A closer look at wisdom teeth development
Wisdom teeth, also known as third molars, typically begin to develop in early adolescence between the ages of 10 to 12 years old. At this stage, the wisdom teeth exist only as immature tooth buds buried in the jawbone.
The formation of wisdom teeth occurs later than all other teeth. Most other teeth start developing in utero or as an infant. But wisdom teeth do not mineralize and show first signs of eruption until the teenage years.
During the late teens and early 20s, the wisdom teeth continue to develop root structures and may slowly emerge or erupt partially or fully in the far back of the jaws. The upper wisdom teeth erupt behind the second molars by age 20, while the lower wisdom teeth erupt just behind the lower second molars between ages 17 to 21.
Why wisdom teeth develop so late
There are a few reasons why wisdom teeth develop later than any other teeth:
- Late growth of the jaws – Wisdom teeth begin to form once the jawbone is large enough to accommodate them. Jaw growth continues throughout adolescence and provides enough space for them to start budding.
- Delayed mineralization – While hidden inside the jaws, wisdom teeth consist of soft tissues without hard mineralized surfaces. They only start to mineralize and harden to allow eruption later in the teens.
- Reduced evolutionary need – The late development of wisdom teeth reflects their lack of essential purpose and function in modern humans.
The continuous growth and lack of differentiation in wisdom teeth
After wisdom teeth initially begin to bud and develop as a teenager, they continue to slowly grow and erupt throughout life rather than stopping after a certain period of time like other teeth.
Several factors contribute to the ongoing growth of wisdom teeth:
- Indeterminate growth – Most other teeth have a predetermined and limited growth cycle. Wisdom teeth growth is indeterminate, meaning there is no set endpoint.
- Lack of contact with antagonists – Wisdom teeth in the upper jaw have no opposing teeth to bite against, which provides resistance to limit growth. This contact seems to signal other teeth to stop growing.
- Reduced wear – There is minimal wear and tear on wisdom teeth since they are only used for chewing and biting to a limited degree. This allows them to keep growing.
- Partial eruption – Wisdom teeth often only partially emerge rather than fully erupting into the mouth due to lack of space. This means they do not complete developmental and differentiation steps.
- Lack of distinct root shapes – Wisdom teeth roots remain less defined and continue to slowly expand and develop. Other teeth develop distinct root shapes and channels that contribute to halting growth.
Overall, wisdom teeth exhibit indeterminate growth not driven by distinct genetic programming or environmental signals to stop. This leads to a high risk of problems if space is limited.
Issues with wisdom teeth continuing to grow
The ongoing growth of wisdom teeth into adulthood can lead to various problems, including:
Impaction
Impacted wisdom teeth are those that do not have enough room to erupt fully or at all into the mouth. Data shows the frequency of wisdom tooth impaction is approximately 9.5% in adults ages 15-24, increasing to 20% by age 40.
Impaction occurs more often in the lower jaw versus the upper jaw due to space constraints. Partial eruption or complete impaction results in higher risks of:
- Pericoronitis – infection around the gum tissue surrounding the crown
- Cysts – fluid-filled sacs that form around impacted teeth
- Damage to adjacent teeth – such as bone loss, caries, or root resorption
- Tooth crowding – pushing other teeth out of alignment
Periodontal disease
The position of wisdom teeth makes them harder to access and clean. Food and bacteria accumulation around partially erupted or impacted wisdom teeth can lead to infection and periodontal disease.
According to research, periodontal disease was five times more likely to develop around impacted mandibular wisdom teeth than fully erupted wisdom teeth.
Crowding and misalignment
The continuous growth of wisdom teeth can displace other teeth from their original aligned position. Crowding occurs as wisdom teeth enlarge and emerge out of line, causing overlapping of teeth.
One study found that 48% of people with wisdom tooth impaction also had some degree of dental crowding. Removal of wisdom teeth reduced incisor irregularity.
Cysts and tumors
Non-impacted wisdom teeth may still develop cysts or benign tumors like odontomas due to ongoing growth. Cysts form from fluid buildup at the crown or roots while odontomas are overgrowths of enamel, dentin, and pulpal tissue.
