M.F.
Hi T. - My son - now 9 - still puts everything in his mouth, fingers, shirt (bites off buttons!!), toys, old drinking straws, anything within reach - WHERE EVER it comes from!!
He has severe ADHD and the Dr told me that this behavior is some type of syndrome (sorry I do not remember the name I think it began with an S or C). Anyway there is basically no way to stop it. He said I could try behavior modification - but did not tell me how to do it!
My oldest is a nail and TOE biter! We have tried everything from rewards, nasty nail polish, taping up her fingers at night, taping gloves on her hands at night - nothing has stopped her.
As annoying as it is - I think "we" as parents have to learn to deal with it in what ever works for us.
Sorry I don't have a magic answer, just know you are not alone.
M. F