Tooth agenesis is the absence of one or more teeth due to a defect in the developmental process. In this case, the absence of a tooth is not because it has fallen out, but because it was never formed to begin with.
It represents one of the most common developmental disorders, affecting more than 6% of the world population and in some cases, it affects facial aesthetics.
Next, we will discuss the types of tooth agenesis, its possible causes, the syndromes associated, and the treatment.
Causes of tooth agenesis
Dental agenesis can occur for various reasons, among them we have:
- Genetics: Tooth agenesis is hereditary, there are many cases of entire families that have congenital absence of certain dental pieces.
- Infections: Infectious processes during pregnancy can affect the development of dental germs in the fetus, and therefore cause tooth agenesis later in life.
- Genetic syndromes: Several syndromes are associated with tooth ageneses, such as Down syndrome and Van Der Woude Syndrome.
- Cleft lip and cleft palate: Agenesis can occur in children with orofacial clefting due to imperfect formation of the maxillofacial structures.
- Evolution: Modern humans have smaller jaws due to changes in our lifestyle and diet, it is believed that the increasingly frequent absence of third molars (wisdom teeth) is due to an evolutionary process.
Types of tooth agenesis
Tooth agenesis is classified into three types depending on the number of missing teeth:
- Hypodontia.
- Oligodontia.
- Anodontia.
Hypodontia
Hypodontia is the absence of 1 to 6 teeth, this is the most common type of dental agenesis worldwide, in most cases, it even goes unnoticed since commonly the absent teeth are the third molars or wisdom teeth.
This, far from being a problem, is convenient for those with this condition since they will not have to deal with wisdom teeth coming in later on.
In case the agenesis affects the anterior teeth, the main problem will be dental cosmetics, but this can be solved with dental implants.
Oligodontia
Oligodontia is the absence of more than 6 teeth, this not only has cosmetic consequences but also affects the functionality of the teeth, this is a very rare type of agenesis and is usually related to genetic syndromes or malformations.
Anodontia
Anodontia is the congenital absence of all teeth, it is an extremely rare condition and usually appears as a result of diseases during the gestation period or due to certain environmental factors such as exposure to nuclear radiation.
We must clarify that anodontia is the lack of formation of all the teeth, it is not the same as edentulism which is the loss of already formed teeth due to diseases such as periodontitis.
Consequences of tooth agenesis
Although in most cases, dental agenesis does not cause negative effects on oral health and can even go unnoticed, in some cases it can have consequences over time.
Among the problems that tooth agenesis can cause we have:
- Cosmetic problems: In addition to wisdom teeth, the teeth most affected by agenesis are usually the incisors, as they are the front teeth, the absence of any of them leads to major aesthetic problems.
- Dental malocclusion: The absence of dental pieces will cause the erupted teeth to move from their position, causing dental crowding, diastemas, and other dental malocclusion problems.
- Pronunciation problems: The absence of teeth, especially in children, can make it difficult to pronounce certain words.
Tooth agenesis in children
Tooth agenesis is quite frequent in children, especially affecting the formation of the premolars, this can cause long-term consequences since the maxillofacial structures are still developing during childhood.
If your child has tooth agenesis, the pediatric dentist will likely recommend the use of space maintainers to ensure that the permanent teeth have enough space to erupt normally.
Treatments for tooth agenesis
In the case of milk teeth, if one or several teeth do not form, the ideal solution is to use space maintainers to preserve the spaces necessary for the eruption of permanent teeth.
In the case of permanent teeth, it is quite common that when a permanent tooth does not form, the patient keeps the baby tooth longer, some even reach adulthood with temporary teeth.
If this is the case, it is ideal to keep the baby teeth in place for as long as possible to prevent the other teeth from moving out of their place.
Once the patient has grown enough, the treatment consists of using prosthetics, such as dental implants, to fill the space and restore functionality and aesthetics.
In patients missing many teeth, you can opt for partial dentures and even All on 4 implants.
Dental agenesis and cancer
Tooth agenesis doesn’t cause cancer, yet, there is some academic research suggesting that the same genetic expression that causes agenesis might be involved in the apparition of cancer later in life.
If this happened to be true, tooth agenesis could help in the early diagnosis and prevention of cancerous processes, elevating the survival rate of oncologic patients.
Tooth agenesis and ectodermal dysplasia
Ectodermal dysplasia is a congenital disease where the structures that come from the ectoderm such as skin, teeth, hair, and nails, don’t get to properly develop or don’t develop at all.
A person with ectodermal dysplasia will likely have tooth agenesis. In some cases, teeth could develop but they will do it in an unusual conical shape.
How often does tooth agenesis occur?
Hypodontia-type tooth agenesis, where between 1 and 6 teeth are missing, is the most frequent developmental alteration worldwide, being harmless in most cases and affecting third molars, teeth that are not necessary.
Dental agenesis of the oligodontia and anodontia types are very rare and are usually related to other developmental disorders such as genetic syndromes, or infectious processes during the gestation stage.
Agenesis affects which tooth/teeth the least?
The least affected are the first and second molars, the first pre-molar, and the central incisors. Tooth agenesis usually affects the last teeth of each group, e.g. the last molar or the lateral incisors.
Can you be born without permanent teeth?
Yes, in this case, the patient usually keeps the baby tooth for a longer time since there is no permanent tooth to replace it, fortunately, it usually affects just 1 tooth, and if necessary, a dental implant can take the place of the absent tooth.
How common is tooth agenesis?
It’s very common, especially in wisdom teeth, it affects more than 6% of the world’s population and in most cases, it goes unnoticed.
References
- Bonczek, O., Krejci, P., Izakovicova-Holla, L., Cernochova, P., Kiss, I., & Vojtesek, B. (2021). Tooth agenesis: What do we know and is there a connection to cancer? Clinical Genetics, 99(4), 493-502. https://doi.org/10.1111/cge.13892
- Schonberger, S., Kadry, R., Shapira, Y., & Finkelstein, T. (2023). Permanent Tooth Agenesis and Associated Dental Anomalies among Orthodontically Treated Children. Children, 10(3), 596. https://doi.org/10.3390/children10030596
- Ritwik, P., & Patterson, K. K. (2018). Diagnosis of Tooth Agenesis in Childhood and Risk for Neoplasms in Adulthood. The Ochsner Journal, 18(4), 345-350. https://doi.org/10.31486/toj.18.0060