The black inside of the big teeth may be caused by dental calculus, caries, pulpitis and other diseases. 1. Dental calculus: This disease is formed by plaque and soft tartar through calcification, related to food debris and bacteria in plaque, epithelial cells and other substances, common triggering factors are smoking, teeth are not aligned and so on. Typical symptoms are yellowish-white or brownish-black tartar attached to the surface of the teeth, which can be manifested as black inside the big teeth, and some patients are also accompanied by bad breath, bleeding gums and other symptoms. 2. Caries: The occurrence of this disease requires the simultaneous presence of bacteria, diet, host factors, can be developed over time, the natural formation of cavities. At first, the teeth have a lusterless white plaque, which then turns yellowish brown, if not treated in time, it will turn black again when stimulated by the outside world, so the black inside of the big teeth may be caries. 3. Pulpitis: the disease is mainly caused by bacterial infection, caries is also a common cause of pulpitis, but also with the abnormal development of the tooth, tooth wear and other factors. Patients may find that the teeth have translucent black or visible obvious black spots, there will also be night pain, temperature stimulation pain and other symptoms. It is recommended that patients with dark inside of their large teeth go to the hospital to improve the relevant examination to clarify the specific cause.