Calculus (dental)
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In dentistry, calculus or tartar is a form of hardened dental plaque. It is caused by precipitation of minerals from saliva and gingival crevicular fluid (GCF) in plaque on the teeth. This process of precipitation kills the bacterial cells within dental plaque, but the rough and hardened surface that is formed provides an ideal surface for further plaque formation. This leads to calculus buildup, which compromises the health of the gingiva (gums). Calculus can form both along the gumline, where it is referred to as supragingival (Template:Gloss), and within the narrow sulcus that exists between the teeth and the gingiva, where it is referred to as subgingival (Template:Gloss).
Calculus formation is associated with a number of clinical manifestations, including bad breath, receding gums and chronically inflamed gingiva. Brushing and flossing can remove plaque from which calculus forms; however, once formed, calculus is too hard (firmly attached) to be removed with a toothbrush. Calculus buildup can be removed with ultrasonic tools or dental hand instruments (such as a periodontal scaler).
Etymology
The word comes from Latin Template:Lang Template:Gloss, from Template:Lang Template:Gloss,<ref>Template:L&S</ref> probably related to Greek Template:Lang Template:Lang Template:Gloss,<ref>Template:LSJ.</ref> which manyTemplate:Who trace to a Proto-Indo-European root for Template:Gloss.<ref name="OETYMD">Template:OEtymD Template:OEtymD</ref> Calculus was a term used for various kinds of stones. This spun off many modern words, including calculate (Template:Gloss), and calculus, which came to be used, in the 18th century, for accidental or incidental mineral buildups in human and animal bodies, like kidney stones and minerals on teeth.<ref name="OETYMD"/>
Tartar, on the other hand, originates in Greek as well (Template:Lang), but as the term for the white encrustation inside casks (a.k.a. potassium bitartrate, commonly known as cream of tartar). This came to be a term used for calcium phosphate on teeth in the early 19th century.<ref>Template:OEtymD</ref>
Chemical composition
Calculus is composed of both inorganic (mineral) and organic (cellular and extracellular matrix) components.
In supra-gingival calculus
The mineral proportion of supragingival calculus ranges from approximately 40–60%, depending on its location in the dentition,<ref name="auto">Template:Cite journal</ref> and consists primarily of calcium phosphate crystals organized into four principal mineral phases, listed here in order of increasing ratio of phosphate to calcium:
- hydroxyapatite, Template:Chem2
- whitlockite, Template:Chem2
- octacalcium phosphate, Template:Chem2
- and brushite, Template:Chem2
The organic component is approximately 85% cellular and 15% extracellular matrix.<ref name="auto"/> Cell density within dental plaque and calculus is very high, consisting of an estimated 200,000,000 cells per milligram.<ref name="auto1">Template:Cite journal</ref><ref>Template:Cite journal</ref> The cells within calculus are primarily bacterial, but also include at least one species of archaea (Methanobrevibacter oralis) and several species of yeast (e.g., Candida albicans). The organic extracellular matrix in calculus consists primarily of proteins and lipids (fatty acids, triglycerides, glycolipids, and phospholipids),<ref name="auto"/> as well as extracellular DNA.<ref name="auto1"/><ref>Template:Cite journal</ref> Trace amounts of host, dietary, and environmental microdebris are also found within calculus, including salivary proteins,<ref name="auto2">Template:Cite journal</ref> plant DNA,<ref>Template:Cite journal</ref> milk proteins,<ref>Template:Cite journal</ref> starch granules,<ref>Template:Cite journal</ref> textile fibers,<ref>Template:Cite journal</ref> and smoke particles.<ref>Template:Cite journal</ref>
In sub-gingival calculus
