Dental Calculus: Structure, Formation and The Treatment for Tartar in Mouth

Dental calculus is the calcified deposit which forms on the surface of tooth or teeth and dental prosthesis. Calculus is also called as ‘tartar’ in layman’s terms.

This is the mineralized bacterial plaque. The dental plaque which is a thin biofilm formed on the surface of the teeth when left uncleaned for long hours serves as a base for further mineralization leading to the formation of calculus. The calculus is a crystalline structure with major components being calcium and phosphorus.

Types of Dental Calculus

There are two types of calculus seen in our mouths.

Supragingival Calculus

As the name suggests supragingival calculus is found above the gingival margin/gum margin and hence is visible to the naked eye. It is mainly formed near the openings of the ducts of the major salivary glands in the mouth. For eg; near the lingual /inner surfaces of the lower anterior teeth and the buccal/outer surface of the upper molars.

The plaque matrix that is formed on the surface of the teeth, derives the minerals from the saliva for calcification and formation of the calculus.

The supragingival calculus most often forms on tooth/teeth surfaces which are not clean and are not properly taken care of, hygienically. The supragingival calculus may also be found on the surfaces of the dentures or prosthesis.

The supragingival plaque may form within two weeks.

This type of tartar is light yellow in color. Sometimes it may get stained with different colors. As this type of dental calculus is visible clinically, it is comparatively easier to remove by scaling.

dental calculus

Dental Calculus

Subgingival Calculus

This type of dental calculus is found beneath the gingival margin, extending into the periodontal pockets. It is usually found on the root surfaces of the tooth. The subgingival calculus is usually not visible to the naked eye on clinical examination.

The subgingival plaque gets minerals from the gingival sulcular fluid and the inflammatory exudate (fluid) forming the subgingival calculus. This dental calculus may be formed as discrete lumps or may cover the entire root surface.

The subgingival calculus takes many months to form and is dark brown, dark green to black in color. It usually forms in one tooth or a group of teeth. Some times it may also form in most of the teeth in the mouth ins a generalized manner.

This variety of calculus is most commonly found on the interproximal regions and inner/lingual surfaces of the teeth.

How To Detect The Sub Gingival Calculus?

The location and the extent of subgingival calculus may be evaluated clinically by the dentist who may use by careful tactile perception with a delicate dental instrument such as explorer to detect the dental calculus.

The subgingival calculus may also be clinically detected by the dentist using a specific probe called CPTIN probe, with a light touch.

When detecting the subgingival calculus the dentist usually runs the probe along the length of the root. The dentist may feel it as a rough surface or a catch on the root surface of the teeth.

In case of severe gingival recession, this subgingival calculus becomes supra gingival as the gums recede, exposing the root surface, making the calculus visible to the eye.

The subgingival calculus is very firmly attached to the root surface which makes it difficult to be removed by dental scaling alone.

Dental Calculus Composition

Dental calculus is primarily composed of inorganic components which contribute to form anywhere between 70-90% of the structure. The rest of the structure is composed of organic components.

Inorganic Components

The major inorganic components found in calculus are as follows.

  • 76% of calcium phosphate (Ca3[PO4]2)
  • 3% of calcium carbonate (CaCO3)
  • 4% of magnesium phosphate (Mg3[PO4]2)
  • 2% of carbon dioxide
  • Traces of sodium, zinc, strontium, bromine, copper, manganese, tungsten, gold, aluminium, silicon, iron, and fluorine.

The percentage of inorganic components that are present in the dental calculus is similar to the other calcified structures that are present in the human body.

The 2/3rd of the inorganic components in calculus is in the form of crystalline structures. There are 4 main crystalline structures that are commonly seen in calculus and any given sample of calculus will have at least 2 or more of these crystalline structures, at a time.

The 4 main crystalline structures seen in calculus are

  • Hydroxyapatite, 58%
  • Magnesium whitlockite, 21%
  • Octacalcium phosphate, 12%
  • Brushite, 9%

Organic Components

The organic component of dental calculus is mainly comprised of a mixture of protein-polysaccharide complexes, desquamated epithelial cells, leukocytes, and various types of microorganisms.

