Features of the structure of milk and permanent teeth. External distinguishing features of milk and permanent teeth

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) are formed 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 that are 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 the 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, they simply indicate the number of the tooth (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

In the tooth, a crown is distinguished (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 the salt crystals, under favorable conditions, 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 transmitted 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

Children's dentistry "Jewellery work" successfully treats caries, pulp periodontitis and other dental diseases in children.

To make you understand the causes of tooth decay, our dentists have prepared this material, which tells in detail about the structure of milk teeth, their features, the period of change of milk teeth to permanent ones. The information provided will help your child maintain healthy teeth.

milk bite

The milk bite consists of two dozen teeth. These are incisors, canines, first molars and second molars. Premolars are absent. The color of the teeth of the first eruption in shade resembles milk cream.

Milk teeth are similar in shape to permanent teeth. But the size of milk teeth is smaller, the layer of hard tissues is thinner, so the dental cavity is more extensive. In the period of formation and resorption of the roots, the apical openings and root canals are wide, the border of the transition of the crown to the root of the tooth is visible.

Milk incisors

The incisors of milk teeth are more prominent than those of permanent teeth. The palate has no furrows. The distal angle of the maxillary lateral incisor is more rounded than the central incisor. At the neck on the lateral incisor, the enamel roller is less pronounced, in contrast to the incisor located in the center. The tips of the incisors in the center of the maxilla may bulge to the side of the lips, and the roots of the upper central incisors may be dilated. For the smaller incisors of the lower jaw, the lower incisors are held on flat roots with grooves on the lateral and medial sides.

milk fangs

The crown of the upper milk canine is shorter than the crown of the permanent tooth. The cutting edge of the milk canine has pronounced tubercles, the root of the canine is rounded.

first milk molars

The crown of the first molar of the upper jaw is stretched in the medial-distal direction, the chewing surface has two tubercles. The palatine surface is convex, the buccal surface of the tooth is ribbed, outlined by a pair of furrows. The first primary molar is held in the upper jaw by three divergent roots with wide apical foramens.

The crown of the lower first primary molar is oriented in the anteroposterior direction. Four tubercles of the masticatory surface are clearly expressed, an enamel ridge is developed. The lower first molar has two widely divergent roots, the distal root being smaller and narrower than the medial one. The buccal surface is divided into distal and medial regions.

Second milk molars

The second upper milk molars are characterized by a beveled crown shape. The posterior buccal root is fused with the palatine. There is an enamel fold in the area between the anterior-lingual and posterior-buccal tubercles. The second milk molars of the lower jaw are identical in structure to the first permanent molars of the lower jaw, they have 5 tubercles, the most pronounced is the anterior buccal.

Resorption of the roots of milk teeth

Milk teeth are replaced by permanent teeth around the age of five. At the same time, the rudiments of permanent teeth begin to gradually grow in the jaws of the child. The roots of milk teeth also dissolve, making room for a new dentition.

The root closest to the rudiment of a permanent tooth is most quickly absorbed. The rudiments of permanent teeth included in the anterior group are located at the lingual surface of the root of temporary teeth. The rudiments of premolars are located between the roots of milk molars. The rudiment of the lower premolar is located closer to the posterior root, and the upper one is closer to the posterior root. Due to this, the resorption of the roots of single-root milk teeth comes from the lingual surface of the root, and then surrounds the root.

Resorption of the roots of milk molars begins from the inner surface of the roots. When the root is resorbed, the granulation tissue is replaced by the pulp of milk teeth, resorption is completed by the time of eruption of the permanent tooth.

The permanent teeth erupt and the roots of the deciduous teeth dissolve normally at the same time. Resorption is accelerated by dead pulp, inflammation, tumors, etc. If the rudiments of permanent teeth are absent, resorption slows down. Dentists take into account these features of resorption of the roots of milk teeth. Teeth with resorbed roots are treated especially at all stages from processing to the installation of a filling.

Eruption of permanent teeth

In healthy children, permanent teeth appear as old milk teeth fall out. Usually, after the loss of a milk tooth, the cutting edge or tubercles of a permanent tooth erupt. Normally, there are slightly fewer permanent teeth than milk teeth. Permanent teeth begin to erupt at the age of six, the first permanent tooth is the molar. If an x-ray is taken at the age of six, the picture will show 3 rows of teeth, of which milk teeth will be reflected in the first row, the rudiments of permanent teeth will be in the second row, and the canines will occupy the third row.