Sub-gingival calculus is composed almost entirely of two components: fossilized anaerobic bacteria whose biological composition has been replaced by calcium phosphate salts, and calcium phosphate salts that have joined the fossilized bacteria in calculus formations.<ref name=":0">Template:Cite book</ref>
The following minerals are detectable in calculus by X-ray diffraction:
- brushite (Template:Chem2)
- octacalcium phosphate (Template:Chem2)
- magnesium-containing whitlockite (Template:Chem2)
- carbonate-containing hydroxyapatite (approximately Template:Chem2 but containing some carbonate).<ref>A. Molokhia and G. S. Nixon, "Studies on the composition of human dental calculus. Determination of some major and trace elements by instrumental neutron activation analysis", Journal of Radioanalytical and Nuclear Chemistry, Volume 83, Number 2, August, 1984, p. 273-281. (abstract)</ref>
Calculus formation
Dental calculus typically forms in incremental layers<ref>Template:Cite book</ref> that are easily visible using both electron microscopy and light microscopy.<ref name="auto2"/> These layers form during periodic calcification events of the dental plaque,<ref name="auto3"/> but the timing and triggers of these events are not well understood. The formation of calculus varies widely among individuals and at different locations within the mouth. Many variables have been identified that influence the formation of dental calculus, including age, sex, ethnic background, diet, location in the oral cavity, oral hygiene, bacterial plaque composition, host genetics, access to professional dental care, physical disabilities, systemic diseases, tobacco use, and drugs and medications.<ref name="auto3"/>
Supragingival calculus formation is most abundant on the buccal (cheek) surfaces of the maxillary (upper jaw) molars and on the lingual (tongue) surfaces of the mandibular (lower jaw) incisors.<ref name="auto3">Template:Cite journal</ref> These areas experience high salivary flow because of their proximity to the parotid and sublingual salivary glands.
Subgingival calculus forms below the gumline and is typically darkened in color by the presence of black-pigmented bacteria,<ref name="auto3"/> whose cells are coated in a layer of iron obtained from heme during gingival bleeding.<ref>Template:Cite journal</ref> The reason fossilized bacteria are initially attracted to one part of the subgingival tooth surface over another is not fully understood. However, once the first layer is attached, more calculus components are naturally attracted to the same places due to electrical charge. This is because the calcium phosphate salts contained in them exist as electrically unstable ions (unlike calcium phosphate, the primary component of teeth). The fossilized bacteria pile up rather haphazardly, while free-floating ionic components (calcium phosphate salts) fill in the gaps.<ref name=":0" />
The resultant hardened structure can be compared to concrete, with the fossilized bacteria playing the role of aggregate, and the smaller calcium phosphate salts being the cement. The "hardened" calculus formations are at the heart of periodontal disease and treatment.<ref name=":0" />
Clinical significance
Plaque accumulation causes the gingiva to become irritated and inflamed, and this is referred to as gingivitis. When the gingiva become so irritated that there is a loss of the connective tissue fibers that attach the gums to the teeth and bone that surrounds the tooth, this is known as periodontitis. Dental plaque is not the sole cause of periodontitis; however it is many times referred to as a primary aetiology. Plaque that remains in the oral cavity long enough will eventually calcify and become calculus.<ref name="auto3"/> Calculus is detrimental to gingival health because it serves as a trap for increased plaque formation and retention; thus, calculus, along with other factors that cause a localized build-up of plaque, is referred to as a secondary aetiology of periodontitis.
