Upper canine teeth in humans. The structure of the jaw and teeth in humans: canines, molars and incisors. Molar teeth - anatomy

Teeth are an integral part of the chewing and speech apparatus and are ossified papillae of the oral mucosa.

An adult has 32 teeth. In the process of life, their change occurs twice.

The anatomy of the teeth of the upper and lower jaws has a slight difference, consisting in the shape of the crowns, the number and structure of the roots.

Anatomy of teeth

In humans, teeth are located in the cells of the alveolar processes of the jaws, which are located in the oral cavity.

1. Crown - is the most massive part, protrudes above the alveolus, and forms rows (upper and lower).
2. Neck - located between the root and the crown and in contact with the mucous membrane of the oral cavity.
3. Root - has an apex through which arteries supplying nutrients, veins, lymphatic vessels, providing an outflow of excess fluid, nerves enter the tooth. The root is inside the alveoli.

The crown is covered with enamel and the root with cement.

Inside the tooth there is a cavity filled with pulp. By structure, it is a loose connective tissue. and performs an important function, it contains nerves and blood vessels.

The basis of the tooth is dentin:

• Primary - formed before eruption.
• Secondary - throughout the life of the tooth.
• Tertiary - for injuries and injuries.

The cavity of the tooth is subdivided into the cavity of the crown and the canal of the tooth root. In accordance with the cavity, the pulp of the crown and the pulp of the root of the tooth are isolated.

Enamel is 97% inorganic and 3% water. Of all the tissues of the human body, it is the hardest, this feature is directly related to its chemical composition. The thickness of the enamel in various places of the crown ranges from 0.1 mm to 2.5 mm. The color changes from yellow to grayish-white, which directly depends on the transparency of the enamel.

Anatomical structure of the tooth

The more transparent the enamel, the more the dentin, which has a yellow color, is translucent. Transparency is characterized by its degree of mineralization and homogeneity.

Enamel is covered with cuticle. The cuticle is a thin, strong shell, devoid of minerals. The main function of the cuticle is to protect the enamel from harmful substances. However, even enamel is prone to decay (caries) with improper care.

The natural environment of the oral cavity is alkaline. After each meal, the breakdown of carbohydrates begins with the participation of various bacteria, the products of which are acids.

After eating, the acidity of the oral cavity increases, which adversely affects the enamel. Therefore, it is necessary to remember the rules of personal hygiene and timely care for the oral cavity.

Types of teeth by main function

By shape, the teeth are divided into:

• incisors;
• fangs;
• small and large indigenous.

The structure of the teeth

There are 4 incisors in the mouth- a pair on the upper and lower jaw. The incisors are chisel-shaped. The function of the incisors is to bite off food. The crown of the upper incisors is much wider than the lower, the root is longer. Incisors have 1 root. The root of the mandibular incisors is compressed laterally.

Humans have 2 canines in each dentition. They have a conical shape, 2 cutting edges. The root is slightly longer than that of the incisors, compressed from the sides. The main function of the fangs is biting off and chewing more solid large food. The upper fangs are larger than the lower ones, and the cutting edge is sharper.

Small molars (premolars) have 1 root, which splits at the end. There are 2 tubercles on the crown for better chewing of food. Often, small molars are called "bicushioned", there are 8 units in the oral cavity.

Large molars (molars) located 6 on each jaw, have a cuboid shape. Their size decreases from front to back. Unlike premolars, they have 4 tubercles and several roots. The upper teeth have 2, and the lower 3 roots. The last molars erupt by the age of 20-30. And sometimes they don't exist at all. They are called wisdom teeth. Their peculiarity lies in the fact that all the roots merge into one, - a conical shape. The main function of molars and premolars is the quality of chewing food.

Change of teeth in humans

There are 2 types of teeth replacement. Milk teeth are formed in the womb at about 7 weeks of gestation, and erupt between the ages of 6 months and 2.5 years. The timing of a child's teething depends on heredity. If the parents' teeth erupted quite late, most likely the baby will have the same thing.

In a healthy child:

1. middle incisors;
2. lateral incisors;
3. first indigenous;
4. fangs;
5. second roots.

Interchangeable bite

In some diseases (for example, rickets) is violated. The number of milk teeth in a child is 20. Unlike permanent ones, they are not so strong, have a yellowish color, and are smaller in size. Despite the fact that milk teeth are replaced by permanent ones, they need proper care and timely treatment.

Permanent teeth erupt at the age of 6-14 years. The exception is eights.

dental formula

Dental formula - a graphic representation of the position of the teeth in the alveolar processes of the jaws. It consists of 4 squares separated by a vertical and a horizontal line.

The horizontal line conditionally divides the upper and lower jaws, the vertical line into the right and left halves. It is customary to record the location of the teeth in a person facing the researcher.

An example of a dental formula

Bite

For a number of reasons, a person may have an abnormal bite (the position of the dentition when the jaws are fully closed).

There are two types of bite:

1. correct (physiological) - the position of the dentition in which the upper jaw overlaps the lower by 1/3, and the molars fully interact with each other;
2. incorrect (malocclusion) - occurs under the influence of congenital or acquired factors.

