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How many generations of teeth do humans have?
Two, the deciduous (or primary) dentition and the permanent (or secondary) dentition.
When do teeth erupt in humans?
No teeth have erupted into the mouth at birth, but by the age of 3 years all the deciduous teeth have erupted.
By 6 years, the first permanent teeth appear and thence the deciduous teeth are exfoliated one by one to be replaced by their permanent successors.
A complete permanent dentition is present at or around the age of 18 years.
Thus, given the average life of 75 years the functional lifespan of the deciduous dentition is only 5% of this total, while with care and luck that of the permanent dentition can be over 90%.
How many teeth are there in humans?
In the complete deciduous dentition there are 20 teeth - ten in each jaw.
In the complete permanent dentition there are 32 teeth - 16 in each jaw.
What are the basic forms of teeth?
In both dentitions there are three basic tooth forms: incisiform, caniniform, and molariform.
Incisiform teeth (incisors) are cutting teeth, with thin, blade-like crowns.
Caniniform teeth (canines) are piercing or tearing teeth, having a single, stout, pointed, cone-shaped crown.
Molariform teeth (molars and premolars) are grinding teeth possessing a number of cusps on an otherwise flattened biting surface.
Premolars are bicuspid teeth; they are peculiar to the permanent dentition and replace the deciduous molars.
What is the crown?
Clinical crown - that portion of a tooth visible in the oral cavity.
Anatomical crown - that portion of a tooth covered with enamel.
What is the Root?
Clinical root - that portion of a tooth which lies within the alveolus.
Anatomical root - that portion of a tooth covered by cementum.
What is the cervical margin?
the junction of the anatomical crown and the anatomical root.
What is the occlusal surface?
The biting surface of a posterior tooth (molar or premolar)
What is the cusp?
A pronounced elevation on the occlusal surface of a tooth.
What is the incisal margin?
The cutting edge of anterior teeth, analogous to the occlusal surface of the posterior teeth.
What is a tubercle?
A small elevation on the crown.
What is a cingulum?
A bulbous convexity near the cervical region of a tooth.
What is a ridge?
A linear elevation on the surface of a tooth.
What is the marginal ridge?
A ridge at the mesial or distal edge of the occlusal surface of posterior teeth. Some anterior teeth have equivalent ridges.
What is a fissure?
A long cleft between cusps or ridges
What is a fossa?
A rounded depression in a surface of a tooth.
What does buccal mean?
- -Towards or adjacent to the cheek.
- -The term buccal surface is reserved for that surface of a premolar or molar which is positioned immediately adjacent to the cheek.
What does labial mean?
- Towards or adjacent to the lips.
- The term labial surface is reserved for that surface of an incisor or canine which is positioned immediately adjacent to the lips.
What does palatal mean?
- Towards or adjacent to the tongue.
- The term palatal surface is reserved for that surface of a maxillary tooth which is positioned immediately adjacent to the palate.
What does lingual mean?
- Towards or adjacent to the tongue.
- The term lingual surface is reserved for that surface of a mandibular tooth which lies immediately adjacent to the tongue.
What does mesial mean?
- Towards to median.
- The mesial surface is that surface which faces towards the median line following the curve of the dental arch.
What does distal mean?
- Away from the median.
- The distal surface is that surface which faces away from the median line following the curve of the dental arch.