Decay and gum disease
Partially erupted wisdom teeth create pockets that are difficult to clean and prone to decay. Food and plaque easily get lodged under the gum flap covering the crown. Pericoronitis and advanced periodontal disease can develop over time.
Surgical extraction as the common treatment
Given the high risks associated with wisdom teeth that continue to grow, surgical removal or extraction is the standard and preferred treatment in most cases. Extraction may be advised for the following reasons:
- Existing impaction or partial eruption that allows infections
- Evidence of cysts, decay, or periodontal disease
- Clear lack of space for full eruption
- Causing pain or symptoms
- Causing crowding or displacement of other teeth
Extraction of wisdom teeth is an outpatient oral surgery with local anesthesia or IV sedation. Post-operative recovery takes around 1-2 weeks.
Antibiotics, pain medication, and salt water rinses are used to manage pain and prevent infections during recovery. Stitches may be placed to close extraction sites as well.
In some cases, dentists may decide to monitor asymptomatic wisdom teeth with regular x-rays. However, this risk of eventual problems is significant, hence the common recommendation for early removal.
The evolutionary basis behind why wisdom teeth don’t stop growing
Wisdom teeth are considered vestigial organs, meaning they served an important function in early ancestral humans but gradually lost relevance as the human diet and lifestyles evolved.
Researchers believe wisdom teeth first evolved approximately 3 million years ago during the Pleistocene era when early humans had coarse, abrasive diets comprised of nuts, seeds, roots, raw meat, and unprocessed grains.
At the time, they provided additional surfaces to grind tougher foods, boosting chewing and grinding power. Humans also had larger jaws and teeth to accommodate wear from rougher diets.
But as food processing techniques developed, including cooking and cutting foods, the need for wisdom teeth decreased. Jaws and teeth became smaller while wisdom teeth became redundant structures deeply rooted in old evolution.
Wisdom teeth stopped receiving key signals and stimuli from diet, wear, and function to regulate their growth. Consequently, they continue to slowly develop without a defined end point, often leading to impaction or other problems in modern humans.
Summary and key points
- Wisdom teeth are last to develop, often only partially erupting in late teens and early 20s
- They exhibit indeterminate growth as vestigial structures, lacking signals to stop growing
- Continuous growth increases risk of impaction, infection, cysts, decay, and other dental problems
- Lack of opposing teeth and occlusal wear allows ongoing enlargement
- Extraction in adolescence or early adulthood prevents most future complications
- Wisdom teeth lost their original evolutionary purpose as human diets and jaws changed over time
- Ongoing growth reflects their vestigial nature rather than a defined biological function
Frequently Asked Questions
How often do wisdom teeth need to be extracted?
According to research, around 65% of young adults have at least one wisdom tooth removed. Full bony impaction of one or more wisdom teeth occurs in 10% to 20% of people. Due to high risks of future problems, extraction is recommended for most partially erupted or impacted wisdom teeth.
Can wisdom teeth continue to erupt after age 30?
Yes, it is possible but uncommon for wisdom teeth to continue to slowly erupt or emerge even after age 30. They can still enlarge and move over time if the root structure is present. Partial impaction early on followed by later eruption accounts for some wisdom teeth appearing later in life.
What is the latest age wisdom teeth can come in?
While uncommon, there are cases of wisdom teeth erupting in people over age 40 or even 50 in rare instances. If the tooth buds are in place, delayed mineralization, lack of space during young adulthood, and the persistent growth potential can lead to very late wisdom tooth eruption.
Should I wait to see if wisdom teeth cause problems before removing them?
No, dentists strongly recommend early wisdom tooth extraction as a preventive measure before around ages 20-25. Monitoring wisdom teeth and waiting for issues to arise first leads to preventable complications and greater surgical risks when patients are older. Removal later on is more complex.
How does it feel to have wisdom teeth removed?
Wisdom tooth extraction is often accompanied by some degree of pain and swelling for the first 3-4 days. Numbness lasting weeks or months is common as well. Discomfort is well controlled with pain medication. By 1-2 weeks, initial healing allows patients to resume normal oral function. Full healing takes about 6 weeks.
