What's a molar

Molar Definition & Meaning - Merriam-Webster

1 of 3

mo·lar ˈmō-lər

: a tooth with a rounded or flattened surface adapted for grinding

specifically : one of the cheek teeth in mammals behind the incisors and canines

see tooth illustration

molar

2 of 3

: pulverizing by friction : grinding

: of, relating to, or located near the molar teeth

molar

3 of 3

: of or relating to a mole of a substance

the molar volume of a gas

: containing one mole of solute in one liter of solution

molarity

mō-ˈla-rə-tē

-ˈler-ə-tē

noun

Word History

Etymology

Noun

Middle English molares, plural, from Latin molaris, from molaris of a mill, from mola millstone — more at mill

Adjective (2)

mole entry 5

First Known Use

Noun

14th century, in the meaning defined above

Adjective (1)

1626, in the meaning defined at sense 1

Adjective (2)

1902, in the meaning defined at sense 1

Time Traveler

The first known use of molar was in the 14th century

See more words from the same century

Dictionary Entries Near

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Molala

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molarization

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“Molar. ” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/molar. Accessed 6 Jan. 2023.

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Kids Definition

molar

1 of 2 noun

mo·lar ˈmō-lər

: a tooth with a rounded or flattened surface adapted for grinding

especially : one behind the premolars of a mammal

molar

2 of 2 adjective

: adapted for grinding

: of or relating to a molar

Medical Definition

molar

1 of 4 noun

mo·lar ˈmō-lər

: a tooth with a rounded or flattened surface adapted for grinding

specifically : one of the mammalian teeth behind the incisors and canines sometimes including the premolars but more exactly restricted to the three posterior pairs in each human jaw on each side which are not preceded by milk teeth

molar

2 of 4 adjective

: pulverizing by friction

molar teeth

: of, relating to, or located near the molar teeth

molar gland

: of, relating to, possessing the qualities of, or characterized by a hydatidiform mole

molar pregnancy

molar

3 of 4 adjective

: of or relating to a mass of matter as distinguished from the properties or motions of molecules or atoms

: of or relating to larger units of behavior especially as relatable to a prior deprivation or motivational pattern of the organism

interest in such molar problems of personality as the ego functions—R. R. Holt

compare molecular sense 2

molar

4 of 4 adjective

: of or relating to a mole of a substance

the molar volume of a gas

: containing one mole of solute in one liter of solution

More from Merriam-Webster on

molar

Nglish: Translation of molar for Spanish Speakers

Britannica.com: Encyclopedia article about molar

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Merriam-Webster unabridged

Molar pregnancy - Symptoms and causes

Overview

A molar pregnancy is a rare complication of pregnancy. It involves unusual growth of cells called trophoblasts. These cells typically become the organ that feeds a growing fetus. That organ also is known as the placenta.

There are two types of molar pregnancy — complete molar pregnancy and partial molar pregnancy. In a complete molar pregnancy, the placental tissue swells and appears to form fluid-filled cysts. There is no fetus.

In a partial molar pregnancy, the placenta might have both regular and irregular tissue. There may be a fetus, but the fetus can't survive. The fetus usually is miscarried early in the pregnancy.

A molar pregnancy can have serious complications, including a rare form of cancer. A molar pregnancy requires early treatment.

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Symptoms

Molar pregnancy

During a molar pregnancy, the placenta doesn't form typically. It can look like a mass of cysts. The fetus either doesn't form or doesn't form regularly and can't survive.

A molar pregnancy may seem like a regular pregnancy at first. But most molar pregnancies cause symptoms that can include:

Dark brown to bright red bleeding from the vagina during the first three months
Severe nausea and vomiting
Sometimes grapelike cysts that pass from the vagina
Pelvic pressure or pain

Because of improved ways of detecting a molar pregnancy, most are found in the first trimester. If it is not found in the first three months, symptoms of a molar pregnancy might include:

A uterus growing quickly and being too large early in the pregnancy
Preeclampsia — a condition that causes high blood pressure and protein in the urine — before 20 weeks of pregnancy
Ovarian cysts
Overactive thyroid, also known as hyperthyroidism

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Causes

An egg fertilized atypically causes a molar pregnancy. Human cells usually have 23 pairs of chromosomes. In a typical fertilization, one chromosome in each pair comes from the father, the other from the mother.

