Each person goes through the stages of the eruption of the first teeth, the development of milk teeth and their subsequent replacement by permanent ones. Despite their similar appearance and function, temporary and permanent teeth have differences, which we will talk about, at the same time we will consider the timing of the appearance of the main teeth, possible problems with them in the process of their development.
The photo shows a diagram of the structure of human teeth
Functional properties of elements
Teeth perform several functions at once. Each element has a distinctive shape according to its purpose. The main role of the units is digestive. The quality of assimilation of useful elements by the body depends on the thoroughness of grinding the products. Only after chewing and moistening with saliva will the food be ready for subsequent processing by the digestive organs.
Chewing one piece lasts on average 10-20 minutes. The force exerted by the teeth on food sometimes reaches 80 kg. Incomplete dentition can lead to disturbances in the digestive system.
Another function of the elements is aesthetic. With malocclusion, a person may develop psychological problems, since the first thing others pay attention to during a conversation is a smile. Teeth also play a role in the formation of syllables. In the absence of one or more elements, the pronunciation of syllables changes: a lisp appears, speech is distorted.
What are teeth called in dentistry: designation systems
- Two-digit numbering. Designation in accordance with international standards. In addition to the tooth number, the quadrant of the oral cavity is indicated. Quadrant numbering starts from the top right side with 1, then to the top left side (2), bottom left (3) and bottom right (4). If the number 21 is written, then we are talking about the central left incisor of the upper jaw.
- Square-digital. In this case, the jaw is divided into two equal areas. The elements of the dental system are counted from 1 to 8. For the most accurate identification of a dental unit, the number, jaw and location are prescribed.
- Universal. An accessible designation in which each unit of the dentition is assigned a number from 1 to 32. The Latin alphabet is used to identify primary teeth.
In addition, the alphanumeric and Haderup systems are used, but they are used extremely rarely in practice.
Tooth anatomy
The structure of all units is the same, but each tooth has a distinctive shape and dimensions, depending on the functions it performs.
Internal structure of teeth in the photo
What does a tooth consist of? The top layer (enamel) is predominantly composed of minerals. It protects the inner layers of the tooth from mechanical, thermal and chemical damage. The rest of the solid surface of the elements consists of proteins and liquid involved in metabolic processes. This layer tends to wear out and wear off over time. Typically, caries first affects the surface of the tooth. For this reason, you should carefully monitor the condition of the oral cavity and carry out hygiene procedures in a timely manner.
If you examine a tooth in cross-section, you can also see dentin. It also consists of mineral substances and protects the pulp with the nerve fibers located in it. Many small channels are localized in dentin, with the help of which metabolic processes in bone tissue are carried out. Through these structures impulses are transmitted between nerve endings. For 1 sq. mm of dentin there are about 70,000 microscopic tubules.
The internal cavity of the elements is represented by pulp. It consists of nerve endings and lymph nodes.
The structure of the tooth should be considered depending on its location relative to the gum. The visible part of the element is the crown. The area of contact between the tooth and the gum is called the periodontium. The root is located in a special cavity, which dentists call the alveolus. The root of the tooth ends at an apex, which is supplied with blood vessels. Through these structures, the elements are fed.
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Difference between baby teeth and permanent teeth.
PHOTO: Caries of primary front teeth. The enamel of baby teeth is thinner and less mineralized, which makes it less resistant to caries.
Unlike permanent teeth, the “lifespan” of primary teeth is much shorter. Resorption of tooth roots begins 2-3 years after their eruption in the oral cavity and continues until they fall out.
Contrary to popular belief, baby teeth, just like permanent teeth, have roots and a nerve (pulp). The roots hold the tooth in the bone. Under the milk tooth is the germ of a permanent tooth. As the permanent tooth erupts, it stimulates the resorption of the roots of the baby tooth, and by the time the baby tooth falls out, only the crown remains.
Since baby teeth (like permanent teeth) have a nerve (pulp), they can hurt if an infection from a carious cavity enters the tooth cavity, causing the development of pulpitis (inflammation of the nerve of the tooth).
392measures and structure.
- Primary teeth are smaller than permanent teeth and have less massive roots;
- Baby teeth have a more complex anatomical structure of root canals, which leads to a more labor-intensive treatment process than in permanent teeth;
- The hard tissues of primary teeth are less mineralized and less resistant to abrasion and the development of caries.
