The most likely cause of dark bleeding gums is gingivitis or periodontitis, both of which are caused by poor oral hygiene over time. People who do not brush and rinse their teeth carefully and do not go to the hospital regularly for scaling treatment will have a lot of food debris, soft tartar and even tartar stored on their teeth and in their periodontal pockets. Tartar is dark brown, and when a large amount of tartar accumulates in the periodontal pockets and near the roots of the teeth, it will make the gums black in color. There is a bloody smell inside the mouth and blood in the saliva. For this group of people, ultrasonic scaling treatment, also known as scaling treatment, should be performed in the treatment, and if the periodontal disease is very serious, it is also recommended to do deep periodontal scaling treatment.