From this article you will learn:
- How many teeth should a person normally have?
- in what cases are there fewer or more of them (33 teeth),
- human dental formula – diagram, teeth numbering,
Human teeth can be temporary or permanent. Temporary teeth normally begin to erupt in children starting at 5-6 months (eruption begins with the central incisors of the lower jaw), but in modern children it can begin earlier. In total, the child must erupt 20 milk teeth - this is 10 teeth in the upper jaw + 10 teeth in the lower jaw. This process will last until the child is 2-2.5 years old.
From about 6 years of age, temporary teeth begin to gradually fall out, and permanent molars erupt in their place. Most permanent teeth fully erupt by age 14, and only the eruption of wisdom teeth (the last teeth on each side of the dentition) usually occurs between 18-25 years. In total, an adult can erupt 32 teeth - 16 teeth each in the upper and lower jaws, but there are rarely exceptions. For example, a person may have a supernumerary 33 tooth, or, on the contrary, there may be fewer teeth.
Teeth of a child and an adult on x-rays –
Thus, how many teeth a person has depends on age. Normally, at the end of the eruption of all temporary teeth in children, there will be 20 of them. Then, from the age of 6, the period of replacing milk teeth with permanent teeth begins, when the child will simultaneously have both milk and permanent teeth in the oral cavity (this period is called the period of replacement teeth). bite). Once all permanent teeth have erupted, a person will normally have 32 permanent teeth. Read more about the timing of teething at the link below.
→ Timing of teething in adults and children
Teeth of ancient people
The dentofacial apparatus of prehistoric and modern humans differs significantly. Ancient people had more than 36 teeth, protruding fangs and a massive jaw. This was explained by the need to chew rough food and raw meat. With the addition of thermally processed foods to the diet, the dentition began to change. The canines were the first to transform, becoming aligned with the bite line. Then the jaw arch narrowed, the interdental spaces disappeared, and the teeth themselves decreased in size. Currently, 32 teeth in humans are the norm, but third molars are considered to be an atavism.
Interesting fact!
The teeth of ancient man cannot be called aesthetic, but they were healthy. According to scientists, cavemen never suffered from caries and other oral diseases.
Possible problems
Despite the fact that changing teeth is a natural physiological process, some children and their parents may encounter a number of problems that require contacting a pediatric dentist.
No molars
The absence of permanent units can be caused by congenital edentia - the complete or partial absence of tooth buds.
Another reason for the absence of molars is previous inflammatory diseases - periostitis or periodontitis, resulting from progressive caries. Inflammatory diseases of the periosteum and periodontal tissues have an extremely negative effect on the condition of the tooth buds and can lead to their death.
Important! It is absolutely necessary to treat baby teeth for caries. You should not assume that the problem will go away on its own with the change of teeth. The progression of the disease can negatively affect the health of the tooth buds.
Molar tooth hurts
The enamel of newly emerging permanent teeth is still poorly formed. The low level of its mineralization makes teeth vulnerable to cariogenic microflora. This can lead to the development of caries and cause pain.
Due to poorly formed enamel, tooth sensitivity to external irritants (cold, hot, sour, sweet) may increase, which is also accompanied by painful sensations.
Important! Normally, permanent teeth do not hurt. If pain occurs, you should contact your pediatric dentist. The specialist will determine the cause of the pain, carry out the necessary treatment, fluoridation or remineralization of tooth enamel.
Molars grow crooked
The incorrect position of permanent teeth can be caused by two reasons - the growth of the permanent unit outpaces the process of loss of baby teeth or they were removed ahead of schedule, which led to incorrect formation of the rudiments of permanent teeth.
In this case, there is only one way out - orthodontic treatment of malocclusion.
Important! A malocclusion must be corrected. The sooner you contact a dentist, the more successful the treatment will be. The child will be prescribed to wear removable or fixed orthodontic appliances that will help straighten the permanent teeth and bite.
