At around the age of 17, wisdom teeth either erupt - or try to, or fail entirely to erupt - in the back of your mouth. Because of the lack of room in the jaw for the large, sharp wisdom teeth, the dental community often encourages them to be removed. But why should you? Do your teeth need all that space? Or is there more to it than that?

When wisdom teeth come into your mouth fully, and not crooked, they're usually harmless, and serve their purpose of being grinders. But it's often the case that a tooth will only erupt halfway, leaving the pierced gum area around it susceptible to food and bacteria which can leak down inside and cause infection - not to mention bad breath. These infections aren't small matters, although they do begin that way. If left untreated, they can cause trismus, the inability to fully open the mouth, and keep spreading until they reach as far as the neck.

Even if a tooth does come out correctly, it's far enough back in the mouth for it to be difficult to reach to clean with a toothbrush and impossible to floss without unhinging your jaw.

However, most wisdom tooth-related problems are caused by the tooth failing to emerge fully from the gum - these teeth, called ‘impacted teeth', can tilt outwards abnormally, crowding the teeth around them and causing pain and irritation of the gums. Such crowding can create a slow-working domino effect, causing other teeth to become crooked. After that, they can only be returned to their original positions with braces.

Cysts can form around the impacted tooth, affecting the bones and expanding the jaw. If they grow large enough, they can fracture the jaw. Sometimes, although not often, cysts can harbor cancerous tumors.

There are many kinds of impaction - mesial, when the tooth is angled toward the front of the mouth; vertical, towards the bottom; horizontal, when a tooth is on its side; and distal, when it angles toward the back of the mouth. There's more: bony impaction is when the tooth hasn't even made it to the gum, but is still stuck behind in the jawbone. Soft tissue impaction describes when the tooth does make it through the bone, but fails to make the final jump through the gum tissue.

But why go through with having these teeth, which are signals that one has come-of-age in some cultures, removed now? Surgery certainly isn't something to which many of us look forward. Unless it's pressing - like, say, a brain transplant-we tend to put it off. But it's best to remove the cause before it becomes a problem, which is why, although the thought of removing these third molars isn't enticing, you should have them out before they can cause discomfort and infection in your mouth. Even if you do manage to avoid these effects for awhile, the bone surrounding the tooth becomes denser as you age, and once you pass forty the tooth becomes more difficult to remove. So what are you waiting for? A few days of pain can save you years of headache.