Calculus is composed of 70-80 % of Inorganic component which is mainly Crystalline in Structure. The four main crystal forms and their percentages are as follows: Hydroxyapatite: 58% Magnesium Whitlockite: 21% Octacalcium Phosphate: 12% Brushite: 9% Generally, 2 or more crystal forms are typically in a sample of calculus. Hydroxyapatite and Octacalcium Phosphate are detected [&hellip