I've often heard my female patients say they'd rather give birth than have their wisdom teeth extracted. I've been lucky enough to experience both those things while fully conscious, (twice!), and I'd have to say that I found having my wisdom teeth taken out a much easier experience than bringing my children into the world. Not only does the dental patient not have any pushing to do, they get to have a good sleep afterwards without being interrupted by the cries of a newborn baby!
So why remove wisdom teeth at all? If there's not enough room for them in your mouth, all sorts of problems can occur. Often wisdom teeth which are squeezing into a crowded mouth will be impacted. An impacted tooth is one that won't ever fully come through into your mouth because it's either on an angle, or there's something in the way like another tooth or some bone. Sometimes impacted wisdom teeth will lie dormant and never cause an issue, but there is certainly a risk of problems which can occur at any time.
Pericoronitis
This is the most common complication that I see with impacted wisdom teeth. When a tooth has partly come through, but there's still a "flap" of gum covering it, it's nearly impossible to clean properly. The result is food and plaque building up in all the nooks and crannies, causing the gum to become sore and swollen. "Pericoronitis" literally means inflammation around the crown of the tooth. It can range from a mild annoyance, to severe pain and swelling which can require antibiotics before the tooth can be taken out. There's also the potential for formation of an abscess, which means a big ball of pus in your jawbone. It's very unpleasant, and in extreme cases can be life threatening.
Damage to other teeth
This is partly related to cleaning again. If an impacted wisdom tooth is butting up against the tooth in front, it creates an area which is very difficult to floss. Anywhere there is plaque left on a tooth there is the potential for decay. You might think it's no big deal if you get a bit of decay in a wisdom tooth which is going to be taken out anyway, but you certainly don't want decay in the tooth in front as well which you are planning to keep.
On the cleaning front yet again, an accumulation of plaque in a hard-to-clean area can cause the damaging gum disease periodontitis. If it begins to affect the tooth in front of the wisdom tooth, it can lose the bone and ligament holding it in place, leading to eventual tooth loss if left untreated.
There's also a small risk of the wisdom tooth getting the urge to try and erupt, (push up through the gum), but being tilted it instead pushes into the tooth in front. This pressure can lead to resorption of the good tooth, where it is slowly eaten away by your own body.
Crooked teeth
There's a popular belief that impacted wisdom teeth will push forward and cause crowded, crooked front teeth. There's currently evidence for and against this theory, as we still see crowding form in people who have already had their wisdom teeth taken out. My advice is to consider this as a possibility when deciding whether or not to have your wisdom teeth taken out, but not to rely on it preventing your teeth from moving at all.
Cysts
These are quite uncommon, but they do occur. A wisdom tooth which remains completely buried under the gum has the potential for a cyst to form around it. While a cyst is not cancerous and is completely benign, is can cause a lot of local damage. A cyst is a sac filled with fluid, which expands and puts pressure on the surrounding bone. The pressure causes resorption, so left unchecked a lot of bone can be destroyed. I have heard of patients presenting with the first symptom of their cyst being a jaw fracture, as their jaw bone became so thing it broke under light trauma before anything else was apparent.
It becomes fairly obvious that if you've experienced any of these problems, you'll need your wisdom teeth taken out. If they're not bothering you at all though, and your dentist says they are impacted, consider the pros and cons of extracting them as a preventative measure. This is especially important if you're planning to be away from accessible medical care, for example going on an overseas trip or military deployment. Another good reason for preventative removal of wisdom teeth is to avoid the need to do it much later in life when you may possibly be in poorer health. You're likely to heal much faster and cope much better with a general anaesthetic in your early 20s than when you're 85 and taking multiple medications for high blood pressure, diabetes, and osteoporosis. The other benefit of having them taken out young is that your bone is softer, making the extractions easier, and that there's more chance of your parents paying for it!