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Missing permanent teeth can be a big mystery to the patients and their relatives. It is difficult to fathom that some teeth may be formed completely normally and erupt into their correct positions, while others just simply don’t turn up!
The truth of the matter is that missing permanent teeth is much more common that people usually believe. It is estimated that almost 20 percent of people, that is one in five, have one or more teeth congenitally missing.
Which Teeth Usually Go "AWOL"?
The most commonly missing tooth is a missing third molar or wisdom tooth. This is also the reason that most people do not realize that a tooth is actually missing in their mouth! The wisdom teeth erupt last into the oral cavity and are the furthest back in placement so no one misses them when they are not there.
Wisdom teeth are also commonly extracted since they do not find the space to erupt properly in the mouth and so people who have had a couple of them extracted are not quite sure if they did have the complete set in the first place or not.
The second premolars and the lateral incisors are the next most commonly missing teeth. These teeth have a place in the middle of the arch and thus play an important role in the normal development of the mouth.
There are a few conditions in which the entire dentition or most of the teeth may be missing. These are extremely rare in occurrence and most of the people affected will only have one or two teeth missing from their full set.
Why Do These Teeth Not Develop?
The answer to this question may never be completely known, although the expression of certain genes has been linked to the occurrence of missing teeth. Parents who have had missing permanent teeth during their life are much more likely to have children facing the same problem.
A theory that has been put forward is that evolution and adaptation to modern living standards may be behind the increasing incidence of missing teeth. Human jaw bones are growing thinner and smaller since their diet has moved from raw meat to soft processed food.
We as a species simply do not need the number of teeth we once did. It is thought that human beings down the line may only have 20 permanent teeth as compared to the 32 that most people have.
There are also certain syndromes like Down syndrome in which the affected children have a high chance of having missing teeth. Technically speaking, there is a thin band of cells called the Dental Lamina which eventually develops and matures into the teeth. Thus, anything from injury to genetic information that prevents this Dental lamina from forming will cause missing teeth.
Interestingly, the incidence of having missing deciduous or milk teeth is much lesser than in permanent ones. A doctor can almost be certain that a deciduous tooth which is missing will not have its permanent counterpart as well.