When plaque is supragingival, the bacterial content contains a great proportion of aerobic bacteria and yeast,<ref>Template:Cite journal</ref> or those bacteria which utilize and can survive in an environment containing oxygen. Subgingival plaque contains a higher proportion of anaerobic bacteria, or those bacteria which cannot exist in an environment containing oxygen. Several anaerobic plaque bacteria, such as Porphyromonas gingivalis,<ref>Template:Cite journal</ref> secrete antigenic proteins that trigger a strong inflammatory response in the periodontium, the specialized tissues that surround and support the teeth. Prolonged inflammation of the periodontium leads to bone loss and weakening of the gingival fibers that attach the teeth to the gums, two major hallmarks of periodontitis. Supragingival calculus formation is nearly ubiquitous in humans,<ref>Template:Cite journal </ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> but to differing degrees. Almost all individuals with periodontitis exhibit considerable subgingival calculus deposits.<ref name="auto3"/> Dental plaque bacteria have been linked to cardiovascular disease<ref>Template:Cite journal</ref> and mothers giving birth to pre-term low weight infants,<ref>Template:Cite journal</ref> but there is no conclusive evidence yet that periodontitis is a significant risk factor for either of these two conditions.<ref>Template:Cite journal</ref>
Prevention
Toothpaste with pyrophosphates or zinc citrate has been shown to produce a statistically significant reduction in plaque accumulation, but the effect of zinc citrate is so modest that its clinical importance is questionable.<ref>Template:Cite web</ref><ref>Template:Cite journal</ref> Some calculus may form even without plaque deposits, by direct mineralisation of the pellicle.
Calculus in other animals
Calculus formation in other animals is less well studied than in humans, but it is known to form in a wide range of species. Domestic pets, such as dogs and cats, frequently accumulate large calculus deposits.<ref>Template:Cite journal</ref> Animals with highly abrasive diets, such as ruminants and equids, rarely form thick deposits and instead tend to form thin calculus deposits that often have a metallic or opalescent sheen.<ref>Template:Cite book</ref> In animals, calculus should not be confused with crown cementum,<ref>Template:Cite journal</ref> a layer of calcified dental tissue that encases the tooth root underneath the gingival margin and is gradually lost through periodontal disease.
Archaeological significance
Dental calculus has been shown to contain well preserved microparticles, DNA and protein in archaeological samples.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> The information these molecules contain can reveal information about the oral microbiome of the host and the presence of pathogens.<ref>Template:Cite journal</ref> It is also possible to identify dietary sources<ref>Template:Cite journal</ref> as well as study dietary shifts<ref>Template:Cite journal</ref> and occasionally evidence of craft activities.<ref>Template:Cite journal</ref>
Removal of calculus after formation
Template:Main Plaque and calculus deposits are a major etiological factor in the development and progression of oral disease. An important part of the scope of practice of a dental hygienist is the removal of plaque and calculus deposits. This is achieved through the use of specifically designed instruments for debridement of tooth surfaces.<ref name="Newman_2011">Template:Cite book</ref><ref name="Darby_2009">Template:Cite journal</ref> Treatment with these types of instruments is necessary as calculus deposits cannot be removed by brushing or flossing alone. To effectively manage disease or maintain oral health, thorough removal of calculus deposits should be completed at frequent intervals. The recommended frequency of dental hygiene treatment can be made by a registered professional, and is dependent on individual patient needs.<ref>Template:Cite journal</ref> Factors that are taken into consideration include an individual's overall health status, tobacco use, amount of calculus present, and adherence to a professionally recommended home care routine.<ref>Template:Cite web</ref>
