Some of the medical conditions that reduce the amount of saliva and lead to widespread tooth decay are Sjögren's Syndrome, Diabetes and Sarcoidosis. There are many medications that impair salivary flow from the salivary glands. Other causes of insufficient saliva production include alcoholic beverages, dehydration, anxiety, chemotherapy, radiation therapy and traumatic injury.
It takes a normal person roughly 20 minutes to begin neutralizing acid in their mouth. A person with dry mouth can take twice as long to neutralize the same amount of acid in their mouth.