Teeth molars are present in children and adults, but their number is different. For example, their 8 kids, and Teens, women and men — from 8 to 12. The number of these teeth in the mouth depends on how much the person cut eights. Have a molar that grew from the top, three roots, lower only two. Is different and the number of channels in a single root there can be multiple channels. They are characterized by a difficult and twisted character.
How many human molars and where they are located
These teeth have a large crown, in the form of video (in the upper part of the jaw) is similar to the diamond, and the bottom — cubic Chewing surface is characterized by the presence of several tubercles 4 to 6, which can be of these types:
- cheek — closer to the cheek;
- lingual — towards the tongue;
- distal — distant tubercles;
- mesial — middle.
The bumps on the tooth surface partitioned by grooves.»Eight» do not necessarily erupt on time: can stay inside of the jaw, i.e. to be impacted. The child they erupt at different times, but to 2.5 years appear almost everything. Schedule of teething is as follows:
- 1 year old he cut the first two molars one above and one below.
- 1.1–1.2 years, there are the first molars. They are located in the lower jaw.
- 1.8 years appear lower.
- In 2 or 2.5 years cut another pair top.
Simultaneously, growing teeth, and if they were cut completely, then comes the time of growth the next couple of molars. This usually occurs in 6 or 7 years. In the first «six» appears on the lower jaw, and a second later on the top. 12 years old or later begin to receive a «seven». The molars are the wisdom teeth — «eight», which begin to grow from 17 years, but is able to cut each person in different ways. The emergence of wisdom teeth individually. Are molars behind the premolars. Usually in adults, there are three pairs of molars — the «six», «seven» and «eight».
The molars of the upper jaw
The molars of the upper jaw largest, they have an average length of 22 mm, with a minimum of 20 mm. Buccal tubercle, which is at the front, depends on the fissures the grooves extending from the front surface, smoothly passing in cheek. Further, the groove extends to the neck of the tooth.
On the back of the tooth tubercle is characterized by a groove which runs along the chewing area, and then proceeds to speaking. Tubercles, which are arranged in front and behind, separated from each other by the strip passing exactly in the center of the chewing surface. This is the Central fissure, connecting the two other grooves.
Tubercles differ in form: near the language they are rounded, and the cheek — conical. Interestingly, anterior tubercles much larger than the posterior. It is sometimes additional, so-called anomalous tubercle. Its name he received because that does not reach normal size and are not involved in chewing.
Among other features worth noting the following. The cheek surface is convex and the fact that separated by groove. Pronounced curvature of the enamel. On the lingual surface of the groove becomes gradually smaller and in the chewing area. The rear part of the molar is more convex than the anterior, but smaller than the surface which is the front.
In the upper jaw they have three roots, which have different shapes. The first one is called procedure for palatinal ie palatal and similar to a cone and two buccal, one more and the second less. The roots squeezed from two sides. The root of the anterior molar has a well-defined structure.
The second molar is located between the teeth of the upper jaw, a few less than the first and has an average size of 21 mm. the overall dimensions can be from 19 to 23 mm. the Crown has its own specifics, which should be considered in detail, since it can occur in people in three different variations.
First, similar to the crown of the first molar, but no anomalous tubercle. And he never appears. Secondly, on the chewing surfaces grow three hillocks, which are located in the front direction. They are formed by combining peredneaziatskogo tubercle from the back. Thirdly, the crown has a rhombic shape and is strongly elongated in the forward direction. On the surface is three tubercles, which are arranged in a triangle. One of the peaks — palatal, and two other — cheek. The most common among people are the first and third types.
The second molars curvature of the crown is clearly apparent, it has three roots. Those roots that are located at the cheeks, able to merge into one. Some people have encountered a situation when all the roots merge into one and have the shape of a cone. In places where they merged, there may be grooves. Perfectly traced and expressed the root. Channels of the second molar can be 3 — in half of cases, a 4 is typical for 40% of the people. Very rare two channels or one.
The third root, which is a molar and is located in the upper jaw, has its own characteristics:
- Irregular shape and size.
- A wisdom tooth may be in the form of sewing.
- On the surface, which takes part in the process of mastication, there is a 3 tubercle. But can meet the teeth, where it will grow 4, and rarely 5 or 6 tubercles.
- Roots have different shapes and sizes that depends on the characteristics of the jaw of each individual and genetic predisposition. The roots can be from 1 to 4-5, while in medical practice, there are 8 teeth with roots.
The molars of the lower jaw
What are the features of the molars of the lower jaw? Also in the bottom jaw are the teeth. First, the root is large, which range from 20 to 24 mm with an average length of 22 mm. On the surface 5 can be placed tubercles, which differ among themselves: 2 — belong to the lingual, 3 — are located at the cheeks.
Between the tubercles is a longitudinal strip — fissure, which runs clearly along the edge of the chewing surface. There is a transverse groove extending from the cheeks to the lingual, while crossing the chewing area.
Tubercle, which is the third and sits at his cheeks, created a small groove extending from the transverse. The buccal surface of the third tooth curve, and speaking has a rather convex shape. The difference is in the structure of the front and rear surfaces. The first has a greater camber than the front, which is much larger than the posterior. The crown is able to deviate to the lingual surface.The number of roots two, and they are divided into front and rear, which are compressed with one and other. The roots are strongly expressed. The first molar is usually channel 3, at least 4, and quite rare on 2 channel.
The second molar tooth on the bottom jaw is different from the first. On the surface for chewing is only 4 tubercles, which are divided into buccal and lingual. They are separated by one transverse and one longitudinal furrows. Sometimes you may meet the fifth, the abnormal tubercle.
The crown resembles in structure the first mandibular molar. The same and the number of roots, divided into front and rear, having a slightly tapered shape. The roots are pronounced, and they are 3 channel — one rear and two front. Some people have four channels. In all cases the roots have the ability to merge.
Third, the lower wisdom teeth larger or smaller sizes, can have different form. The crown is covered with 4 or 5 humps, although third lower molars characterized by the presence of tubercles and 6-7. There are bumps in the rear and front that are larger and higher than the first. The roots of these 2 teeth, and they often merge into one cone.