Chemotherapy and radiation can cause a number of problems in the mouth, some of which might include: mouth sores, infections, dry mouth, bleeding of the gums and lining of the mouth and general soreness and pain of the mouth. It can be harder to control these things while undergoing treatment as the immune system is generally compromised as a result of the treatment. There are some special mouth rinses that can be prescribed to help with discomfort during treatment. It is very important to see your dentist before treatment begins and then to continue with recommended follow-up care.