Black spots on teeth are a common concern, but the cause of this discoloration varies widely, ranging from simple surface stains to serious underlying dental problems. These dark marks can appear on the enamel, the deeper dentin layer, or on existing dental materials like fillings. Only a thorough professional examination, often including X-rays, can accurately determine the origin of the spot and the necessary course of action. This article categorizes the different sources of black spots, clarifying whether the discoloration is cosmetic or a sign of active disease.
Black Spots Caused by Tooth Decay
The most significant cause of a black spot is dental caries, commonly known as a cavity or tooth decay. This decay results from a breakdown of the tooth structure when bacteria metabolize sugars and starches, producing acids. These acids dissolve the mineral content of the tooth enamel in a process called demineralization. If this process is not reversed, the damage progresses into the softer, underlying dentin, forming a cavity.
The discoloration turns black or dark brown as the decay penetrates deeper layers and traps pigments. A hard, dark spot, often found in the pits and fissures of chewing surfaces, may be arrested decay, meaning the decay process has slowed or stopped. Arrested decay is less urgent than active decay, which tends to be softer and may appear a lighter brown or orange. However, any dark spot caused by decay indicates a structural breakdown and warrants dental monitoring, especially if associated with sensitivity or pain.
Extrinsic Stains from Diet and Environment
Dark spots that are purely superficial are categorized as extrinsic stains, meaning they adhere only to the exterior surface of the enamel. These stains do not indicate structural damage but are caused by the deposition of chromogens, which are colored compounds found in certain consumables. Common culprits include deeply pigmented foods and beverages such as coffee, tea, red wine, and dark sodas.
Tobacco use, whether smoking or chewing, is another major source of extrinsic staining that can cause dark, widespread discoloration. Certain oral hygiene products, specifically mouthrinses containing chlorhexidine, can also bind to the tooth surface and cause a dark stain. Poor oral hygiene exacerbates this issue by allowing plaque to remain on the tooth, which readily absorbs these external pigments.
Other Sources of Dark Discoloration
Beyond decay and surface stains, other factors can lead to dark spots or discoloration on the teeth. Calculus, or hardened dental plaque, often appears as a dark buildup near the gumline after absorbing environmental pigments. This hard deposit cannot be removed by brushing alone and requires professional scaling.
Old amalgam (silver) fillings can also cause teeth to darken. These fillings, composed of a metal alloy, can oxidize over time, causing the filling itself to turn black. Furthermore, metallic ions can leach into the surrounding tooth structure, giving the entire tooth a grayish or dark shadow. A single tooth turning dark without visible surface decay might also signal internal damage, such as trauma that has caused the death of the tooth’s nerve tissue. This internal necrosis results in the discoloration of the dentin from the inside out, often requiring endodontic treatment.
Professional Diagnosis and Treatment Paths
A dental professional begins the diagnosis of a black spot with a thorough visual inspection and the use of a dental explorer, a thin instrument used to check the texture and depth of the spot. X-rays are used to assess the internal structure of the tooth, revealing decay hidden beneath the enamel surface or between teeth. The treatment recommendation is based directly on the confirmed cause of the discoloration.
If the dark spots are diagnosed as extrinsic stains or calculus, the solution is a professional cleaning and polishing to remove the pigments and hardened deposits. For early-stage or arrested decay, a dentist may recommend non-surgical management, such as applying fluoride varnish or placing a dental sealant to prevent further progression. Active decay requires restorative treatment, such as removing the decayed material and placing a dental filling or, in cases of extensive damage, a crown. Maintaining a healthy, spot-free smile involves consistent brushing twice a day, daily flossing, and regular professional check-ups to catch issues early.