In the maternity hospital, the pediatrician treats the baby very carefully, checking, among other indicators, whether there are any congenital pathologies in the development of his bones and joints.
Features of the structure of the bone tissue of a newborn baby
The joints of a newborn are very similar in structure to the joints of an adult, but the skeletal system is very different. Only about 50% of the constituents of bone tissue can be attributed to ash substances. Everything else is mainly cartilaginous elements, which provide the possibility of the child's growth and will gradually decrease in volume. This process usually lasts up to 18 years and is fully completed only by 25 years.
Bone tissue in a newborn is contained only in tubular bones, while other elements of the skeleton include only small points of ossification, which increase as the baby grows.
Such a composition makes the child's skeletal system very plastic, which means that the bones and joints of the newborn are easily deformed. The baby's skeleton is so vulnerable that it can change even under prolonged exposure to gravity. That is why the child should not be allowed to be in the same position for a long time or to carry him in his arms in a constant position. The newborn should be periodically turned over to another barrel, transferred to the other hand, etc.
For the same reason, pediatricians do not advise putting the baby on its feet too early, even if he himself tries to do it. Such experiments can lead to deformation of individual bones and the entire skeleton of a child.
How does a baby's skeleton grow?
The structure of the bone tissue of a newborn also has its own differences. The bones of a newborn are a coarse fibrous bundle system in which a number of bone plates are irregularly located. If the bones of an adult have significant cavities filled with yellow bone marrow, then in an infant such cavities are very small and contain mainly red bone marrow.
Thanks to the large amount of red bone marrow, the child's skeletal system receives an adequate supply of blood, which is necessary for its growth. This process occurs intensively until about two years of age. After some decline, the growth process resumes with renewed vigor already in puberty.
Bone growth in length is provided by the epiphyseal cartilage. Its peripheral edge remains active until the age of twenty-five, due to which the bones have the main opportunity to increase in length and the child becomes taller.
The periosteum is responsible for the thickening of the bones, their growth in width. In a child, it is dense, thick and functionally more active. This feature of the periosteum is very favorable for the child, since even with fractures, the periosteum often remains intact, and the bone protected by it grows together faster and without dangerous consequences for the child's musculoskeletal system.
The basis of the tissue of the joints of the newborn, like his bones, is cartilage tissue. The mobility of all the elements that form the joints also differs. Since the newborn has not yet had time to develop the joints, the range of possible movements is still very small, but the likelihood of dislocation in case of careless handling is quite high. Such immaturity of the joints, as a rule, persists up to three and even up to five years, that is, until the tissue of bones and joints has developed sufficiently, and the child has not mastered the science of controlling his body to the fullest.
The skeleton is an especially important part of the full, healthy functioning of the human body. Thanks to the bones, the body is always in shape and the right position. Bones form the skeleton, which in turn also performs a protective function of internal organs and systems from external influences. All this applies to both adults and children from the womb.
Formation of the fetal skeleton
More than 70% of the bones are made of very strong bone tissue, which contains many minerals. The main ones include: magnesium, phosphorus and calcium. Necessary for the full formation of the fetal skeleton and other elements: zinc, copper, aluminum and fluorine. The fetus receives these and other substances through the placenta from the mother's body. Therefore, it is extremely important for pregnant women to eat well and of good quality. Starting from the fifth week of pregnancy, the foundations of cartilage are laid in the fetus - the future bones of the spine and shoulder girdle. The outlines of the pelvic girdle also appear. The fetus, which is already 9 weeks old, has developed fingers and jaw bones. Many people know that a newborn baby has more bones than an adult. This is due to the fact that in the future, the cartilage will grow together, forming one bone. The complete completion of the formation of the skeleton will occur at the age of 24.
How many bones does a child have?
Many parents are convinced from their own experience that a child's bones are more likely to bend than injured. Not considering, of course, serious damage. Very often newborns fall out of bed or sofa, while "pah-pah" everything is fine. All this is because cartilage predominates in their skeleton, which will further strengthen and become bones. So how many bones does a child have? A newborn man has 300 fragile bones in his little body. And only by the age of 24-25 206 strong, strong bones will be formed from them.
