What is Odontogenic Tumors of the Jaws?
Odontogenic tumors in the jaw come from leftover cells related to tooth development. These tumors range from harmless growths called hamartomas to actual tumors. According to the World Health Organization’s fourth edition of the classification of odontogenic tumors, they are categorized as either benign (non-cancerous) or malignant (cancerous). They are then further divided based on the original cell type – whether they came from epithelial cells (the cells that cover the surfaces of the body), ectomesenchymal cells (cells involved in developing specific tissues in the body), or a mix of both.
What Causes Odontogenic Tumors of the Jaws?
When a gene changes or ‘mutates’, it can affect the cell cycle, specifically the G1-S checkpoint period. This can lead to the development of dental cysts or tumors. Research suggests that mutations in specific genes (called ameloblastin, KRAS, FHIT, and P53) may contribute to the formation of these dental tumors.
Over time, our understanding of what causes these tumors has evolved. Initially, they were thought to be related to physical injury, lack of proper nutrition, and chronic irritation from tooth decay. However, this idea has changed. Current studies indicate that these tumors express proteins similar to those found in developing teeth, such as cytokeratin and vimentin. Other research has linked dental tumors to the absence of the ‘stratum intermedium layer’, a certain layer of cells.
At the genetic level, it’s been observed that certain genes show different levels of activity in patients with these tumors, especially in cases of a type of tumor called ameloblastoma. Some genes are overactive, while others are underactive. For example, the overactive genes include c-fos proto-oncogene (FOS), tumor necrosis factor receptor 1A (TNFRSF1A), cyclin-dependent kinase inhibitor 1A (CDKN1A), collagen type VIII alpha 1 (COL8A1), matrix metalloproteinase 12 (MMP-12) and WNT5A and WNT-1. The genes showing decreased activity include sonic hedgehog (SHH), cadherin 12 (CDH12), cadherin 13 (CDH13), transforming growth factor beta 1 (TGFB1), patch (PTCH), among others.
The origin of ameloblastomas is currently thought to be associated with problems in the normal functioning of a certain signaling pathway in our cells, known as the mitogen-activated protein kinase (MAPK) pathway. Approximately 63% of ameloblastoma cases have been found to have a mutation in the BRAF gene, which is responsible for activating the MAPK pathway. Moreover, recent studies have found that mutations in other genes, such as the smoothened (SMO) gene, which is involved in the SHH signaling pathway, may also play a role in the development of ameloblastomas.
Risk Factors and Frequency for Odontogenic Tumors of the Jaws
The chance of getting odontogenic tumors (tumors that start in the jaw or teeth) is different depending on where you live. In North America, they account for 1% of all mouth conditions. However, in African countries, these tumors can make up as much as 19% of all mouth conditions.
Signs and Symptoms of Odontogenic Tumors of the Jaws
Odontogenic tumors are growths that can occur in your teeth or jaw. They come in various types and can affect people at different stages of life. Here are some key ones:
- Ameloblastoma is the most common form. It often presents as a painless growth in the molar region of the lower jaw. Different types include multi-cystic or solid (most common), uni-cystic (found in younger patients), and peripheral (found in the gums).
- Adenomatoid odontogenic tumors, although rare, predominantly affect young women and are often located in the upper front jaw.
- A calcifying epithelial odontogenic tumor, also known as a Pindborg tumor, is very rare, mostly affecting people between 30-50 years of age. It tends to occur in the lower jaw and typically presents as a slow-growing, painless growth.
- Squamous odontogenic tumor is another rare condition that can be clinically aggressive. Patients usually experience slow-growing, painless swelling and loosening of teeth.
- The odontogenic ghost cell tumor, another rare condition, tends to affect the areas in front of the molars and usually presents as a painless expansion.
- Ameloblastic fibroma usually presents in adolescents as a painless swelling.
- Odontoma, the most common odontogenic tumor, affects patients during their childhood or adolescence.
- Odontogenic fibroma, a rare condition, tends to affect the lower teeth in the maxilla, and presents as a painless swelling.
- Odontogenic myxoma typically affects children and can present as a painless swelling.
- Cementoblastoma usually presents as a painful jaw swelling.
There are also malignant odontogenic tumors, which can be particularly aggressive. These include:
- Ameloblastic carcinoma, usually appearing as rapid painful growth in the posterior lower jaw.