Prevention of dental diseases

If you do not properly care for your teeth, a large number of dental diseases occur. The most common disease is caries. Caries occurs due to damage to the enamel. In advanced form, caries turns into pulpitis - inflammation of the pulp, which contains blood vessels and nerves. Negligent attitude to the health of the teeth can lead to their removal.

Therefore, a number of rules should be observed:

• Be sure to brush your teeth in the morning and evening.
• Use daily.
• Use fluoride-containing dental products, including fluoride toothpaste.
• Try to brush your teeth after every meal. If this is not possible, use mouthwash or chewing gum.
• Stick to proper nutrition.
• Visit the dentist regularly.

It is especially important to monitor the health of the teeth of pregnant women, since during development the child needs a large amount of calcium, which is often taken from the enamel of a pregnant woman.

Changes in the quantitative composition of enamel can lead to rapid. There is a misconception that pregnant women should not receive dental treatment. It is allowed to fill and remove teeth during pregnancy, but it is advisable to refuse teeth whitening.

Dental health has a great impact on human life. Diseases of a dental nature negatively affect the state of the whole organism, therefore, one must take a responsible attitude to the oral cavity, do not forget about personal hygiene and timely visits to the dentist.

Related video

Teeth in humans begin to form at the stage of intrauterine development (7-8 weeks). Part of the epithelium thickens, then the curved fold grows with its edges deep into the surrounding tissue, forming a dental plate (1). The fold itself is uneven, clusters of cells (dental papillae) form along it, above them something like bells protruding upwards is obtained. Later, enamel is formed from this epithelium itself (2), and dentin and pulp are formed from the tissues inside the bell (3). The same tissue supplies stem cells for the growing tooth. Large folds (2.3), laid down the very first, become the rudiments of milk teeth. At the 5th month of pregnancy, the rudiments of permanent teeth begin to develop from smaller bell-shaped folds (4).

This process itself determines the structure of the tooth in the future: since the enamel protein matrix is ​​formed only from the area of ​​the ingrown epidermis, the shape of the crown and the thickness of the tooth enamel in an adult strongly depend on the characteristics of its intrauterine development at the end of the second month of pregnancy. An insufficiently deeply ingrown or undernourished epidermal lamina will give rise to a small crown, or a crown with a defect in the enamel or with thin enamel. At the same stage, the number of teeth is laid, and the rudiments of both milk and permanent teeth are immediately formed. Normally, a person has 20 milk and 28-32 permanent teeth, however, there may be more or less teeth: it depends on the number of markers, signal sources.
The roots of the tooth are formed before its eruption, and the final shape is taken 6-8 months after it (sometimes later).

Sometimes the third molars do not grow at all, sometimes they grow inside the jaw, creating problems.

After the eruption of permanent molars, dental plastic disappears, and new teeth cannot appear. However, if “extra” rudiments are preserved in the jaw, they can sometimes be activated. The shape and arrangement of teeth is unique to each person. According to some studies, early human ancestors had 44 teeth, so sometimes atavisms occur regarding the increase in the dentition: either additional teeth in the main arches, or additional teeth in the palate.

Important! The formation of teeth depends on the characteristics of the course of pregnancy. Maternal malnutrition, beriberi (especially lack of vitamin D) or the use of antibiotics can lead to dental hypoplasia in a newborn, and milk and permanent teeth can be damaged.

dental formulas

In humans, different teeth have different functions, and there are four types of shape. To describe the location of the teeth, there are so-called dental formulas. The human dental formula includes 32 teeth.

In a simple version of the dental formulas, the number of the tooth is simply indicated (No. 1 is the central incisor), in the second case, a number is added that indicates which jaw and side the tooth is located on.

The dental formula for the milk bite is written in Roman numerals or denoted as numbers 5-8.

Anatomical structure of the tooth

A crown is distinguished in the tooth (protrudes above the gum, covered with enamel), a root (placed in the hole of the jaw, covered with cement) and a neck - the place where the enamel ends and the cement begins, such a neck is called "anatomical". Normally, it should be slightly below the level of the gums. In addition, the “clinical neck” is distinguished, this is the level of the gingival sulcus. The neck looks like a narrowed part of the tooth, above and below it it usually expands.

Normally, the clinical neck is higher than the anatomical one, and the gum border runs along the enamel. However, with age, the gums atrophy, and the enamel is destroyed. At a certain time, it may happen that the clinical and anatomical necks coincide. In old age, when the gum goes down, and the enamel becomes thinner, worn out and disappears (near the neck it is thinner and disappears earlier), a gap appears again between these conditional boundaries, but now the level of the clinical neck will pass through the exposed dentin of the tooth.

The crown of the incisors is chisel-shaped, slightly curved, with three cutting tubercles; at fangs - flattened-conical; in premolars, prismatic or cubic, with rounded sides, with 2 masticatory tubercles; molars (molars) have a rectangular or cubic shape with 3-5 masticatory tubercles.

The tubercles are separated by grooves - fissures. The incisors, canines and second premolars have one root, the first premolars have a double root, and the molars have a triple root. However, sometimes molars can have 4-5 roots, and the roots and canals in them can be curved in the most strange way. That is why tooth depulpation and canal filling is always done under x-ray control: the dentist must make sure that he has found and sealed all the canals.

