Calculus, or tartar, is a hardened substance that forms on teeth. A calculus bridge occurs when this calculus stretches across multiple teeth or fills in the gaps between them. It develops because ...

Plaque becomes a problem when it morphs into something else. Left unchecked, plaque hardens into calculus (also called tartar ...

"However, it can be easily removed with brushing, but after 48 hours the plaque starts to calcify and becomes a grey or brown hard substance called calculus (tartar) which is difficult to remove.