him sugar/starch to chew on that he doesn't need. HE is not going to grind his teeth down to the gums. Enamel is the hardest substance in the body and those baby teeth have a lot of enamel on them. Adults clench and grind for emotional and psychological reasons, children not so much.