What distinguishes molars from other teeth: structure, function, disease

Molars (or large molars) are characterized by a pronounced relief, having in its structure many tubercles on the chewing side. In the structure of all representatives of this species, several roots are distinguished. Localized in the distal parts of the dental arch. They occupy several positions on the upper and lower jaw:

• 6 position;
• 7 position;
• 8 position.

In the dentition, they are located immediately behind the premolars. In some cases, there are additional large molars - wisdom teeth.

Molars are the largest of the human oral cavity. Their main purpose is to ensure that solid foods are thoroughly chewed.

Structure

These teeth, like all the others, have both general principles of anatomical structure and their own characteristics.

Mostly the most massive part is

dentine (directly bone substance). Outside, dentin is protected from the adverse effects of food and environmental factors by a special structure - enamel.

Enamel is the hardest tissue in the human body. This is mainly due to its main function - mechanical protection of the tooth. In its chemical structure, it consists of 97 - 98% inorganic compounds and 2-3% water (the lowest percentage of water in comparison with all other tissues of the body). Its thickness can reach 1.8 - 2.1 mm. The thickness of the enamel is different for different teeth and their different areas.

The molars are located in the alveolar processes of the upper and lower jaw. In the tissue structure, there are:

• hard tissue (enamel, dentin, dental cement)
• soft tissue (pulp).

In the anatomical structure, it is customary to distinguish:

• crown - a protruding part, visually determined above the gum;
• neck (anatomical and clinical neck are also distinguished);
• roots - located deep in the gum and provide a secure fixation in the bone structure of the jaws.

In the normal dentition of a person, there is a certain number of molars:

• I, II, III - located on the upper jaw (left and right);
• I, II, III - located on the lower jaw (left and right).

In practice, in some cases, IV molars are also distinguished - wisdom teeth. This is also a variant of the norm, although it often brings discomfort and pain.

Teething process

Eruption is an important and painful period in the development and formation of the child's dentition. In infancy, milk molars erupt, then permanent ones. This happens consistently and on time.

The teething process is a traumatic and painful condition. Damage to the soft tissues of the gums occurs, which is often accompanied by bleeding. During this period, it is necessary to ensure a decrease in the number of microorganisms in the oral cavity with the help of frequent and regular rinsing of the oral cavity with antiseptic solutions (furacilin, etc.).

Also, with severe pain syndrome, it is possible to use systemic analgesics and local irrigating anesthetics.

Functions

The fundamental function is to grind and grind food during the act of chewing. They ensure a thorough crushing of the food, while ensuring the normal subsequent movement of the food bolus through the digestive tract.

They also play an important role in the formation of the correct bite. This is very important because correct bite ensures adequate chewing, correct articulation during speech. On the contrary, a malocclusion contributes to the appearance of difficulties during the act of chewing, during speech, adversely affects the mandibular joint, gradually changing its position and disrupting functionality.

Upper molars

Located in the distal upper jaw. An adult has 3 pairs of them (2 pairs without wisdom teeth). They have several surfaces and their own structural features.

Buccal surface

The buccal side is convex. A furrow stands out on it, which is a retention point for many pathogenic bacteria. Therefore, caries often develops here. When cleaning, pay special attention to these areas, as the ducts of the salivary glands open near the buccal surfaces.

Chewing

The chewing surface has its own characteristic features that define the teeth to this group. There are a large number of hillocks here. Depending on the degree of their differentiation, the shape of the tooth is determined.

One of the most relatively stable structures in the structure of the upper molars is the trigone, one of the triangular surfaces. Trigon unites 3 tubercles:

• lingual mesial (protoconus);
• vestibular mesial (paracone);
• vestibular distal (metacone).

Palatine

An important morphological structure, the Carabelli tubercle, is located on the palatal surface. It is localized at the border of the medial and palatal sides of the crown. In terms of severity, they can be completely different. In some cases, this tubercle may have its own root.

Mesial

The line of the enamel-cement border is straight or slightly convex. The root system from the mesial side varies greatly. It can be divergent, barrel-shaped, conical, or cylindrical. In some cases, there is a tendency for the fusion of the palatine edge with the medial-buccal.

Distal

Its anatomical structure is similar to the medial one. Brushing the distal surface of both upper and lower molars does not provide the proper cleaning effect. Therefore, it is necessary to use dental floss.

Lower root

The lower molars are localized in the distal parts of the lower jaw. Several surfaces are also distinguished in their anatomical structure.

Buccal

From this side, there is a clear narrowing towards the crown of the crown. The buccal surface is divided into 2-3 parts by 1 or 2 grooves, respectively. The 2nd lower molar has only 1 groove and the surface is divided into only 2 parts.

The line of the enamel-cement border can be convex or concave, as well as irregular in shape. These are all variants of the norm.

The root system on the buccal side can be cylindrical, bell-shaped, conical.

Chewing

Several bumps are distinguished on the chewing surface, which ensure thorough grinding of food. In the 1st lower molar, there are 5 such main cusps. The longitudinal medial groove of the chewing surface is involved in the formation of two tubercles - the medial-lingual and distal-lingual. The medial-buccal, distal-buccal, and distal tubercles (at the bottom of the first molar) are also identified.

Lingual

The lingual surface has 2 uniform convex parts, separated by a groove, which is a continuation of the lingual groove on the chewing surface.

