Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain she has a Dry Mouth or Xerostomia and it can be due to a number of reasons like Hormonal imbalances, allergic reaction to any medicine, salivary gland dysfunction, nerve damage supplying the major salivary glands, Oral infections like Thrush.. As she is using desensitizing tooth paste Sensodent since 3 years it can be one of the cause.. You need to consult an Oral Physician and get evaluated and he/she can do a thorough clinical evaluation and treatment of underlying cause can resolve the problem.. As of now she can such on lemon drops, tart candies and chew sugar free chewing gum.. Artificial saliva drops containing methyl cellulose can be instilled multiple times a day in mouth for lubrication.. Drink plenty of water. Hope this information helps.. Thanks and regards. Dr.Honey Nandwani Arora.