In adolescence, children do not have milk teeth. The dentition of adolescents consists of permanent teeth. To make a correct diagnosis, pediatric dentists remember the main stages in the development of permanent teeth. The hydontal fissure in differential diagnosis is noticeable along the lateral walls of the root, not being determined in the area of the apex. A compact plate of the wall is well marked along the root.

This phase is typical at the age of six for the lower central incisors, at the age of eight for the central and lateral incisors of the upper jaw, at 7-8 years old for the lateral lower incisors, at 8 years old for the first lower molars.

In the second stage, the walls of the tooth root have already been built, but are not close enough in the region of the root apex. This is marked by an apical foramen, clearly visible on x-rays. The periodontal fissure is well defined.

The roots of permanent teeth in adolescents are finally formed at the age of 10 to 15 years. The exact answer about the formation of the roots of the teeth is given by radiographic images, which clearly outline the boundaries of the periodontium and at the same time, there is no apical opening. By the age of 18, the uubs and jaws are fully developed. However, the dentist should take into account the anatomical differences between permanent teeth in children and adults.

In permanent teeth, children have more pulp but less hard tissue. Children's teeth are less resistant to irritation and mechanical stress.

This article is devoted to the consideration of the structure and functioning of teeth - a vital organ of the human body. Teeth are a mirror image of human health; their poor condition can be used to judge various functional disorders of the body. In addition, today a beautiful smile is the key to success in a career and in personal relationships. The structure of the article involves the coverage of various issues, including the structure of human teeth; the scheme of their location in the dentition; difference between milk teeth and permanent teeth; the need for proper dental care, etc.

Functions of teeth

Teeth are bone formations in the oral cavity, which have a certain structure, shape, are characterized by the presence of their own nervous and circulatory apparatus, lymphatic vessels, are ordered in the dentition and at the same time perform various functions. Teeth are actively involved in breathing, as well as in the formation and pronunciation of sounds, the formation of speech. In addition, they perform the primary mechanical processing of food, that is, they participate in one of the main functions of the body's vital activity - nutrition.

It should be noted that insufficiently chewed food is poorly digested and can cause disturbances in the functioning of the gastrointestinal tract. In addition, the absence of at least a few teeth affects diction, that is, the clarity of pronunciation of sounds. The aesthetic picture also deteriorates - facial features are distorted. Poor condition of the teeth can also lead to bad breath, as well as to the development of various diseases of the oral cavity and chronic infections of the body as a whole.

The structure of human teeth. The location in the jaw

The norm for a person is the presence of teeth in the amount of 28-32 units. By the age of 25, the complete formation of the dentition usually occurs. The teeth are located on both jaws, according to which the upper and lower dentitions are distinguished. The structure of the human jaw, teeth (their typical classification) are as follows. Each row contains 14-16 teeth. The rows are symmetrical and are conventionally divided into left and right sectors. Teeth are designated by serial numbers - two-digit numbers. The first digit is the top sector or from 1 to 4.

During the closure of the jaws, the front teeth overlap the lower ones by 1/3 of the crown of the tooth, and this ratio of the dentition to each other is called bite. In case of improper closing of the teeth, a curvature of the bite is observed, which leads to a violation of the chewing function, as well as to an aesthetic defect.

The so-called wisdom teeth may be absent and, in principle, not appear in the oral cavity. Today there is an opinion that this is a normal situation and the presence of these teeth is no longer necessary. Although this version causes a huge amount of controversy.

Teeth are unable to regenerate. Their change occurs once during a person's life: first, a child has milk teeth, then at the age of 6-8 years they change to permanent ones. Usually by the age of 11 there is a complete replacement of milk teeth with permanent ones.

The structure of the tooth. Anatomy

The anatomical structure of a human tooth suggests that conditionally it consists of three parts: the crown of the tooth, the neck and the root.

The crown of a tooth is the part of it that rises above the gum. The crown is covered with enamel - the strongest tissue that protects the tooth from the damaging effects of bacteria and acids.