This process takes place due to the intake of calcium and other necessary substances into the body.
Bone injury in a child
How many bones are in the body of a small child is clear, now about their injuries. To the great delight of parents, childhood injuries recover quickly.
All due to the fact that in the child's body there are cells responsible for the structure of bone tissue. And if it happens that the child is injured, these cells fall on the injured area. Thus, even a fracture will heal much faster in a child than in an adult. Childhood trauma will go away after 2-4 weeks, adult trauma - 6-8. How many bones are in the child's body, all young mothers need to know and not only. This will allow you to be more educated in this area and provide the help you need child in case of injury.
Difference between the bone of an elderly person and a child
How many bones are in the skeleton of a child, we figured it out. Now, many anxious question: "What is the difference in the skeleton of an elderly person and a child?" Bones in children are much thinner than in adults, including the elderly. Thanks to this, the child's motor apparatus is much more mobile and elastic. Closer to a 12-13-year-old child, they are almost completely similar to adults. However, in some places, cartilage is still found. During adulthood and closer to old age, the relief of the cranial bones is noticeably smoothed out.
Also, with the loss of teeth, the weight of the skull decreases, which can provoke an irregular bite and cause facial asymmetry.
The most pronounced changes in the structure of the skeleton with age occur in the spine. After 40-50 years, this part of the skeleton becomes more compressed and slightly shorter than it was before. This is due to the fact that the intervertebral discs and vertebrae are tighter to each other. After 60 years, the growth of bone tissue begins, and spike-like formations appear on the body.
So, the main differences between the skeleton of an elderly and a small person:
- The main and first difference is, of course, the quantity. How many bones do a young child and an elderly person have? Child - 300 bones, adult - 206.
- The bone tissue of a child is rich in spongy substance than the bone of an elderly person.
- Mobility is also an important difference. The skeleton of a child is more active and elastic, which cannot be said about the skeleton of the elderly.
- With age, tissue changes, which leads to weakening of the bones of the skeleton. A noticeable decrease in calcium and fluoride in the body first of all makes itself felt.
After birth, the child continues to grow and differentiate the bone, the formation of the skeleton. In the body, the functions of bone tissue are diverse: first, it is the support and protection of internal organs, bone marrow; secondly, bones, in fact, are a reservoir of inorganic (calcium, phosphorus, magnesium) and some organic substances; thirdly, bone tissue in extreme conditions is a protection against acidosis, after the functions of the kidneys and lungs are exhausted; fourthly, it is a "trap for foreign substances" (heavy, radioactive, etc.).
Bone architectonics can be divided into two types: trabecular and cancellous. The structure of the trabecular bone resembles the ethmoid structure that surrounds the vessels. Osteophytes in it are scattered throughout the structure. In the fetus and embryo, almost all bones of the skeleton have a trabecular structure. After birth, this structure persists in the vertebrae, flat bones, and also in the tubular bones, being a temporary structure during the formation of lamellar bone.
Dense bone is the ultimate structure inherent in the adult skeleton. It consists of a system of Haversian canals and is built from a hard calcified matrix. Osteophytes in it are arranged in an orderly manner and are oriented along the vascular canals. The development of dense bone is gradual, as the motor load increases.
The main cellular elements of bone tissue are osteocyte, osteoblast and osteoclast. Osteogenesis in humans is unique and differs from all representatives of the animal world. The final bone structure is formed after birth, which is associated with the onset of stable walking.
By the time a child is born, the diaphysis and epiphyses of the tubular bones are already represented by bone tissue. All cancellous bones (hands, feet, skull) are made of cartilage tissue. By birth, ossification nuclei are formed in these bones, giving rise to dense bone. By the points of ossification, one can judge the biological age of the child. The growth of tubular bones occurs due to the growth of cartilage tissue. Elongation of bones occurs due to the growth of cartilage tissue in length. Bone growth in width occurs at the expense of the periosteum. At the same time, from the side of the medullary canal, the cortical layer of the periosteum is subject to constant resorption, as a result of which the volume of the medullary canal increases with bone growth in diameter.
