Odontoma: Understanding Your Pathology Report

by Jason Wasserman MD PhD FRCPC
May 4, 2026

An odontoma is a noncancerous growth that develops within the bones of the jaw and is made up of the same tissues that form a normal tooth — enamel, dentin, cementum, and sometimes pulp. It is the most common type of odontogenic tumor (a tumor arising from tooth-related tissues), making up roughly one in five of all odontogenic tumors. Odontomas are most often discovered in children and teenagers, particularly when a permanent tooth fails to erupt through the gum on schedule, and a dental X-ray is taken to determine why.

Odontomas are classified as hamartomas rather than true tumors. A hamartoma is a growth made up of normal tissues that have grown in a disorganized way in a place where they belong, rather than tissue that has begun to behave abnormally. This distinction matters because hamartomas grow only to their natural size, do not spread, and are reliably cured by simple removal.

This article will help you understand the findings in your pathology report — what each term means and why it matters for your care.

What causes an odontoma?

The cause of most odontomas is not known. They are not linked to anything the patient or parents did or did not do, and they are not contagious. Several theories have been proposed to explain why they form, including local injury to the tooth bud (the early structure that develops into a tooth) during childhood, infection, and possibly genetic factors that affect tooth development. In most patients, an odontoma develops as an isolated finding with no associated medical condition.

A small number of patients with multiple odontomas — especially complex odontomas appearing alongside other unusual features — may have an inherited condition called Gardner syndrome, which is described later in this article.

Types of odontoma

The current World Health Organization classification recognizes two main types of odontoma. They look different under the microscope and on dental X-rays, but behave the same way and are treated the same way.

Compound odontoma — Made up of multiple small, tooth-like structures (sometimes called “denticles”) clustered together within a thin fibrous sac. Each denticle has the same architecture as a normal tooth — an enamel-covered crown, a dentin core, and a thin layer of cementum on the outside — but is much smaller and not anchored in the jaw the way a real tooth would be. The number of denticles can range from a few to dozens. Compound odontomas are most often found in the front of the upper jaw.
Complex odontoma — Made up of the same dental tissues as a compound odontoma — enamel, dentin, cementum, and occasionally pulp — but arranged as a disorganized mass without recognizable tooth shapes. On X-ray, it looks like an irregular white (calcified) lump rather than a cluster of small teeth. Complex odontomas are most often found in the back of the lower jaw, in the area of the molars.

Some odontomas show features of both types and are called combined or mixed odontomas. The treatment is the same regardless of which type is found.

What are the symptoms of an odontoma?

Most odontomas cause no symptoms and are discovered by chance on a dental X-ray taken for another reason — most often to investigate a tooth that has not come through the gum on schedule. When symptoms do occur, they tend to be mild and slow to develop:

Failure of a tooth to erupt — The most common reason an odontoma is discovered. The odontoma sits in the path of the developing permanent tooth and physically blocks it from emerging into the mouth.
Retained baby tooth — A baby (deciduous) tooth that has not fallen out at the expected age, because the permanent tooth that should be pushing it out is blocked underneath.
Swelling — A firm, painless bulge along the jaw, more common with larger complex odontomas.
Tooth displacement — Larger odontomas can push neighboring teeth out of position.
Pain or infection — Uncommon, and usually only when the odontoma is exposed to the mouth or becomes secondarily infected.

How is the diagnosis made?

The diagnosis is made after a tissue sample is examined under the microscope by a pathologist. An odontoma is usually first suspected on a dental X-ray, panoramic X-ray, or cone-beam CT, which shows a well-defined white (radiopaque) area within the jawbone, surrounded by a thin dark (radiolucent) halo. The radiopaque appearance is what distinguishes an odontoma from most other jaw lesions, including odontogenic cysts, which appear dark on X-ray. A compound odontoma often shows multiple small tooth-shaped structures on imaging, whereas a complex odontoma appears as an irregular calcified mass. Imaging alone is often suggestive but cannot make the diagnosis with certainty, since other calcified lesions of the jaw can look similar. The odontoma is removed by an oral and maxillofacial surgeon, usually together with any associated unerupted tooth that cannot be saved, and sent to the laboratory.

