A black dot on the gums represents a localized pigmented lesion on the gingiva that can have a wide range of causes. These spots may be a result of external factors, such as materials introduced during dental work, or they can be related to the body’s natural production of color pigments. While many dark spots are harmless, a definitive diagnosis requires a dental professional. Any newly appearing or changing spot warrants a professional examination to determine its exact nature, as a small number of lesions may indicate a serious health concern.
Common Causes Related to Dental Work and Injury
One frequent non-melanin-related cause for a dark spot is an Amalgam Tattoo. This results from the accidental embedding of silver-mercury particles into the gum tissue during dental procedures. It often occurs during the placement or removal of an amalgam (silver) filling, or after a tooth extraction when fragments fall into the socket. The metallic components are inert once lodged, creating a flat, non-painful, bluish-gray or black stain on the mucosa.
Amalgam tattoos are benign and do not typically change in size, shape, or color once fully formed, though they are permanent unless surgically removed. A dentist can often diagnose this condition based on its appearance and proximity to a tooth with an amalgam restoration. In some cases, a dental X-ray can confirm the diagnosis by revealing the presence of tiny radiopaque metal fragments within the soft tissue.
Another common cause of localized black or dark red discoloration is a hematoma, or blood blister, resulting from localized trauma. This can happen from aggressive brushing, biting the gum tissue, or injury from sharp food. The discoloration is simply blood pooling beneath the surface layer of the gum tissue. Such traumatic lesions usually resolve on their own within a few weeks as the body reabsorbs the blood.
Benign Pigmentation Spots
The majority of oral dark spots result from the natural accumulation of melanin, the pigment responsible for skin, hair, and eye color. Physiological Pigmentation is a common, genetically determined variation where melanocytes produce more pigment. This results in diffuse, symmetrical, light brown to black patches across the gum tissue. This condition is often seen in individuals with darker skin tones, including those of African, Asian, or Mediterranean ancestry, and requires no medical intervention.
A solitary, flat, and well-defined dark spot is often an Oral Melanotic Macule, which is essentially the mucosal equivalent of a freckle. This lesion is caused by an increase in melanin production by the melanocytes in the basal layer of the epithelium, without an increase in the number of pigment-producing cells. Melanotic macules are typically small and harmless, though they must be differentiated from more concerning lesions.
Other benign spots include Melanocytic Nevi, which are true moles composed of a benign proliferation of nevus cells. Oral nevi are rare compared to skin moles, presenting as a small, solitary, brown or blue nodule or macule that tends to remain stable over time. Because it can be clinically difficult to distinguish a nevus from an early malignant lesion, a biopsy is often performed for any newly discovered, solitary pigmented lesion.
Systemic Conditions and Serious Concerns
Pigmentation can also be a symptom of underlying systemic conditions or the result of medication use, which should be investigated by a healthcare provider. Some prescription drugs, notably the antibiotic minocycline, cause a blue-gray or black discoloration of the gums and other oral tissues. This drug-induced hyperpigmentation is usually reversible after the medication is discontinued.
Hormonal or endocrine disorders can also lead to diffuse gum darkening. Addison’s Disease, a rare disorder involving insufficient hormone production by the adrenal glands, causes elevated levels of adrenocorticotropic hormone (ACTH). This hormone stimulates melanin production, resulting in dark patches on the gums, lips, and other mucous membranes.
The most serious, though rare, concern is Oral Malignant Melanoma, a cancer that develops from melanin-producing cells. Oral melanoma is aggressive and can initially present as an irregular brown or black macule, similar to a benign spot. Since the hard palate and gingiva are the most common intraoral locations, any persistent or changing pigmented spot must be examined to rule out this diagnosis.
Indicators That Require Immediate Dental Consultation
The distinction between a harmless spot and a serious lesion relies on specific visual indicators, following the established warning signs for melanoma. Immediate consultation is necessary for any pigmented spot that displays these characteristics:
- Asymmetry: One half of the spot does not match the other half.
- Border: Irregularity, such as ragged, notched, or blurred edges.
- Color: Variation, particularly multiple shades of brown, black, blue, or red within the same area.
- Diameter: Larger than six millimeters, though smaller lesions can also be malignant.
- Evolution: Any noticeable change in size, shape, color, height, or new symptoms like bleeding or itching.
If a dentist suspects a serious lesion after clinical assessment, a biopsy will be performed to obtain a definitive diagnosis.