Prophylaxis (dentistry)
Dental prophylaxis refers to all preventive measures that are intended to prevent diseases of the teeth and the gums from developing or worsening. Dental prevention is a synonym . Prophylaxis is derived from the ancient Greek προφύλαξις prophýlaxis “caution”, which itself comes from προφυλάσσω prophylásso “to beware of something”.
First and foremost, there is the preventive medical check-up for the early detection of pathological conditions. The group prophylaxis affects selected larger population groups (e.g. examinations of school children by school dentists), while the individual prophylaxis only applies to individuals.
Types of prophylaxis
A further distinction is made between collective or mass prophylaxis ( affects large sections of the population) and semi-collective prophylaxis (limited to special groups). The collective prophylaxis includes z. B. the fluoridation of teeth through drinking water, food additives and toothpaste. Among the base Prophylactic measures include brushing your teeth, using dental floss and low-sugar diet. They should be part of every daily oral hygiene routine. Intensive prophylactic measures are aimed at people with an increased risk of caries or periodontitis as part of individual prophylaxis .
History
It is known from the Stone Age that people poke their teeth clean with willow sticks for dental care. The first toothpaste was handed down from ancient Egyptian doctors (approx. 4000 years ago), a mixture of ground pumice and wine vinegar on chewing sticks.
Alfred Kantorowicz was a pioneer of caries prophylaxis and school dental care between 1920 and 1960 .
Caries and periodontal prevention
Caries diseases of the teeth and diseases of the tooth support system have their common cause in plaque and its metabolic products . The primary caries and periodontal prophylaxis is directed to the creation of a possible plaque and calculus free mouth . This goal can only be achieved through appropriate oral hygiene measures.
Oral hygiene measures
In oral hygiene a distinction is made between dental care and denture hygiene . The aim of oral hygiene is the regular and thorough removal of food residues and plaque in order to prevent tooth decay, periodontal diseases and bad breath. Mouth rinses, sprays and mouthwashes alone cannot clean teeth and prosthesis surfaces sufficiently, at most larger food residues can be rinsed out.
The long-term success of existing dental restorations (mostly fillings ) also depends on good oral hygiene. In addition to the oral hygiene measures that everyone can carry out at home, regular professional teeth cleaning by the dentist or his auxiliary staff is usually recommended. For the patient, the aesthetic aspects are also very important in all oral hygiene measures. The teeth should be and stay as shiny and bright as possible. If there are accumulated stains and deposits, this can be done with mechanical plaque removal or professional teeth cleaning. However, when it comes to the “inner” tooth color, this can only be changed by tooth whitening (bleaching). However, clean teeth are also a prerequisite for this.
Toothbrushing technique
According to a ten-country study by University College London from August 2014, there are no differences in the various recommended toothbrushing techniques. It is criticized that dentists , dental organizations and professional associations in different countries recommend different techniques, which only lead to confusion and a loss of confidence of the patients in the educational efforts of the dental profession. There is also a lack of evidence-based studies on the effectiveness of the various toothbrushing techniques.
One should gently clean the teeth with a simple horizontal brushing motion, holding the toothbrush against the teeth at a forty-five degree angle. A mechanical brush should be held like a pencil and not with a fist to avoid pressing the toothbrush too hard. It is crucial that you brush specifically where the plaque has settled , and this is on the chewing surfaces and at the transition between tooth and gum , both on the outside and inside of the teeth.
A prophylactic effect by brushing your teeth has not yet been scientifically proven due to insufficient or insufficient quality studies.
Dental care (mechanical)
The Fourth German Oral Health Study (DMS-IV) showed in 2006 that 74.2% of children, 73.4% of adolescents, 72.8% of adults and 60.6% of seniors brush their teeth twice a day. This means that the importance of daily oral care, as recommended by dentists, is widespread, but not yet an integral part of oral hygiene for every fourth person. In addition to the toothbrush (manual or electric) and the toothpaste, the sugar-free chewing gum, the mouthwash / mouthwash solutions and sometimes (especially for adults) the dental floss were used.
