I have such a dry mouth at night ; even with my mouth closed.  When I wake up, I have a crusty substance on the outside of my mouth.   I never have crust any other time, but chew gun often because i have a dry mouth during the day   What causes the crust?  I would really appreciate your help. Thank you.
Thanks for your query, I have gone through your query.  The Chat Doctor.  The crust could be because of the