Plaque is a soft, colorless or pale yellow film of bacteria constantly forming on tooth surfaces. A black deposit on teeth is typically not standard plaque but signals something more concerning. Black discoloration usually signals a severe external stain, hardened calculus (tartar), or dental decay. Understanding these possibilities is the first step toward finding the correct treatment.
Plaque, Stains, or Calculus?
Plaque is a sticky, non-mineralized biofilm removable with proper brushing and flossing. If left undisturbed, minerals from saliva harden the plaque into dental calculus (tartar), which adheres firmly to the tooth surface. Calculus is rough, porous, and requires professional intervention for removal.
Stains are discolorations adhering to the outside (extrinsic) or incorporated into the tooth structure (intrinsic). Black discoloration is generally a result of staining agents or the mineralization process itself. Black calculus may be caused by dark staining agents or signal bleeding gums, where blood pigments mix with the hardened deposit.
External Sources of Black Surface Stains
A common source of black surface discoloration is chromogenic bacteria, such as certain Actinomyces species. These bacteria produce dark pigments appearing as a thin, continuous black or brown line along the gumline. The pigment forms when bacterial hydrogen sulfide interacts with iron in saliva, creating insoluble ferric sulfide.
Factors like iron supplementation, dietary habits, and saliva pH influence stain formation. While often seen in children, this staining can affect adults and tends to recur even after professional cleaning.
Other extrinsic factors also adhere to the enamel, causing discoloration. Frequent consumption of dark beverages like coffee, tea, and red wine (which contain tannins) can lead to black or dark brown staining. Tobacco use, including smoking and chewing, causes dark surface deposits that adhere to the tooth structure and existing plaque or calculus.
Black Discoloration from Decay and Fillings
Black discoloration can signal a serious, structural issue within the tooth. Deep dental decay (caries) appears black as bacteria break down the tooth structure. As decay progresses into the inner dentin layer, the damaged tissue becomes dark, signaling a need for immediate restorative treatment.
Old dental restorations, specifically silver amalgam fillings, can also cause a black or gray appearance. Amalgam is a metal alloy that can tarnish or corrode over time, causing the filling itself to turn black. Metallic ions from the amalgam can also leach out and stain the surrounding tooth structure, resulting in intrinsic staining.
If a gap forms between an old filling and the tooth, fluids can seep underneath, leading to oxidation or recurrent decay, which also appears dark. A darkened filling warrants a dental examination to rule out underlying decay.
Professional Treatment and Prevention
Removing black deposits requires professional intervention because the color usually stems from hardened calculus or deeply set stains. Dental professionals use scaling and root planing to remove hardened black tartar, especially below the gumline. Surface staining can be eliminated using professional polishing with a gritty paste or an air/water-jet system.
If the black area is identified as dental decay, the dentist will remove the decayed material and place a new filling or a crown. Prevention focuses on improving oral hygiene to minimize plaque and calculus formation, which attract dark pigments.
Fundamental preventative measures include brushing twice daily with fluoride toothpaste and flossing every day. Limiting high-staining agents reduces extrinsic staining. Regular dental check-ups and professional cleanings every six months are important for removing deposits promptly.