After enjoying acidic foods such as fruit or zitronensäurehaltiger drinks brushing damages the with a toothbrush - easily etched - enamel. The role of the fluoride ion is that of a biocatalyst . If the pH value drops due to acid attacks, the CaF 2 top layer functions as a "slow releasing device". The released fluoride ion ensures the reincorporation of calcium and phosphate ions in the sense of remineralization. The remineralization process must be given enough time before brushing your teeth. However, other studies have shown that such a waiting time is not necessary as the remineralization process is slow; the positive effect of waiting is counteracted by the mostly contained sugar, which is broken down into lactic acid.
Rinse mouth
Rinsing the mouth with water after every meal and drinking sugary or acidic drinks reduces the bacterial flora, the food residues and the acid content, which promotes the prevention of dental diseases. In particular, the mouth should only be rinsed after vomiting because the tooth enamel is attacked by the stomach acid and should not be damaged with the toothbrush.
Toothbrushes
An electric toothbrush is basically an alternative to the conventional (non-electrically operated) toothbrush. A conventional toothbrush is just as good for dental care if used correctly, but it is often misused. Using an electric toothbrush, on the other hand, is a little easier. It is important to change the brush heads regularly. The brush head should be changed after about six to eight weeks, but at the latest when the bristles bend apart.
- Using the electric toothbrush
- The brush head is placed on the edge of the gum and moved over the tooth, starting from the gum. For each tooth, you start anew at the gum and brush from tooth to tooth. This ensures that the area around the gum line and the space between the teeth are cleaned as much as possible. According to current knowledge, a "massage" of the gums is not necessary. An electric toothbrush should not be used in a scrubbing manner. It is important to think about the easily forgotten last tooth and especially its back.
- Using the conventional toothbrush
- Brushes with medium-hard, rounded plastic bristles are particularly recommended. The ideal length of the brush head is 30 mm to 35 mm with 20 to 40 bristles combined in bundles. The brush head and handle should be shaped so that all teeth can be easily reached and cleaned. Special children's toothbrushes are available in stores.
toothpaste
Toothpaste supports the cleaning effect of the toothbrush through its content of polishing agents and other additives. They should achieve a high degree of cleaning, but have a low abrasive effect so as not to damage the tooth enamel . A toothpaste containing fluoride should be used to brush your teeth. In the evening in particular, it makes sense not to rinse your mouth after brushing your teeth. Because this allows the active ingredients of the toothpaste to work longer. The foam is only spat out. If you don't like this because of the taste, you should make sure to only rinse your mouth lightly.
Toothbrush tablets
Toothbrush tablets are pressed from dry raw materials. Due to the dry production process, fluorides and other ingredients cannot react with one another. In addition, preservatives can be dispensed with. Toothbrush tablets are not swallowed, but should be included in dental care in accordance with the package insert.
Interdental spaces
The spaces between the teeth also need to be looked after. They require special care as they can hardly be reached with a toothbrush. This is done thoroughly at least once a day with dental floss, tooth sticks or space brushes (so-called interdental brushes).
Floss
The evening is best for this. There are waxed and unwaxed dental floss on the market. The waxed version is recommended for beginners, as it tears less easily and slides better over the approximal contact point. More experienced users can use the unwaxed dental floss with an even better cleaning effect. If the interdental spaces are very narrow, dental floss is used, which is placed around one of the abutting surfaces and cleans the tooth by moving it up and down below the point at which the teeth meet laterally. For wider spaces and for the maintenance of bridges, the use of dental floss with fluffy, thicker parts is also helpful.
Tooth Stick
If the interdental spaces are slightly open, tooth sticks are suitable for removing plaque. The flat side of the stick points towards the gums. The stick is carefully moved back and forth between the inward / outward directions. There is a risk of injuring the gums. Toothed sticks such as Miswak have been used since ancient times .
Interdental brushes
Interdental brushes (including interdental brushes) are available in various diameters, shapes and designs. In the case of periodontal disease , they are considered to be the most effective care tool. Interdental brushes are also used for bridges or dentures on implants . Caution is advised in confined spaces as the gingival papilla can be injured or displaced.
Chemical plaque inhibition
Rinsing solutions, gels and toothpastes contain active ingredients that inhibit the formation of plaque or the formation of metabolic products of plaque. An attempt is made to partially dissolve existing plaque chemically .