Under the microscope, the pathologist looks for the dental tissues that make up an odontoma — enamel matrix (or empty spaces left where enamel was, since enamel often dissolves during tissue processing), dentin, cementum, and sometimes pulp tissue. In a compound odontoma, these tissues are organized into recognizable miniature tooth structures with a normal arrangement: enamel on the outside of a crown, dentin underneath, and cementum on the root surface. In a complex odontoma, the same tissues are present but arranged in a haphazard pattern with no recognizable tooth shape. Surrounding the lesion is a thin fibrous capsule, which represents what would normally have been the dental follicle of a developing tooth. Once the diagnosis is confirmed, no further imaging or testing is usually needed.

Gardner syndrome and multiple odontomas

Most patients with an odontoma have a single isolated lesion and no associated medical condition. However, the discovery of multiple odontomas — particularly when accompanied by other unusual findings such as extra (supernumerary) teeth, bony growths called osteomas, skin cysts, or a family history of colon polyps — should prompt evaluation for Gardner syndrome. Gardner syndrome is a variant of familial adenomatous polyposis (FAP), an inherited condition caused by a mutation in the APC gene. People with FAP develop hundreds to thousands of polyps in the colon and rectum starting in adolescence, and have an extremely high lifetime risk of colon cancer if the colon is not removed. The dental and bony findings of Gardner syndrome can appear before the colon polyps and are sometimes the first clue to the diagnosis. For this reason, when multiple odontomas are identified, referral to a medical geneticist or genetic counselor is recommended. Confirming the diagnosis allows the patient to begin colon cancer screening at the appropriate age and allows family members to be tested.

A single isolated odontoma in a patient with no other features and no family history is not a sign of Gardner syndrome and does not by itself require genetic evaluation.

What is the prognosis?

The outlook for an odontoma is excellent. It is benign, does not turn into cancer, and grows only until it reaches its mature size — usually during the years that the surrounding teeth are still developing. Once the odontoma is removed, recurrence is essentially never seen. The only situation that requires longer-term attention is a patient with multiple odontomas who is later diagnosed with Gardner syndrome, in which case follow-up is directed at the colon and the other features of the condition rather than at the original odontoma.

What happens after the diagnosis?

Treatment is led by an oral and maxillofacial surgeon, often working with a general dentist or pediatric dentist, and (when an unerupted permanent tooth is involved) with an orthodontist.

Enucleation — The standard treatment. The odontoma is shelled out of the bone in one piece, often very easily because of its well-defined fibrous capsule. The empty socket fills in with new bone over several months.
Management of the unerupted tooth — Once the odontoma is removed, an obstructed permanent tooth often erupts on its own over the following months, particularly in younger patients. If the tooth does not erupt on its own, an orthodontist can place a small attachment on it and slowly pull it into position with braces or other orthodontic appliances. In rare cases, the involved tooth is too damaged or too far out of position to save, and is removed at the same operation.
Genetic evaluation — When multiple odontomas or other features of Gardner syndrome are present, referral to a medical geneticist is part of the treatment plan.

Follow-up X-rays are typically taken at 6 and 12 months to confirm that the bone is healing and that any preserved tooth is moving into the right position. Long-term follow-up beyond that is usually not needed for an isolated odontoma.

Questions to ask your doctor

Which type of odontoma do I (or my child) have — compound, complex, or combined?
Where exactly was the odontoma located, and how large was it?
Was the entire odontoma removed?
Was an unerupted tooth involved, and was it preserved or removed?
If the tooth was preserved, will it erupt on its own, or will orthodontic treatment be needed to bring it into position?
If the tooth could not be saved, what are my options for replacing it?
Were any other unusual findings noted on the imaging or pathology report, such as multiple odontomas or extra teeth?
Should I be evaluated for Gardner syndrome or familial adenomatous polyposis, and what does that involve?
What is the schedule for follow-up X-rays?
Are there any other teeth that should be monitored?