In a complete molar pregnancy, one or two sperm fertilize an egg. The chromosomes from the mother's egg are missing or don't work. The father's chromosomes are copied. There's none from the mother.

In a partial or incomplete molar pregnancy, the mother's chromosomes are present, but the father supplies two sets of chromosomes. The embryo then has 69 chromosomes instead of 46. This most often occurs when two sperm fertilize an egg, resulting in an extra copy of the father's genes.

Risk factors

Factors that can contribute to a molar pregnancy include:

Earlier molar pregnancy. If you've had one molar pregnancy, you're more likely to have another. A repeat molar pregnancy happens, on average, in 1 out of every 100 people.
Age of the mother. A molar pregnancy is more likely in people older than age 43 or younger than age 15.

Complications

After removing a molar pregnancy, molar tissue might remain and continue to grow. This is called persistent gestational trophoblastic neoplasia (GTN). GTN happens more often in complete molar pregnancies than it does in partial molar pregnancies.

One sign of persistent GTN is a high level of human chorionic gonadotropin (HCG) — a pregnancy hormone — after the molar pregnancy has been removed. In some cases, the mole that causes the molar pregnancy goes deep into the middle layer of the uterine wall. This causes bleeding from the vagina.

Persistent GTN is usually treated with chemotherapy. Another treatment possibility is removal of the uterus, also known as hysterectomy.

Rarely, a cancerous form of GTN known as choriocarcinoma develops and spreads to other organs. Choriocarcinoma is usually successfully treated with chemotherapy. A complete molar pregnancy is more likely to have this complication than is a partial molar pregnancy.

Prevention

If you've had a molar pregnancy, talk to your pregnancy care provider before trying to get pregnant again. You might want to wait six months to one year. The risk of having another molar pregnancy is low, but it's higher once you've had a molar pregnancy.

During future pregnancies, a care provider may do early ultrasounds to check your condition and make sure the baby is developing.

By Mayo Clinic Staff

Associated Procedures

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Molar teeth and their features

Publication date: 10/01/2019

Molars or large chewing teeth are the largest dental units located on the upper and lower jaws on the left and right sides. They are designed for chewing and grinding food. The last molar in each dentition is the wisdom tooth, which can erupt at any age or not erupt at all. In an adult in the oral cavity, from 8 to 12 molars, when in preschool children - 8.

When do molars erupt?

Molars are the last teeth that erupt in the lower and upper dentition of a child. As a rule, the first units appear on the lower jaw at the age of 12-18 months, a month later the molars erupt on the upper row as well. The second molars are shown in a child aged 24-30 months.

Replacing the primary molars of the lower jaw takes place at the age of 6-8 years. In place of the upper units, molars grow only by the age of 9-12. However, these are average figures, they may vary depending on individual characteristics. nine0003

Timing of eruption depends on the following factors :

hereditary predisposition;
general health of the child;
congenital features;
climatic conditions of residence;
nature of food;
gender of the child.

Features of molars

Large molars differ from other groups not only in external characteristics, but also have other features :

are the largest units in each arch;
have the largest chewing surface;
have a powerful root system;
upper molars slightly larger than those of the lower jaw;
have a stronger surface finish;
are able to withstand weight up to 75 kg;
upper molars have 4-6 canals while lower units generally have only 3 canals;
maxillary molars have 3 roots (palatal, bucco-medial, bucco-distal), rarely 4; nine0018
chewing teeth of the lower jaw have only 2 roots;
wisdom teeth are the very last molars, which may appear by the age of 50 or not erupt at all;
the last molars are very often located not in the masticatory arch, that is, they can grow horizontally or with a slight inclination, located buccally or towards the tongue or palate;
wisdom teeth have 1 to 5 masticatory cusps;
the last molars often have a complex root configuration (curvature, fusion). nine0018

All this entails the peculiarities of the treatment of such teeth. The presence of a large number of complex root canals, as well as difficult access compared to other groups of teeth, requires highly qualified doctors and modern equipment for quality therapy.

