Dentin, also known as dentin, is one of the hard dental substances and proportionally forms its main mass. After tooth enamel, it is the second hardest substance in our body and lies between the tooth enamel, which is on the surface, and the root cement, which is the surface of the root. The dentin encloses the pulp, the tooth pulp, which is permeated with blood and nerve vessels.
As with tooth enamel, the crystals of hydroxyapatite form the majority of the components in dentine, but this proportion is not as high as in tooth enamel, which makes dentine slightly softer. In terms of color, the dentin is significantly more yellow than the light enamel, which is why exposed tooth necks form a strong contrast to the enamel color.
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Read more on the topic: Tooth structure
The cells that form dentin are called odontoblasts. They lie on the edge of the pulp, the pulp, towards the dentin layer and have small cell processes that completely penetrate the dentin and act as a kind of antenna. They swim together with nerve fibers in a liquid and can thus receive pain stimuli and pass them on to the pulp. The odontoblasts do not subside after dentin formation, but are preserved for life, so that dentin can always be formed.
The primary dentine is the first dentine that is formed during tooth development. Any dentin that occurs after that is called secondary dentin. Due to the preservation of the odontoblasts, there is constant dentin formation. This ensures that the pulp gradually withdraws. That is the reason why older people feel thermal stimuli less well and the tooth pulp in this patient group is significantly smaller than in adolescents. The dentin that is reproduced throughout life is called secondary dentin, while there is another form of dentin.
$config[ads_text2] not foundThe so-called irritant dentin is formed when a painful stimulus reaches the pulp through the dentinal canals. This tertiary or irritant dentine tries to protect the pulp from pain stimuli and to protect the nerve inside the pulp from damage. Tertiary dentine is also formed when the teeth are stimulated by tooth decay or when the teeth are worn down when grinding.
The dentin forms the middle layer between tooth enamel and pulp and creates a connection between these two structures. Through the processes of the odontoblasts, which lie on the edge of the pulp and reach through the dentin to the enamel, any stimuli that reach the tooth from the outside will also reach the inside of the pulp. The tooth feels cold, warmth or pain through these extensions and transmits these signals to the brain so that the dentin acts as a mediator.
Furthermore, the tertiary or irritant dentine forms a protective mechanism for the tooth, in that the dentine is formed in the event of any pain stimuli. It tries to protect the pulp at the affected area where the stimulus arrived so that it is not irritated or even damaged. Tertiary dentine is formed in the event of irritation from grinding, tooth decay or inflammation of the gums, periodontitis. However, due to the regular and constant formation of secondary dentin, which takes place throughout life, the pulp gradually retreats, so that the older the person, the less sensitive the teeth.
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The majority of pain in the dentin is caused by tooth decay. The caries "eats" its way from the outside in. It arises on the outermost layer, the tooth enamel, and gradually progresses. Once the caries has reached the dentin, it is not reversible and must be treated to prevent it from enlarging.
$config[ads_text2] not foundDue to the softer structural properties, caries can spread faster in dentin than in enamel, which increases the risk of pulp infection. Once the bacteria have arrived in the dentine, the pain stimuli are passed on to the pulp and the brain through the nerves in the dentine, resulting in toothache. This can arise when chewing, eating, but also for no reason and can take on very strong proportions.
Only removing caries and filling the defect with a filling material helps therapeutically. Furthermore, pain in the dentin can arise if it is exposed. This phenomenon occurs primarily on the necks of the teeth when the gums are pulled up by too forceful brushing and the dentin is no longer covered with gums. As a result, stimuli of any kind arrive much more intensely and directly and generate pain stimuli, as the region is very sensitive. Wedge-shaped defects on the tooth necks are also caused by grinding and pressing and erosion due to too much acid.
Read more on the topic: Tooth neck is exposed - what to do?
When the dentin is exposed, the patient experiences unpleasant symptoms. The dentinal canals are now directly on the surface and the stimuli that reach the tooth are now directly on the nerve fibers. Usually, the enamel or gums are the protective layer that weakens an incoming stimulus before it reaches the dentin and nerves. The lack of protection means that the stimulus is stronger and more intense.