There are several types of surfaces:

Occlusion - the surface at the point of closure with a paired tooth on the opposite jaw.
Facial (vestibular) - the surface of the tooth from the side of the cheek or lip.
Lingual (lingual) - the inner surface of the tooth, facing the inside of the oral cavity, that is, the surface with which the tongue comes into contact when pronouncing sounds.
Contact (approximal) - the surface of the dental crown, facing the teeth located in the neighborhood.

Neck - part of the tooth, located between the crown and the root, connecting them, covered by the edges of the gums and covered with cement. The neck has a narrowed shape.

The root is the part of the tooth with which it is attached to the tooth socket. Depending on the classification type of tooth, the root may have from one to several processes. This issue will be considered in more detail below.

Histological structure

The histology of each tooth is exactly the same, however, each of them has a different shape in accordance with its function. The figure very clearly demonstrates the layered structure of human teeth. The photo displays all dental tissues, as well as the location of blood and lymphatic vessels.

The tooth is covered with enamel. This is the strongest fabric, consisting of 95% of mineral salts such as magnesium, zinc, strontium, copper, iron, fluorine. The remaining 5% are organic substances - proteins, lipids, carbohydrates. In addition, the composition of the enamel includes a liquid involved in physiological processes.

Enamel, in turn, also has an outer shell - the cuticle, which covers the chewing surface of the tooth, however, over time it tends to thin and wear out.

The basis of the tooth is dentin - bone tissue - a set of minerals, strong, surrounding the cavity of the entire tooth and the root canal. Dentin tissue includes a huge number of microscopic channels through which metabolic processes occur in the teeth. Nerve impulses are transmitted through the channels. For reference, 1 sq. mm of dentine includes up to 75,000 tubules.

Pulp. Periodontium. Root structure

The inner cavity of the tooth is formed by the pulp - a soft tissue, loose in structure, penetrated through and through by blood and lymphatic vessels, as well as nerve endings.

Human teeth look like this. The root of the tooth is located in the bone tissue of the jaw, in a special hole - the alveolus. The root, as well as the crown of the tooth, consists of a mineralized tissue - dentin, which is covered on the outside with cement - a tissue that is less durable than enamel. The tooth root ends at the top, through the hole in which the blood vessels that feed the tooth pass. The number of roots in a tooth varies according to its functional purpose, from one root in the incisors to 4-5 roots in the chewing teeth.

Periodontium is a connective tissue that fills the gap between the tooth root and the jaw socket in which it is located. The fibers of the tissue are woven into the cementum of the root on one side, and into the bone tissue of the jaw on the other, which ensures a strong attachment to the tooth. In addition, through the periodontal tissues, the nutrients of the blood vessels enter the tooth tissues.

Types of teeth. incisors

Human teeth are divided into four main groups:

incisors (central and lateral);
fangs;
premolars (small chewing / molars);
molars (large chewing / molars).

The human jaw has a symmetrical structure and includes the same number of teeth from each group. However, there are some anatomical features in such a matter as the structure of human teeth and the teeth of the lower row. Let's consider them in more detail.

The front teeth are called incisors. A person has 8 such teeth - 4 on top and 4 on the bottom. The incisors are designed to bite food, divide it into pieces. The special structure of the front teeth of a person is that the incisors have a flat crown, in the form of a chisel, with fairly sharp edges. Three tubercles protrude anatomically on sections, which tend to wear off during life. On the upper jaw, two central incisors are the largest of all representatives of their group. The lateral incisors are similar in structure to the central incisors, however, they are smaller. Interestingly, the cutting edge of the lateral incisor itself also has three tubercles, and often takes on a convex shape due to the development of the central (middle) tubercle. The root of the incisor is single, flat and takes the form of a cone. A characteristic feature of the tooth is that three pulp tops protrude from the side of the tooth cavity, which correspond to the tubercles of the cutting edge.

The structure of the upper teeth of a person is slightly different from the anatomy of the teeth of the lower row, that is, everything is exactly the opposite on the lower jaw. The central incisors are smaller in comparison with the lateral incisors, have a thin root, shorter than that of the lateral incisors. The front surface of the tooth is slightly convex, but the lingual surface is concave.

The crown of the lateral incisor is very narrow and curved towards the lips. The cutting edge of the tooth has two angles - the central one, more acute, and the lateral one, more obtuse. The root is characterized by longitudinal grooves.

