Dental Care

Impacted Wisdom Teeth

In this article we'll give you some more detailed information about impacted wisdom teeth. We've already discussed some basic information about wisdom teeth in one of our other articles.

You'll learn about the different types of wisdom teeth that are “impacted” and what experts believe causes this usually painful and sometimes serious condition.

Like all other teeth, wisdom teeth form and erupt through the gums during the natural process of maturation.  Most teeth come in normally, or almost normally, anyway. 

But the wisdom teeth of some people fail to come in at all, and in others they only partially erupt through the gums.  An impacted wisdom tooth is one which has not emerged from the gums completely or has failed to emerge into the anatomically correct position.

Reasons why impacted wisdom teeth can occur

There might not be enough room in the dental arch to accommodate the tooth adequately, causing the adjacent teeth, gum or bone to force it out of position during the eruption process.

The tooth's "eruption path" might be obstructed by the presence of other teeth; or the angle of eruption might be improper, either pitched forward, backward, upward or sideways.

Several types of impacted wisdom teeth exist

The dental classifications for different types of impacted wisdom teeth include mesial, distal, horizontal, vertical, soft-tissue and bony impactions. 

An impacted wisdom tooth can be assigned to one of first four of these classifications based on the general angulation of the affected tooth.  The last two classifications are based on the degree of eruption from the gum.

The most common type of impacted wisdom tooth is a mesial impaction, the dental term for a tooth which has erupted from the gum angled forward, toward the front of the mouth. 

The other three types of impactions caused by improper angulation, in order of their frequency, are vertical, horizontal and distal impactions. 

Vertical impactions involve upright teeth pointed toward the head, while horizontal impactions involve teeth pointed sideways or lying on their side.  In a distal impaction, the tooth is angled toward the back of the mouth or throat. 

Impacted wisdom teeth can also be classified based on how far they have erupted from the gum. 

If a wisdom tooth has penetrated through the jawbone and has almost fully erupted but is still covered by at least some gum, it is called a soft-tissue impaction. 

A tooth covered by gum and at least some of the jawbone is known as a partial-bony impaction.

While a tooth completely covered by the gum and still fully encased in the jawbone is a complete-bony impaction.


The primary cause of impacted wisdom teeth is insufficient space in your dental arch behind your second molar. 

Without enough room to come in properly, the nearby gum, bone and/or teeth can force the wisdom tooth out of its proper position while it's making its way to the surface. 

The underlying reason for the insufficient space is not completely understood, but there does appear to be a relationship between having large teeth, tooth crowding elsewhere in the mouth, and the occurrence of impacted wisdom teeth. 

Evolution may have played a role, as our jaws have become smaller over the course of millions of years.  However, many theorize that our modern diet may have at least an equal effect on the size of our jaws.

Some dental experts believe the coarse, tough diet people ate during the Stone Age caused extensive tooth wear and a reduction in the overall size of the teeth, allowing sufficient space in the jawbone to accommodate the wisdom teeth when they erupted. 

In contrast, the softer diet we enjoy today typically does not require repetitive grinding or otherwise result in any significant amount of this type of tooth wear.  The teeth remain larger and leave less space available for wisdom tooth eruption.

An alternate theory also exists. Like the "tooth wear" theory mentioned above, this theory also contends that the reason for the insufficient space is due to differences in the diets of prehistoric and modern humans. 

However, instead of focusing on the tooth wear caused by the Stone Age diet, the experts who espouse this theory believe the prehistoric diet probably required significantly more chewing and thus significantly more activity in the muscles used for chewing.  This amount of muscular activity could, they claim, have stimulated more growth in the jawbone, thereby providing more room for wisdom tooth eruption.


Most impacted wisdom teeth are extracted.  There are two main reasons for this practice:  they frequently cause a great deal of pain and suffering, but more importantly, if left in place some ultimately lead to serious medical complications.

Removing an impacted wisdom tooth addresses both problems.


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