GI - Teeth Revision Flashcards
What does heterodont mean?
All the teeth are different (mammals and some reptiles)
What does homodont mean?
All teeth the same (e.g reptiles and fish)
What does hypsodone mean?
High crowns (equines and bovids where you can only see the tip of the tooth)
What does brachydont mean?
Low crowns (carnivorous mammals)
What does diastema mean?
The gap between the incisors and cheek teeth (normal in herbivores)
What is the difference between the gingiva and mucogingival line?
Gingiva (gum) = tightly attached to bone
Mucogingival line = above this line, oral mucosa becomes loose.
How to carnivores move their jaw?
Move jaw sideways to engage carnassial teeth (big ones at the back of the mouth).
Close jaw to shear/crush.
How do omnivores move their jaw?
Combined crush/grind action.
How do herbivores more their jaw?
Close jaw on herbage -> move jaw sideways while held close to grind plant material.
What does secodont mean?
Staggered teeth food for gripping hard and soft objects (carnivores)
What are the trident system starting numbers for deciduous and permanent teeth?
Deciduous = 5,6,7,8
Permanent = 1,2,3,4
In what order at the teeth starting from cranial to caudal?
Incisor, canine, premolar, molar
What is the crown, root and peridonteum?
Crown = exposed part
Root = buried part
Peridontium = supporting structures
What are the five layers to the tooth?
- Enamel
- Dentine
- Cement
- Pulp
- Nerve
What are the three layers to the peridonteum?
- Periodontal ligament
- Alveolar bone
- Gingiva
What are the key features of enamel?
- Hardest structure
- Cannot repair (tooth appears off white when damaged)
- Only on the crown
- Not alwaysys present
What are the key features of dentine?
- Living tissue (odontoblasts)
- Primary (most, mineralised collagen)
- Secondary (formed after eruption, continues to grow, decreases size of pulp)
- Tertiary (reaction to damage)
What are the key features of cementum?
- Similar to bone
- Attached to perdiontal fibres
- Laid down on annual basis (ridges)
- Completely covers herbivores teeth
What are the key features of pulp?
- Feeds odontoblasts
- Contains blood vessels, lymph, nevres
- Narrows with age as dentine deposition occurs
- Closed apex (when finished erupting)
- Open apex (when continually erupting)
What is the role of the peridontium
Attach, support, protect
What are closed roots?
Root apex has closed off (= no more growth)
Horses/cattle = tooth erupts slowly and continously
Carnivores = teeth erupt to fixed height
What are open roots?
Root apex is open, tooth grown continuously and erupts (e.g. rodent incisors).
At which stage to horses and carnivores teeth erupt?
Horses - teeth erupt as they grow and the roots close later in life. Continuously erupt for life.
Carnivores - teeth erupt as they finish growing. Erupt until a fixed height.
