thanks so much for your response gal, very helpful!
I agree it´s ok to bend the rules especially in this case as his preocuppation comes from an observed tendency of patients to abuse chewing gum. I only use it if I will have a face to face interaction with someone due to the breath, and I try to avoid these as much as possible these days. As soon as the talking is over I throw the gum away. Its great to know its no big deal!