Molars are considered the heaviest units in dental treatment practice, especially wisdom teeth. Proper care and regular preventive examinations will help maintain their health. When the first signs of damage to the molars appear, we recommend that you immediately sign up for a consultation with our dentistry "KAS +". Timely detection of problems with teeth guarantees their high-quality treatment with minimal risk and long life. nine0003

Molars and premolars: the main differences and features - iOrtho Center

The difference between molars and premolars

The main difference between molars and premolars lies in their location on the jaw. The premolars are placed closer to the front of the dentition, and the molars are somewhat receded inward.

Their number is also different. There are always two premolars on each side of the upper and lower jaws. Molars can be either two or three. Still others are also called "wisdom teeth". They grow later than the rest and often appear only by the age of 20-25. This process is often accompanied by malaise and fever. However, not all people on earth have thirds. A certain genetic predisposition can cause the absence of "wisdom teeth" in the oral cavity. nine0003

Position of molars

Molars are the sixth, seventh and eighth teeth of a permanent row in both the upper and lower jaws. They are located deepest, leaving premolars, canines and incisors in front. In children, the fourth and fifth teeth of each row are called molar.

Features of the structure of molars

Molars have a characteristic structure. On the upper jaw they have three roots and four canals. The lower jaw has two roots and three canals. At the same time, the number of canals also differs depending on the location of the individual tooth. Thus, the first of them often have one more channel than the next two. nine0003

The main feature of this type of teeth is the area of their chewing surface. It is they who have the greatest load during the chewing of food particles. The molars themselves also have a difference between themselves, which is associated with the structure of the jaw.

Molar differences

Often the surface of each molar tooth is shaped like a triangle. It has a certain number of tubercles, which take an active part in chewing food. The number of such tubercles can be different. There are usually three, but sometimes more. nine0003

Such bumps are connected with each other by special combs. On the upper and lower jaws, the structure of these elements is different. In the upper dentition, the top of the surface triangle is directed towards the tongue. This form is called a trigon. On the lower jaw, the apex of such a triangle is directed towards the cheek, which is called the trigonid. The size of the first and second types of teeth practically do not differ.

Possible lesions of small molars

Carious lesions of milk and molars in children are observed quite often. This is due to the tuberosity of their surface, in which food particles and bacteria can linger. Since children at an early age do not always actively and properly brush their teeth, these residues can lead to enamel damage and a deeper spread of caries. nine0003

Depending on the degree of damage, caries can penetrate exclusively into the enamel, and into the dentin or even the cementum. In the latter case, we are talking about deep caries, which often requires serious treatment or even tooth extraction.

Another lesion is a change in the structure of tissues, which may be associated with a metabolic disorder in the human body or other diseases. Such an ailment can also be the result of malnutrition or constant diets in which a sufficient amount of nutrients does not enter the body. nine0003

At any age, a person can experience excessive tooth wear that can lead to enamel erosion and other serious damage. Teeth can wear out in different situations, such as:

if a person has bad habits of grinding his teeth, etc.;
in case of malnutrition or malnutrition;
in the presence of ailments of the endocrine system;
due to a genetic predisposition to enamel depletion. nine0018

All of these lesions can be the result of both an incorrect lifestyle and various diseases or heredity. Regardless of the reasons, it is necessary to start treating the injuries that have appeared immediately so as not to aggravate the process.

Replacing deciduous molars with permanent molars

Molar teeth are the first permanent teeth to appear in a child's mouth. It starts around the age of five. Growth begins with the first molar tooth, which appears in a free place in the depths of the jaw, closer to the milk that has not yet fallen out. nine0003

The second molar usually grows at the age of 12-13 years. It also takes up free space and does not replace the milk tooth. The last, or “wisdom teeth”, may grow up to 25 years or not appear at all.

