Black spots on the teeth may be caused by tooth decay or deformed central cusp fracture, etc., as follows. 1. Tooth decay (caries): the role of bacteria, food and other factors lead to demineralization and decomposition of dental tissues, stained with black pigment, most commonly found on the occlusal surface and adjacent surfaces of the teeth. 2. Fracture of deformed central cusp: deformed central cusp is commonly found in mandibular premolar, which is a conical protrusion at the central fossa of occlusal surface. After the central cusp is fractured, it can be manifested as a round black ring with a light yellow or brown dentin shaft in the center, and a black dot can be seen in the center of the shaft, which is the medullary angle that protrudes into it. There may be other reasons for black dots on the teeth, and it is recommended to visit the hospital in time to receive regular treatment early.