Chlorhexidine digluconate
Chlorhexidine is effective against aerobic , anaerobic , gram-positive and gram-negative bacteria ( germs ). Depending on the concentration, it has a bactericidal and bacteriostatic effect . In a 0.1 percent to 0.2 percent aqueous solution , it can be used to reduce germs in the mouth. For long-term use, solutions with a lower concentration of 0.05 to 0.06% are recommended. Dental sprays with a high concentration (1.5%) are also available; the latter are used to reduce germs on toothbrushes and dentures. The use of chlorhexidine should be done after consulting the dentist. The effectiveness of chlorhexidine as a caries prophylaxis is controversial and "the data from clinical studies are not convincing [on this]".
Amine fluoride with tin fluoride
The combination of amine fluoride with tin fluoride is available as a solution or in gel form (fluoride content 0.025% F). The plaque-inhibiting and plaque-reducing effect is similar to that of chlorhexidine digluconate.
Enzymes
Attempts to limit plaque formation in humans with enzymes have so far been unsuccessful.
Sanguinarin
Sanguinarine is an alkaloid from the Canadian bloodroot ( Sanguinaria canadensis ). Toothpastes and rinsing solutions are added. It achieves its anti- microbial effect by interfering with nucleic acid synthesis and the enzymatic activity of plaque bacteria.
Tartar inhibitors
Tartar inhibitors are also additives in toothpastes and rinsing solutions; these are pyrophosphates , polyphosphonates , phosphonates and zinc citrate . They are supposed to inhibit the precipitation of calcium salts from the saliva. The effectiveness has not yet been proven.
Surfactants
Due to their chemical structure, surfactants can accumulate on surfaces and thus have a desorbing effect on the plaque bacteria. They hold the plaque bacteria in their foam and promote flushing. They are also added to toothpastes and rinsing solutions.
Other substances
They are not suitable as the sole means of removing plaque and their effectiveness has not been clearly proven, but they are added to toothpastes and rinsing solutions: hexetidine , phenols , quaternary ammonium compounds such as cetylpyridinium chloride .
bacteria
A new development is the use of lactic acid bacteria, for example as the main component of toothpaste: Lactobacillus paracasei against caries pathogens. These are able to specifically recognize caries bacteria, attach to them and then remove them.
Plaque levelers
Plaque levelers are substances that color the plaque and thus make it more visible. In the past, erythrosine was mostly used, today food coloring is used in tablet form or as a solution.
Solid color
Tablets with erythrosine stain areas of plaque on the teeth and the oral mucosa . The dye, which contains a lot of iodine but is approved as a food coloring, is suspected of causing allergies and should therefore not be used in the long term. See also iodine intolerance .
Two-tone staining
The test differentiates between older and newer plaque by means of various color additives. More neglected areas on the tooth become visible and can be cleaned more thoroughly in the future. The coloring tablets contain brilliant blue ( CI 42090) and phloxin B (CI 45410) as coloring agents . Phloxin (tetrachlorotetrabromofluorescein) is one of the xanthene dyes.
UV light
This rinsing solution specially developed for the dental practice contains fluorescein . Dental plaque fluoresces under UV light . This coloration remains invisible in normal light. When used properly, no health risks are to be expected.
Previously used solutions with the dyes fuchsine or crystal violet may contain amines that are harmful to health due to the manufacturing process . Continuous use of large amounts poses a carcinogenic risk.
Denture hygiene
Even dentures ( "The Third") needs intensive care. Removable dentures are cleaned thoroughly at least once a day. The surface of the denture, like your own teeth, is affected by plaque deposits, as are the spaces between the jaw and the denture and between your own teeth and the denture. Careless denture hygiene can result in bad breath, gingivitis and tooth decay on the remaining teeth, which can lead to the loss of additional teeth.
- Removable dentures are always cleaned outside of the mouth so that no food residues and bacteria stick to the underside of the denture.
- The coarse deposits are removed with a soft toothbrush at least once a day, preferably after each meal.
- The toothpaste should only contain a small amount of abrasive material in order to avoid abrasion damage and thus a rough surface of the prosthesis in which bacteria can settle.
- A cleaning bath with denture cleaning tablets is carried out once a day, which ensures hygienic cleanliness even in places that the toothbrush cannot reach.
Tongue hygiene
The coatings on the tongue are removed with a tongue scraper . Make sure that the scraper is positioned as far back as possible and is guided forward with very gentle pressure over the tongue. The removed substance is spat out and the mouth is then rinsed out.
