dentition

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A comparison of deciduous and adult teeth

Dentition (from Latin dentire "to tooth") or toothing is the breakthrough of teeth from the jaw into the oral cavity . The teeth of humans and most mammals go through two dentitions ( diphyodontia ).

physiology

The eruption of the teeth is timed to match the general body growth and the proportions of the jaw and facial skull. The teeth of the deciduous dentition need around 2 to 4 years to fully develop, the teeth of the permanent dentition an average of 12 years. Single-rooted teeth such as the front teeth and especially the canines are embedded very deeply in the jawbone at the beginning of the root formation, multi-rooted teeth are less deep in the alveoli . The resorption processes (breakdown) of the tooth roots begin in milk teeth immediately after their root formation is complete. The actual dissolution of the milk tooth roots is always preceded by the dissolution of the surrounding alveolar bone and the tooth-holding apparatus. The hard substances are broken down by osteoclasts and dentoclasts , the tissue structures of the periodontal membrane are broken down by fibroblasts and phagocytes .

Breakthrough phases

The following table provides an initial overview of the different eruption phases of the teeth. The annual figures are guidelines and should not be viewed as fixed specifications for individual individuals.

age 1. – 2.5. 2.5-6. 6-9 9-10 10-14
First dentition eruption of
the milk teeth
Use phase of the milk teeth First mixed dentition phase
(6-year molar, incisors)
Resting phase of the change of teeth Second mixed dentition phase

First (lacteal) dentition

The eruption of the milk teeth (Latin: dentes decidui, (from Latin : dens 'tooth', and decidere ' to fall')) normally occurs continuously from mesial (front) to distal (back) in humans between the ages of 6 and 30 months . The first milk tooth to emerge in the child who is about six months old is generally a central lower incisor. This is followed by the upper central incisors, the lateral incisors, the deciduous canines, the first deciduous molars and finally the second deciduous molars. Teething can be painful and sometimes associated with attacks of fever. After the deciduous incisors have passed through, the edentulous distal alveolar processes are still in contact. This contact is lost when the first deciduous molar penetrates (first physiological bite elevation ).

Main article on first dentition: primary dentition

Second (permanent) dentition (change of teeth)

Tooth change: An upper incisor (
tooth 11 ) has fallen out. The lower central permanent incisors ( teeth 31 and 41 ) have erupted. Secondary finding: left unilateral crossbite .
Mixed dentition ( OPG )

The eruption of the permanent teeth (Latin: dentes permanentes, (from Latin : dens 'tooth', and permanent 'remain')) also starts from the beginning in humans between the ages of 6 and 14. An exception are the wisdom teeth , which only erupt in adulthood (or at the age of 16–30 years), if they are created at all.

The first molars (so-called six - year molars ) usually erupt before all other permanent teeth and because they usually erupt before the deciduous incisors are lost (hence also called six-year molars), laypeople often consider them to be delayed milk teeth. As such, they are often neglected in dental care (“ they fail ”) and are often damaged very early on.

The table shows the average eruption times of the permanent teeth :

teeth OK teeth Lower jaw teeth age
1st molar 16, 26 36, 46 06-7
Central incisor (incisor) 11, 21 31, 41 06-8
Lateral incisor (incisor) 12, 22 32, 42 08th-9th
Canine tooth (canine) in the lower jaw 33, 43 09-11
1st premolar 14, 24 34, 44 10-12
Canine tooth (canine) in the upper jaw 13, 23 11-13
2nd premolar 15, 25 35, 45 11-13
2nd molar 17, 27 37, 47 12-14
Wisdom tooth 18, 28 38, 48 17.-30.

For the tooth designation see: Tooth scheme

Overall, as in primary dentition, the lower teeth are usually "one step ahead" of the upper ones. It is noteworthy that in the upper jaw (but not in the lower jaw) the first premolars (4-er) break through in front of the canines. This is called the "jump around the corner". This enables the canine (3) to be guided into the correct position by the 1st premolar through a recess ("notch") on the mesial surface. Deviations in the eruption times are also possible for permanent teeth, especially if milk teeth are lost prematurely.

See also

Web links

Commons : Orthopantomograms  - collection of images, videos and audio files

Individual evidence

  1. a b c Joseph Maria Stowasser : Der Kleine Stowasser , Latin-German school dictionary . G. Freytag Verlag, Munich
  2. Klaus D. Mörike et al .: Textbook of macroscopic anatomy for dentists . Gustav Fischer Verlag, Stuttgart 1969