What are the different types of tartar and how are they formed?

The light yellow coloured types are formed by plaque which have been calcified by saliva. It therefore is found mainly at the saliva duct openings; at the cheeks near the upper molar teeth and on the tongue side of the lower front teeth. These types of tartar also tend to be located at or above the gum line; where plaque is in constant contact with saliva. Tartar which are brown in colour are basically the light yellow types but have been stained by food pigments or from smoking. Lastly, the black variety of tartar are those formed by plaque which have been calcified by blood pigments. They are therefore commonly seen under the gum line or if the gum shrinks, it may expose this type of tartar and make it seem like it is above the gum line. This type of tartar is often found in those with gum disease; and bleeding gum is often associated.