A grey spot or discoloration on a tooth signals an intrinsic change within the tooth structure, indicating an underlying issue rather than a simple surface stain. This hue change occurs when pigments are absorbed into the dentin, the layer beneath the enamel, making the discoloration permanent. Unlike external stains, an intrinsic grey spot points to a specific internal problem that requires professional diagnosis to determine the appropriate course of action.
Common Causes of Grey Discoloration
The most frequent cause of a single grey tooth is pulp necrosis, often called a “dead tooth,” typically resulting from dental trauma. An injury can sever the blood vessels supplying the pulp, causing internal bleeding. The breakdown products of this blood, primarily iron sulfides, seep into the microscopic dentin tubules. This process causes the tooth to gradually take on a dark grey or blue-grey appearance.
Advanced dental caries, or deep decay, is another common cause. The bacterial infection progresses through the enamel and dentin to reach the pulp chamber. If the decay is severe enough to cause pulp death, the non-vital tissue remains inside the tooth and releases pigments, leading to grey discoloration. This grey spot often appears as a shadow visible through the outer tooth structure, indicating significant internal damage.
Older silver amalgam fillings can cause a tooth to appear grey due to metal ion leaching, sometimes referred to as an “amalgam tattoo.” Over many years, metallic ions, such as silver and tin, slowly dissolve and migrate into the surrounding dentin. This permanently stains the tooth structure grey or blue-black. While this staining is purely cosmetic, it can make the entire tooth appear darkened.
Less commonly, widespread grey or blue-grey discoloration is attributed to exposure to tetracycline antibiotics during tooth formation in early childhood or in utero. The drug binds to calcium ions within the developing dentin. Upon later exposure to light, the drug oxidizes to create a deep, intrinsic stain. These developmental stains are typically diffuse across multiple teeth, rather than appearing as a single localized spot.
When to Seek Professional Evaluation
Noticing a grey spot requires a prompt dental evaluation, as the underlying cause may be an active infection or a dead tooth needing intervention. The dentist begins the diagnostic process with a thorough visual examination and tactile probing to check for signs of decay or structural damage. This clinical assessment is followed by essential diagnostic imaging to confirm the tooth’s internal condition.
Dental X-rays are used to look for specific signs of internal pathology, such as deep decay beneath the enamel or changes in the periapical bone surrounding the root tip. These changes often indicate a chronic infection. The X-ray also allows the clinician to examine the internal pulp chamber and root canal space for signs of calcification or previous dental material placement.
To confirm if the tooth is non-vital, a dentist performs pulp vitality testing, often using a thermal stimulus. A chilled cotton pellet is applied to the tooth surface, and the patient’s response is measured against a healthy control tooth. A lack of response, or a delayed and dull sensation, suggests that the nerve and blood supply are compromised and the pulp tissue has died.
Treatment Options Based on the Cause
Treatment for grey discoloration depends entirely on the accurate diagnosis, ranging from restorative procedures to cosmetic correction. If the grey spot is a shadow from a deep cavity, treatment involves removing the infected dentin before placing a tooth-colored composite resin filling. For extensive decay compromising structural integrity, a full-coverage dental crown may be necessary to protect the remaining tooth structure from fracture.
When discoloration results from pulp necrosis following trauma, the first step is root canal therapy to eliminate the dead and infected tissue causing the color change. After the root canal is completed and the tooth is sealed, the internal discoloration can be addressed with internal bleaching. This technique involves placing a specialized bleaching agent inside the cleaned pulp chamber for several days to lighten the dentin from the inside out.
For intrinsic staining that cannot be resolved with internal bleaching, such as severe tetracycline stains or persistent discoloration from old amalgam, cosmetic solutions are available. Composite bonding involves applying a tooth-colored resin material directly to the tooth surface to mask the grey stain in a single appointment. A more durable option is the placement of porcelain veneers, which are thin, custom-made shells bonded to the front surface of the tooth to permanently cover the discoloration.
Preventing Future Tooth Discoloration
Preventing the conditions that lead to grey spots involves consistent oral hygiene, protective measures against trauma, and mindful dietary choices. Maintaining a diligent home care routine includes brushing twice daily with fluoride toothpaste and flossing once a day to remove plaque and debris. Regular professional check-ups and cleanings allow the dentist to detect and treat small cavities before they progress into the deeper dentin layer.
To prevent trauma-induced discoloration, using a properly fitted mouthguard is recommended for participation in contact sports or activities with impact risk. Mouthguards absorb and distribute the force of a blow, reducing the likelihood of nerve damage that causes the grey appearance. They protect soft tissues and prevent the shearing of the tooth’s blood supply.
Dietary habits also play a role in preventing grey discoloration. Reducing the frequency of consuming sugary and acidic foods and drinks limits enamel exposure to acid attacks, minimizing the risk of deep decay. Opting for water over sodas and limiting snacking helps saliva neutralize acids and remineralize the tooth surface.