The tooth is fixed in the alveolar socket with the help of strong collagen strands. The cement covering the root is built from collagen impregnated with mineral salts, and the periodontium is attached to it. The tooth is fed and innervated by the arteries, veins and processes of the trigeminal nerve entering the opening of the root apex.

The length of the root is usually twice the length of the crown.

Histological structure of the tooth

The tooth is made up of three types of calcified tissue: enamel, dentin, and cementum. Enamel is the strongest, dentin is 5-10 times weaker than it, but 5-10 times stronger than ordinary bone tissue. Both dentin and enamel are a protein mesh-fibrous matrix impregnated with calcium salts, although dentin is located between the enamel and dense bone tissue in structure. If crystals of mineral salts (apatites) are lost, the strength of the tooth can be restored, since under favorable conditions the salt crystals will again be deposited on the protein framework; however, if part of the protein matrix of the enamel is lost (for example, when chipping, drilling or grinding), this loss for the tooth is irreplaceable.

The thickness of the enamel on the lateral surfaces of the crown is 1-1.3 mm, on the cutting edge and masticatory tubercles up to 3.5 mm. The tooth erupts with non-mineralized enamel, at which time it is covered with a cuticle. Over time, it wears out and is replaced by the pellicle, and further mineralization of the pellicle and enamel occurs in the oral cavity due to the salts contained in saliva and dentogingival fluid.

There are no cells inside the dentin, it can partially compact and loosen, the protein matrix can grow in it, but only in the chamber limited by the inner surface of the enamel. Nevertheless, age-related demineralization predominates in humans. Dentin consists of thin, calcified tubules that run radially from the enamel to the pulp. When foreign substances or liquid enter these tubules, the increased internal pressure is transferred to the pulp, causing pain (the greater, the greater the pressure inside the dentinal tubule).

The pulp is loose connective tissue. It is penetrated by nerves, lymphatic and blood vessels and fills the pulp chamber of the crown and root, and the shape of the chamber can be any. The larger the pulp relative to the overall size of the tooth, the weaker and more sensitive it is to temperatures and chemicals.
Pulp functions:

• transmits sensory information to the brain;
• nourishes the living tissues of the tooth;
• participates in the processes of mineralization and demineralization;
• its cells synthesize proteins that are embedded in the protein matrix of the tooth.

The structure of milk teeth

A child is born with practically formed rudiments of milk teeth. They begin to erupt already at 3-4 months of age and already at this time require care. By the time of eruption, the teeth have not yet fully formed roots, since the root grows for a rather long time. The rudiments of permanent teeth also continue to develop in the jaw, they grow crowns, but the roots will begin to form only at the time of the change of teeth.

In milk teeth, the tops of the roots are bent to the buccal side, and between their roots are the rudiments of permanent ones.

Milk teeth have a weaker layer of dentin and less mineralized enamel, their roots are shorter and thicker than those of the permanent teeth of the same name. The cutting edge of the incisors usually has mild tubercles, chewing tubercles are also insignificant. The large volume of pulp and a thin layer of dentin makes such teeth more sensitive to sour, sweet, hot. Since they are less mineralized, they are more susceptible to caries and pulpitis, and local anesthetics during treatment inhibit the production of stem cells and dentin growth in the rudiments of permanent teeth.

Important: caries that began in milk teeth is easily transmitted to the permanent ones that have replaced it, since the bacteria that cause it continue to develop in the oral cavity. The baby usually gets these bacteria from the mother if she feeds him with the same spoon that she eats herself, or licks a fallen nipple (instead of washing it).

Replacement of permanent teeth

By the time of the change of teeth and the active beginning of the growth of the jaw branches, the child has 20 teeth. At this time, there are 2 molars on each side, but there are no premolars. It is the premolars that will occupy the free space that has appeared in the branches growing in length. If the jaw does not grow fast enough, a defect in the dentition may appear.

When changing teeth, the growing rudiment of a permanent tooth compresses the roots of the milk, compresses the blood vessels that feed them. Gradually, the roots of milk teeth, lacking nutrition, begin to collapse and completely dissolve, so that only the neck of the tooth and the crown remain. However, the rudiments of permanent ones may also suffer. Sometimes they are involved in the process and are completely destroyed, sometimes enamel defects occur, since its protein-collagen matrix, which is formed from the epithelium, can easily be damaged at this stage. Hypoplasia (underdevelopment) of the tooth and teething with damaged enamel are very common in recent years.

Anomalies of teeth and dentition

Anomalies in the structure of the tooth

• too large (more than five) number of roots;
• underdevelopment of the root;
• uncharacteristic shape (styloid, hook-shaped, conical, flat crowns);
• underdeveloped, deformed crown;
• thin enamel;
• increased abrasion of enamel;
• the absence of all or part of the enamel.

Anomalies of change of teeth

• the root may not resolve in time;
• the tip of the root can pierce the bone, causing an ulcer in the gum;
• the root is completely exposed, as all the tissue (both bone and gum) above it is destroyed;
• the permanent tooth began to grow before the milk tooth fell out;
• an additional row of permanent teeth is formed or teeth are not in the palate;
• not enough space for normal tooth growth.

Anomalies of the dentition

• malocclusion;
• anomalies in the arrangement of teeth in the dentition.

