The cheek-teeth serve mainly for the grinding of the food pre-crushed by the incisors. The molars are divided into two groups:
- Front molars (Dentes premolares, premolars) and the
- Rear molars (Dentes molars)
The front molars (premolar)
The anterior molar/premolar is also called premolar or bicuspid (from lat. to “twice” and cuspis “pointed”). In contrast to the posterior molars, the premolars also have deciduous predecessors, which serve to grind the food before the change of teeth.
Today, humans have only 2 premolars (front molars) per half of the jaw, which are referred to as 14, 24, 15, 25, 34, 44, and 35, 45. Our mammalian ancestors originally had twice as many premolars, i.e. four front molars per half of the jaw. In humans, the individual premolars have two to three cusps of the dental crown, which makes the function of grinding possible.
The lower premolars show a very pronounced crown alignment. The number of individual tooth roots and root canals varies between the individual premolars. Teeth 14 and 24 usually have two tooth roots and two tooth canals as well as two tooth cusps on their surface.
Teeth 15 and 25, on the other hand, have only one tooth root and one or two tooth canals. These also have two cusps on their surface. Teeth 34 and 44 have one root and one root canal, rarely also two root canals.
They also have two cusps. Teeth 35 and 45 have only one root and one root canal, but two or three cusps. Deviations from this scheme are possible.
The rear molars (molar)
The back molars belong to the large molars and are not found in the child’s dentition. For this reason, they are also known in the vernacular as the increment tooth. They are also called molars and are particularly large and strong.
They have pronounced cusps (tubercula) and dimples (fissures). In humans, the 6th, 7th and 8th teeth belong to the molars, which means that humans have three large molars per half of the jaw, a total of 12 posterior molars. The first posterior molar (6th tooth) usually breaks through at the age of 6 years and is therefore called a six-year molar.
The second back molar (7th tooth) does not appear until the age of 12, the last molar (8th tooth) does not break through until adulthood between the ages of 18 and 25. For this reason it is also called the wisdom tooth. As with premolars, the number of tooth roots and root canals as well as the number of tooth cusps between the individual molars varies.
The two teeth 16 and 26 have three tooth roots, four root canals and four tooth cusps. Teeth 17 and 27 each have three roots and root canals and four cusps. Teeth 36 and 46 have two tooth roots and three root canals, but five tooth cusps.
Teeth 37 and 47 have the same structure, but only four tooth cusps. Teeth 18, 28 and 38, 48 do not have a fixed number of roots, canals and cusps and are individually very different. Deviations from this pattern are also possible for the large posterior molars.