Ds currently has sores on the corners where he has been poorly. I have some cream, but its only really become apparent to me in the last few weeks how much he does it.
We were on the bus the other day and he picked up a ticket and promptly started chewing on the corner. He chews his bears/toys, always has his fingers in his mouth, and he chews clothes (sleeves,neck,coat). We were shopping today and he started chewing the corner of packaging 
I think Iv'e only really noticed now because I have cream for his sores and I am constantly telling him not to put things in his mouth either that or I am a terrible mother. Its a problem now.
I have asked him about his teeth. They are fine, dentist has said the same on visits.
Anyone got any advice on what could be causing it, or if its a habit how I break it?
The words 'don't put that in your mouth' are getting boring and are not working!