What is an impacted tooth?
An impacted tooth is one which has not come into the mouth by the time it would be expected to have. In other words it is stuck. The most common reason for a tooth to become impacted is lack of space. Other reasons may include cysts and tumors associated with the tooth, fusion of the tooth to the surrounding bone or nearby teeth, or in some instances for unknown reasons a tooth just fails to complete its movement into the mouth.
Which teeth become impacted and why?
The tooth most likely to become impacted is the wisdom tooth, or
third molar. These teeth are the third set of permanent (adult)
molars. They are called wisdom teeth because they are supposed to
enter the mouth by the "age of wisdom," roughly eighteen years of
age. Hence why they are also know as the "eighteen year molars," in
contrast to the first or six year molars and the second or twelve
year molars. Wisdom teeth are not only the most likely teeth to be
impacted, but also the most likely to be deformed, missing or
present in extra numbers. Most people have four wisdom teeth: upper
right and left and lower right and left. Some people are missing one
or more wisdom teeth and others have extra sets (as many as triple
in my experience).
Since many people do not have enough room for all of their teeth to come in, the one most likely to be stuck or impacted is the last one to form, the wisdom tooth. The other teeth had used up the available space as they came into the mouth. When a person has crowded teeth, the wisdom tooth may have even less space available after the rest of the teeth are straightened. Not all people have impacted wisdom teeth, some people do have enough room for their wisdom teeth.
Many theories have been proposed to try to explain why so many people do not have enough room for all of their teeth, especially for the wisdom teeth. The most popular has been that our jaws have been getting smaller as humans have developed. However, studies done on ancient and modern skulls do not support this idea. What these studies do show is that in our ancestors, before modern dental care was available and to a lesser degree even today, the most commonly missing or decayed tooth s the first or six year molar. By the time that he wisdom tooth was ready to start to enter he mouth it may have had enough room in our very distant ancestors.
The wisdom tooth is not the only tooth that may become impacted. Other teeth that are often impacted include the canine or eye teeth and the premolars or bicuspids (small molar like teeth behind the eyeteeth). Any tooth may become impacted if it does not enter the mouth on time. Some people have extra teeth and if these do not have room, these too may become impacted.
What, if anything needs to be done?
Does anything need to be done for an impacted tooth? The answer depends on a few things. First, if there is enough room and the tooth is an important one for function or cosmetics, then if possible, an attempt is made to bring the tooth into position with a combination of surgery and orthodontics (braces). This is commonly done for impacted canine or eyeteeth. If the tooth does not have enough room, is an extra tooth or is deformed, often it needs to be removed.
happens if nothing is done?
Large cyst associated with impacted third molar, displacing it and eroding roots of teeth.
Sometimes the answer is nothing, for a while anyway. Nothing may
happen for years. If the tooth persists on trying to come into the
mouth it may push against the nearby teeth and damage them. If the
gum opens up enough over an impacted tooth to allow bacteria from
the mouth to enter the space around the impacted tooth, it may
become infected. Depending on the type of bacteria, several problems
An impacted tooth may cause difficulties with proper tooth cleaning and allow plaque (which is full of bacteria) to accumulate. This may lead with time to periodontal (gum) disease and spread to the nearby teeth. Other types of bacteria may cause tooth decay. The wisdom tooth or a nearby tooth may become decayed. Less commonly, the sack of tissue that surrounds the wisdom tooth may start to enlarge and fill up with fluid, forming what is called a cyst. A cyst may continue to grow and damage the jawbone, nearby teeth or other structures. This sack may also form tumors or growths. Although most of these are benign (and may still grow like the cysts) some may rarely be malignant (cancer).
Delaying treatment may also place the nearby teeth at risk. Many patients come in to have a wisdom tooth removed because of pain, but many times the tooth in front of it is so badly damaged that it is the one that hurts. Sometimes a wisdom tooth may not cause problems until the person is much older, as old as the nineties in my experience. That is definitely not a good age to be having wisdom teeth removed.
is the best time to do something?
A large cyst associated with an impacted third molar in an
older patient. Removing this tooth at this point in time is a
much more difficult operation and carries higher risks of
A large cyst associated with an impacted third molar in an older patient. Removing this tooth at this point in time is a much more difficult operation and carries higher risks of complications.
Most of the problems with impacted teeth tend to develop with time.
However, the best time to treat these teeth is before the problems
develop. If a tooth has enough room and is to be brought into the
mouth, there is a limited window of time to do this. As time passes,
the tooth becomes harder and harder to move until it loses the
ability to move. If a tooth does not have enough room, the best time
to remove it is before it causes problems (infection, gum disease,
decay, damage to other teeth, etc.) but before it finishes its
To a certain degree, an impacted tooth closer to the surface can be easier to remove. But, the structures that anchor a tooth in the jaw are the surrounding bone and the roots, not the gum that covers it. The more mature and harder the bone and the more developed and longer the roots, the harder the tooth becomes to remove. A common mistake is to wait for the tooth to come in more, hoping that it becomes easier to remove. The easiest time to remove a wisdom tooth is when the roots are about half to three quarters formed.