- Clear cell odontogenic carcinoma, which typically affects elderly women, and presents as a painful jaw swelling.
- Primary intraosseous carcinoma, which predominantly affects men and can be aggressive.
- NOS sclerosing odontogenic carcinoma, which usually affects the molar areas of the lower jaw.
- Ghost cell odontogenic carcinoma is very rare and often found in the upper jaw.
Diagnosing these tumors accurately can be challenging and requires detailed medical investigation.
Testing for Odontogenic Tumors of the Jaws
Odontogenic tumors are abnormal growths that occur in the teeth or tissues related to the teeth. These tumors can originate from different parts of the tooth-forming apparatus. For instance, some grow only from the outer (epithelial) part while others can arise from both the epithelial part and the inner connective tissue (ectomesenchyme). Understanding their appearances can help doctors diagnose them accurately.
Tumors that only grow from the tooth’s outer part like ameloblastoma, can appear differently based on the type. The multi-cystic type resembles a honeycomb or a soap bubble on x-ray images. The uni-cystic type looks like a transparent single cavity and can mimic a cyst. Tumors like adenomatoid odontogenic tumor look like a transparent area around an unerupted tooth, usually a canine. A calcifying epithelial odontogenic tumor, also known as a Pindborg tumor, appears as a cloudy area with small opaque spots.
Tumors that grow from both tooth’s outer part and the inner connective tissue like odontogenic ghost cell tumor generally appear as a clear area with opaque spots. Compound odontoma shows as opaque teeth-like structures in a transparent area. Complex odontoma looks like a solid opaque mass surrounded by a clear area.
Tumors that grow from the inner connective tissue like odontogenic fibroma often appear as a clear area with hard to see borders and small opaque spots. Larger variations may produce multiple clear areas. Odontogenic myxoma appears as one or many clear areas and may cause the teeth to dissolve. Lastly, cementoblastoma usually looks like an opaque lesion surrounded by a thin clear area and can result in the dissolving of the tooth root.
Cancerous odontogenic tumors, also known as malignant odontogenic tumors, may need additional imaging tests like CT or PET scan to define their extent and to check if they have spread. These look like unclear clear areas with severe decay of the hard outside part of the tooth. Some have a mixed appearance of clear and opaque areas resembling fibrous disruptions. These cancer forms often affect the nearby bone and soft tissues and may cause thinning of the surrounding bone and root dissolution.
Treatment Options for Odontogenic Tumors of the Jaws
When it comes to treating tumours that develop only from dental tissue (odontogenic epithelium), there’s no definitive best treatment approach; however, it’s generally agreed that aggressive interventions are crucial to successfully treating them. Treatment methods can range from simple removal and scraping away of the tumor (a process known as enucleation and curettage), to more extensive resections (tissue removal). Most medical professionals lean towards the method of removing the tumor along with a small margin (about 1 cm) of surrounding bone—a strategy typically followed by lower recurrence rates.
Some cases of unicystic ameloblastoma, a specific group of tumors, are incorrectly identified as dentigerous cysts. Therefore, it’s important that any potential cystic formations are fully examined. Depending on the sub-category of the tumor, different treatments will be needed—some requiring simple removal and scraping, and others necessitating more extensive tissue removal.
The treatment of a malignant ameloblastoma, a cancerous growth, follows the standard procedure used for solid-type ameloblastomas, along with additional steps to manage the spread of the tumor to other parts of the body.
As for adenomatoid odontogenic tumors and odontogenic ghost cell tumors, they are generally well-bound and encased by a thin layer of tissue. This makes it easier to remove and scrape the area, which usually results in successful treatment.
Tumours such as ameloblastic fibroma and odontoma can also be treated similarly. In particular cases of recurrence (for ameloblastic fibroma), or any other abnormal regrowth, more invasive methods might be considered.
As for odontogenic myxoma—a type of tumor that doesn’t have a protective casing and holds a higher risk of invasion into surrounding structures—meticulous removal and testing of the tumor and surrounding structures is required.
Lastly, for cementoblastomas majority of cases require teeth extraction and tumor removal, followed by scraping and/or cutting of the bone around the area as a pre-emptive method to reduce the likelihood of recurrence.
For the most severe cases – malignant odontogenic tumors – removal of the tumor remains the best line of treatment, potentially combined with interventions to manage any potential dissemination to other tissues (metastases). Similarly, the routine use of chemotherapy and radiation therapy is still a controversial topic, and is usually kept in reserve for cases involving recurrence or cases where total surgical removal of the tumor is not an option.