In all cases of anomalies with resorption of the roots, milk teeth must be removed. If the teeth grow in two or three rows or are crooked, extraction of milk teeth may also be indicated. At the same time, too early tooth extraction (for example, due to caries) can cause permanent teeth to start growing earlier, or cause the growth of additional teeth (usually they are small, conical in shape). Additional teeth corresponding in shape to molars are formed less frequently.

Important! 5-7 years is the second critical age for dental health. It is during this period that the problems of permanent occlusion and defects in the dentition are laid, so the change of teeth should be taken very seriously and not to neglect trips to the pediatric dentist.

Video - The structure of the tooth. Types and functions of teeth

Video - Anatomy of teeth

Each of us at least once, but asked ourselves questions about what the cavity of a molar tooth is, how many roots and canals it has. What is their topography and anatomy? How many nerves are in the cavity of the molar located on top, and how many are in the one below? Working length of the root canal - what is it? These questions are also relevant for doctors, because the process of their treatment, restoration or removal depends on the number of canals and roots.

Introduction

In dentistry, since 1971, there has been the so-called Viola two-digit system. According to it, the units of the upper and lower jaw of a person are divided into four quadrants, each of which has 8 teeth (we recommend reading: how often can X-rays of the lower jaw be taken?). Quadrants in adults are numbered as 1, 2, 3 and 4, and in children - from 5 to 8 (see table). Therefore, if you suddenly hear from a dentist that you are undergoing medical treatment of root canals of 46 or 36 units, do not be alarmed.

Each unit has its own individual structure. The number of channels and roots depends on where it is located and what function it performs. From this article you will learn what a tooth cavity is and why pulpitis affects it. Also read about the concept of root canal working length. You will learn about the methods of expanding dental recesses and their medical treatment, you will see a photo of three-channel pulpitis.

How is a human tooth arranged?

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This article talks about typical ways to solve your questions, but each case is unique! If you want to know how to solve your particular problem - ask your question. It's fast and free!

The elements of a human tooth can be conditionally divided into:

• crown;
• neck;
• root.

The crown is located above the gum and has a special coating called enamel. Under the enamel is a strong layer of dentin, which in its structure resembles bone tissue.

The cavity of the tooth located inside the crown is called the "pulp". It passes into a narrow canal of the tooth root, at the base of which there is a small hole. Through it, nerve endings and blood vessels pass into the cavity of the tooth. Inflammation of the pulp is called pulpitis. It is an indication for opening the cavity of the tooth and cleaning the root canals. The most difficult thing is to treat pulpitis in the cavity of three-channel units (for example, in the sixth one). In advanced cases, it is necessary to remove the tooth, and if it is also on top and in the last rows (6, 7 or 8), then this is also inconvenient.

The tooth neck is located inside the gum. It does not have an enamel coating, but is protected by cement. The continuation of the cavity of the tooth is its root. It is located in the alveolus - a small tooth cavity. Its structure differs from the structure of the crown and neck. The enamel layer is absent, and the dentin is permeated with collagen. Nerves and blood vessels pass through the root canal into the dental cavity.

The number of roots and canals in the teeth

The number of channels, as well as their working length, is not the same for each unit. In order not to get confused, a special scheme has been developed in dentistry. Its principle is as follows: the human jaw is divided vertically in the center, the numbering is made from the central incisors towards the ears.

The number of channels differs from the number of root bases. The cavities of teeth such as incisors can be with one, two or three channels. In order to accurately determine the number of these dental canals and their location, the doctor makes an x-ray for the patient. It helps him to carry out the procedure of opening the cavity of the tooth more accurately.

Let us consider in more detail how many channels and roots are present in each cavity. What is the difference between their numbers in the upper and lower jaws?

On the upper jaw

According to a special dental numbering system for root teeth, their countdown starts from the central incisors. The upper units, which are numbered from one to five, have one root each, 6, 7 and 8 are three-channel.

In most cases, the upper incisors and canines have one channel each, the fourth unit (24th premolar) has three channels in 8% of patients, in other cases there are 2 or 1. Premolar number five (25) can have a different number of channels. In 1% of people, this tooth is three-channel, in 24% it is two-channel, and in the rest it is single-channel. The sixth upper tooth (26th molar) may have three or four recesses (50:50 ratio). The seventh root in most cases (70%) is the owner of three channels, but it can also be four-channel (30%).

On the lower jaw

The lower units, starting with the first incisor and ending with the fifth premolar, have one characteristic that unites them: they all have one cone-shaped root. Next come the "sixes" and "sevens" - they are two-rooted. The "eights" of the bottom row can have both 3 and four roots.

How many canals are in the cavity of the lower teeth? So, the central incisors in 30% of cases have 2 recesses, in the remaining 70% - one each. The second incisor can be either one- or two-channel (50:50), the third canine in 7% of cases is single-channel. The 4th premolar usually occurs with one root socket, but sometimes with two. The fifth premolar is mostly single-canal. In 60% of cases, the 36th molar (the 6th lower tooth) has three recesses, but there may be 2 or 4. The lower "seven" in 70% of cases has 3 canals, but there are also four.

Wisdom tooth and features of its anatomical structure

Wisdom teeth are called the extreme eighth units of the lower and upper jaws. The cavity of these teeth often affects pulpitis, as they erupt very fragile. These crooked wisdom units have a peculiar anatomical structure of the tooth cavity (we recommend reading: how is wisdom tooth 8 removed on the upper and lower jaws?).

