Impacted wisdom teeth | Wisdom tooth extractions
What are wisdom teeth? / Which teeth are they?
"Wisdom teeth" are a type of molar. Molars are the chewing teeth found furthest in the back of the mouth. Most people have 1st, 2nd and 3rd molars. A person's third molars are their wisdom teeth. (See our graphic below.)
When do a person's wisdom teeth come in?
Third molars will erupt (come into place) right behind their neighboring second molars, if there is room for them and they are aligned properly.
With most people, this eruption process takes place during their late teens or early twenties (usually ages 18 to 24 years), although eruption outside of this age range is not uncommon.
If there is not enough room for the teeth, or they are not aligned properly, they may never fully erupt. (See "Impacted Wisdom Teeth" below.)
How many wisdom teeth does a person have?
People usually have four wisdom teeth: upper left, upper right, lower left, and lower right. (See "Types of impacted wisdom teeth" graphic below.)
If they don't, it's due to their genetic makeup. It's been estimated that about 25% of all people are lacking one or more of their third molars. (Faculty, 1997)
What are "impacted" wisdom teeth?
In dental terminology, an "impacted" tooth refers to a tooth that has failed to fully emerge into its expected position.
This failure to erupt properly might occur because there is not enough room in the person's jaw to accommodate the tooth, the tooth's eruption path is obstructed by other teeth or because the angulation of the tooth is improper.
How likely is it that your wisdom teeth will be impacted?
Studies evaluating relative younger age groups (ages 17 to 30 years, a population relatively less likely to already have had their wisdom teeth removed) have suggested that the incidence of having at least one impacted third molar runs on the order of 65 to 72%. (Faculty, 1997)
Classifications of impacted wisdom teeth.
Dentists use a number of terms, in combination, to describe the positioning of impacted wisdom teeth. They are mesial, distal, horizontal, vertical, soft-tissue and bony.
The terms mesial, distal, horizontal and vertical refer to the general angulation (positioning) of the impacted tooth.
Mesial impactions.
The most common type of impacted wisdom tooth is the "mesial impaction." The term "mesial" means that the tooth is angled forward, toward the front of the mouth.
Vertical, horizontal and distal impactions.
The other types of impactions, in order of frequency of occurrence, are the vertical, horizontal, and distal types.
As illustrated in the graphics below, a distal impaction has an angulation that is generally directed towards the rear of the mouth. Horizontally positioned impactions have an alignment where they are lying on their side. Vertical impactions have a relatively normal orientation.
Vertically impacted wisdom tooth.
Horizontally impacted wisdom tooth.
Soft-tissue and bony wisdom tooth impactions.
In combination with the mesial, vertical, horizontal, and distal classifications, wisdom teeth are also categorized as soft tissue or bony impactions.
- A "soft tissue" impaction is one where the upper portion of a wisdom tooth (the tooth's crown) has penetrated through the bone, but has not yet fully erupted through the gum tissue.
- The term "bony" impaction indicates that the wisdom tooth is still encased in the jaw's bone.
Need more detailed information? Give our other pages a look.
The remainder of our topic's pages cover wisdom-tooth subjects in much greater detail. Things like:
- Reasons why wisdom teeth should be extracted.
- Potential risks and complications associated with this surgery.
- Why some of the justifications given for their removal simply aren't valid.
We also provide information about:
- The extraction process and what to expect.
- How much your surgery is likely to cost.
- When's the best age to have wisdom teeth removed?
- Post-operative healing and aftercare instructions.
[Reference sources referred to on this page.]
Why might a wisdom tooth be impacted?
The reason why some wisdom teeth are impacted is not an easy question to answer. A primary cause of wisdom-tooth impaction simply seems to be a condition of inadequate jawbone space behind a person's second molar.
Why this lack of space exists is not fully understood. There does, however, seem to be a correlation between large tooth size or the presence of generalized tooth crowding and having impacted wisdom teeth.
Modern man's diet may play a role in third molar impaction.
It has been theorized that the coarse nature of stone-age man's diet had the effect of producing extensive tooth wear (not just on the chewing surface of the teeth but also in between, where neighboring teeth touch against each other).
This type of wear could result in a collective reduction of the "length" of a person's teeth (as a set), thus creating enough jawbone space to accommodate the wisdom teeth by the time they erupted. In comparison the diet of modern man does not usually cause a significant amount of this type of tooth wear.
It has also been argued that the coarse nature of stone-age man's diet, as compared to modern man's relatively soft diet, probably required more chewing-muscle activity. This activity could have stimulated greater jawbone growth, thus providing more space for wisdom teeth.
Additionally, the harsh and threatening world of the caveman no doubt often lead to the occurrence of broken teeth and even tooth loss. Once a tooth (or a portion of it) is missing the teeth behind it have a tendency to move forward. This type of shifting would make more jawbone space available for wisdom teeth. In comparison, with the advent of modern dentistry there are relatively few reasons why a tooth should be lost or remain in a state of disrepair.
1) The basics...
What are they?
Impacted teeth.
2) Wisdom removal...
Reasons to.
Reasons not to.
3) Having them out...
The procedure.
Aftercare.
Complications.
Costs.