Fangs. chewing teeth

The fangs are designed to break food into smaller pieces. The anatomy of the tooth is such that on the back (lingual) side of the crown there is a groove that disproportionately divides the crown into two parts. The cutting edge of the tooth has one well-developed, pronounced tubercle, which makes the shape of the crown cone-shaped, often similar to the fangs of predatory animals.

The canine of the mandible has a narrower shape, the edges of the crown converge in the medial tubercle. The root of the tooth is flat, the longest in comparison with the roots of all other teeth and is deflected inward. Humans have two fangs in each jaw, one on each side.

The canines together with the lateral incisors form an arc, in the corner of which the transition from cutting teeth to chewing teeth begins.

Let us consider more carefully the structure of a human molar, first - a small chewing one, then a large chewing one. The main purpose of chewing teeth is a thorough mechanical processing of food. This function is performed by premolars and molars.

Premolars

The first premolar (indicated by the number 4 in differs from the canine and incisors in its prismatic shape, the crown has convex surfaces. The chewing surface is characterized by the presence of two tubercles - buccal and lingual, grooves pass between the tubercles. The buccal tubercle is much larger than the lingual tubercle in size. The root of the first premolar is still flat, but it already has a bifurcation into the buccal and lingual parts.

The second premolar is similar in shape to the first, however, its buccal surface is much larger, and the root has a conical shape, compressed in the anteroposterior direction.

The chewing surface of the first lower premolar is beveled towards the tongue. The crown of the tooth is rounded, the root is single, flat, with grooves on the frontal surface.

The second premolar is larger than the first due to the fact that both tubercles are equally developed and symmetrical, and the depressions in the enamel (fissure) between them take the form of a horseshoe. The root of the tooth is similar to the root of the first premolar.

There are 8 premolars in the human dentition, 4 on each side (on the upper and lower jaws). Consider the anatomical features and, in general, the structure of the human teeth of the upper jaw (large chewing teeth) and their differences from the structure of the teeth of the lower jaw.

molars

The maxillary first molar is the largest tooth. It is called large. The crown resembles a rectangle, and the chewing surface is a rhombus shape with four tubercles, between which an H-shaped fissure is distinguishable. This tooth is characterized by three roots: one straight - the most powerful, and two buccal - flat, which are deflected in the anteroposterior direction. These teeth, when the jaws are closed, rest against each other and are a kind of "limiters", and therefore undergo enormous loads during a person's life.

The second molar is smaller than the first. The crown has a cubic shape with an X-shaped fissure between the tubercles. The roots of a tooth are similar to those of a first molar.

The structure of human teeth (the layout of the molars and their number) completely coincides with the location of the premolars described above.

The first molar of the lower jaw has five tubercles for chewing food - three buccal and two lingual with an Zh-shaped fissure between them. The tooth has two roots - posterior with one canal and anterior with two. In addition, the anterior root is longer than the posterior one.

The second molar of the mandible is similar to the first molar. The number of molars in humans is the same as the number of premolars.

The structure of the human wisdom tooth. Baby teeth

The third molar is popularly called the "wisdom tooth", and in the human dentition there are only 4 such teeth, 2 in each jaw. In the mandible, the third molar can have a variety of cusp development. Often there are five. But in general, the anatomical structure of the “wisdom tooth” of a person is similar to the structure of the second molar, however, the root most often resembles a short and very powerful trunk.

As noted earlier, milk teeth appear first in a person. They usually grow up to 2.5-3 years. The number of temporary teeth is 20. The anatomical and histological structure of a human milk tooth is similar to the structure of a permanent one, but there are some differences:

The crown size of milk teeth is much smaller than that of permanent teeth.
The enamel of milk teeth is thinner, and the composition of dentin has a lower degree of mineralization compared to molars, which is why children so often develop caries.
The volume of the pulp and root canal of a milk tooth is much larger compared to the volume of a permanent one, which is why it is more susceptible to the occurrence of various inflammatory processes.
The tubercles on the chewing and cutting surfaces are weakly expressed.
The incisors of milk teeth are more convex.
The roots are bent towards the lip, they are not as long and strong in comparison with the roots of permanent teeth. In this regard, changing teeth in childhood is an almost painless process.