They appear later than everyone: at 20, and at 30, and even at 40 years old. The difference in their anatomical structure lies in the number of roots, which can be from two to five. These roots are rather crooked (see photo), so they cause many problems during treatment procedures, and especially during the determination of the working length, expansion of the channels and filling. The number of channels in the "eights" can reach up to five pieces.

How is root canal treatment carried out?

An important step in the process of root indentation treatment is the determination of the working length of these canals. Not everyone knows the definition of the length of the tooth root. So, the working length of the root canal is the distance from the edge of the frontal units to the apical constriction preceding the apical foramen. There are several methods for determining the working length of the root canal. The most commonly used calculation method, X-ray and electrometric methods.

Root canals are treated by endodontics. When an endodontist treats a root canal, the manipulations are carried out in the following sequence:

Diagnostic methods

The first stage of root canal treatment is diagnostics, which will help the doctor make the correct diagnosis and decide on the method of treatment. To do this, the patient needs to undergo an x-ray to examine the part of the crown that the doctor cannot see. This procedure allows you to understand how many roots and canals the tooth cavity has. If the X-ray examination is ignored, then the cavity of the diseased tooth will have to be opened again (we recommend reading: X-ray of the child's jaw: is it possible to take a picture with milk teeth?).

Preparatory procedures

After the X-ray image of the tooth cavity is carefully studied, the diagnosis is made, and the stages of the upcoming therapy are planned, it is necessary to tell the patient about everything in detail. Next, you need to issue a documented consent to the opening and further treatment of the tooth cavity.

An important point in preparing for the treatment of root deepening is to obtain information from the doctor about the presence of allergic reactions in the patient to anesthetics. If such information is not available, then an allergy test is performed. At this stage, the chemical treatment of the instruments with which manipulations will be performed is carried out.

Anesthesia administration and anesthetic application

Before starting treatment, the patient is anesthetized the area of ​​the jaw where the intervention will be performed. Anesthesia can be superficial and in the form of an injection. The first type of anesthesia blocks sensitivity not only in the cavity of the teeth, but also on the mucous membrane. It is usually used to numb the area where the doctor is about to inject the anesthetic.

For surface anesthesia, the following drugs are used:

Opening of a molar tooth

What is the opening of the cavity of the tooth? In order to remove the pulp and clean the root canals, the dentist needs to provide good access to them. The opening of the tooth cavity can be started immediately after turning the caries and removing sawdust from the dentin. The process of opening the cavity of the tooth begins with the smallest bur, after which a large spherical one is used.

Canal treatment

Canal treatment is divided into mechanical (scraping out the contents with special tools) and chemical (drug treatment of root canals with disinfectants injected with a thin needle). To date, the following scheme of drug treatment of the root canal is used: sodium hypochlorite is applied after the use of each instrument and the completion of mechanical cleaning, then hydrogen peroxide, and after it - distilled water. Drug treatment of root canals is carried out immediately after the opening of the tooth cavity is completed.

filling

The final stage of root canal treatment is hermetic filling of the cavity. Root recesses are filled with a special filling material (usually gutta-percha). The filling helps the tooth stay strong and does not allow pathogenic bacteria to penetrate into its cavity.

Filling the cavity of the tooth is:

• temporary;
• permanent.

During temporary filling, the tooth cavity is filled with a non-hardening paste that has healing properties. This type is used in cases with advanced three-channel pulpitis or periodontitis.

If there is not a single sign that there is inflammation in the tooth cavity, then removal (for example, the 6th) is not performed, and a permanent filling is installed. In this case, no consequences.

Prevention of root canal diseases

For an ideal “order” in the oral cavity, it is necessary:

• take good care of her;
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Teeth are such a strong part of the body that they surpass even bones. This is due to the special structure of tissues and their structure.

But, unfortunately, these organs are the only ones that do not have regenerative properties, and therefore are not able to restore themselves.

Location on the upper and lower jaw

As a rule, in adulthood a person has 32 teeth. Dentists determined the name and schematic position of each of them. Conventionally, the entire oral cavity is divided into four segments, which include the right and left sides of both jaws.

Each segment has a specific set of teeth:

• 1 medial and 1 lateral incisor;
• fang;
• premolars (2 pcs.);
• molars (3 pieces, one of which is a wisdom tooth).

They will be clearly shown in the following video:

In professional dentistry, not the names of crowns are most often used, but their numerical definition. Each crown has its own serial number, starting from the center line of the jaw. There are two methods of numerical designation.

The first uses a number series up to 10. Crowns of the same name are assigned their own number with the obligatory specification of the jaw and side.

For example, the central incisor is No. 1, the last molar (wisdom tooth) is No. 8. During treatment, the dentist indicates in the medical document the number of the tooth, jaw (upper or lower) and side (left or right).

When using the second technique, each crown is assigned a two-digit number, starting with 11. A certain ten indicates its segment.

When designating milk teeth, only Roman numerals are used. One number is assigned to paired crowns, starting from the center.

Structure of various kinds

Photo: the main parts are the crown, neck and root

All human teeth differ from each other in their shape and functional features.. The main differences are revealed precisely in the structure of the main parts, which include the crown, neck and root.

