If it is caused by calculus or pigmentation, periodontal treatment is needed; if it is caused by tooth decay, filling or root canal treatment is needed after removing the decayed part of the tooth. 1. Pigmentation. It is possible that the oral hygiene is not good, tartar accumulation of pigmentation to the teeth, the need for periodontal treatment to remove tartar plaque, pigmentation. 2. Dental caries. Teeth with black gaps may be teeth adjacent to the surface of the cavity, bacterial invasion of tooth tissue at the same time pigmentation leads to the gap looks black, the need to use special instruments to remove the decay of the tooth tissue after direct filling or root canal treatment after resin filling. It is recommended to go to the dental hospital to check the condition of the teeth and make targeted treatment.