The enamel-cement border on the lingual surface is practically straight. Enamel bleeding is extremely rare.

Mesial

From the mesial side, the slope to the lingual side of the buccal surface is clearly defined. The main contour line is convex or straight. The lingual contour, as a rule, is uniformly convex, occasionally inclined. Its most convex part is in the middle third of the crown.

The enamel-cement border is straight, slightly convex with a slight slope towards the buccal side.

Distal

In the five-tubercular type of molars (1 lower), the distal tubercle is located on the distal side in the middle part. Its apex can be displaced to the buccal side or it can be on the midline of the crown and be symmetrical.

The distal root is narrower than the medial root and has a wedge-shaped shape.

Molars in children

It is known that the dentition in children is significantly different from that of adults. So, if in adults 12 molars are normally determined (3 on each side on the upper and lower jaw), then in children, only 8 (the first and second) are normal. The third large molars erupt in adulthood or remain in the gum cavity. This is also a variant of the norm.

As with adults, children have molars in the back of the jaw. In a row, they are the fourth and fifth from the central anterior incisors. In children, they are preceded by canines.

Process eruptions occurs individually for each child. However, there are indicators of the norm, in which the average (most common) indicators indicate the period of eruption of the first and second molars in a child.

So, normally, the eruption of the first upper molars occurs at 13-19 months of the baby's life, the lower ones - at 14-18 months; the second molars erupt between 23 and 31 months in both jaws.

Wisdom teeth erupt in adulthood, purely individually. However, they can also remain in the gum cavity. This is also one of the variants of the norm, if it is not accompanied by the development of purulent-inflammatory processes or pericornitis.

Possible diseases

Molars are the most massive teeth in the human mouth. Their complex structure, constant contact with food and significant mechanical stress during the act of chewing cause a large number of diseases.

One of the most common and dangerous diseases is caries. Due to the structure (flattened and bumpy chewing surface, on which there are a considerable number of furrows) a relatively large amount of food residues remains on the molars after a meal (in particular, in furrows).

After each meal, an oxidized environment is formed in the oral cavity, in which pathogenic microflora actively develops and multiplies.

Caries

Caries is caused by a large number of bacteria. However, streptococcus mutans plays a fundamental role in the emergence of this disease. The waste products of this organism have a detrimental effect on the state of the entire dentition.

The fundamental mechanism of enamel destruction in caries is the formation of lactic, acetic and pyruvic acids due to the processing of sugars by microorganisms. Enzymes and waste products of pathological microflora destroy directly the surface a layer of enamel, and the above acids have a detrimental effect on the mineral substances of the enamel, destroying it when this.

If the situation is maintained for a long time, in which there is an increased level of acidity in the oral cavity, the dissolution of mineral crystals of enamel begins. Caries is progressing.

Pulpitis

In dentistry pulpitis is called a pathological condition in which inflammatory processes develop that affect the pulp of the tooth and, accordingly, the nerve. The acute form of this disease is accompanied by intense pain, often unbearable, which stimulates the patient to visit the dentist.

With pulpitis, atrophic and destructive processes of hard tissues reach a stage at which chemicals and bacteria penetrate the pulp cavity and cause inflammatory reactions in which the neurovascular plexus is affected tooth.

Cystic neoplasms

Cyst is a root pathology and is characterized by the development of an infectious focus. A cyst is a purulent formation surrounded by a capsule. It is often the result of a lack of adequate treatment or improperly performed filling.

The onset of the pathology is sluggish, asymptomatic. The pain syndrome is connected only after the cyst has significantly increased in volume.

Periodontitis

A pathological condition characterized by the development of an inflammatory process at the apex of the root. The fundamental reasons for the appearance and development of periodontitis are untimely and incorrect filling of the canals. With the progression of the pathology, the formation of an abscess at the root apex is observed. Symptoms periodontitis directly depends on the stage of the course of the disease.

There are the following stages of periodontitis:

• sluggish;
• sharp;
• chronic form with periodic exacerbations.

Periostitis

Periostitis is a pathological condition characterized by the development of inflammation of the periosteum. It is also a consequence of the lack of treatment for purulent-inflammatory diseases or improper filling of the canals.

Pericornite

A widespread disease that is accompanied by inflammation of the gum tissue due to eruptions. It often develops in children during the eruption of "permanent" large molars or in adults, with the eruption of wisdom teeth. As a result of slowing down or stopping the eruption process, bacteria enter the resulting wound and cause inflammatory reactions.

Finally

Molars are an important part of the dentition of both an adult and a child. Correct positioning and shaping ensures the correct bite.

The function of these teeth is difficult to overestimate. They play one of the main roles in the mechanical processing of food. These teeth ensure thorough grinding and grinding of food. Thanks to this, the food bolus can move further along the digestive tract without injuring the pharynx and esophagus.

However, due to its complex anatomical structure and features of eruption, there are many pathologies that affect these teeth.

In the absence of proper treatment and prevention the emergence and development of diseases is inevitable. Perhaps their progression and the development of serious complications.

With timely access to medical help from a highly qualified dentist and compliance with all his recommendations, the effect is dramatically positive. There is a leveling of negative symptoms, a cure of pathology and an improvement in the patient's quality of life.