The crown is the part of the tooth that protrudes from the gum tissue.. It has four contact surfaces specific to each tooth:

• occlusal - the place of contact with paired opposite crowns;
• vestibular (facial), facing the lips or cheek;
• lingual (lingual), facing the oral cavity;
• proximal (cutting), in contact with opposite crowns.

The crown smoothly passes into the neck, connecting it to the root. The neck is distinguished by some narrowing, on which connective tissue is located around the entire circle, which allows the tooth to be firmly held in the gum.

The tooth itself at the base has root located in the alveolar cavity. Depending on the localization, it can be either single or multi-rooted and differ in its length.

incisors

Figure 1: Medial upper incisor. a - vestibular, b - medial, c - lingual surfaces; d — vestibular-lingual, e — medio-distal section; e - cutting surface; 1,2,3 - sections in the area of ​​the crown, in the middle of the root and closer to the top of the root, respectively.

The appearance of the incisors of different jaws has special differences:

• central incisor located on the upper jaw, has a chisel-like appearance, a flat wide crown and one root. The vestibular side is slightly convex. Triple tubercles may be found on a beveled incisal edge;
• lower first incisor has a flat shortened root and a slightly convex surface. The inner side has a concave shape. The ridge edge and tubercles are poorly defined. This cutter is considered the smallest of the entire series;
• lateral incisor has a chisel-like appearance. Its contact part is represented by pronounced elevations. The root is flattened at the edges, and slightly deviated towards the tongue in the neck area.

fangs

Figure 2: Right upper canine. a — vestibular, b — medial, c — lingual surface, d — vestibular-lingual, e — medio-distal section; e - cutting surface; 1,2,3 - sections in the area of ​​the crown, in the middle of the root and closer to the top of the root, respectively.

The fangs are characterized by a diamond shape and a pronounced convexity of the outer surface.. On the side adjacent to the surface of the tongue, there is a groove on the crown that divides the tooth into two unequal areas.

The cutting side has the form of a triangle. In some people, the length of the central portion of the incisal side is longer than that of adjacent teeth.

The lower canine differs little from the upper. The main difference is in a more narrowed shape and a slight deviation inside the oral cavity of the flat root.

Premolars

Figure 3: Right upper first premolar. a — vestibular, b — medial, c — lingual surface, d — vestibular-lingual, e — medio-distal section; e - cutting surface; 1,2,3 - sections in the area of ​​the crown, in the middle of the root and closer to the top of the root, respectively.

After the canines are the premolars - the first molars, which have their own differences:

• superior first premolar, can be recognized by its prismatic shape, which has convex sides of the vestibular and inner surfaces.

  From the side of the cheek, the roundness is more pronounced. The cutting part has volumetric rollers at the edges, between which there are large fissures. The root is flattened and forked;

• second premolar differs in root: here it is slightly cone-shaped, slightly compressed from the front side;
• first premolar (lower), instead of rollers, it is distinguished by a pronounced roundness and two tubercles of the cutting part. Its single root is slightly flattened from the edges along the entire length;
• second premolar larger than their siblings of the same name. Its contact surface is distinguished by two symmetrically developed large tubercles and a horseshoe-shaped fissure.

molars

Figure 4: Right upper first molar. a - vestibular surface; b - medial surface; in - lingual surface; g - medio-distal section; e — chewing surface, 1,2,3 — slices in the area of ​​the crown, in the middle of the root and closer to the top of the root, respectively.

The molars are the largest teeth of the entire row and have some features in the anatomical structure:

• the most voluminous is first one on top. Its crown is rectangular in shape. It is distinguished by strongly developed four cusps with an H-shaped fissure. This molar is three-rooted, with one of the roots straight and the others slightly deviated;
• second molar smaller than its first counterpart. It has the shape of a square, and the fissures are located in the letter X. The buccal side of the tooth is distinguished by pronounced tubercles;
• lower first molar, characterized by the presence of five tubercles, forming fissures in the form of the letter Zh. The molar has a double root;
• second molar (lower) completely copies the structure from the first molar.

Eights (wisdom)

The wisdom tooth should be considered as a separate item, since not everyone grows it. But even if it erupted, then its appearance is often accompanied by problems. In appearance, it differs only slightly from the second molar..

Differences can be noted only in the structure of the root. This tooth has the most powerful one and is located on a shortened spliced ​​volumetric trunk.

Internal structure

Figure 5: internal structure

All teeth have a different anatomical structure, but at the same time they have a similar internal structure.. When studying the histological structure, the following components are distinguished:

Enamel

This is a coating of the tooth that protects it from the aggressive effects of the external environment.. First of all, it protects the dentin of the crown from destruction. Enamel consists of microscopic elongated prisms glued together with a special substance.

With a slight thickness of the enamel layer, which is in the range of 0.01 - 2 mm, it is the strongest tissue in the human body. This is due to the special composition, 97% of which is occupied by mineral salts.

Strengthening the protection of enamel occurs due to a special shell - pelikuly resistant to acids.

Dentine

Located just below the enamel and is a coarse fibrous tissue, something like a porous bone. The main difference from ordinary bone tissue is a low hardness index and a large amount of minerals in the composition.

