Grinding teeth

My son is 19 months old and has started to grind his teeth again. I try to give him his toothbrush but he ended up tearing it to pieces. Then I gave him cold teething toy... he discarded that after five minutes. He chews on his fingers, shoes, and plastic toys. I even tried teething tablets. If anyone else is going through this and found something that works please tell me. I don't want him ruining his teeth.

Are all his back teeth in yet? He could be teething.

He has his two year back teeth in, but his eye teeth on both top and bottom broke through over a month ago... still somewhat growing.

Give him a clothe that's damp on one corner and frozen.

I actually just read an article on teeth grinding. It could be a vitamin B12 deficiency

B12? I am going to have to ask his doctor about that on the 29th. That is very interesting.