When you floss (you do floss, right?), you probably notice a sticky, yellowish substance called plaque stuck to the thread. This thin film of tiny food particles and bacteria is the reason you floss and brush in the first place: Because it's the main trigger for tooth decay and gum disease, removing it decreases your risk for disease.
But this isn't the only form of plaque you should be concerned about. That same sticky substance can also interact with your saliva and harden into what's commonly known as tartar. Dentists, however, have a different term: They refer to these calcified deposits as calculus. And it's just as much a source of disease as its softer counterpart.
You might have noticed that this form of plaque has the same name as an advanced type of mathematics. Although dental calculus has little in common with algebra's cousin, both terms trace their origins back to the same linguistic source. The word “calculus” in Latin means “small stone;” it became associated with math because stone pebbles were once used by merchants long ago to calculate sales and trades.
The term became associated with the substance on your teeth because the hardened plaque deposits resemble tiny stones or minerals—and they can be “as hard as a rock” to remove. In fact, because they adhere so firmly it's virtually impossible to remove calculus deposits with brushing or flossing alone. To effectively eliminate calculus from tooth surfaces (including under the gum line) requires the skills and special dental tools of dentists or dental hygienists.
That's why we recommend a minimum of two dental cleanings a year to remove any calculus buildup, as well as any pre-calcified plaque you might have missed with daily hygiene. Reducing both plaque and calculus on your teeth fully minimizes your risk of dental disease. What's more, removing the yellowish substance may also brighten your smile.
That's not to say daily brushing and flossing aren't important. By removing the bulk of plaque buildup, you reduce the amount that eventually becomes calculus. In other words, it takes both a daily oral hygiene practice and regular dental visits to keep your teeth healthy and beautiful.