Why does the inside of a tooth turn black?
Oct 18, 2025
Source: Cainiu Health
Dr. Liu Chao
Introduction
In general, black discoloration inside teeth may be caused by dietary pigment deposition, pulp necrosis, dental caries, tartar buildup, or tetracycline staining. It is recommended to seek timely medical attention, identify the underlying cause, and receive appropriate treatment under a doctor's guidance. In daily life, maintain brushing teeth morning and evening, use dental floss to clean interdental spaces, and schedule regular oral examinations and professional cleanings.
Under normal circumstances, black discoloration inside teeth may be caused by factors such as dietary pigment deposition, pulp necrosis, dental caries, tartar buildup, or tetracycline staining. It is recommended to seek timely medical attention to determine the underlying cause and receive appropriate treatment under a doctor's guidance. Specific analyses are as follows:
1. Dietary pigment deposition: Long-term consumption of dark-colored foods such as coffee, strong tea, and chocolate, or habits like smoking and chewing betel nuts, can lead to gradual penetration of pigments into the interior of teeth, resulting in blackening. Reduce intake of dark-colored foods, quit smoking and limit alcohol consumption, rinse your mouth after meals, brush thoroughly every day with fluoride toothpaste, and undergo regular dental cleanings to remove surface stains.
2. Pulp necrosis: When teeth are affected by trauma or infection, the pulp tissue may die. Blood components break down and hemoglobin infiltrates the dentinal tubules, causing the inside of the tooth to appear black. Root canal treatment is required to remove the necrotic pulp tissue, disinfect the root canal, and fill it. After the procedure, a dental crown restoration can be performed to restore the tooth’s normal color and shape.
3. Dental caries: Bacterial erosion of the tooth leads to demineralization and breakdown of dental tissues, forming cavities. Decomposed tissue within the cavity and bacterial metabolic products can cause internal blackening of the tooth. For early-stage (shallow) caries, topical applications of medications such as sodium fluoride glycerin paste, silver nitrate solution, or ammoniated silver nitrate solution can promote remineralization. For moderate and deep caries, decayed tissue must be removed and the cavity filled with restorative materials such as composite resin, glass ionomer cement, or polycarboxylate zinc cement.
4. Tartar buildup: If dental plaque remains uncleared for a long time, it mineralizes into tartar. Some tartar may adhere to the cervical region of the tooth or internal crevices, appearing black or brown. Professional periodontal cleaning is needed, using an ultrasonic scaler to remove tartar. After treatment, use medicated mouthwashes such as compound chlorhexidine solution, hydrogen peroxide solution, or metronidazole mouthwash to prevent gingival inflammation.
5. Tetracycline-stained teeth: Consumption of tetracycline antibiotics during childhood results in drug components depositing in the dentin, leading to internal black discoloration of teeth, commonly seen in permanent teeth. Mild cases can be improved with teeth whitening treatments such as cold-light bleaching. Moderate to severe cases require porcelain veneers or crown restorations to cover the discolored inner structure and enhance the tooth's appearance.
In daily life, maintain consistent brushing morning and night, use dental floss to clean interdental spaces, and schedule regular oral examinations and professional cleanings. Avoid administering tetracycline antibiotics to children during tooth development to reduce the risk of internal tooth discoloration.