- the hard tissues of baby teeth are much thinner than those of permanent teeth: the inflammatory process quickly reaches the nerve of the tooth;
Kinds
What are the units? Teeth in the oral cavity are divided into 4 types: incisors, canines, molars and premolars. The human jaw is symmetrical and each part (right and left) has the same number of elements. If this does not happen, then they talk about malocclusion development, which requires immediate correction.
Incisors
Incisors are the elements located in the center of the jaw. There are 8 such units in total - 4 at the bottom and 4 at the top. The peculiarity of the anatomy of the incisors is that they have a flat crown with a sharp cutting surface. There are 3 tubercles on the cuts of the incisors, which wear off over time. The centrally located elements are usually larger than the lateral incisors, since they bear more load when chewing food.
The upper central teeth are most susceptible to damage in the form of cracks in the enamel and chips. It is in these areas that aesthetic defects associated with improper placement of elements in the oral cavity and trema are usually noted.
Crown – part of the tooth protruding above the gum
It should be noted the main functions of the incisors are the primary capture of food, cutting pieces and chewing them. The central elements are the first to begin to chop the food and pass it further. Due to the sharp cutting edge, units and twos crumble and crush food for further normal absorption. The incisors protect the remaining elements from severe damage during chewing loads. In addition, they protect the digestive organs from the development of chronic diseases associated with insufficient absorption of nutrients by the intestines.
On the upper jaw, the units have impressive dimensions - up to 23 mm including the root system. Unit width is from 4 to 6 mm. Thanks to the flat crown, the chewing load is distributed evenly between all areas of the tooth. The thinnest enamel of the incisors is in the area of contact with the gum. It is this part that is most vulnerable to carious processes.
Several features of incisors should be noted:
- rounded root shape;
- the presence of grooves on the surface of the root;
- chisel shape;
- greater curvature of the incisors located on the sides.
Fangs
A person has 2 fangs on each jaw. They resemble a triangle in shape and are easily recognized among other elements of the series. With the help of fangs, a person can bite off pieces of hard foods - apples, carrots, crackers. The elements have only one long root. The upper units are larger than the lower ones. Some patients resort to extension procedures to give greater effect to the canines on the upper jaw.
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Premolars
The first premolar is also called a quadruple. The main function of the tooth is transitional and exciting. Due to the wider crown, the elements take part not only in biting off pieces of food, but also in grinding it to the desired state.
On the chewing surface of the element there are several types of chewing tubercles - flat and vestibular. The first tubercle is located closer to the cheek, and the last one is directed towards the oral cavity. In rare cases, three-tubercle or four-tubercle teeth are found. An anomaly is observed if the palatine tubercle passes into the median tubercle.
Due to the many grooves and fissures, pathogenic bacteria can accumulate on the surface of premolar teeth, especially if oral hygiene is insufficient. For this reason, these segments should be given the most attention when brushing your teeth. The second premolar of the upper and lower rows has larger dimensions, but is shaped like a quad.
Molars
Molars have the same structure as the rest of the series. But, despite this, several features can be identified that are characteristic only of sixes and sevens. The main function of molars is to grind and grind food during chewing. They play an important role in the formation of an anatomically correct bite.
Each half of the jaw has 4 molars below and above. Molars have several chewing surfaces. The buccal surface of the tooth is convex. There is a groove on it, which is a place where pathogenic flora accumulates. These areas also need to be given special attention when brushing your teeth, since the salivary glands are located near the buccal surface, which are affected during the development of carious processes.
There are 3 tubercles on the chewing surface: paracone, protocone and metacone. On the buccal side there is also the most important morphological structure of bone tissue - the Carabelli tubercle. The degree of expression of the structure is varied.
In some cases, the Carabelli tubercle may have its own process
The mesial border of the molars has a slightly convex shape. The root system on this side varies in shape among different patients. It can be cylindrical or barrel-shaped. The structure of the distal surface of the molars is similar to the mesial one. The only difference is inaccessibility during hygiene measures. For high-quality cleaning of the last elements, it is better to use floss or irrigator.
Wisdom tooth
Eight, or wisdom teeth, usually appear on the surface of the gums in adulthood. The shape of the element is similar to 6, but has more powerful roots. The number eight is considered the most problematic tooth: it is difficult to break through to the surface and quickly collapses. Dentists may have difficulty removing figure eights due to their abnormal position in the mouth and crooked roots, which can be diagnosed using x-rays. In such cases, the problem area is immediately extracted, otherwise purulent inflammation of the soft tissues may develop. Another serious complication of improperly positioned wisdom teeth is the destruction of the roots of adjacent units.
