A broken tooth that suddenly appears black can be alarming, signaling a significant biological event beneath the tooth’s hard outer surface. Unlike a simple chip, this dark discoloration requires immediate professional dental assessment. The black or dark gray hue is not merely cosmetic; it indicates internal trauma or overwhelming infection. This article explains the causes and serious health implications of this discoloration.
Internal Damage and Pulp Necrosis
The most concerning reason a broken tooth turns black is the death of the innermost tissue, known as pulp necrosis. The pulp chamber contains nerves, connective tissue, and blood vessels (the tooth’s source of vitality). When a tooth suffers trauma, the blood vessels supplying the pulp can be severed.
Once the blood supply is cut off, the tissue inside the tooth dies. This discoloration is caused by the breakdown of blood components trapped within the dentin. The iron-containing protein hemoglobin breaks down, forming dark pigments like hemosiderin that seep into the dentin tubules. This internal staining gives the tooth a characteristic dark gray or black appearance.
A lack of immediate pain often accompanies this process, which can delay treatment. The tooth loses its ability to sense hot or cold because the nerve has died. Because this color change is intrinsic, simple brushing or external whitening treatments will not affect the dark shade.
Surface Staining and Deep Decay
While internal pulp death is a frequent cause, the black color can also originate from the outside or from long-standing decay exposed by the break. If the broken section was previously compromised by untreated dental caries, the black color is the result of deep decay accelerated by exposure to the oral environment. Bacteria consume sugars and produce acid, which eats away at the tooth structure, leaving behind dark, softened tissue.
The break itself can create new surface irregularities susceptible to external staining agents. Consuming dark liquids like coffee, tea, or red wine, or using tobacco products, can cause brownish-black discoloration on the fractured surface. This type of staining usually appears as a localized patch rather than the uniform gray-black seen with pulp necrosis.
Another source of deep discoloration is old dental restorations. If the broken tooth contained a silver amalgam filling, the metal components can oxidize. These oxidized metal ions can leach into the surrounding dentin, causing a dark, bruised appearance revealed when the tooth breaks.
Serious Health Consequences of the Color Change
Ignoring a broken tooth that has turned black is inadvisable, as the discoloration signals an ongoing health threat. Whether the cause is deep decay or pulp necrosis, the dead or infected tissue provides a breeding ground for harmful oral bacteria. This bacterial buildup eventually leads to the formation of a periapical abscess, a pocket of pus that forms at the tip of the tooth’s root.
If the infection remains untreated, the abscess pushes bacteria into the jawbone and surrounding soft tissues. This causes localized swelling, severe pain, and bone loss that compromises the tooth’s stability. In serious instances, the infection can spread beyond the jaw.
The bacteria can enter the bloodstream and cause systemic issues such as sepsis, a life-threatening condition. Infections from upper teeth carry a risk of spreading to the sinuses or, in rare cases, to the brain, potentially leading to a brain abscess or meningitis. A severe infection in the floor of the mouth can also lead to Ludwig’s Angina, causing swelling that may obstruct the airway.
Professional Treatment Options for Repair
Addressing a broken, black tooth begins with a thorough clinical and radiographic examination to diagnose the discoloration source. If the diagnosis confirms pulp necrosis or a deep internal infection, the standard treatment is a root canal procedure. This involves the dentist creating an opening, removing all infected pulp tissue, and then cleaning, shaping, and sealing the interior space.
If the tooth is structurally compromised or the infection is widespread, extraction may be the only viable solution to prevent infection spread. If the tooth is saved via a root canal, the next phase focuses on structural integrity and cosmetic repair. The now non-vital tooth is inherently more brittle and often requires a full-coverage crown to protect it from future fracture.
To address the discoloration, internal bleaching can be performed after the root canal is complete. Bleaching material is placed inside the tooth for several days to lighten the dentin from within, significantly improving the dark color. Finally, a crown or a porcelain veneer is typically placed over the tooth to restore its shape, function, and appearance.