Check-ups
At the dentist's, the patient fills out a questionnaire about their general medical history ( anamnesis ). This usually happens when he is treated for the first time in a practice. General diseases can affect dental health and pose specific treatment risks. In addition to the written self-assessment of the patient, the patient and doctor hold a conversation. The doctor may ask the patient to fill out a nutrition questionnaire in order to better assess the individual risk of tooth decay. This is followed by the intraoral findings, to determine which the doctor examines the patient's teeth, gums and the rest of the oral mucosa . The saliva flow rate is determined in individual cases .
The documentation of the tooth status follows. The recording of the condition of the teeth is referred to as tooth status . Missing teeth, replaced teeth, tooth decay, fillings, inlays , onlays , implants as well as misalignments or other dental diseases are recorded in writing or as a picture. As a white point ( white spot ) demineralized visible spots on the teeth referred to as initial carious lesion . If fluoride is used regularly and sufficiently, further destruction of the tooth enamel and thus the tooth can be stopped.
If the caries is more advanced and visible as a dark area or a hole, the dentist removes the diseased parts with the drill, cleans the cavity and provides the tooth with a filling . In this way, the progressive destruction of the diseased tooth can be prevented. If decayed teeth are not treated, the number of causative bacteria in the oral cavity increases and teeth that have previously been healthy are also at risk of decay. In many countries, such as the USA , such an examination is not carried out by dentists but also by dental hygienists .
Caries prophylaxis
Caries prophylaxis means preventive measures to prevent caries ( tooth decay ).
Contagion prevention
Tooth decay is an infectious disease , i. that is, it is caused by cariogenic bacteria ( Streptococcus mutans ). For example, some parents tend to clean the pacifier by licking it or sucking it off if the pacifier has fallen on the floor. The temperature of the milk in milk bottles is sometimes checked by the parents using preliminary costs. This makes it possible for the child to be infected with caries-causing oral bacteria . The most common transmission occurs via the pacifier and the milk bottle teat between mother and toddler. Other ways of transmission are also possible, for example through toys that are put into the mouth by children in playgroups or in kindergarten , thereby transmitting bacteria. A transmission, i.e. infection, can also take place through jointly used cutlery, jointly used toothbrushes or through kissing. The level of the concentration of Streptococcus mutans in saliva correlates closely with the risk of tooth decay. The microorganisms produce organic acids from low molecular weight carbohydrates , which attack the tooth by dissolving the minerals present in the hard tooth substance. Sugar from food is broken down into lactic acid . Only microorganisms that control this metabolic process (acidogenic microorganisms) and can survive in a strongly acidic environment (aciduric microorganisms) then continue to multiply. An early detection of the risk of caries, especially of pregnant mothers or carers, by means of suitable microbiological saliva tests as part of preventive examinations, is indicated.
Caries prophylaxis with fluorides
Here the effect of fluorides has been scientifically best researched. Fluorides are found in minerals around the world, albeit in varying amounts from region to region, and have been ingested with food and drinking water since time immemorial. Ingesting too large amounts can lead to acute or chronic poisoning ( fluorosis ).
Three possible mechanisms are listed for the caries-inhibiting effect of fluoride:
- the remineralization of decalcified enamel areas is promoted,
- the fermentation of sugar in the oral cavity is inhibited and
- the fluoride-rich tooth enamel becomes less acid-soluble.
The natural fluoride supply is generally sufficient for the human organism, but these amounts seem to be too low for adequate caries prophylaxis. For this reason, fluorides are also added, for example locally via toothpaste and mouthwash solutions or systemically in the form of tablets or fluoride-added table salt.
Fluoride application
Fluorides increase the resistance of the teeth against the attacks by the acidic metabolic products of the bacteria in the plaque or acids from food (fruit juices, soft drinks). Every toothpaste should contain fluoride for regular use. It is also possible to use a highly concentrated toothpaste (Duraphat toothpaste) 1–2 times a week. This requires a prescription and is relatively expensive. There are also various gels available that are only available from pharmacies . In patients with a high risk of tooth decay, an additional fluoride application by the dentist may be necessary.
Recommendations of the DGZMK
The German Society for Dentistry, Oral and Maxillofacial Medicine gives recommendations on caries prophylaxis with fluorides, especially in children and adolescents, based on the knowledge that fluorides mainly have a caries-inhibiting effect through direct contact with the hard tooth substance.
