Dental cleanings which is known as scaling/polishing is removing plaque and tartar deposits that built up on the teeth over time. Teeth are also covered in saliva which contains calcium and other elements which help strengthen and protect the teeth. As calcium deposits on the teeth, a lime scale like structure builds up in a pipe or kettle. It is usually tooth coloured and can easily be mistaken as part of the teeth, but it varies from brown or black in colour.