After birth, the bone in its development is rebuilt many times - from a coarse-fibrous structure to a structural bone.
With age, there is a process of osteogenesis - remodeling of bone tissue. Bone density builds up gradually. The content of the main mineral component of bone tissue - hydroxyapatite - increases with age in children.
In general, there are three stages in the process of bone formation:
1) the formation of the protein base of bone tissue; it mostly occurs in utero;
2) the formation of crystallization centers (hydroxyapatite) followed by mineralization (osteosynthesis); it is characteristic of the postpartum period;
3) osteogenesis, when the process of bone remodeling and self-renewal occurs.
At all stages of osteogenesis, vitamin D and the normal presence of Ca, Mg, and P ions in food are required. An indispensable condition for the correct formation of the skeletal system is exposure to air, external insolation.
With a lack of any of these components, the child develops rickets, characterized by changes in the bone and muscular system, disorders of the central nervous system.
In children, in contrast to adults, the younger the age, the more abundantly the bones are supplied with blood. The blood supply to the metaphyses and epiphyses is especially developed. By the age of 2 years, a single system of intraosseous blood circulation is formed, the network of epimetaphyseal vessels and growth cartilage are well developed. After 2 years, the number of bone vessels decreases significantly and increases again by puberty.
The periosteum is thicker in children than in adults. Due to it, the bone grows in thickness. Bone marrow cavities form with age. By the age of 12, the bone of a child already resembles the bone of an adult.
In the development of bones in children, periods can be distinguished when bones are especially sensitive to harmful factors.
1. Breast, early or preschool period, the first 3 years of life, when bone growth and calcification, saturation and deposition of minerals (calcium, phosphorus) occur. Various osteopathies easily arise - rickets, rickets-like conditions. Therefore, rational feeding of the child, adherence to the daily regimen is of particular importance.
2. School and adolescence, when the differentiation and accumulation of bone mass is completed. Children have borderline osteochondropathy. Risk factors for impaired bone formation in children are nutritional disorders, inadequate physical activity.
Skull
The skull of a newborn is made up of many bones. Sutures such as sagittal, coronal, occipital, are open. Their closure begins by 3-4 months of age. In term babies, the lateral fontanelles are closed at birth. The posterior, or small, fontanelle, located at the level of the occipital and parietal bones, is open in 25% of newborns. It closes at 4-8 weeks of age. The large fontanelle is located at the junction of the parietal and frontal bones, or the coronal and sagittal sutures. It is always open, and its size in a newborn ranges from 3x3 cm to 1.5x2 cm. Normally, the large fontanelle closes by 10-18 months.
The shape of the head in children can be different, but more often it is round, symmetrical. The facial skull develops with age.
Spine
The human spine is a unique bone formation that contributes to its upright posture, which is formed parallel to the growth of the child. Gradually, with age, the spine acquires its own curves, which take over the movement of the center of gravity of a walking or standing person.
The first bends of the spine appear from the beginning of holding the head and shoulder girdle, and by 2-4 months the anterior bend of the cervical spine is formed. After the development of the ability to stand upright and walk, an anterior bend forms in the lumbar spine and almost simultaneously a thoracic bend of the spine. The uneven growth of individual segments of the body, spine, head and limbs leads to the fact that the center of gravity of the body during the growth of children significantly moves. So, if in a newborn in an upright position the center of gravity is at the level of processus xyphoideus, then in an older child it moves down, but does not reach the level of the navel. At the age of 5-6 years, the center of gravity is already below the navel, and by 13 years - below the level of the iliac crests.
In children, in contrast to adults, the fixation of the spine is unstable, imperfect, and under the influence of external factors (incorrect posture) persistent deformities of the bones of the spine (scoliosis and pathological posture) can occur.
