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What Is a Wisdom Tooth?

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From babyhood to adolescence, teeth erupt in stages: first incisors, then canines, premolars and molars, and, finally, wisdom teeth. The latter is often the most intriguing: what is a wisdom tooth? Dentists call them third molars, and they appear at the back of the mouth. Some people never experience a single problem with their wisdom teeth, but they can cause pain, infection and other instances of discomfort in others.

Where and When Wisdom Teeth Come In

People usually develop four wisdom teeth, each emerging behind the molars on both sides of the upper and lower jaw. According to the American Dental Association (ADA) Mouth Healthy site, they usually appear between the ages of 17 and 21. How they emerge differs from one individual to the next. Fred Quarnstrom, DDS from the American Dental Board of Anesthesiology explains that wisdom teeth may only partially erupt, or even stay buried within the gum tissue. Teeth that don't appear, but remain covered by this tissue or bone instead, are called "impacted" teeth.

Why They Come In

Because wisdom teeth cause so many problems and are not really needed for chewing, doctors speculate about their function. Wisdom teeth begin growing in the jaw around the age of seven, and not just before or at birth like other teeth, according to Kamal Busaidy, BDS, FDSRCS of The University of Texas Health Science Center at Houston. Throughout most of human history, our typical diet has been abrasive to teeth. Under the circumstances, wisdom teeth may have been useful in the past for replacing molars that had become worn out. Now that diets are softer, teeth don't wear out as quickly, and there are no gaps for wisdom teeth to fill. Dr. Quarnstrom claims there is also some evidence that modern jaws are smaller than those of prehistoric humans.

What Happens

Problems with wisdom teeth primarily include pain and discomfort, infections, gum problems and tooth decay. Some of these are due to the difficulty brushing so far back in the mouth. Brushing with a slim, long-handled toothbrush can help to prevent these problems. Impacted wisdom teeth can give rise to serious problems when cysts form below the teeth. These cysts can cause bone loss in the jaw and put pressure on the jaw nerves.

Problems with wisdom teeth usually end with their removal. Dentists often prefer to remove wisdom teeth when patients are in their late teens or early 20s, before they cause problems. At this age, wisdom teeth roots have not solidified in the jaw bone and are easier to remove than in older patients. Removing wisdom teeth later in life also carries a slightly higher risk of damage to a major nerve in the jaw, called the inferior alveolar nerve. In addition, younger patients often recover faster from sedation.

According to Busaidy, adolescents wearing braces or other orthodontic appliances often have their wisdom teeth removed at the end of their treatment. This is because emerging wisdom teeth can alter tooth alignment after they have been straightened.

So, what is a wisdom tooth? It has nothing to do with growing wiser – only growing older. If your wisdom teeth give you pain or discomfort, see your dentist. Early treatment greatly reduces your risk of bigger problems later.

If you've had or need to have your wisdom teeth extracted, find out more about wisdom teeth recovery in the Colgate Oral Care Resources.