The main structural substance of dentin is collagen fiber. There are two types of dentin: superficial and internal (near-pulp). It is the inner layer that determines the intensity of new dentin growth.

The surface layer of dentin has a high density, therefore, it has a protective function and prevents the penetration of infection into the tooth cavity.

Cement

It is a bone tissue with a fibrous structure, consisting mainly of multidirectional collagen fibers impregnated with lime salts. Covers the dentin in the neck and root area, acting as a link between periodontium and dentin.

The thickness of the cement layer depends on the location: on the neck it is up to 50 microns, on the tops of the root up to 150 microns. There are no vessels in the cement, so the tissue is nourished through the periodontium.

Unlike ordinary bone tissue, cement is not able to change its structure and transform. There are two types of cement: cellular and acellular.

1. Cellular is located on the first third of the root and the area of ​​bifurcation of multi-rooted teeth and ensures the regular deposition of new layers of dentin, which ensures a tight fit of the tooth to the periodontium.
2. acellular located on the lateral surface of the roots, protecting them from damaging effects.

crown cavity

Under the dentin is the cavity of the crown, repeating the shape of the crown. It is filled with pulp - this is a special tissue with a loose structure that nourishes the entire tooth and has the function of an additional connection.

In the presence of tubercles on the chewing part of the tooth, pulp horns are formed in the cavity of the crown, completely copying them. Unlike other components, the pulp is permeated with numerous fibers of nerve, blood and lymphatic vessels. It is because of this aspect that the penetration of infection into the cavity of the tooth leads to inflammation and severe pain manifestations.

Depending on the structure of the tissue, there are root and coronal pulp.

1. root pulp It is characterized by a dense structure with a predominance of voluminous bundles of collagen fibers, which actively prevent the penetration of infections to the root apex.
2. coronal pulp softer and contains a major network of blood vessels and nerve fibers. With age, the production of cells that form the pulp increases and narrows completely.

During tooth development the pulp is directly involved in the formation of dentin. In addition, it is the pulp that performs trophic, sensory and reparative function.

All pulp vessels are located in the root canal, into which they enter through the apical opening of the root canal apex. Several nerve trunks and the pulpal artery from the upper jaw pass here.

The artery is located in the root canal in the center and is in contact with the venous vessels. Nerve fibers closer to the horns of the pulp are transformed into a double plexus, spreading along the bottom of the cavity, penetrating into the initial layer of dentin.

The bottom of the cavity on single-rooted teeth passes into the canal in a funnel-like manner, on multi-rooted teeth it is strongly flattened, while it has clearly defined openings in the canals.

Gum

It is part of the periodontium, which is directly responsible for the preservation of the root system and the neck of the tooth.. Has a special structure.

The gum tissue consists of two layers: free (external) and alveolar. Free gum tissues are located on the outer surface of the mucosa and are responsible for trophism and sensory.

In addition, they have a protective function, reducing the risk of mechanical damage or the spread of infection. The alveolar part of the gum is adjacent to the periodontal tissues and is responsible for the stability of the teeth.

Dairy

Figure 6: dairy almost identical to constant

The temporary teeth of a child practically do not differ in their structure from the permanent teeth of an adult. And this applies not only to the histological, but also to the anatomical structure. There are still discrepancies, but they are very small.

Another small feature is that on milk teeth, the cutting part has practically no teeth. As a rule, their surface smoothed.

If we consider the difference in the histological structure, it can be noted that the structure of the enamel of temporary crowns is slightly different.

The enamel layer is slightly thinner and the amount of minerals it contains is much lower than in permanent crowns. Unlike them, children's enamel is covered with a protective film - a cuticle that is resistant to aggressive environments.

A detailed study of the structure of the teeth will make it possible to understand the possible process of their destruction and stop it in time. Knowing the anatomy of crowns, you can not be afraid of the unknown and go to the dentist for treatment with less fear.

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A beautiful smile is fashionable. Therefore, dental health is given great attention these days. Unfortunately, not everyone can boast of their impeccable appearance, although modern dental developments can bring them as close as possible to the ideal.

In our article, we will not talk about this. We will discuss the anatomical structure of a human tooth, a diagram of which is shown on our website.

The molars are the only human organ that does not regenerate on its own.. That is why they need to be protected and regularly monitored for any changes in their condition. After all, it is not without reason that a regular examination by a dentist every 6 months is recommended.

Molar teeth require careful care

If we consider enlarged, then each molar, the photo of which can be seen on our website, consists of a crown and a root part. Crown part- the one that is above the level of the gums, is covered on top with the most durable tissue in the human body - enamel, which protects its softer inner layer - dentin, which is the basis of the tooth.

Despite the strength and reliability, enamel is incredibly susceptible to external influences. Violate her condition can, and poor care, and bad habits, and heredity. Pathogenic bacteria enter the cracks in the enamel, causing intense tissue destruction. A person develops a carious process that also captures dentin.

If left untreated, the infection penetrates into the root part, acute pulpitis and other equally dangerous ailments develop.

As for the structure of the root part, then its main elements are arteries, veins and nerve fibers that feed the tooth. They are located in the pulp of the root canal and through the apical opening are connected to the main neurovascular bundle.