In conclusion, I would like to note that, of course, the structure of a person’s teeth, their arrangement in the jaw, closure (occlusion) have individual characteristics that are characteristic of each individual. However, the dental apparatus of any person is involved in the performance of vital body functions throughout life, in accordance with this, over time, the structure of the teeth and their structure change. It must be remembered that most pathological processes in dentistry develop in childhood, so it is important to monitor the condition of the teeth from the first years of life. This will help to avoid problems with teeth at a conscious age.

Despite the apparent simplicity, teeth are a very complex and rather fragile system, with a multilayer histological structure, each of the layers has an individual purpose and has certain properties. And the fact that the change of teeth occurs only once during a lifetime makes the structure of the human jaw (teeth, their number) different from the anatomy of the jaw of representatives of the fauna.

The structure of a milk tooth in children has a number of features, knowledge of which allows you to choose the right way of care. This will ensure in the future a timely change, health and proper development of permanent occlusion.

Differences between a milk tooth and a molar

The anatomy of the teeth of children, both temporary and permanent, has similarities and differences. The general is the presence of a crown, root, neck and internal cavity. Their functions are also identical - holding and chewing food. There are differences between dairy chewing units and permanent ones:

Dairy in the bite grows 20 pieces, while permanent - 32.
Type difference. Temporaries have incisors, canines, first molars, second molars. Premolars are added to the permanent ones.
The color of dairy is bluish-white, in constants it is yellowish.
Dairy products are smaller.
The width of the crown is greater than the height.
The hard tissues of milk teeth are thinner.
Dentin is less mineralized.
The roots are shorter and have a greater divergence to the sides.
Wide internal cavity with pulp.
The structure of the tooth in children suggests the presence of a pronounced enamel roller on the neck - the place where the root passes into the crown.
Dentinal tubules are wider.
When changing to permanent teeth in milk teeth, the roots are resorbed.

At the age of six months, many babies acquire their first teeth. Their timing may vary. It happens that the eruption is delayed for 2-3 months. This situation is a variant of the norm, but it should not be ignored by parents. Late eruption may be due to genetic predisposition, lack of vitamins, hypothyroidism, lack of tooth germs (dentia).

When teething in children, there are 2 rules according to which this happens in most babies:

Pairing. If, for example, the front lower incisor on the left climbs, then most likely the tooth on the right will immediately appear.
Growth starts from below, with the exception of the lateral incisors, which appear first from the upper jaw.

Temporary teeth come out in the following order:

the first to appear are the lower central incisors - at 6-7 months;
upper central incisors - 8-9 months;
upper lateral incisors - 9-11 months;
lower lateral incisors - 11-13 months;
lower small molars - 12-15 months;
upper small molars - 13-20 months;
lower fangs - 16-22 months;
upper fangs - 17-23 months;
lower large molars - 20-26 months;
upper large molars - 26-33 months.

This order of eruption is an approximate scheme and may differ in different children.

The process of changing them to permanent ones begins at the age of 5-6 and ends by the age of 12-14. Replacement becomes possible due to the ability of the roots of temporary teeth to dissolve. The replacement goes like this:

The germ of a permanent tooth begins to develop. Increasing in size, it puts pressure on the bone plate, which separates the germs from the milk roots.
Cells that dissolve bone minerals appear - osteoclasts.
The pulp changes, turning into a young connective tissue rich in osteoclasts.
Dairy roots experience the action of osteoclasts from the inside and outside and are absorbed.
All that remains is the crown, which loosens and falls out.

The structure of the tooth is a combination of hard (enamel, dentin, cementum) and soft (pulp) tissues. Each chewable unit consists of:

root (the part located inside the gum);
crowns (visible part);
neck (the place where the root passes into the crown).

Enamel covers the crown and is the hardest tissue in the body. Beneath it is porous and softer dentin. The root is located in the deepening of the gums - the alveolus. The structure of milk teeth provides for the presence of an internal cavity in which there is a bundle (pulp) consisting of a nerve and blood vessels that provides nutrition and saturation of incisors, canines and molars with minerals through channels located in the roots.