Rib cage
Than less child, so his chest is relatively wider and shorter, while the ribs are horizontal. A child's chest is more rounded than that of an adult. Its transverse size in a newborn is 25% larger than the mid-longitudinal one, their chest is in a state of inspiration, as it were. Subsequently, the chest grows in length, while the ribs descend, forming an obtuse angle with the spine, and its front diameter is growing rapidly. Effective rib breathing is formed at 3 years of age. By the age of 12, the chest passes into a state of maximum inspiration, and by the age of 15, the final increase in its transverse diameter is completed.
Pelvic bones in children early age resemble a funnel. The formation of gender differences in the pelvis begins at puberty.
Methods for examining the skeletal system and joints
Data on the history of diseases of the skeletal system are usually collected from the words of parents, close relatives or those involved in raising the child. Older children may themselves add significant value to the medical history. When questioning, pay attention to the timing of the appearance of certain changes. Firstly, they reveal the presence of pain (arthralgia, myalgia, osalgia), secondly, changes in the configuration of bones and joints, and thirdly, the state of mobility in the joints. When complaints of pain are noted, their localization, symmetry, nature and intensity, duration, frequency are noted. Then they ask about the factors that contribute to the intensification or disappearance of pain (warmth, rest, medications). The next point is the establishment of mobility disorders (morning stiffness, restriction of movement due to pain, etc.). After that, they ask about the connection between the onset and the appearance of pain or changes in the joints, bones with any disease (previous infections, injuries).
Inspection is carried out from top to bottom (head, torso, limbs), while good lighting is important. In young children, attention is paid to pathological changes in the shape of the head, which are especially often observed in rickets. The bones of the skull can be oblique, asymmetrical, the frontal, parietal and occipital tubercles increase. Often there is a thickening of the occipital bone and its smoothness.
With congenital syphilis, pathological fragility of the skull bones can develop. In newborns, the deformity of the skull associated with birth trauma is manifested by a tiled arrangement of bones (found on top of each other), their depression or protrusion, often with subsequent subperiosteal hemorrhages (cephalohematomas). Brain hernias can also be observed.
The head is measured for assessment purposes physical development or to identify pathology (micro- and macrocephaly).
Microcephaly develops in utero or with early closure of sutures (against the background of vitamin D hypervitaminosis). A large head with macrocephaly as a pathological condition most often develops in violation of hemoliquorodynamics - hydrocephalus. In this case, the fontanelles and even the seams are always open.
On examination, attention is paid to the age proportionality of the development of the facial and cerebral skull.
Then the chest is examined. Pay attention to its shape, symmetry, uniformity of participation in the act of breathing, various deformations ("chicken breast", funnel chest, Filatov-Garrison peripneumonic sulcus, heart hump, etc.), indicating a congenital or acquired defect.
The child's posture is assessed in a standing position: heels together, hands at the seams. In case of postural disorders, there are lateral curvatures of the spine - scoliosis, lagging of the shoulder blades from the chest, stoop, pathological lordosis (increased forward bending of the spine) and kyphosis (increased backward bending of the spine). Lateral curvature of the spine - scoliosis (this is always a pathology) is especially often noted. Suspicion of scoliosis must be confirmed by X-ray.
It is necessary to examine the tenderness of the vertebrae when feeling and moving, especially if the child complains of pain in the spine.
Inspection of the upper limbs is performed to determine their length and the presence of deformation. There are standards for the development of limbs in children of different ages. Long-handedness is more often detected in connective tissue diseases (Marfan's disease). Shortening of the limbs is associated with Down's disease and chondrodystrophy. The fingers are also examined to identify the symptom of "drumsticks", osteopathies, arthritis and other changes.
When examining the lower extremities in a newborn, attention is paid to the symmetry of the gluteal folds, the number of folds on the inner thighs (with congenital dislocation of the hip joint, there are more folds), shortening of the limbs, X- or O-shaped curvature of the legs (with rickets). Often, older children are diagnosed with flat feet, which is a pathological condition. To determine it, plantography is carried out - they study the footprint on a sheet of paper.
