And second, it helps to prevent tooth decay and infection by destroying bacteria and fungi in the mouth. Sometimes dry mouth can be caused by medications. In those cases, doctors try to adjust the dose. Artificial saliva (kind of like eye drops, only for the mouth) may also be useful. And dentists recommend that you keep your mouth moist by sipping water throughout the day, and by avoiding spicy and salty foods and caffeine, which has a drying effect.

Left untreated, simple tooth decay and cavities can become more serious, leading to infections in the pulp that lies beneath the tooth surface and sometimes causing a painful pocket of pus, also known as an abscess, to develop. When it reaches this stage, the decay is referred to as periodontal disease, or simply gum disease, and it is the primary cause of tooth loss in adults over 35. Such decay attacks not only the gums, but also the bone and other tooth-supporting structures.

The earliest stage of periodontal disease is called gingivitis, and since many people don't experience any significant pain or discomfort at this stage, if you don't see your dentist regularly you may have the disease for years before getting the proper. The lack of any warning pain makes it especially important to brush and floss every day and to look for other signs of its progression. These include tender, swollen gums, or gums that bleed, particularly when you brush or floss your teeth; gums that turn a dark reddish color, a receding gum line, pain when you chew, tartar buildup on the tooth surface, and overly sensitive teeth. If you experience any of these, you should see a dentist as soon as possible.

If the gingivitis remains untreated, the infection can spread from the gums into the ligaments and bone that support the teeth. This may cause the teeth to become loose and eventually to fall out, a condition known as periodontitis.

Dentists diagnose gum disease with a combination of an oral examination and dental X-rays. In the examination, they will use a probe to measure the space between the teeth and the gums. In a normal mouth, a V-shaped groove runs between the two, measuring at most three millimeters deep, but if pockets form, the probe will push deeper into the gum tissue, and how deep it goes is a good indicator of how far the infection has progressed. They will then use the X-rays to determine if any of the underlying bone has been lost.

The good news is that you can prevent most cases of gum disease simply by brushing and flossing properly every day.