Features of milk teeth

In addition to the general signs of difference with permanent teeth, each temporary tooth has its own characteristics:

Incisors. They differ in configuration and shape, being more convex. They do not have furrows from the side of the sky. The enamel ridge is more pronounced in the central incisors than in the lateral incisors. They also have a less rounded distal angle than the upper lateral incisors. The roots of the central upper incisors are dilated, often with curved tips. The lower central ones have flat roots with grooves on the lateral and medial sides.
First molars. The crown of the upper first molar is more convex on the palatal side, while it is divided into 3 parts by 2 grooves on the buccal surface. They also have 3 widely spaced roots, which have sharp ends with wide apical openings. The buccal surface of the crown of the lower first molar is divided into 2 parts. It is similar to the crown of the corresponding permanent molar. The enamel roller is well expressed at the place of transition of the root to the crown. This molar has 2 widely spaced roots. The long and wide medial is much larger than the distal.
Second molars. The upper second molars do not have a sign of a root, since the posterior buccal is fused with the palatine. Their other features are the oblique shape of the crown and the enamel fold. In the lower second molars, the structure of the roots exactly repeats the anatomy of the permanent roots, differing only in that they diverge to the sides. There are 5 tubercles on the chewing surface of the crown: 2 on the lingual margin and 3 on the buccal.
Fangs. The upper canine on the cutting surface has a sharp tooth with a short crown, which has convex surfaces. The tooth on the lower canine is erased later, the crown is narrower than the upper one, and the root is rounded with a curved top.

Despite the fact that temporary teeth will be replaced by permanent ones, they need to be protected, properly cleaned and treated in a timely manner. This contributes to the proper development of permanent bite:

Since temporary teeth are less mineralized than permanent teeth, caries develops rapidly and can provoke a rapid onset of pulpitis. Therefore, you need to start brushing them from the moment of eruption, using a silicone toothbrush that is put on your finger.
In the future, soft brushes with artificial bristles, appropriate for age, should be used. The size of the cleansing surface should not cover the area of 2 chewing units.
For cleaning, it is necessary to choose a paste that does not contain fluoride, since at this age children still do not know how to spit and rinse their mouths. After the child learns to do this, the fluorine content in the paste should be selected taking into account its presence in the water of the region of residence, since excesses of this element can lead to enamel fragility.
At 2 years old, it is necessary to teach the child to self-hygiene of the oral cavity.
Children under 6 years of age should be supervised by adults when cleaning.
The first visit to the dentist should be made at 1.5 years. In the future, it is recommended to visit a doctor every 3 months, since caries in children occurs quickly.
Milk teeth should not be removed unnecessarily, as this may cause the permanent ones to grow incorrectly.

Preserving healthy temporary teeth until the physiological change will avoid problems with permanent ones in the future, not only associated with caries, but also more complex ones - with bite and proper growth of the facial bones.

The structure of a human tooth is as complex as the structure of any other organs. Moreover, its biochemical structure includes only four components: water, minerals, organic and inorganic compounds. Most of the water and organic matter is contained in the pulp and dental cement. And in terms of the number of inorganic compounds, enamel and dentin are in the lead. Of the mineral components, calcium, magnesium, sodium, potassium, phosphorus and fluorine are isolated.

Teeth ( dentes) , located in the alveoli of the upper and lower jaws, serve to capture and grind food, and also participate in the formation of speech.

How human teeth are arranged: anatomical features

The anatomical structure of the tooth is the crown, neck and root. The crown of the tooth (corona dentis) protrudes above the gum. Inside the crown there is a tooth cavity (cavitas dentis) containing the pulp (pulp) of the tooth (pulpa dentis). The crowns of all teeth have several surfaces. The lingual surface (facies lingualis) faces the tongue; the vestibular (buccal) surface (facies vestibularis, s. facialis) is located on the side of the vestibule of the mouth; the contact surfaces, anterior (medial) or posterior (lateral), face neighboring teeth located adjacent, anterior or posterior. The closure surface, or chewing (facies occlusatis, s. masticatoria), faces the teeth of the other jaw (upper or lower).

How is the neck of the tooth cervix dentis) . It is a short section between the crown and the root of the tooth. The root of the tooth (radix dentis), cone-shaped, is located in the dental alveolus. Speaking about the structural features, it is worth noting that each tooth has from one to three roots. Each root has an apex of the tooth root (apex radicis dentis), on which there is an opening of the apex of the tooth root (foramen apicis dentis), leading to the root canal of the tooth (canalis radicis dentis). A nerve, an artery pass through the hole and a canal into the cavity of the tooth, and a vein passes from the cavity of the tooth.