The following standard sequence is helpful for rapid skeletal screening and documentation:
1. Inspection from the front, arms extended along the body. At the same time, the shape of the legs, the position of the head, the symmetry of the shoulders, the triangles of the waist are determined, the deformation of the chest, the symmetry of the hips are excluded.
2. Side view. Determine the shape of the chest, abdomen, shoulder blades protrusion, the shape of the back.
3. Inspection from the back. Reveal the symmetry of the angles of the shoulder blades, the shape of the spine, the shape of the legs, the axis of the heels.
4. At the end of the examination, the child is offered to walk around the office to identify gait disorders.
Based on the results of the inspection, testing is carried out: 1) without deviations - negative values \u200b\u200bfor all items; 2) minor deviations requiring the supervision of a pediatrician - with positive answers to questions 3-7; 3) significant deviations requiring further examination and treatment by an orthopedist or vertebrologist - positive answers to 5 questions (1, 2, 8, 9, 10).
Palpation of bones is a medical procedure. It is aimed at detecting softening of bones, fontanelles or sutures of the skull in newborns and infants. The ribs and bones of the extremities are also palpated, the joints are examined, and on the basis of changes in their shape, size and range of motion, one or another pathology is judged. If necessary, an X-ray examination is prescribed. It is carried out in case of suspicion of inflammatory-dystrophic changes in bones, joints; for bone tumors, for determining bone (biological) age, for diagnosing diseases accompanied by osteoporosis, bone softening. Laboratory methods are also used to diagnose diseases of the skeletal system: the level of Ca, P, alkaline phosphatase in the blood and urine is determined.
Teeth
In children, the first teeth are milk teeth. They are cut in sequence.
The formation of the bite of milk teeth is of great importance. It is formed by the age of 2.5-3.5 and is characterized by the following positions:
1) small spaces between teeth;
2) absence of wear of teeth;
3) the distal surfaces of the upper and lower dental incisors are located in the same frontal plane;
4) orthognathic bite, when the upper incisors slightly cover the lower incisors.
The next period of tooth development begins at the age of 3.5 - 6 years. At this time, interdental gaps (diastemas) appear - between the incisors or three - between the other teeth. The teeth are already worn out, the lower and upper teeth do not match. The orthognastic bite becomes straight. The milk bite of the teeth is of great importance for the formation of the ability to chew food and the development of speech.
The period of mixed bite begins with the appearance of permanent teeth, while milk teeth are also preserved. The first permanent teeth erupt at the age of 5 - these are the first molars. Then milk teeth consistently fall out and permanent teeth appear. By the age of 11, second molars erupt. Third molars (wisdom teeth) appear at the age of 17-20, and sometimes even later. To estimate the number of permanent teeth, use the following formula:
X \u003d 4n - 20, where n is the child's age, years.
Children of any age often have dental disease - caries, in which there is a gradual destruction of the tooth structure. Therefore, in the upbringing of a child, caries prevention takes a special place.
In this regard, it matters balanced diet, adherence to the principles of feeding a child breast milk... Particular importance is attached to the content of fluoride in food, as a means of preventing caries. Children should brush their teeth with prophylactic pastes that do not contain fluoride, but it must be contained in food. In addition to fluoride, the child also needs calcium.
A rational diet should also include organic, low-digestible carbohydrates. The latter have a positive effect on the growth of the normal flora of the oral cavity. For the correct development of teeth, the prevention of caries, a diet containing starch, glycogen, disaccharides, glucose is needed. It is important to teach your child how to chew food correctly. After eating, be sure to rinse your mouth and brush your teeth with paste, at least twice a day - in the evening and in the morning.
The skull at the time of birth is represented by a large number of bones connected by wide cartilaginous and connective tissue layers. The seams between the bones of the vault (arrow-shaped, coronal, occipital) are not formed and begin to close only from 3-4 months of life. The edges of the bones are even, the teeth are formed only in the 3rd year of the child's life. The formation of seams between the bones of the skull ends by 3-5 years of age. The overgrowth of seams begins after 20-30 years.
