Calculus
Calculus is the hard residue ranging from yellow to brown forming on teeth when oral hygiene is incomplete or improper. Calculus is formed from Plaque (a soft sticky substance that accumulates on teeth; composed largely of bacteria and food substances suspended in saliva) which can build up and become hard. This hard plaque is known as tartar or calculus. Brushing and flossing alone cannot remove calculus. A dentist or hygienist must remove it manually to stop the disease process.