And how is the very substance of a human tooth arranged? It consists of dentine, enamel and cementum. Dentin (dentinum) is located around the cavity of the tooth and the root canal. The outer crown of the tooth is covered with enamel (enamelum), and the root is covered with cement (cementum).

In an adult, there are normally 32 teeth in the dental alveoli, which differ in shape and size depending on their location in the dental alveoli of the jaws. There are incisors, canines, small molars and large molars, which are arranged symmetrically in the form of two dentitions - upper and lower. In the dental alveoli of the upper and lower jaws there are 16 teeth each. On each side of the dentition, counting from the median plane, there are 8 teeth. In the dentition of each jaw on one side (from the middle outward) there are 2 incisors, 1 canine, 2 small and 3 large molars, which are usually denoted as a number row: 2, 1, 2, 3.

Incisors, canines and molars differ in the shape of the crown and the number of roots. For each type of teeth, their crowns have characteristic features. The incisors (dentes incisivi), medial and lateral, have a chisel-shaped crown, which is wider than that of the lower incisors.

cutting edge ( margo incisalis) spicy. On the lingual surface near the neck there is a tubercle of the tooth (tuberculum dentis). One of the anatomical features of the tooth is that under the crown there is a girdle (cingulum) in the form of a small elevation, passing backwards into the marginal scallops (cristae marginales). The root of the incisors is single, cone-shaped; the root of the lower incisors is depressed from the sides.

Fangs ( dentes canini) have a conical crown with a sharp apex and a single long root squeezed from the sides. The lower canines have a shorter root than the upper ones. The vestibular (buccal) surface of the crown is convex. On the lingual surface near the neck of the tooth there is a tubercle, better expressed at the upper canine. The cutting edges converge to the pointed apex of the tooth (apex cuspidis).

Small molars, or premolars ( dentes premolares) , located posterior to the fangs, have a single root, squeezed from the sides, with longitudinal grooves. The crown of small molars is round or oval, on the chewing surface it has two tubercles (buccal and lingual), separated by an intertubercular groove (sulcus intertubercularis). Large molars, or molars (dentes molares), located behind small molars, have a cuboid crown with three to five tubercles. The largest molar is the third, it erupts later than the others, and it is called the wisdom tooth (dens serotinus). On the chewing surface there are four tubercles (two buccal and two lingual), separated by grooves. The tops of the tubercles (apices cuspidum) have the shape of triangular scallops (cristae triangulares) and end with elevations of enamel, which are called tooth points (cuspides dentis).

Another important anatomical feature of the structure of the teeth is that the large molars of the lower dentition have two roots each (anterior and posterior), and the upper row has three roots each (one lingual and two buccal). The cavity of different teeth and the canals of their roots have different shapes and sizes.

These photos show the detailed structure of a human tooth:

Features of milk teeth in children (with photo)

In newborns, teeth have not yet erupted, they are inside the jaws.

Teething (they are called milk teeth - dentes decidui) occurs in children over 6 months of age. up to 2 years. In place of the erupted milk teeth, permanent teeth (dentes permanentes) are laid. Children have fewer teeth than adults. At the age of 2-2.5 years, the number of milk teeth reaches 20. Among the milk teeth in children there are (in one dentition on each side): two incisors, one canine and two large molars. There are no small molars among milk teeth. Features of milk teeth are also that they are smaller in size than permanent ones, and their roots are shorter.

In children 5-7 years old, milk teeth begin to fall out and permanent teeth (dentes permanentes) appear in their place. The eruption of permanent teeth ends by the age of 13-15.

See what baby teeth look like in these photos:

Innervation of teeth: the maxillary teeth innervate the superior alveolar nerves (from the maxillary nerve) and their posterior, middle, and anterior branches. The lower alveolar nerve (from the mandibular nerve) goes to the teeth of the lower jaw.

Blood supply: teeth of the upper jaw - anterior and posterior superior alveolar arteries (from the maxillary artery); lower jaw teeth - inferior alveolar artery. Venous blood flows through the veins of the same name.