Injuries
Due to their activity and lack of experience, children can accidentally injure a newly emerging permanent tooth. Due to mechanical damage, cracks and chips may appear on it. The damage looks unattractive. Caring for such teeth is complicated, since food debris can get stuck in the cracks, which will certainly lead to the development of caries.
Important! If a child accidentally injures a permanent tooth, it is necessary to seek help from a dentist. The specialist will assess the complexity and depth of the damage and will build up the missing volume of tooth tissue with composite materials.
Tooth loss
Loss of healthy permanent teeth can only occur as a result of severe trauma to the jaw, for example, during a child’s fall or fight. A diseased molar may fall out on its own. In this case, you will also need to consult a specialist. Most likely, the child will undergo temporary prosthetics for the lost unit, which will not disrupt the formation of a correct permanent bite.
The tooth is loose
Looseness of a permanent tooth is an alarming symptom indicating a pathology of the dentofacial apparatus or the presence of inflammation. Consultation with a specialist is required!
Name of human teeth
Depending on the location and structure, dental units have their own functional characteristics and are called differently.
- Incisors.
On both jaws there are four front teeth in humans - medial and lateral incisors, which are used for biting food. - Fangs.
Sharp teeth designed for chewing hard foods. - Premolars.
"Fours" and "fives" on the left and right sides of each jaw arch grind soft or small pieces of food. - Molars.
Three large outer teeth in each row are aimed at grinding coarse substances. - The canines
and incisors are part of the anterior group, or the “smile zone,” and the human molars are part of the chewing segment.
In addition, teeth are divided into temporary and permanent. In the first case, we are talking about dairy products that appear in children from the fifth month of life to three years. The second refers to the final bite, which is formed between six and thirteen years of age. Milk teeth differ from permanent teeth only in size, but in structure they are identical.
How many teeth does a person have?
The number of teeth a person has depends on age and anatomical features. The child has a set of 20 primary teeth, which are replaced by a permanent bite of 28 teeth. Third molars erupt, as a rule, after twenty years or do not grow at all, which is not a pathology.
In dentistry, a single numbering of human teeth is adopted. Doctors classify teeth as lower and upper and distinguish the right and left segments of the jaws. Each of them includes two incisors, a canine, two premolars and three molars. The countdown starts from the first front tooth and ends, accordingly, with a figure eight. Sometimes a number is added to the serial number indicating the location zone. For example, the right canine of the top row is numbered 13. This order in the schematic representation is called the formula of human teeth.
Polyodontia
In rare cases, an anomaly such as polyodontia is observed - supernumerary, or extra teeth in a person. Dental units can appear in the primary and permanent dentition anywhere in the jaw, separate from or fused with the main teeth. The defect affects not only the aesthetics of the smile, but also leads to the formation of incorrect occlusion, impairs the quality of chewing food and diction. Most often, supernumerary teeth are removed in childhood or built into the dentition.
Edentia
There is also a deviation of the opposite meaning called edentia - congenital or acquired absence of dental units. The causes of the phenomenon include heredity or improper development of the embryo in the womb. People without teeth cannot fully eat and speak, have a deformed facial contour and weakened immunity.
Molars - normal or abnormal?
Speaking of molars! Why do some have them and others don't? And why is both their absence and their presence considered the norm?
The study of the evolution of molars shows that they are facing imminent extinction - complete disappearance from the human mouth. Once upon a time, the human jaw could accommodate as many as 44 teeth, today there are 32, but a tendency towards reduction is observed, which is due to soft food. A few hundred years and molars can completely disappear. Some modern people never have them!
It turns out, from the point of view of modern dentistry, the number of teeth in a person’s mouth from 28 to 32 is considered the norm. If you have a full set of teeth (32), we congratulate you on reaching the norm. But in practice, only a select few reach the standard of a complete set!
Dimensions of human teeth
The upper central incisors are twice as wide as their antagonists. The remaining dental units of the same name have approximately equal parameters. The size is determined using special tables with the optimal size and permissible deviations. Experienced doctors calculate proportions by dividing the length of a person’s teeth by the width. A result of about 0.75 millimeters is considered close to ideal. For more detailed diagnostics, other professional formulas and techniques are used.