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Patients perceive thermal stimuli and painful stimuli, such as lightning bolts, which are very uncomfortable. Exposed dentin can have several causes. Brushing your teeth with too much pressure in the posterior area and front teeth can stimulate the gums to pull themselves up. The necks of the teeth are exposed and are much more sensitive to stimuli. Just pulling cold air through the oral cavity can trigger a painful stimulus.
Furthermore, grinding and pressing at night can cause abrasion due to the heavy chewing load on the teeth, which exposes the dentin. Another cause arises from acidic foods which, if consumed in excess, gradually dissolve the tooth enamel and become evident as erosion. Erosion is also possible due to frequent vomiting in the eating disorder form bulimia. The corrosive gastric acid constantly hits the enamel of the teeth and gradually dissolves it, which is why the dentin can be exposed.
Dentin can also appear if too often abrasive toothpaste with a whitening effect is used to rub off the tooth enamel. This phenomenon can also come into play if teeth are bleached too often.
Some manufacturers have products on the market that can seal the dentin canals on the surface. They form a kind of seal. These so-called desentisizers are applied to the exposed tooth necks and cured with a curing lamp. The liquid settles into the ends of the channels and closes them off, making them less sensitive. This process is repeated three times. After half a year to three quarters of a year, however, this protective layer wipes away again, which is why the sealing only provides temporary relief. Another temporary solution is the application of highly concentrated fluoride varnishes, which also achieve a temporary protective effect.
In the case of massive plaster defects, only a definitive plastic filling helps to cover the sensitive area and also restore the aesthetics, since dentin is significantly darker and more yellow than tooth enamel. However, these fillings do not last long-term when chewed, which is why alternatives such as crowns, veneers or surgical crown lengthening through mucous membrane should be considered. The gums that have pulled up do not grow back into their original place.
$config[ads_text1] not foundIn the case of massive defects, the exposed tooth neck can only be covered by a mucosal graft. As a rule, a piece of mucous membrane and connective tissue is surgically removed from the palate and sewn back into the neck of the tooth. However, this intervention is a purely private service and is not covered by the statutory health insurance.
The term dentin adhesive filling describes a special way of attaching a plastic filling to a tooth. This is necessary because dentin has special material properties and therefore requires special treatment. Dentin is water-loving (= hydrophilic) due to its high organic content. The plastic is just the opposite, it's hydrophobic, which means it won't bond with water. If the dentist tries to connect the hydrophobic plastic with the hydrophilic dentin, it only works with an intermediary.
After their chemical hardening, so-called primers enable a firm bond between dentin and resin and can thus overcome the natural barrier between the two substances. The primer is a thin-bodied substance that protects the dentin from drying out and at the same time creates a micromechanical connection that bonds dentin and resin over the long term. Due to this strong bond, no special anchoring is necessary through special grinding by the dentist and can thus conserve substance.
Slight, superficial injuries to the dentin can be regenerated with concentrated fluoride applications. In the case of deep and severe damage, for example due to caries, this must first be removed and the defect covered with plastic again. If the lesion is so large that a filling cannot replace it, dentures are necessary. Partial crowns, veneers or crowns can repair the defect.
Dentin differs in structure and color from tooth enamel. While the enamel bears the radiant white, the dentin is yellowish and much darker. However, this discoloration is not pathological, but normal. If the person concerned finds this unaesthetic, dentin can be bleached. However, liquid is always withdrawn from the substance, which can weaken the structure. Thus, it should be weighed whether whitening is necessary. Fillings and dentures such as veneers and crowns can also cover up discoloration.
Due to its nature, dentin is the second hardest structure in our body after tooth enamel. If the body receives too little fluoride through food and dental care, the dentin becomes softer and weakened. The dentin can only be strengthened by remineralising the hard tooth substance through regular fluoridation and thorough dental care. Dentin is able to store fluoride in the mass and thus strengthen it, which is why targeted fluoridation once a week provides lasting protection for the tooth. In this way, the dentin can also be protected from tooth decay in order to promote natural oral health.
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In contrast to tooth enamel, dentine can regenerate. The dentin-forming cells, the odontoblasts, remain active after formation and can form dentin again without perishing, as is the case with enamel. The odontoblasts regularly form dentin throughout their life, so that the pulp gradually retreats over the course of life and the mass of the dentin increases. In addition, they are able to form dentin in response to certain stimuli and thus have a natural protective function.
