Updated 5th of February 2023

Oligodontia is a congenital dental condition called agenesis and is characterized by a situation where more than six permanent teeth have not developed. Dental agenesis is the most common dental developmental anomaly in humans and appears in 2.2-10% of the general population. Oligodontia can negatively impact the mouth, making eating and speaking a challenge, and affecting the appearance of the smile.

The absence of third molars (wisdom teeth) is very common, and is considered to be a normal variation, therefore it does not classify as being dental agenesis. Studies of congenital missing teeth show that the mandibular second premolar is the most affected tooth, followed by the maxillary lateral incisor, maxillary second premolar, mandibular central incisors, mandibular second molar and mandibular lateral incisor.

Tooth agenesis is classified by the number of missing teeth:

  • Hypodontia refers to less thank 6 missing teeth, excluding wisdom teeth.
  • Oligodontia is when 6 or more teeth are absent.
  • Anodontia refers to a rare condition where all the teeth are missing.

Dental genesis

Clinical features

To detect congenitally missing teeth, a panoramic x-ray taken at the right age can show whether there is tooth agenesis of baby or adult teeth. A child should have all his baby teeth erupted by the age of three. A teenager should have all her adult teeth out by the age of 14, except for wisdom teeth.

There are oral conditions that may be associated with congenitally missing teeth:

  • Microdontia where teeth appear smaller than normal.
  • Misplaced positioning of adult teeth, which is a consequence of the absence of neighbouring teeth acting as a guide during eruption.
  • Retrognathic maxilla (backwards) and prognathic mandible (advanced)
  • Significant mandibular angle (back of the lower jaw) and a flatter chin, which might happen when more than one tooth is missing.

Causes of oligodontia

Although oligodontia is mainly caused by genetics, environmental factors can lead to having missing teeth during dental development.

The most accepted theory of oligodontia is an abnormality regarding the dental lamina, which is a band of tissue under the gums where teeth form. Family history is the most common cause, where the mutation of specific genes prevents the dental lamina of performing its function. Other factors may also affect the dental lamina.

Tooth agenesis can occur alongside other conditions, such as:

  • Cleft lip / cleft palate.
  • Genetic disorders, such as Down Syndrome (a condition in which a person has an extra chromosome) or ectodermal dysplasia (a group of conditions in which there is abnormal development of the skin, hair, nails, teeth, or sweat glands).
  • Infectious diseases, such as candida or rubella.
  • Low birth weight, especially in twins.
  • Maternal smoking during pregnancy.
  • Environmental causes such as radiation, allergies, chemotherapy, toxic epidermal necrolysis, or exposure to polychlorinated biphenyls (PCBs).

Treatments of Oligodontia

Children with oligodontia may wear partial dentures until they are old enough for other treatments:

  • Orthodontics can move teeth to either close a space of a missing tooth or create a space big enough to have the missing tooth replaced by either a bridge or a dental implant.
  • Maryland bridges are a good treatment option to replace lateral incisors. This is often combined with orthodontic treatment.
  • Partial dentures may be used to replace several missing teeth.
  • Dental implants are a good option to replace missing teeth, for people who want a fixed and stable treatment.

When should you suspect oligodontia for you or your child?

If your child’s primary teeth don’t come out by the age of 4, or permanent teeth by age 14, then a dentist should evaluate the issue during a routine office visit.

If you or your child has oligodontia, here are some questions to consider asking your dentist:

  • How many teeth are missing?
  • Is this condition interfering with nutrition or digestion?
  • What are the treatment options?
  • How long will treatment take?


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  4. Bozga A, Stanclu RP, Mănuc D. (A study of prevalence and distribution of tooth agenesis). J Med Life. 2014 Oct-Dec; 7(4): 551–554.
  5. Cleveland Clinic, (Hypodontia (Missing Teeth)).
  6. ScienceDirect, (Oligodontia).
  7. Oral Health Group, (Non-Syndromic Oligodontia: A Case Report).
The information above should be used as a reference only. Any medical decision should not be taken before consulting a health care professional.