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Possible problems
At the moment the molars appear, certain dental problems are possible. In order to take timely measures to eliminate them, parents must have an idea about them.
Molars do not erupt
A situation is possible in which baby teeth do not fall out in a timely manner, or they have fallen out, but molars have begun to appear in their place. The reason for this must be determined by the dentist, who must be visited without delay. A general x-ray is usually taken to show the degree of development of the molars.
Among the options for the lack of eruption of molars in due time can be indicated:
- Hereditary predisposition, which is the cause of a possible delay in the appearance of molars. If the x-ray shows that the process of forming the rudiments of teeth is underway, then you will just have to wait a little for their appearance.
- Adentia. Disturbances in the processes of formation of tooth germs during the intrauterine development of a child, inflammatory processes can lead to a similar pathology - the absence or death of tooth germs. The solution is prosthetics.
Pain
The first time after teething, the tooth is poorly protected from caries and the effects of various bacteria. This is explained by the low degree of enamel mineralization at the initial stage. Almost nothing interferes with the development of caries; tooth tissue is destroyed, pulpitis occurs, with the subsequent risk of its transition to periodontitis. Severe pain, changes in body temperature and deterioration in well-being may occur.
It is highly advisable not to let the situation get worse, not to cause severe pain, but to visit a dentist as soon as painful sensations appear. If a child is predisposed to caries, it is better to carry out preventive procedures, for example, fissure sealing. The folds on the chewing surface are covered with a composite material that protects such natural cavities from the accumulation of food debris in them, the development of bacteria, and inflammatory processes.
In the worst case, you can lose a tooth.
Teeth grow crooked
A common situation is when the molar has already begun to erupt, but the baby tooth does not want to fall out. The result is that the new tooth seeks alternative growth paths, which leads to its displacement and change in the direction of growth. Hence the malocclusion and the alignment of the dentition. Treatment by an orthodontist will be required.
If this situation occurs, you should not remove or loosen a baby tooth yourself; you should visit a doctor.
Loss of molars
An alarming symptom of the presence of diseases (caries, etc.) in the oral cavity, or there are problems with the entire body (connective tissue diseases, diabetes, etc.). A visit to the doctor is mandatory.
This is necessary to develop a strategy for restoring a lost tooth. This is necessary for the proper growth of the remaining teeth and the formation of the maxillofacial system. Considering that the jaw tissue is still in the process of growth, prosthetics are only possible temporary, which must be adjusted as the jaws develop. Permanent prosthetics will be available only after their formation is completed.
Injuries
The first few years after teething, teeth are at increased risk of injury from impact. Sports injuries, falls, and blows can lead to chipping of parts of the tooth and cracks. Be sure to contact a dentist who will restore the lost part with modern materials.
Classification of dental surfaces
To conveniently describe the localization of the pathological process, dentists use a term such as “crown surface”. There are 4 types of such surfaces:
Where is the eye tooth + photo
- Chewable. This part of the tooth faces the elements on the opposite jaw. In canines and incisors, this area is represented by the cutting edge.
- Vestibular. Located in the vestibule of the oral cavity. The vestibular surface of the anterior teeth has an area of contact with the lips. In the molars, this part is in contact with the inner shell of the cheek and is called the buccal surface.
- Lingual or lingual - the area of elements facing the tongue. It is in this area that the largest amount of plaque accumulates due to the difficulty of carrying out hygiene measures. The lingual side of the elements is not visible to others during a conversation, so many patients seek to install corrective systems on the inside of the tooth.
- Approximal. This type of surface is divided into medial and distal. In the first case, the area is located closer to the middle of the dentition, in the second case, closer to the edge of the arch.
Tooth surfaces
Regeneration of dental tissues
Restoration of enamel, dentin, pulp and cement is possible, but not in all clinical cases.
Regeneration of the anterior and chewing teeth, as a rule, occurs due to the following processes:
- replenishment of enamel with minerals, which is carried out both from saliva and through the blood vessels of the pulp;
- in the pulp chamber, cellular elements form a special connective tissue capsule around the inflammatory focus, thereby preventing further spread of infection;
Features of milk elements
Milk units act as precursors of permanent elements. They usually appear in the first year of a baby's life. Usually the period of eruption of the first incisors is accompanied by painful symptoms for the baby. About 2-3 years may pass between the appearance of the first and the eruption of the last milk tooth. A 3-4 year old child has 20 fully formed baby teeth in his mouth.
The structure of teeth in children
The change of the primary occlusion to a permanent one is carried out from 6-7 years of age. The shape of the permanent elements will differ little from their predecessors. The only difference is the more massive crown part and dense enamel.
