The main problem with dry mouth (xerostomia) is that it occurs when there is an imbalance between the amount of saliva your saliva produces and the amount of saliva the tissues in your mouth can absorb. The saliva generally will contain substances such as glucose, bacteria, lipids, proteins and vitamins. When you have a dry mouth, you can no longer properly absorb the nutrients from the foods you eat and the dead cells in your mouth begin to break down causing bad breath, gum disease and cavities. This can occur if you are a smoker, have diabetes or you have a poor diet. In addition, a dry mouth may be the result of poor oral hygiene including neglecting to brush your teeth or floss.