What Minerals Cause Tartar and How They Harden Plaque

January 9, 2026 •

4 min read

Over 70% of the population experiences some form of tartar buildup during their lifetime. Dental tartar, also known as calculus, is the hardened version of dental plaque that can lead to gum disease and tooth decay if left untreated. This hard, mineralized deposit is primarily caused by specific minerals found naturally in your saliva.

Quick Summary

Tartar forms when dental plaque hardens, a process driven by the mineralization of calcium, phosphate, and magnesium from saliva. These minerals crystallize the sticky bacterial film, creating a rough, hard deposit that requires professional removal. The rate of buildup is influenced by individual saliva composition and oral hygiene habits.

Key Points

Calcium and Phosphate: These two minerals are the primary ingredients in saliva that cause plaque to harden into tartar.
Magnesium's Contribution: While less dominant than calcium and phosphate, magnesium is also a minor component of the mineralized tartar deposit.
Plaque is the Precursor: Tartar forms when dental plaque is not removed promptly and begins to absorb minerals from saliva.
Speed of Formation: The hardening process can begin within 24 to 72 hours of plaque accumulation.
Professional Removal is Necessary: Once plaque has mineralized into tartar, it can no longer be removed by brushing and requires professional scaling.
Prevention is Key: The best way to prevent tartar is through consistent and thorough removal of plaque with daily brushing and flossing.
Role of Saliva: The composition of an individual's saliva, particularly the concentration of minerals, directly influences their susceptibility to tartar buildup.

The Core Minerals in Tartar Formation

Dental plaque is a soft, sticky film of bacteria that constantly forms on your teeth. If not removed daily through brushing and flossing, this plaque absorbs minerals from your saliva, causing it to harden into tartar. The primary culprits behind this mineralization process are calcium and phosphate, with magnesium also playing a contributing role.

Calcium: The Primary Calcifying Agent

Calcium is the most abundant mineral in the human body, with a significant amount circulating in saliva. Saliva is naturally supersaturated with calcium and phosphate, which is essential for the remineralization of tooth enamel to counteract acid erosion. However, when plaque is present, this same process works against you. Calcium ions in the saliva bind to the organic matrix of the plaque, providing the foundational structure for the crystalline formation that becomes tartar.

Phosphate: A Partner in Mineralization

Phosphate is another crucial mineral present in saliva that works alongside calcium to form dental calculus. Studies have even suggested that in individuals prone to heavy tartar formation, phosphate levels in plaque can be up to three times higher than in those who are not, suggesting its critical role in the mineralization process. The combination of calcium phosphate crystallizes the plaque, transforming its soft texture into a cement-like hardness. This is why tartar is primarily composed of various forms of calcium phosphate crystals, such as hydroxyapatite.

Magnesium: A Less Common Contributor

While calcium and phosphate are the main drivers, magnesium also makes up a small percentage of the mineral content in dental tartar. Specifically, a form known as magnesium phosphate is found in hardened calculus. The presence of magnesium can influence the crystal structure of the mineral deposits, potentially affecting the rate and density of tartar formation. Research has shown that magnesium levels can also be related to an individual's caries resistance, as it can affect calcium levels and mineralization within the oral environment.

The Mineralization Process: Plaque to Calculus

The transformation of soft plaque into hard calculus begins quickly, often within 24 to 72 hours of plaque accumulation. The rough, hardened surface of tartar provides an ideal environment for more plaque to adhere, leading to a vicious cycle of buildup. This process is influenced by several factors:

Salivary pH: A higher, or more alkaline, pH level in the mouth can increase the precipitation of calcium phosphate salts, accelerating tartar formation.
Saliva Composition: Individuals with higher concentrations of calcium and phosphate in their saliva are naturally more prone to rapid tartar buildup.
Location in the Mouth: Tartar often forms heavily near the salivary ducts, such as behind the lower front teeth and on the buccal surfaces of the upper molars, due to the high concentration of mineral-rich saliva in these areas.

Comparison of Supragingival vs. Subgingival Tartar Minerals

The mineral composition of tartar differs slightly depending on its location. Tartar above the gumline (supragingival) forms from saliva, while tartar below the gumline (subgingival) forms from gingival crevicular fluid, which is more enriched with different minerals.


Feature	Supragingival Tartar	Subgingival Tartar
Location	Above the gumline, visible	Below the gumline, hidden in pockets
Primary Mineral Source	Saliva	Gingival crevicular fluid
Mineral Composition	Higher content of calcium phosphate crystals like hydroxyapatite	More magnesium whitlockite; less brushite and octacalcium phosphate
Appearance	White or yellowish-white	Dark brown to greenish-black from blood products
Texture	Hard, clay-like consistency	Typically harder and denser

Preventing Mineral-Induced Tartar Buildup

Since the minerals come from your saliva, you cannot stop the process entirely. However, preventing plaque from accumulating is the most effective way to control tartar formation.

Best Practices for Prevention

Brush your teeth thoroughly twice a day for two minutes, ensuring all surfaces are reached.
Floss daily to remove plaque from between your teeth and along the gumline where brushing cannot.
Use tartar control toothpaste. Many contain pyrophosphates or zinc, which interfere with calcium phosphate crystallization.
Utilize an antimicrobial mouthwash to reduce bacteria that contribute to plaque formation.
Schedule regular professional dental cleanings to remove any tartar that has formed.

Conclusion: Understanding the Minerals to Protect Your Smile

Ultimately, the minerals that cause tartar—primarily calcium, phosphate, and magnesium—are natural components of your saliva. They are not inherently bad; in fact, they play a vital role in protecting your enamel through remineralization. The problem arises when these minerals interact with persistent dental plaque that has not been properly removed. This process of mineralization hardens the plaque into tartar, which can only be removed by a dental professional. Therefore, the most effective strategy for managing tartar is diligent and consistent oral hygiene to prevent the plaque from ever having a chance to harden.

For more information on managing your oral health, visit the American Dental Association's official website.

Frequently Asked Questions

No, once plaque has hardened into tartar (calculus), it cannot be removed with regular brushing, flossing, or over-the-counter tools. Attempting to scrape it off at home can damage your teeth and gums. Professional cleaning (scaling) by a dentist or dental hygienist is required.

Tartar tends to form more heavily near the ducts of your salivary glands, where saliva rich in minerals like calcium and phosphate flows directly onto the teeth. This is why it is commonly found on the back of the lower front teeth and the outside of the upper molars.

The calcium and phosphate that cause tartar come from your saliva, not directly from your diet. Your body naturally regulates mineral levels in saliva. However, a high-sugar or high-starch diet fuels the bacteria that create plaque, which then attracts the minerals from saliva to harden.

Plaque is a soft, sticky, colorless film of bacteria that constantly forms on your teeth and can be removed by brushing. Tartar, or calculus, is what forms when plaque is not removed and hardens due to minerals in your saliva.

Yes, some individuals are more genetically predisposed to heavy tartar buildup due to the specific mineral composition and pH of their saliva. However, good oral hygiene can effectively manage this predisposition.

Tartar control toothpastes often contain chemical compounds like pyrophosphates or zinc. These agents work by interfering with the crystallization of calcium and phosphate ions from saliva into hardened tartar, helping to reduce its formation on the teeth.

If left untreated, tartar can lead to a range of oral health issues, including gum inflammation (gingivitis), periodontal disease, bad breath, and tooth decay. Its rough surface creates a breeding ground for more plaque, exacerbating these problems.