CTB 3 – Tooth morphology and mastication Flashcards
Why do humans have a higher metabolic rate than replies?
Reptiles just grab their food and swallow
Humans need their energy faster, therefore chew food to reduce size, increase SA and hence a faster digestion
How long is the masticatory sequence?
Cycle is 1 second
How is the masticatory sequence controlled?
Neural circuitry
Describe the masticatory sequence.
- Lower jaw orbits
- Mouth opens and food collected by tongue
- Tongue picks up particles and mixes with saliva by pressing into the hard palate
- Food moves laterally to posterior canine teeth (1 side)
- Food falls laterally during chewing are put back in the mouth by the contraction of the BUCCINATOR
- Relax before closing
- Once tongue and cheek are out of the way there is fast closure of tooth-food contact
- Mandible slows just before contact to allow for perception of food properties to judge the strength of bite
What is the function of the tongue in the masticatory sequence?
- Tongue picks up particles and mixes with saliva by pressing into the hard palate
- Food moves laterally to posterior canine teeth (1 side)
What is the main component of food chewing dependent on?
Physical properties of foods
What is the function of sensory feedback during the masticatory sequence?
Monitors food properties
What is the most sensitive part of the oral cavity in the masticatory sequence? What is the discrimination of these?
Tongue and hard palate
1-2mm
Where are the most important sensors during mouth closing
TMJ
What type of receptors does the PDL have?
Mechanoreceptors
What particle size can teeth detect?
8 – 15 microns
What force reaches a maximum when food is swallowed?
When cohesive force is max
What forces are applied to cause distortion to food?
- Stress
- Strain
- Stiffness
- Yield strength
- Brittle
- Hardness – stress for perm indentation
- Fracture strength - tough foods have slow feeding rates
What is yield strength?
Stress at which a solid begins to perm deform
What is the function of anterior teeth?
Biting and gripping
What is the function of posterior teeth?
Fracturing food
What is the function of secondont teeth? Give an animal example.
Slicing function for meat – only peaks in the tooth – e.g. cat
What is the function of bunodont teeth? Give an animal example.
For eating meat and plants – flattened occlusal surfaces for crushing and grinding – human
What animals have selenodont teeth?
Cow, deer, sheep, goat
What animals have lophodont teeth?
Elephant, mouse
What animals have selenolophodont teeth?
Horse
What is the shape of the selenodont, lophodont and selenolophodont teeth?
Complex infolding for herbivory to eat plants etc
What shapes in the posterior teeth are limited during tooth mastication?
Cusps and dips
What are the 4 occlusion surfaces of upper and lower teeth to aid different types of mastication?
- Alternation – teeth interdigitate to grip not fracture food
- Opposition – cusps fit into basins for crushing
- Shearing – oblique/parallel movement movements of crest past each other
- Grinding – mortar and pestle motion
