Not everyone has to hassle with wisdom teeth. Some people aren’t born with a complete set and studies have shown that approximately a third of people are born without any. And while some people may have the teeth, they never see them emerge. Why?
For that, you can thank evolution. Wisdom teeth are known as vestigial structures. These are parts of our body, such as the tailbone, that once had a use but no longer do in our modern lives.
Wisdom teeth served a purpose long, long ago when we foraged for foods like twigs and tough, raw meats. Since we no longer need that extra grinding power our bodies have evolved away from them.
Our jawbones have decreased in size as well. That’s why wisdom teeth are prone to trouble, and in most instances need to be removed soon after they appear.
Are missing wisdom teeth an anomaly?
Oral health is an essential part of public health, but dental treatments can be expensive. One common dental anomaly is congenitally missing teeth (CMT), where a person is naturally missing one or more permanent teeth.
That said, missing wisdom teeth are not considered a case of congenitally missing teeth (CMT) because wisdom teeth are not considered permanent teeth. SO MISSING TEETH ARE NOT AN ANOMALY.
CMT refers to the congenital absence of permanent teeth, particularly the incisors, premolars, and canines. Wisdom teeth, on the other hand, are considered to be third molars, which are not essential for proper bite or function. Therefore, the absence of wisdom teeth is not classified as CMT.
Otherwise, CMT can negatively impact both esthetics and function, leading to malocclusion, periodontal damage, reduced chewing ability, and changes in appearance. Therefore, early diagnosis and treatment of CMT are essential to prevent these complications and reduce the need for costly treatments.
In the case of missing wisdom teeth, there is virtually no harm to the individual. In fact, a good number of people actually opt to have their wisdom teeth removed to avoid the complications associated with them. Though an individual with wisdom teeth will have to weigh the advantages and disadvantages of wisdom teeth to determine whether they want to keep them or get them extracted.
Prevalence of missing teeth
According to a study performed in Bangladesh to identify the prevalence of at least one missing wisdom teeth, whereby the individual, aged between 10 and 50 years, had no previous history of surgical tooth extraction, and had no known cases congenital disorders or craniofacial deformity, the following were the findings:
- More females than males were observed to be missing at least one missing wisdom teeth, at the rate of 40.1% vs. 36.8% which can be attributed to differences in craniofacial morphology between the sexes
- There was a higher incidence of missing wisdom teeth in the upper jaw compared to the lower jaw
- There was a greater likelihood of having a missing wisdom tooth on the right side of the mouth than the left side
- The formation of wisdom teeth starts at age 3-4 and calcification starts at 7-10, with the crown completing at 12-16 years old.
- Differences in genetics, diet, mastication, and race can affect jaw size and facial growth, leading to differences in the prevalence of missing wisdom teeth across populations.
- Patients with missing wisdom teeth were more likely to have hypodontia (missing teeth) and microdontia (smaller teeth) than those with all their wisdom teeth.
Factors affecting missing wisdom teeth
Tooth agenesis refers to the lack of one or more teeth, either primary or permanent, such that it’s not visible in the oral cavity through dental X-rays. Third molars, or wisdom teeth, are the most commonly affected teeth, with around 50% of people experiencing some form of anomaly – remain un-erupted, partially erupted, or completely missing.
Agenesis is the most common dental anomaly and can occur in varying degrees. The prevalence of third molar agenesis varies depending on the population being studied, with reported rates ranging from 12.7% in British populations to 41% in Korean populations.
Dental anomalies can be caused by environmental factors, genetics, systemic diseases, dietary habits, and masticatory function. Third molar agenesis has been linked to dental numeric and morphological variations, such as delayed development and reduced tooth size.
Human evolution and changes in cooking methods have played a significant role in the absence of wisdom teeth. The evolution of the human brain resulted in a larger skull and a smaller jaw with less space for all teeth. Due to cooking methods, there was less biological need for third molars.
Pain felt by our ancestors with impacted wisdom teeth, due to smaller jaws, meant they were less likely to reproduce, favoring those without wisdom teeth.
Researchers have discovered that changes in genes affecting teeth development occur independently of brain evolution. Thousands of years ago, mutations (genetic variants) prevented the formation of wisdom teeth, which were favorable due to man’s smaller jaw. Positive selection led to these variants becoming more widespread.
It is also thought that around 80% of non-syndromic tooth agenesis is caused by changes in genes involved in facial and tooth development, including the genes AXIN2, MSX1 and PAX9. However, the exact genetic cause of wisdom teeth agenesis is unclear.
Research suggests that the absence of wisdom teeth is heritable. A study of same-sex twins found that monozygotic (identical) twins had a slightly higher prevalence of third molar agenesis than dizygotic twins.
The authors reported that agenesis of third molars was associated with additive genetic factors that accounted for approximately 60-80% of the variation seen in the study, with the environment accounting for the remainder of the variation.
Association with Other Teeth
The relationship between third molar agenesis and agenesis of other teeth is interesting. One study reported that third molar agenesis was more common where there was agenesis of other teeth. The authors suggested this indicates continued human evolution towards fewer teeth, as third molars might be vulnerable to genetic factors that affect the overall number of teeth.
Variations in Root Mineralization
Root mineralization is the process of mineral deposition that occurs in the roots of teeth. The timing and rate of root mineralization can vary among individuals and can be influenced by various factors, including genetics. This may in turn have implications for the timing of wisdom tooth eruption and potential dental problems associated with them.
Environmental factors and ethnic differences
Exposure to certain environmental factors can also contribute to missing wisdom teeth. For instance, studies have shown that certain populations have a higher prevalence of wisdom teeth agenesis compared to others.
For example, a study conducted in the United States found that individuals of Asian descent had the highest prevalence of missing wisdom teeth, while individuals of African descent had the lowest prevalence.
Similarly, a study conducted in Saudi Arabia found that 26% of the population had at least one missing wisdom tooth, with higher prevalence rates found among females.
Lifestyles and medical conditions
Exposure to chemotherapy, certain viruses, and various medications at a young age can also affect the development of permanent teeth, including wisdom teeth. One study found that children who received local anesthesia injections in the gums between the ages of 2 and 6 years were more likely not to develop wisdom teeth than other children.
From the points above, we can conclude that the absence of wisdom teeth is a common evolutionary adaptation due to changes in the human skull and jaw structure. Furthermore, genetic factors play a significant role in determining whether or not an individual will develop wisdom teeth, as well as the rate of root mineralization. Exposure to certain environmental factors, medications, and viruses can also contribute to missing wisdom teeth.
Fortunately, there is generally no cause for concern if an individual does not have wisdom teeth. In fact, the absence of wisdom teeth can often prevent dental problems such as overcrowding, impaction, and infections.
However, it is important to note that the absence of wisdom teeth does not mean that an individual is immune to dental issues, and regular dental check-ups and good oral hygiene practices are still crucial for maintaining optimal dental health.