Carbohydrate constitutes between 1.9% and 9.1% of the total organic component in the dental calculus. The common carbohydrates that can be seen in the calculus are galactose, glucose, rhamnose, mannose, glucuronic acid, galactosamine, and sometimes arabinose, galacturonic acid, and glucosamine.

5.9% to 8.2% of the organic component is formed by the salivary proteins which include most amino acids.

0.2% of the organic content is formed by Lipids which is in the form of neutral fats, free fatty acids, cholesterol, cholesterol esters, and phospholipids.

How Does The Dental Calculus Attach To The Tooth Surface?

There are 4 ways with which the calculus attaches to the tooth surface. The ease with which the dental calculus can be removed from the tooth surface depends on the manner with which it is attached to the tooth surface.

The 4 modes of attachment are

  • Attachment by means of an organic pellicle
  • Mechanical locking into surface irregularities, such as caries lesions or resorption lacunae.
  • A close adaptation of the undersurface of calculus to depressions or gently sloping mounds of the unaltered cementum surface
  • Penetration of bacterial calculus into the cementum

Dental Calculus Formation

As we already mentioned earlier dental calculus is actually the mineralized dental plaque.

The soft dental plaque hardens by the precipitation of mineral salts. This process usually starts between the 1st and 14th days of plaque formation in the mouth. But calcification itself occurs within 4 to 8 hours.

The plaque may be 50% mineralized within 2 days and 60% to 90% mineralized within 12 days. However, it is not necessary for all the dental plaque to undergo calcification. Plaque that does not transform into calculus reaches the level of its maximal mineral content within 2 days.

Another important thing to remember here is that microorganisms are not always necessary to form dental calculus, because it has been studied and proven that calculus readily occurs in germ-free rodents as well.

Who Is At Risk?

People belonging to one or more of the following categories may be at an increased risk of getting dental calculus.


Older people are at a higher risk of getting calculus than the younger ones.


Smoking has been linked with an increased incidence of supragingival calculus along with extrinsic stains.

Diet & Nutrition:

People who suffer from deficiencies of vitamin A, Vitamin B3 or Vitamin B6 are believed to be at a higher risk of getting calculus. Increased intake of protein, phosphorus, dietary calcium, bicarbonate, and carbohydrate is also linked with a higher incidence of calculus.

Salivary Composition:

Salivary flow, ph of saliva and the saliva constitution are also believed to be important factors that influence the formation of calculus. Higher ph of saliva, low salivary secretion & flow and higher calcium content in saliva are the main culprits.


Increased stress may also have a link with an increased occurrence of calculus in individuals.

Dental Calculus Treatment

Tooth brushing and dental flossing are only effective as long as the dental plaque isn’t mineralized and hasn’t transformed into calculus. Once the dental calculus is formed as it is firmly attached to the tooth surface, it can’t be removed with a toothbrush.

The removal of dental calculus can only be done in a dental clinic by the dentist or a dental hygienist using special instruments. The instruments that are used for these purposes are called scalers, curettes, and root planers.

dental scalers

The process itself is called dental scaling. The scalers can be of different types. Hand scalers, ultrasonic scalers, sonic scalers etc.

Dental scaling may be performed with or without anaesthesia. This procedure may require more than one visit depending on the severity. In some cases, your dentist may prescribe an anaesthetic gel or an oral analgesic to tackle the postoperative sensitivity.

You may need to do a follow up after the procedure.

Once the dental scaling has been completed and all the calculus is removed, it is necessary to maintain good oral hygiene to prevent the recurrence of calculus.

Here are some guidelines for you to follow.

  • Practice the correct brushing techniques.
  • Use dental flosses and interdental brushes regularly.
  • Use mouthwashes, if prescribed by the dentist (overuse isn’t recommended)
  • Visit your dentist once every six months.
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Medical Disclaimer

This content is strictly the opinion of the author and is for informational and educational purposes only. It is not intended to provide medical/dental advice or to take the place of medical advice or treatment from a personal physician or a dentist. All readers/viewers of this content are advised to consult their doctors or qualified health professionals regarding specific health questions.

The publisher of this content takes NO responsibility for possible health consequences of any person or persons reading or following the information in this educational content. All viewers of this content, especially those taking prescription or over-the-counter medications, should consult their physicians and/or the dentists before beginning any nutrition, supplement, medications or lifestyle program.