As for dairy, they begin to fall out from the age of 9. In their place, permanent teeth grow, which occurs at about 10-12 years of age. Usually these are the last molars, the growth of which must be waited for to fill the adult dentition (not counting the "wisdom teeth"). nine0003

Is it possible to loosen deciduous molars?

The process of tooth loss always begins with the softening of its root. This is due to the fact that the jaw grows, freeing up more free space for a permanent tooth. Thus, while the milk tooth is still in the hole, the root is already beginning to take its correct place.

In this regard, dentists categorically do not recommend specifically loosening milk molars. If they fall out prematurely, the growth of the jaw may stop. As a result, there will not be enough space for permanent teeth, and they will begin to grow crookedly, breaking out of the general dentition. nine0003

Signs of imminent emergence of molars

The first signs of imminent emergence of molars are visible even before the loss of milk teeth. These include:

expansion of the jaw, which can be seen when gaps appear between other milk teeth;
the appearance of sufficient free space behind the extreme lateral milk teeth;
gum swelling.

At the same time, the temperature does not necessarily have to rise or the child's well-being worsen, as was the case with the growth of milk teeth. That is why the appearance of the first molars often goes unnoticed. nine0003

Helping a child to replace teeth

The process of replacing teeth is often painless and uncomfortable. The roots of milk teeth dissolve on their own, and the dental crown falls out without hindrance. However, there are a number of recommendations that should be followed during this period.

The main one is the systematic rinsing of teeth for disinfection. This is necessary in order to avoid bacteria getting into the hole, which will be formed in place of the falling out tooth. In addition, the sharp edges of a crown that has become detached from the gingiva may cause minor soft tissue damage. So that they do not become inflamed, it is important to exclude any infection. nine0003

If your child experiences any pain during the replacement of teeth, a doctor should be consulted immediately. It is impossible to eliminate pain by improvised methods in any case.

Molar teeth and prevention of their loss

Molar teeth are stronger than milk teeth. However, they need proper care to prevent them from falling out, because new ones will not grow in place of the lost tooth.

Prevention of molar tooth loss lies in proper oral hygiene. It includes systematic brushing of teeth, the use of dental floss and mouthwash. In addition, you should carefully monitor the condition of the teeth and consult a doctor if even minor damage is detected.

Proper balanced nutrition is also essential. Especially in childhood and adolescence, care must be taken to ensure that sufficient amounts of calcium and vitamin D enter the body.

Position of premolars

Premolars are also classified as posterior teeth, but they are located closer to the front of the jaw. These are the two teeth that follow the fangs on each side. There are no premolars in the milk bite. Their place is occupied by the same number of milk molars. After they fall out, and the molars take their place in the depth of the jaw, the required number of premolars appears in their place.

Upper premolars

The crown of the upper premolars is prismatic. The buccal and palatine honors often have a convex surface. The first and second premolars in a row also have their differences. nine0003

First premolar

The difference of the maxillary first premolar lies in the predominance of the vestibular surface over the palatal. Its contact surfaces are rectangular in shape. The buccal tubercle has two distinct slopes. The root of such a tooth often has a bifurcation.

Second premolar

In this tooth, the buccal surface usually dominates over the palatal, which is more rounded. In most cases, this premolar tooth has a single conical root. However, there are also cases when it has a bifurcation. nine0003

Mandibular premolars

These premolars have a convex vestibular surface and a wide longitudinal ridge. They have only one root. It has a conical or oval shape.

First premolar

The first tooth has two cusps on the chewing surface. Buccal - larger in size and has a pronounced inclination. The root of the tooth has flattened lateral parts, and shallow furrows stand out on the lateral surfaces. nine0003

Second premolar

The distinguishing feature of this tooth is that it is larger than the first. It has a developed lingual tubercle. The contact parts of this premolar are convex.

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