- From a dental point of view, no fluoridation measures are required before the age of six months. If fluoride is given, toothpaste containing fluoride should not be given at the same time, as overdoses (risk of dental fluorosis) can occur.
- The first milk teeth should be cleaned with children's toothpaste (maximum 500 ppm fluoride) 1–2 times a day.
- At the beginning of the third year of life (i.e. when the child is two years old), the milk teeth should be brushed twice a day, thorough cleaning in the evening is particularly important.
- In addition, the use of table salt containing fluoride is recommended; special fluoride tablets are generally not necessary and should only be given after consulting the dentist .
See also the academic dispute on fluoridation
Caries prophylaxis with xylitol
Xylitol is a sugar substitute that occurs naturally and also in the human metabolism as an intermediate product that is added to dental care chewing gum . Xylitol can form complexes with calcium and saliva proteins in the oral cavity , which is said to lead to a remineralization of tooth structure. With sufficient xylitol intake - according to studies at least 5 grams per day in several servings - no plaque forms on the teeth and thus the development of caries is prevented. Xylitol is absorbed by various microorganisms. However, due to the lack of metabolism, this leads to the death of these microorganisms. First and foremost, Streptococcus mutans should be mentioned, which is responsible for the formation of plaque and subsequently for dental caries. Thus, a reduction in tooth decay through xylitol alone is considered to be possible to a high degree.
Nutritional advice and guidance
In addition to general nutritional advice, a tooth-healthy diet is the focus from a dental perspective. Sugar in particular promotes the development of tooth decay. Sugar is a low molecular weight carbohydrate that also promotes caries in the form of honey , glucose and fructose .
| Food | Sugar content in g / 100 g |
|---|---|
| confectionery | → 90 → 60 → 20 → 20 |
| Spreads | → 75 → 60 → 50-60 |
| Canned fruit | 16-44 |
| Sweetened fruit juice |
10-20 |
| Fresh fruit bananas |
18th |
| Dried fruits | 40-64 |
| Cola drinks | 8-11 |
| tomato ketchup | 28-30 |
Snacks between meals
The pH in the mouth drops after a meal . Depending on the food you eat, it takes different amounts of time for the bacteria in your mouth to process the remains into acid. The saliva automatically neutralizes the pH value after a while. The process can be accelerated with "chewable toothbrushes" , toothbrush tablets or dental care chewing gum. However, this cannot replace brushing, as the germs that damage the gums are not affected and the plaque is not removed.
To neutralize the acid in the mouth, an alkaline mouthwash solution made from one tablespoon of baking soda to 0.5 liters of water can be used.
Tooth enamel erosion
Acidic drinks such as cola and energy drinks are also important, as acid can also attack tooth enamel. In particular, erosions occur on the tooth when acidic drinks are consumed repeatedly throughout the day.
Sealing of deep fissures
After the teeth have erupted, the fissures can be colonized by microorganisms. Since fissures can be very deep (up to 1 mm) and very narrow (50 μm), effective cleaning is often impossible.
In the case of people at risk of caries, the dentist can seal the still caries-free fissures with a thin synthetic resin or composite material shortly after the tooth eruption, in order to prevent colonization by the oral flora (fissure sealing). If the fissure is already colonized, it must first be cleaned by grinding or sandblasting and possibly expanded a little (extended or invasive fissure sealing).
See also
literature
- S2k guideline for caries prophylaxis in permanent teeth - basic recommendations of the German Society for Dental Preservation (DGZ) and the German Society for Dentistry, Oral and Maxillofacial Medicine (DGZMK). In: AWMF online (as of June 2016)
- S2k guideline fluoridation measures for caries prophylaxis of the German Society for Dentistry, Oral and Maxillofacial Medicine (DGZMK) u. a .. In: AWMF online (January 2013)
- S2k guideline for fissure and dimple sealing of the German Society for Children's Dentistry eV (DGKiZ), the German Society for Dental Preservation (DGZ) and the German Society for Dentistry, Oral and Maxillofacial Medicine (DGZMK) and a .. In: AWMF online (as of January 2017)
- Christoph Benz: Dental project - typical problems in old people's homes - solution approaches for practice. In: ProAlter. 3/2006, pp. 63-66.
