by Jason Wasserman MD PhD FRCPC
April 10, 2026
A fibroma of the oral cavity is a common benign (non-cancerous) growth that forms inside the mouth. It is made up of fibrous connective tissue — the same type of dense, supportive tissue found throughout the body — and is not a tumour in the usual sense. A fibroma is the mouth’s response to repeated irritation or injury: when the lining of the mouth is repeatedly traumatised, it can produce a firm, overgrown bump of scar-like tissue at the site.
A fibroma is not cancer, it is not precancerous, and it will not turn into cancer. Biopsies of oral lumps are often performed to confirm that a finding is benign rather than more serious, and a fibroma result is reassuring.
What causes a fibroma?
Most oral fibromas develop in response to chronic irritation or repeated trauma to the lining of the mouth. When the mucosa is repeatedly injured, the body responds by laying down extra fibrous tissue as a form of protective repair, and over time, this can build up into a firm, painless lump. Common sources of irritation include:
- Cheek or lip biting. Repeatedly biting the same area of the inner cheek or lip is one of the most common triggers. Many people do this unconsciously, especially under stress.
- Ill-fitting dentures or dental appliances. Dentures, partial plates, or retainers that rub against the gum or cheek lining can create persistent friction that stimulates fibrous tissue growth.
- Sharp or broken teeth. A jagged tooth edge that constantly irritates the tongue or cheek can produce a fibroma at the contact site.
- Orthodontic appliances. Braces or other orthodontic hardware that repeatedly contacts the inner cheeks or lips can cause localised fibrous overgrowth.
- Dental procedures or trauma. A physical injury to the mouth — such as a dental extraction site that heals with excess fibrous tissue — can also produce a fibroma.
In some cases, no clear source of irritation is identified.
What are the symptoms?
Most fibromas cause no pain and are discovered by the patient or a dentist during a routine check. Common features include:
- A small, firm, smooth lump inside the mouth — typically on the inner cheek, tongue, gum, or lip.
- The surface usually matches the colour of the surrounding tissue, though it may appear slightly paler.
- The lump is usually painless, but can become sore or tender if it is repeatedly bitten or rubbed by a dental appliance.
- A larger fibroma may occasionally cause minor difficulty chewing or speaking if it is in a position that interferes with these actions.
Fibromas are typically slow growing and may stay the same size for years, particularly if the source of irritation is removed.
How is the diagnosis made?
The diagnosis is made by a pathologist who examines the removed tissue under a microscope. A fibroma is usually removed entirely in a minor surgical procedure called an excision — the growth is cut away under local anaesthetic and sent to the pathology laboratory. In some cases, only part of the lump is removed as a biopsy to confirm the diagnosis before deciding on further management.
The removal serves two purposes: it provides tissue for the pathologist to examine and confirm the diagnosis, and it usually cures the fibroma at the same time.
What does the pathology report describe?
Under the microscope, a fibroma of the oral cavity has a characteristic and recognisable appearance. The pathologist typically reports the following features:
- Normal squamous surface lining. The surface of the fibroma is covered by squamous cells — the same flat cells that normally line the inside of the mouth. Seeing normal surface cells is reassuring because it confirms there is no dysplasia or cancer at the surface of the growth.
- Dense fibrous tissue beneath the surface. The body of the fibroma is made up of collagen — a structural protein that forms the scaffolding of connective tissue — arranged in dense bundles. Long, thin cells called fibroblasts are scattered throughout. These are the cells that produce collagen; their presence here reflects the body’s repair response to chronic irritation.
- Little or no active inflammation. Unlike a fresh wound or acute injury, a fibroma typically shows minimal inflammatory cells. This is because it represents a mature, stabilised tissue response rather than an ongoing injury.
Margin
If the fibroma was completely removed by excision, the pathologist will examine the margin — the edge of the removed tissue — to determine whether the entire fibroma was taken out.
- Negative margin (clear margin). No fibroma tissue is found at the cut edge, meaning the growth appears to have been completely removed.
- Positive margin. Fibroma tissue extends to the cut edge, suggesting a small amount may remain. Because fibromas are benign, this is not dangerous, but it may mean the fibroma could gradually grow back, particularly if the source of irritation is still present.
What happens next?
If the fibroma was completely removed by excision, no further treatment is needed in most cases. The biopsy result confirms the diagnosis, and the growth itself has been removed.
The most important step after removal is to identify and address any ongoing source of irritation in the mouth. If a fibroma developed because of a habit such as cheek biting, a poorly fitting denture, or a sharp tooth, that source of friction should be corrected. Without addressing the cause, a new fibroma could form at the same site over time.
A follow-up appointment with your dentist or oral surgeon is usually recommended to confirm that the site has healed normally and that no new changes have appeared. Any new or persistent lump in the mouth — even if a fibroma was previously diagnosed — should be evaluated, since other types of oral growths can occasionally look similar to a fibroma.
Questions to ask your doctor
- Was the fibroma completely removed, or is there any concern about the margin?
- Is there a source of irritation in my mouth that may have caused this, and how do I address it?
- Do I need a follow-up appointment to check that the removal site has healed?
- Is there any risk that a new fibroma could form at the same site?
- Should I return if I notice any new or changing lumps in my mouth?
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