Dental calculus, which is also known as tartar, is hardened dental plaque. When saliva and other fluids in the oral cavity interact with bacterial plaque on the teeth, the plaque hardens and forms a rough surface that encourages further plaque to form; this plaque will eventually also harden and form calculus, learning to calculus buildup. The build up of calculus, which forms both above and below the gumline, eventually causes the gums to recede and become inflamed, and it also leads to bad breath. Because calculus is so hard and so firmly layered onto the teeth, it cannot be removed with a toothbrush or with floss and must be removed in a dentist’s office, using either ultrasonic or hand-held dental instruments.

Calculus is made up of a combination of inorganic and organic material, including mineral crystals, bacterial cells and yeast cells, proteins and fatty acids, DNA, and environmental debris including food and smoke particles. Microscopic examination clearly shows that dental calculus forms in layers, as new plaque coatings calcify, but layers calcify at different rates in different areas of the mouth and in different people, and the reasons for these calcification events are largely unknown. Dental calculus formation is influenced by the composition of bacterial plaque and the oral hygiene practices of the patient, but it is also affected by access to professional dental care, genetics, systemic diseases, gender, ethnic background, age, diet, and the use of tobacco or certain drugs or medications.

When plaque is allowed to accumulate on the teeth, the gum tissues, or gingiva, become inflamed. The condition of inflamed gingiva is called gingivitis. When gingivitis progresses, the gum tissues may become inflamed so significantly that the connective tissues that attach the gums to the teeth separate, and the teeth may become mobile and possibly fall out. This advanced stage of gum disease, characterized by this attachment loss, is called periodontitis. While periodontitis may arise for reasons other than a proliferation of dental plaque, plaque is the most common cause. Dental calculus creates a rough, sticky surface on the teeth that traps additional plaque, which subsequently calcifies and attracts more plaque; therefore, calculus is a significant contributing factor to periodontitis.

Nearly all humans have some supragingival calculus, or calculus that has formed coronal to the gumline. When the periodontal tissues detach from the teeth, it allows the formation of subgingival calculus. Proper and regular oral hygiene, including brushing the teeth twice a day and flossing once a day, can help reduce the amount of plaque on the teeth, thereby reducing the amount of calculus. Only clinical tools can remove calculus, however, which underscores the necessity for regular checkups and professional cleanings. At a professional cleaning, a dental hygienist will use professional hand tools or ultrasonic instruments to carefully and precisely clean away calculus that has accumulated. Without proper oral hygiene and professional cleanings, periodontitis develops. While many adults may require dental appointments less frequently, patients with periodontitis must have their teeth professionally cleaned more often, and, when teeth have fallen out or bone has deteriorated, these patients may require surgery to repair the jaw before any other treatment can occur.