@Heather, thank you for the advice
My three year old does this. We have a silicon bristled teddy bear and plastic tubes that we give her to chew on.
My son did this a lot. Would put literally anything in his mouth . He was even chewing wood off our table , leather off seat but this has really lessened Since he got used to his chewy - we were advised to get this from sensory direct. We are in the Uk
Oral stims mean you will need to replace it with something he can safely seek that oral stimulation. There's loads of sensory items out there for oral input seekers. I'd buy a ton of these and redirect as often as you can from unsafe items to the safe items.