What else can Odontogenic Tumors of the Jaws be?
When it comes to identifying the type of jaw lesions, doctors usually narrow it down to cystic, tumorous (neoplastic) or blood vessel-related (vascular) conditions, the latter being the least common. To determine between the different lesions, a thorough health check-up is essential, along with imaging tests (radiography) and tissue studies (histology). Lesions that are clearly-defined and single-chambered (unilocular) are often a sign of cystic conditions.
Here are a few examples of these types of lesions:
- Dentigerous cyst: This usually appears as a clear, single-chambered lesion that painlessly swells around the impacted third molar tooth.
- Traumatic bone cyst: This often shows as a clear, single-chambered lesion that affects the molar and premolar area of the lower jaw in younger adults. It always avoids the alveolar canal, which lies at the bottom of your jaw.
- Aneurysmal bone cyst: This mainly impacts the long bones and spine rather than the jaw in young adults. It can appear as a clear, single-chambered or multi-chambered lesion with significant swelling of the outer layer of the bone and tooth displacement.
There are also some less common conditions such as:
- Intraosseous mucoepidermoid carcinoma: This is the most common type of tumor in the salivary gland that can occur within the jaw. Most often, it affects middle-aged patients’ lower jaws. It can be either a single-chambered or multi-chambered lesion.
- Hyperparathyroidism (brown tumor): Patients with this condition usually complain about bone pain, abdominal cramps, and kidney stones. Kidney dysfunction is the top cause of secondary hyperparathyroidism.
- Arteriovenous vascular malformations: This more often affects individuals between the ages of 10 and 20, with the lower jaw being the most frequent site. Symptoms often include loose teeth, gum bleeding, and an audible whooshing sound from blood flow (bruit). Typically, these types of lesions are clear, with multiple-chambered spaces. Doing an aspiration on all unidentified jaw lesions is crucial to exclude these types of malformations, as they might cause life-threatening bleeding.
What to expect with Odontogenic Tumors of the Jaws
If a benign tumor is properly removed through surgery, the chance of it coming back is pretty low. The only exception is for a type of tumor called ameloblastoma, which has a return rate of about 10-20%, depending on the specific type of ameloblastoma.
The majority of harmful gum-originating tumors are either a bad form of ameloblastoma or a cancer known as odontogenic carcinoma. The chances of surviving these types of tumors are higher if the person is under 57 years old, if they don’t have other health problems, if the tumor is removed through surgery, and if the cancer hasn’t spread to their lymph nodes.
Generally, about 88% of people who have these tumors removed through surgery are still alive after five years. However, only about 26.6% of people who choose not to have surgery live past five years. If the cancer has spread to the lymph nodes, which are small glands throughout your body that help to fight off illness, the chances of survival are quite low.
Possible Complications When Diagnosed with Odontogenic Tumors of the Jaws
Complications of facial tumors can be due to the tumor itself or the surgery to remove it. If a tumor gets larger over time, it can distort the jaw and upper jawbone causing unevenness of the face, pain, movement of teeth, poor bite, or the tumor coming back. Sometimes, harmful cells from the tumor can spread to other parts of the body, with the lungs and lymph nodes in the neck being the most common places they travel to.
On the other hand, complications can also arise from the surgery. This can include heavy bleeding after the operation that may interfere with breathing, infection, and disturbance of feeling caused by unintended damage to the jaw nerve. Other complications can also happen, such as inhaling substances into the lungs, a blood clot in the deep veins, and a blood clot in the lungs. To avoid these post-operation complications, all necessary precautions must be taken.
Common Complications:
- Unevenness of the face
- Pain
- Movement of teeth
- Poor bite
- The tumor coming back
- Spread of harmful cells to other body parts
- Heavy bleeding after the operation
- Infection
- Disturbance of feeling due to nerve damage
- Inhaling substances into the lungs
- Blood clot in the deep veins
- Blood clot in the lungs
Preventing Odontogenic Tumors of the Jaws
We need to make sure patients understand the normal progression of various types of tooth-related tumors, and know what signs to watch out for like quick growth, changes in feeling, pain, and lumps in the neck. It’s also important for patients to know how to check their own bodies and keep regular appointments with their doctor. This helps to spot any possible return of the tumor or development into a more serious disease.
