What is calculus in the context of dental hygiene?

In dental hygiene, calculus refers to a hard, mineralized deposit that forms on the teeth as a result of plaque that has been allowed to harden. This buildup results from the accumulation of minerals in saliva and can lead to gum disease if not removed. Calculus cannot be easily removed by routine brushing or flossing, which is why professional dental cleaning is necessary to eliminate it. Professional removal is essential because calculus provides a rough surface that can harbor additional plaque and bacteria, contributing to further oral health issues.

The other options describe elements unrelated to the nature of calculus. Soft material that is easily removed by brushing refers to plaque. Regular dental checkups, while crucial for monitoring oral health and catching issues early, are not a definition of calculus itself. The process of whitening teeth pertains to cosmetic dentistry rather than the buildup of tartar on the teeth. Therefore, the understanding that calculus is a hard buildup requiring professional intervention is key to maintaining good oral hygiene.