Why Do We Have Wisdom Teeth?
Wisdom Teeth— Why Do We Have Them?
Countless patients explain that wisdom teeth don’t seem like a very ‘wise’ idea. Why do we have wisdom teeth if we just have to get them out?
So why do we have wisdom teeth anyway?
One of the early theories is that through evolution, our jaws have changed in size and now we can no longer fit the same number of teeth we originally had, or rather our ancestors had, in our jaws. However, studies done by Dr. P.R. Begg in 1954–supported by work done by Varrela in 1990 and Odusanya & Abayomi in 1991–supports the opposite theory. Contrary to the evolutionary theory, scientists explain that evolution of the jaw would take much longer and when comparing the relative jaw sizes of our ancestors, there is no significant difference.
Evolutionary changes have not kept pace with dietary changes in humans over the last 500 years and that has lead to an increase in impaction rates. These scientists studied skulls from people 500 years ago and counted the percentage of impactions they had.
An impaction is when the crown of the tooth is covered by some other tissue.
The crown of the tooth should be all the way in the mouth, with the roots down through the gums and into the bone–this is the normal healthy state for a tooth. By studying these skulls, they were able to come up with a percentage for impactions and only 500 years ago they found there was a low impaction rate which is much different from the 75% impaction rate that we have now.
So what happened in that 500 years?
When studying the individual teeth, it’s found that people from 500 years ago had much more attrition. Attrition is where the teeth wear down from grinding hard. This attrition can grind down on the top, between the teeth, and on the sides because the individual teeth move slightly in their sockets. Because the diet 500 years ago was a much coarser, attritive diet, there was more abrasion to the teeth and the interproximal wear (between teeth) decreased the overall length and width of the teeth when they lied side by side, thus making it possible for wisdom teeth to fit in the dental arch in a proper way. In fact, recent studies of modern Aborigines, who even in today’s modern world have a very coarse, attritive diet, have shown a very low impaction rate. Their diet consists of food that is not well cleaned and may have grit, sand, or other abrasive debris still in them. Other foods in their diet are tough, fibrous, and require more chewing unlike today’s refined diet which doesn’t wear the teeth down. Another study that reconfirmed these findings was by Odusanya & Abayomi. They studied African boys who were brought up in rural areas verses those brought up in urban areas and found there was an increased incidence of impactions in the urban population.
Although many people have the misfortune of having wisdom teeth, many people are born with fewer than the normal four wisdom teeth or may not have any wisdom teeth at all. A visit to our office or your dentists’ office will determine the position of your wisdom teeth (if you have them at all) and if you need to have them removed.