CTB 4 – Evolution functional adaptions of jaws and dental tissues Flashcards
Where is the dental lamina derived from?
Ectodermal epithelium
What is a homodont? Animal example.
Same teeth within the dentition
Crocodiles
What is a hetrodont? Animal example.
Different teeth within the dentition
Most mammals - human
What is a polyphydont? Animal example.
Teeth continually replaced when animals grow
Fish, amphibians and reptiles
What is a diphydont? Animal example.
2 generation of teeth
Human have primary and permament
Vertical replacement in humans
When teeth are replaced in elephants what orientation do they erupt?
They are replaced horizontally
What is the tooth attachment of teeth to the jaw (3 types)? Animal examples.
- Acrodonty, to tip of jaw, bony fish
- Pleurodonty, to side of jaw, reptiles
- Thecodonty, embedded in sockets, human and dinosaurs
What is the tooth connection of teeth to the jaw (3 types)?
- Ankylosis – via bone only
- Gomphosis – by unmineralized fibres if tooth in socket – human
- Aulacodonty – by unmineralized fibres if tooth no set-in socket
What is brachyodont? Animal example.
Low crowned teeth
Human
What is hypsodont? What is the reason for these teeth?
High crowned teeth
When enamel surface is lost the gum line lowers to compensate this as their teeth are being ground down
What is the function of a tooth comb in some animals?
For grooming and brushing their fur
What are the carnassial teeth and what is their function?
- Upper premolar (P4) and 1st lower molar (M1)
- Shearing and slicing meat
What TMJ movement do carnivores have?
Vertical movement – scissoring movement
What TMJ movement do herbivores have?
Horizontal movement
What is the difference in the levels of the TMJ and teeth in carnivores and herbivores?
Carnivores - TMJ and teeth are at the same level
Herbivores - TMJ above tooth rows
What are the muscles of mastication that allow for vertical and horizontal movement?
Vertical - Temporalis
Horizontal - Masseter
What is special in herbivores incisors?
There is a gap behind incisors called a diastema
What is special about granivores incisors? Animal example.
Every growing incisors
Such as rodents
What is the function of large incisors in carnivores?
For grabbing
What animal types have a horny pad?
Grazers and browsers
How many rows of teeth do rodents have?
2
What is the evolutionary trend in the number of teeth? Animal examples.
Become fewer and fewer
- Fish – 1000’s teeth
- Amphibians less
- Mammals even less
Where is the placement of teeth in fish?
Oral cavity and pharynx
What is the dental formula for human teeth?
3/3 I, 1/1 C, 4/4 P, 3/3 M
When does tooth growth in humans stop?
At sexual maturity