The fontanelles of the skull of a newborn
The most characteristic feature of the newborn's skull is the presence of fontanelles (non-ossified membranous areas of the cranial vault), due to which the skull is very elastic, its shape can change during the passage of the fetal head through the birth canal.
The large fontanelle is located at the intersection of the coronal and sagittal sutures. Its dimensions are from 1.5x2 cm to 3x3 cm when measured between the edges of the bones. The large fontanelle usually closes by the age of 1-1.5 years (nowadays, it is often already by the 9-10th month of life).
The small fontanelle is located between the occipital and parietal bones; by the time of birth, it is closed in 3/4 of healthy full-term babies, and in the rest it closes by the end of the 1-2 month of life.
Lateral fontanelles (anterior wedge-shaped and posterior mastoid) in term infants are closed at birth.
The structure of the skull of a newborn
The cerebral section of the skull is significantly larger in volume than the facial one (in a newborn, it is 8 times, and in adults only 2 times). The eye sockets of the newborn are wide, the frontal bone consists of two halves, the superciliary arches are not pronounced, the frontal sinus is not formed. The jaws are underdeveloped, the lower jaw consists of two halves.
The skull grows rapidly up to 7 years. In the first year of life, there is a rapid and uniform increase in the size of the skull, the thickness of the bones increases by 3 times, the structure of the bones of the cranial vault is formed. At the age of 1 to 3 years, ossification points merge, cartilaginous tissue is gradually replaced by bone. In the 12th year, the halves of the lower jaw grow together, in the 2nd - 3rd year, due to the increased function of the chewing muscles and the completion of the eruption of milk teeth, the growth of the facial skull increases. From 3 to 7 years old, the base of the skull grows most actively, and by the age of 7 years, its growth in length basically ends. At the age of 7-13, the skull grows more slowly and evenly. At this time, the fusion of individual parts of the skull bones is completed. At the age of 13-20, mainly the facial part of the skull grows, sex differences appear. Thickening and pneumatization of the bones occurs, which leads to a decrease in their mass.
Spine of an infant
The length of the spinal column in a newborn is 40% of its body length and doubles in the first 2 years of life. However, different parts of the spinal column grow unevenly, for example, in the first year of life, the lumbar region grows most rapidly, and the coccygeal one is the slowest.
In newborns, the vertebral bodies, as well as the transverse and spinous processes, are relatively poorly developed, the intervertebral discs are relatively thicker than in adults, they are better supplied with blood.
The spine of a newborn has the appearance of a gentle arc, concave in front. Physiological curves begin to form only from 3-4 months. Cervical lordosis develops after the child begins to hold his head. When the child begins to sit (5-6 months), thoracic kyphosis appears. Lumbar lordosis begins to form after 6-7 months, when the child begins to sit, and intensifies after 9-12 months, when the child begins to stand and walk. At the same time, sacral kyphosis is formed compensatory. Bends of the spinal column become clearly visible by 5-6 years. The final formation of cervical lordosis and thoracic kyphosis is completed by 7 years, and lumbar lordosis - by the period of puberty. Thanks to the bends, the elasticity of the spinal column increases, shocks and concussions when walking, jumping, etc. are softened.
Due to the incompleteness of the formation of the spine and the poor development of the muscles that fix the spine, pathological bends of the spine (for example, scoliosis) and posture disorders easily develop in children.
Baby's ribcage
The chest of a newborn has a conical shape, its anteroposterior size is larger than the transverse one. The ribs extend from the spine almost at right angles and are horizontal. The rib cage is, as it were, in the position of maximum inspiration.
The ribs of young children are soft, pliable, easily bend and spring when pressed. The depth of inspiration is mainly provided by the excursions of the diaphragm, the attachment point of which, when breathing is difficult, is retracted, forming a temporary or permanent Harrison sulcus.