Hand instruments are specially designed tools used by dental professionals to remove plaque and calculus deposits that have formed on the teeth.<ref name="Newman_2011" /><ref name="Darby_2009" /> These tools include scalers, curettes, jaquettes, hoes, files and chisels.<ref name="Newman_2011" /><ref name="Darby_2009" /> Each type of tool is designed to be used in specific areas of the mouth.<ref name="Darby_2009" /> Some commonly used instruments include sickle scalers which are designed with a pointed tip and are mainly used supragingivally.<ref name="Newman_2011" /><ref name="Darby_2009" /> Curettes are mainly used to remove subgingival calculus, smooth root surfaces and to clean out periodontal pockets.<ref name="Newman_2011" /><ref>Template:Cite journal</ref> Curettes can be divided into two subgroups: universals and area specific instruments. Universal curettes can be used in multiple areas, while area specific instruments are designed for select tooth surfaces.<ref name="Darby_2009" /> Gracey curettes are a popular type of area specific curettes.<ref name="Darby_2009" /> Due to their design, area specific curettes allow for better adaptation to the root surface and can be slightly more effective than universals.<ref name="Newman_2011" /><ref name="Darby_2009" /> Hoes, chisels, and files are less widely used than scalers and curettes. These are beneficial when removing large amounts of calculus or tenacious calculus that cannot be removed with a curette or scaler alone.<ref name="Newman_2011" /> Chisels and hoes are used to remove bands of calculus, whereas files are used to crush burnished or tenacious calculus.<ref name="Newman_2011" />
Ultrasonic scalers, also known as power scalers, are effective in removing calculus, stain, and plaque. These scalers are also useful for root planing, curettage, and surgical debridement.<ref name="Newman_2011" /> Not only is tenacious calculus and stain removed more effectively with ultrasonic scalers than with hand instrumentation alone, it is evident that the most satisfactory clinical results are when ultrasonics are used in adjunct to hand instrumentation.<ref name="Newman_2011" /> There are two types of ultrasonic scalers; piezoelectric and magnetostrictive. Oscillating material in both of these handpieces cause the tip of the scaler to vibrate at high speeds, between 18,000 and 50,000 Hz.<ref name="Newman_2011" /> The tip of each scaler uses a different vibration pattern for removal of calculus.<ref name="Newman_2011" /> The magnetostrictive power scaler vibration is elliptical, activating all sides of the tip, whereas the piezoelectric vibration is linear and is more active on the two sides of the tip.<ref name="Newman_2011" />
Special tips for ultrasonic scalers are designed to address different areas of the mouth and varying amounts of calculus buildup. Larger tips are used for heavy subgingival or supragingival calculus deposits, whereas thinner tips are designed more for definitive subgingival debridement.<ref name="Newman_2011" /> As the high frequency vibrations loosen calculus and plaque, heat is generated at the tip.<ref name="Newman_2011" /> A water spray is directed towards the end of the tip to cool it as well as irrigate the gingiva during debridement.<ref name="Newman_2011" /> Only the first 1–2 mm of the tip on the ultrasonic scaler is most effective for removal, and therefore needs to come into direct contact with the calculus to fracture the deposits.<ref name="Newman_2011" /> Small adaptations are needed in order to keep the tip of the scaler touching the surface of the tooth, while overlapping oblique, horizontal, or vertical strokes are used for adequate calculus removal.<ref name="Newman_2011" />
Current research on potentially more effective methods of subgingival calculus removal focuses on the use of near-ultraviolet and near-infrared lasers, such as Er,Cr:YSGG lasers.<ref name="Schoenly_2011">Template:Cite journal</ref><ref name="Ting_2007">Template:Cite journal</ref> The use of lasers in periodontal therapy offers a unique clinical advantage over conventional hand instrumentation, as the thin and flexible fibers can deliver laser energy into periodontal pockets that are otherwise difficult to access.<ref name="Ting_2007" /> Near-infrared lasers, such as the Er,CR:YSGG laser, have been proposed as an effective adjunct for calculus removal as the emission wavelength is highly absorbed by water, a large component of calculus deposits.<ref name="Ting_2007" /> An optimal output power setting of 1.0-W with the near-infrared Er,Cr:YSGG laser has been shown to be effective for root scaling.<ref name="Ting_2007" /> Near-ultraviolet lasers have also shown promise as they allow the dental professional to remove calculus deposits quickly, without removing underlying healthy tooth structure, which often occurs during hand instrumentation.<ref name="Schoenly_2011" /> Additionally, near-ultraviolet lasers are effective at various irradiation angles for calculus removal.<ref name="Schoenly_2011" /> Discrepancies in the efficiency of removal are due to the physical and optical properties of the calculus deposits, not to the angle of laser use.<ref name="Schoenly_2011" /> Dental hygienists must receive additional theoretical and clinical training on the use of lasers, where legislation permits.<ref>Template:Cite web</ref>
See also
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