The dentin below the gum level is covered with cement, which is attached to the periodontium with the help of collagen fibers. The roots of human teeth, the photo illustrates them very well, are hidden in the alveoli - a kind of depressions in the jawbone.

Any defeat requires its complete removal. A broken root cannot be restored.

The structure of the jaw and molars of an adult deserves a separate section. This will be discussed below.

Types of human teeth

When visiting a dental office, we hear different, unusual names for our ears and, sometimes, we don’t even understand what it is about. This section is intended to understand the name of a person's teeth in order, if necessary, to learn to delve into the degree of dental problems found in you.

So, in the mouth we have:

• Central and lateral incisors;
• fangs;
• Premolars or small molars;
• Molars or large molars.

In order to indicate their position on the upper and lower jaw, in dental practice, the so-called dental formula is used, according to which the numbers of milk teeth are written in Latin numerals, and indigenous ones in Arabic.

With a full set of teeth in an adult, the entry of the dental formula will be as follows: 87654321 / 123465678. A total of 32 pieces.

On each side are 2 incisors, 1 canine, 2 premolars, 3 molars. Molars are also commonly referred to as wisdom teeth, which are the last to grow. As a rule, after 20 years.
As for the children, then their dental formula will have a different look. After all, there are only 20 milk teeth. But we’ll talk about this a little later, and now we’ll deal with the structure of incisors, canines, premolars and molars, and also discuss their differences.

Features of the structure of the upper teeth

The smile zone includes central and lateral incisors, canines and premolars. Molars are also called chewing, because their main purpose is to chew food. Each of them looks different.

So, units central incisors. Their coronal part is thickened and slightly flattened, they have one long root. Doubles also have a similar shape - lateral incisors. They, as well as the central incisors, have three tubercles from the cutting edge, from which 3 pulp spurs extend along the dental canal.

fangs their shape resembles the teeth of an animal. They have a pointed edge, a convex shape and only one tubercle on their cutting part. First and second premolars, or, as dentists call them, the four and five have a very great external similarity, the difference is only in the size of their buccal surface and in the structure of the root.

Next come molars. The six has the largest size of the crown part. She looks like an impressive rectangle, and the chewing surface in its shape resembles another geometric figure - a rhombus. Six has 3 roots - one palatine and two buccal. The seven differs from the six in slightly smaller sizes and different structures of fissures. But eight or, according to popular belief, not everyone even grows a wisdom tooth. Its classical form should be the same as that of ordinary molars, and its root resembles a powerful trunk. The upper wisdom teeth are considered the most capricious.

They can begin to disturb a person even at the stage of their eruption, and when removed, they can create a difficult situation due to their twisted and twisted roots. On the opposite jaw are their antagonists. They will be the subject of our next section.

Features of the structure of the lower teeth

What the teeth and fangs of a person consist of, the photo conveys quite accurately, as well as their appearance. It can be judged from it that the structure of the teeth of the lower jaw is completely different from their structure in the upper jaw. Let's consider this point in more detail.

The teeth of the lower jaw have the same names as the upper ones, and their structure will be slightly different.

Central incisors are the smallest in size. They have a small flat root and 3 mild tubercles. Lateral cutter only a few millimeters larger than the central one. He also has a very small size, a narrow crown and a small flat root.

lower fangs they are similar in shape to their antagonists, but at the same time they are narrower and slightly tilted back.

First premolar on the lower jaw it has a rounded shape, a flat and flattened root, as well as some beveling towards the tongue.

Second premolar slightly larger than the first due to more developed tubercles and the presence of a horseshoe-shaped fissure between them.

The first molar, that is, the lower six, has the most tubercles. Its fissure resembles the letter Zh, in addition, it has as many as 2 roots. In one of them - one channel, and in the second - two. The second and third molars are very similar in shape to the first.

They are distinguished only by the number of tubercles and fissures located between them, which, especially on the figure eight, can have a bizarre shape.

What do milk teeth look like?

Milk teeth are the precursors of permanent teeth. They begin to appear as early as the first year of a baby's life and, as a rule, the lower central incisor breaks through the gum first. Many parents remember the period of teething with a shudder. They bring so much torment to the crumbs. This process is not fast - it is extended in time.

It can take two or even two and a half years from the appearance of the first tooth to the last.

The average three-year-old toddler has a full set of teeth in the amount of 20 pieces in his mouth. With them, the child will walk until the age of 11 - 12. But they will begin to change to indigenous ones from 5 to 7 years. Photos of toothless school-age children are kept by parents in family albums. But back to what it is, the structure of milk teeth in children. Let's start with their shape. It will be approximately the same as that of the permanent ones.

The difference will be only in their small size and snow-white color. However, the degree of mineralization of enamel and dentin is weak, so they are more susceptible to caries. Therefore, care for them should be regular and thorough.

The structure of the milk tooth is also distinguished by a large volume of pulp, which is incredibly prone to inflammation. That is why in children caries rapidly turns into pulpitis.

Milk teeth do not have long roots, besides, they do not sit tightly in the periodontal tissue. This greatly facilitates the process of replacing them with permanent ones. Although for children, the process of removing them is always stressful.

Teeth are considered one of the most complex systems in our body. Their importance for our full life is invaluable. Therefore, taking care of their condition and health should start from an early age. And make it a rule to visit the dentist every six months.