In children, the degree of mineralization of enamel and dentin is weaker than in adults. Therefore, their dental care should be carried out with special care. The milk tooth is designed in such a way that most of its volume is occupied by the pulp, so caries in children becomes more complicated faster.
Another difference between milk units and permanent ones is short roots. For this reason, tooth loss in children sometimes occurs unnoticed and painlessly.
Signs of the imminent appearance of molars
You can determine when you should soon wait for the baby teeth to begin replacing with permanent teeth based on several signs:
- The gradual growth of the baby's jaws leads to increasing gaps between the teeth.
- The tooth begins to wobble. This is due to the fact that the already small root begins to gradually dissolve, causing the fixation of baby teeth to be significantly weakened.
- A fallen tooth indicates that the formed permanent one, which is about to appear, pushed it out.
- Swelling and redness may appear on the gums at the site of the eruption of a permanent tooth.
- Pain in the gums, where the permanent tooth erupts, increased temperature, and poor health of the child indicate problems have arisen, and it is necessary to see a doctor. The process of erupting molars should be painless.
Malocclusions
With a correct bite, the teeth of the upper jaw protrude onto the elements of the lower jaw by no more than 1/3. This position will make it easier for the jaws to chop food. Malocclusions are usually associated with the following conditions:
- The upper units overlap the lower ones by more than ½. This type of bite is usually called a deep bite.
- Certain groups of teeth may not fit together at all. In this case, they talk about an open bite.
- Distal bite. What it is? The problem is said to occur when the upper jaw is overdeveloped.
- If the lower jaw is pushed forward, then there is a mesial deviation.
- When the structures are displaced relative to each other, a cross anomaly occurs.
If not treated promptly, malocclusions can cause toothless jaws. For this reason, it is important to contact an orthodontist at the first sign of a problem.
Teething order
At the time of birth, the baby has no teeth, but there are exceptions to this rule. Often, the order of growth of baby teeth is as follows:
- Teething begins at the age of 6-8 months. The first to appear are the central incisors of the lower and then the upper jaws. This is the very moment when you should worry about choosing the first toothbrush for your offspring.
- Between 8 and 12 months, the lateral incisors are added.
- At 10-16 the fangs take their place.
- At one and a half years, the back teeth (or molars) usually erupt completely.
The primary dentition completes its formation by the age of three, when the second back teeth begin to grow.
Carefully monitor the teething process until it is completed, since during this period the first pathologies may appear, such as childhood bruxism (teeth grinding). At the slightest suspicion, consult an orthodontist.
What is a dental formula
A dental formula or diagram is a brief description of the dental structure of the human dentition using numbers and Latin letters.
The letters are abbreviations from the Latin names of teeth accepted in medicine:
- I – these are dentes incisivi or incisors.
- C is for dentes canini or fangs.
- P stands for dentes premolars or premolars.
- M stands for dentes molars or molars.
The alphanumeric dental formula is common in many countries, including America, which is why it is sometimes called American. After the letters in the formula there is always a digital fraction, where the numerator indicates the number of teeth on the upper jaw, and the denominator on the lower jaw.
The dental formula of a healthy adult with a normal bite and 32 teeth looks like this:
This formula indicates that on each human jaw there is:
- 2 pairs of incisors;
- 1 pair of fangs;
- 2 pairs of premolars;
- 3 pairs of molars.
Dental formula in the absence of some teeth
It is not difficult to correctly number dental units with a healthy dentofacial apparatus; it is much more difficult to indicate the location of the teeth if a person does not have any molars, incisors, canines or premolars. In this case, the dentist indicates the number 0 opposite a certain group of teeth, rather than shifting the number series.
If the patient has any anomalies in the development of the dentofacial apparatus, for example, teething in the wrong place (hyperdontia, polydontia), the dentist prescribes an individual formula. In addition to numerical designations, the doctor generates a detailed report on the structure of a person’s dentition.
Alternative names for human teeth
In addition to the official names, there are also alternative names for human teeth. They are not written in dental records, but have long been used in informal communication, since these teeth in people are located or grow in certain places or at certain times.
Eye teeth
The upper canines are called eye teeth because of their close location to the branches of the facial nerve. When they become inflamed, the pain radiates to the eye area and upper face. How close the incisive canals and the dental nerve are located to each other is shown in the figure:
Wisdom tooth
The wisdom tooth is the posterior third molar. He was called “wise” because he grows up in adulthood - when a person has already gained wisdom (by about 20 years).
