Yes, blood can cause discoloration of the teeth, but the degree and permanence of the stain depend entirely on where the blood originates and how deeply the pigments penetrate the tooth structure. A temporary surface stain from bleeding gums requires a different response than a deep, lasting discoloration from an internal injury.
The Biological Mechanism of Discoloration
The color change that occurs when blood contacts the tooth surface is a direct result of hemoglobin, the protein within red blood cells that transports oxygen. Hemoglobin contains an iron-bearing molecule called heme, which is intensely colored. When red blood cells break down, a process known as hemolysis, the heme is released into the surrounding environment.
In the context of tooth trauma, when blood enters the microscopic tubules of the dentin—the layer beneath the enamel—the released hemoglobin begins to chemically change. This breakdown forms hematic molecules, which are dark and become trapped deep within the hard tissue of the tooth. These dark pigments are what give the tooth a noticeable grey, brown, or black hue from the inside. This chemical reaction results in a persistent stain that cannot be removed by simple brushing or external whitening products.
External Versus Internal Staining
Blood-related discoloration falls into two main categories: external, or extrinsic, stains that affect the enamel surface, and internal, or intrinsic, stains that penetrate the dentin.
External stains are typically temporary and result from blood adhering to the surface of the tooth. The most common cause is bleeding gums, which can occur due to gingivitis, early periodontal disease, or overly aggressive brushing and flossing. A recent minor injury or a dental procedure like an extraction can also leave residual blood pigments on the enamel.
These stains reside on the outer layer of the tooth and are generally easy to remove. Maintaining excellent oral hygiene and having a professional dental cleaning is usually sufficient to erase this type of surface discoloration.
Internal stains are far more serious and permanent, resulting from a hemorrhage within the pulp chamber, which is the soft center of the tooth containing nerves and blood vessels. This often follows significant dental trauma, such as a blow to the mouth, or can be a consequence of pulp tissue death (necrosis) due to deep decay. When the pulp is damaged, blood spills into the chamber and the hemoglobin pigments leach into the surrounding dentinal tubules.
The iron-containing compounds become lodged deep within the microstructure of the tooth, causing the entire tooth to darken uniformly. This intrinsic discoloration typically manifests as a dark grey, black, or deep brownish-red color. This internal staining indicates a severe underlying problem that requires immediate attention from a dentist, as the tooth’s internal health is compromised.
Prevention and Treatment Options
For external stains, maintaining superior gum health is the primary defense. Consistent, gentle brushing twice daily and flossing once a day prevents the plaque buildup that leads to gingivitis, the most frequent cause of gum bleeding.
Regular professional dental cleanings allow a hygienist to remove hardened plaque and surface stains before they become more noticeable. To prevent the internal staining that results from injury, wearing a properly fitted mouthguard during contact sports or high-risk activities is an effective preventative measure. Seeking prompt dental care immediately after a traumatic injury can also minimize the risk of internal bleeding and subsequent discoloration.
Treatment for existing stains varies based on their location. External stains are routinely managed with a professional dental cleaning, which uses specialized instruments to scale away and polish the pigmented deposits from the enamel. Consistent home care then prevents their recurrence.
Intrinsic stains, however, require more involved procedures because the pigment is trapped deep inside the tooth. If the internal discoloration is a result of pulpal necrosis, the first step is often an endodontic procedure, or root canal therapy, to remove the dead or damaged tissue. Following this, the tooth may be treated with internal bleaching, where a powerful whitening agent is placed inside the tooth chamber for a period of time. If bleaching is unsuccessful due to the severity of the stain, the tooth can be cosmetically restored with a porcelain veneer or a full crown to cover the discoloration.