My son will be 3 in 4 months. he still puts anything/everything i

I don't know what the official name for htis is. Constantly reminding your son to not put things in his mouth should eventually work (I know this can be very tiring). My older son who is now five had the same problem but has slowly grown out of it (mostly). We still have to remind him not to suck his thumb and put toys near his mouth. Sometimes now it only goes so far as to getting the toy close to his mouth and then he remembers himself that he is not supposed to put things other than food in his mouth.

This is probably not much in terms of help but I haven't yet found another solution. Lucky for me my younger son doesn't have the problem