How plaque hardens into tartar and why professional cleaning is necessary for its removal.

Tartar (calculus) forms when dental plaque mineralizes with calcium from saliva. This hardened deposit cannot be removed by brushing or flossing and requires professional dental instruments for removal. Tartar provides a rough surface that attracts more plaque, creating a cycle of buildup. It forms most commonly on the inner surfaces of lower front teeth and outer surfaces of upper molars, near salivary gland openings.