When the baby begins to walk, the sternum drops, and the ribs gradually take a tilt position. By the age of 3 years, the anterior-posterior and transverse dimensions of the chest are equal in size, the angle of inclination of the ribs increases, and costal breathing becomes effective.
By school age, the chest flattens, depending on the body type, one of its three forms begins to form: conical, flat or cylindrical. By the age of 12, the chest moves to the maximum expiration position. Only by the age of 17-20 does the chest take on its final shape.
Pelvic bones in a child
The pelvic bones in young children are relatively small. The shape of the pelvis resembles a funnel. The pelvic bones grow most intensively during the first 6 years, and in girls, in addition, during puberty. The change in the shape and size of the pelvis occurs under the influence of body weight, abdominal organs, under the influence of muscles and the influence of sex hormones. The difference in the shape of the pelvis in boys and girls becomes noticeable after 9 years: in boys, the pelvis is taller and narrower than in girls.
Up to 12-14 years old, the pelvic bone consists of 3 separate bones connected by cartilage, the fused bodies of which form the acetabulum. The acetabulum in a newborn is oval, its depth is much shallower than in an adult, as a result of which most of the femoral head is located outside of it. The articular capsule is thin, the ischio-femoral ligament is not formed. Gradually, with the growth of the pelvic bone in thickness and the formation of the edge of the acetabulum, the head of the femur sinks deeper into the joint cavity.
Limbs in children
In newborns, the limbs are relatively short. Subsequently, the lower limbs grow faster and become longer than the upper ones. The highest growth rate of the lower extremities occurs in boys at the age of 1215 years, in girls at the age of 13-14 years.
In a newborn and a child of the first year of life, the foot is flat. The line of the transverse joint of the tarsus is almost straight (S-shaped in an adult). The formation of articular surfaces, ligaments and arches of the foot occurs gradually, after the child begins to stand and walk and as the bones of the foot ossify.
Teeth in children
Milk teeth in children usually erupt from the age of 5-7 months in a certain sequence, while the teeth of the same name on the right and left halves of the jaw appear simultaneously. The order of eruption of milk teeth is as follows: 2 internal lower and 2 internal upper incisors, and then 2 external upper and 2 external lower incisors (by the year - 8 incisors), at the age of 12-15 months - the anterior molars (molars), at 18-20 1 month - canines, at 22-24 months - posterior molars. Thus, by the age of 2, a child has 20 milk teeth. For an approximate determination of the proper number of milk teeth, you can use the following formula:
where: X is the number of milk teeth; n is the child's age in months.
Replacement of milk teeth with permanent
The period of replacing milk teeth with permanent ones is called the period of a changeable bite. A permanent tooth usually erupts 3-4 months after the milk has fallen out. The formation of both milk and permanent bite in children is a criterion for the biological maturation of a child (dental age).
In the first period (from eruption to 3-3.5 years), the teeth are closely spaced, the bite is orthognathic (the upper teeth cover the lower ones by one third) due to insufficient development of the lower jaw, there is no tooth wear.
In the second period (from 3 to 6 years), the bite becomes straight, physiological gaps appear between the milk teeth (as preparation for the eruption of permanent, wider teeth) and their wear.
The change of milk teeth to permanent ones begins at the age of 5. The order of eruption of permanent teeth is usually as follows: at the age of 5 - 7 years the first molars (large molars) erupt, at 7 - 8 years old - internal incisors, at 8 - 9 years old - external incisors, at 10 - 11 years old - anterior premolars, at 11 - 12 years old - posterior premolars and canines, at 10 - 14 years old second molars, at 18 - 25 years old - wisdom teeth (may be absent). For a rough estimate of the number of permanent teeth, you can use the formula:
where: X is the number of permanent teeth, n is the child's age in years.
Teething symptoms
In some children, teething may be accompanied by an increase in body temperature, sleep disturbances, diarrhea, etc. The formation of both milk and permanent bite in children is an important indicator of the biological maturation of a child. A permanent bite should normally be orthognathic or straight.