- Klaus M. Lehmann, Elmar Hellwig: Dental Propaedeutics. 9th edition. Urban & Fischer, Munich / Jena 2002, ISBN 3-437-05390-6 .
- Elmar Hellwig, Joachim Klimek , Thomas Attin: Introduction to tooth preservation . Urban & Schwarzenberg Verlag, Munich 1995, ISBN 3-541-18601-1 .
- Volker Ladenthin: Dental care in all-day school. In: engagement. Journal for Education and School. Issue 1, 2008, pp. 64f, ISSN 0723-3507 .
Web links
Individual evidence
- ^ Wilhelm Pape: Concise dictionary of the Greek language. Braunschweig 31914, Volume 2, p. 798. Keyword προ-φύλαξις ( digitized version )
- ^ Wilhelm Pape: Concise dictionary of the Greek language. Braunschweig 31914, Volume 2, p. 798. Keyword προ-φυλάσσω ( digitized version )
- ↑ Ali Vicdani Doyum: Alfred Kantorowicz with special reference to his work in İstanbul (A contribution to the history of modern dentistry). Medical dissertation, Würzburg 1985, pp. 212-218 and more often.
- ↑ a b What's the best way to brush teeth? University College London, 7th August 2014.
- ↑ J. Wainwright, A. Sheiham: An analysis of methods of toothbrushing recommended by dental associations, toothpaste and toothbrush companies and in dental texts. In: British dental journal. Volume 217, Number 3, August 2014, p. E5, ISSN 1476-5373 . doi: 10.1038 / sj.bdj.2014.651 . PMID 25104719 .
- ↑ Jochen Paulus: What use is cleaning and prophylaxis? Südwestdeutscher Rundfunk, February 14, 2017, accessed December 10, 2018 .
- ↑ Summary DMS-IV study 2006 (PDF; 74 kB) by the Institute of German Dentists
- ↑ H. Michel: How does the fluoride really work? ( Memento of the original from July 19, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. In: ZBay. 3/2000, p. 41.
- ↑ 30 minutes of parental leave are unnecessary. Retrieved February 6, 2020 .
- ↑ JI Gluch: As an Adjunct to Tooth Brushing, Interdental Brushes (IDBs) are More Effective in Removing Plaque as Compared With Brushing Alone or the Combination Use of Tooth Brushing and Dental Floss. In: Journal of Evidence Based Dental Practice. Volume 12, Issue 2, June 2012, pp. 81–83, ISSN 1532-3382 , doi: 10.1016 / j.jebdp.2012.03.016
- ^ Autio-Gold J: The role of chlorhexidine in caries prevention . In: Opera Dent . 33, No. 6, 2008, pp. 710-6. doi : 10.2341 / 08-3 . PMID 19051866 .
- ↑ E. Kramer: Prophylaxis primer: Fundamentals of dental health. 10th edition. Deutscher Zahnärzte Verlag, 2008, ISBN 978-3-7691-3391-2 .
- ↑ A. Sharma et al .: Dermatoglyphic interpretation of dental caries and its correlation to salivary bacteria interactions: An in vivo study In: JISPPD. Vol. 27, No. 1, 2009, pp. 17-21. PMID 19414969 doi: 10.4103 / 0970-4388.50811
- ↑ Caries in small children due to primary infection with Streptococcus mutans. In: Monthly Pediatrics. Volume 150, Issue 5, May 2002, pp. 603-607. ISSN 0026-9298
- ↑ P. Jain, P. Nihill, J. Sobkowski, MZ Agustin: Commercial soft drinks: pH and in vitro dissolution of enamel. In: Gen Dent. 55 (2), Mar-Apr 2007, pp. 150-154. PMID 17333990
- ↑ M. Kitchens, BM Owens: Effect of carbonated beverages, coffee, sports and high energy drinks, and bottled water on the in vitro erosion characteristics of dental enamel. In: J Clin Pediatr Dent. 31 (3), Spring 2007, pp. 153-159. PMID 17550037
- ↑ BM Owens, M. Kitchens: The erosive potential of soft drinks on enamel surface substrate: an in vitro scanning electron microscopy investigation. In: J Contemp Dent Pract. 8 (7), Nov 1, 2007, pp. 11-20. PMID 17994150
