Cold sores, also called fever blisters, are groups of fluid-filled blisters that are caused by the Type 1 of the herpes simplex virus. They are most often found around the lips but can also be seen on the nose, cheeks or fingers. The sores are contagious and are easily spread by kissing an infected person or sharing eating utensils, towels or razors.

According to WebMD.com, 90 percent of people get at least one cold sore during their lives. After the first infection many people develop antibodies and never see a cold sore again. However, about 40 percent of American adults suffer from repeated cold sores.

Canker sores are small ulcers with a white or gray base and red border. They are found inside the lips and are not contagious. Their exact cause is uncertain but some experts believe that immune system problems, bacteria or viruses may be involved.

Fatigue, stress, or allergies can increase the likelihood of getting a canker sore, and conditions like ulcerative colitis and Crohn's disease also make people more susceptible.

Leukoplakia is a thick, white-colored patch that forms on the inside of the cheeks, gums or tongue. The patches are caused by excess cell growth and are common among tobacco users. It can also be caused by ill-fitting dentures. A danger is that Leukoplakia can progress to oral cancer, and a dentist may recommend a biopsy if a patch appears to be threatening.

Your mouth produces a sticky film called plaque that is loaded with bacteria. When you eat or drink substances with sugars or starches, the bacteria produces acids that attack the tooth enamel. After many attacks, the enamel can break down and a cavity will form. Preventing cavities is easy if you practice proper brushing techniques and make regular visits to your dentist.

Gum disease, also called periodontal disease, is caused when bacteria in plaque release toxins that irritate the gums and cause gum tissues to break down. If left untreated, it can also spread to the bone that supports your teeth. The two stages of gum disease are:

Gingivitis:
Gingivitis causes red, swollen gums that bleed easily when the teeth are brushed. It normally does not cause pain.

Periodontitis:
Periodontitis will develop if the gum disease gets worse. The gums pull away from the teeth, leaving deep pockets where bacteria can grow and spread to the bone that supports the teeth. Gums can also shrink back from the teeth, causing teeth to become loose or fall out.

Not properly caring for baby teeth when they come in can lead to early childhood tooth decay, also known as early childhood cavities or baby bottle tooth decay. Giving a child a bottle with sugary liquids many times a day or allowing them to fall asleep with a bottle in their mouth can lead to cavities. In severe cases, decayed teeth may need to be extracted by a dentist.

Early childhood tooth decay can be prevented by brushing your child's teeth as soon as they start coming in, wiping down teeth and gums with a gauze pad after feedings and beginning to floss as soon as all teeth have appeared. You should also start dental visits by the child's first birthday.

Oral cancer can affect the lips, gums, cheek-lining, tongue and hard or soft palates inside the mouth. The American Cancer Society estimates 35,720 new cases of oral cancer will be diagnosed in the United States in 2009, and that 7,600 people will die from the disease. Using tobacco and alcohol are risk factors in developing oral cancer, but approximately 25 percent of oral cancer patients have no known risk factors.

Regular dental examinations are essential in catching and treating oral cancer, so be sure to visit your dentist regularly.

Signs of oral cancer include:
-A sore that bleeds easily or does not heal.
-A color change of the oral tissues.
-A lump, thickening, rough spot, crust or small eroded area.
-Pain, tenderness, or numbness anywhere in the mouth or on the lips.
-Difficulty chewing, swallowing, speaking or moving the jaw or tongue.
-A change in the way the teeth fit together.