Size deviations from the norm occur due to improper formation of the jaw, fusion of tooth buds, or genetic predisposition. Teeth that are too large are called macrodentia, and abnormally small teeth are called microdentia. Pathologies are accompanied by problems with bite and chewing functions, but can be successfully corrected by a dentist.
Interesting fact!
The longest tooth in the world belongs to an Indian teenager. The size of its crown is almost four centimeters. About a year ago, the tooth was removed, and the young man was included in the Guinness Book of Records.
Dental formula
In order to improve the convenience of describing each tooth, numbering them, and filling out cards, it is customary to record the order of the teeth using a special formula. There are several varieties of it.
Zsigmondy-Palmer system (quadratic-digital)
Arabic numerals are used, numbering starts from the central incisors in each direction:
- 1 and 2 – incisors.
- 3 – fang.
- 4, 5 – premolars.
- 6-8 – molars.
Milk teeth are designated differently - using Roman numerals:
- I and II – incisors.
- III – fang.
- IV and V – molars.
Two-digit Viola system
Teeth numbering uses 2 digits. The jaws are divided into 4 quadrants. The first digit shows its number.
For adults this is:
- 1 – upper jaw on the right.
- 2 – upper jaw on the left.
- 3 – lower jaw on the left.
- 4 – lower jaw reference.
For a similar description of baby teeth, numbers 5 to 8 are used.
So, there are 8 teeth in each quadrant, its number is shown by the second digit. Thus, the first molar of the lower jaw on the left is designated 35, and the child’s canine from the lower right is designated 43. Therefore, the phrase that “treatment of the 48th tooth is required,” or, for example, the 55th, does not indicate the doctor’s lack of qualifications or what - or pathology in your child, who suddenly acquired so many teeth.
The structure of the human tooth
Anatomy
From an anatomical point of view, a human tooth consists of three parts.
- Crown.
The visible part protruding above the gum. It has four sides: the occlusal, or cutting edge, in contact with the antagonist teeth; contact wall adjacent to adjacent dental units; vestibular and lingual surfaces facing the lips and tongue, respectively. - Root.
Fixed in the socket by connective tissue, located in the recess of the jaw. As a rule, premolars have two roots, and molars have three, four or even five. The remaining dental units have one root canal. - Neck.
It is located between the coronal part and the root of a human tooth, surrounded by periodontium.
Histology
What are human teeth made of? Let's look at the cross-section of the structure of a human tooth.
- Enamel.
A transparent protective coating of the crown, almost entirely consisting of inorganic microelements. - Dentine.
The hard base of the tooth, containing 80% mineral components and 20% organic substances. The shade of dentin is responsible for the color of dental units, as it shines through the enamel. - Cement.
The bone tissue covering the tooth root. Plays the role of a fastening element connecting the tooth to the alveolus. - Pulp.
Soft tissue filled with bundles of nerves and capillaries. Painful sensations during caries are explained precisely by the presence of nerve endings.
Human wisdom teeth
A “wisdom tooth” is the third outer molar with three to five roots. In structure it is no different from its “neighbors”. To the question “How many wisdom teeth does a person have?” cannot be answered unambiguously. They erupt around the age of twenty, one on each side of both jaws. However, there are people without wisdom teeth. This is a variant of the norm, since in the process of human evolution the need for the “eight” disappeared, and the structure of the jaws underwent corresponding changes. Today, third molars are considered a vestigial organ.
Diagnostics
An erupted supernumerary tooth is detected during examination of the oral cavity; it is often dystopic, that is, abnormally located.
Diagnosis of unerupted (impacted) supernumerary teeth is carried out using x-ray examination. Often, X-ray diagnostics of supernumerary teeth is difficult due to the fact that in the image their contours overlap the contours of the complete teeth. For more accurate diagnosis, 3D computed tomography is used. The results of these studies make it possible to obtain comprehensive information about the relative position of erupted and impacted complete and supernumerary teeth.
