Oral functions - feeding Flashcards
What is ingestion
movement of food from the external environment into the mouth
how is ingestion achieved
by biting (anterior teeth) and/or using ‘tools’ (cutlery, cups etc)
lips provide anterior oral ‘seal’
what happens after ingestion
material is moved from the front of the mouth to the level of the posterior teeth
(stage 1 transport)
how is material moved from the front of the mouth to the level of the posterior teeth
- food is gathered on tongue tip
- tongue retracts, pulling the material to the posterior teeth (pull back process - takes ~1second)
- associated with retraction of the hyoid bone and narrowing of the oropharynx
What happens after stage 1 transport
mechanical processing
why does mechanical processing occur?
some solid foods must be broken down and mixed with saliva before they can be swallowed
moist solid foods have to have fluid removed before transport and swallowing
how is mechanical processing achieved
foods chewed (or masticated) by premolar and molar teeth
soft foods squashed by tongue against hard palate
What muscles act in a co-ordinated manner to process food
- mandibular muscles
- supra-hyoid muscles
- tongue muscles
- lips and cheeks
How does the tongue act in chewing
- controls the bolus
- gathers food and rotates to reposition the bolus on the occlusal table
- along with cheeks, keeps the bolus on the chewing surfaces
- moves bolus from side to side of mouth
- gathers bolus for transport
how do the cheeks and tongue keeps the bolus on the chewing surfaces
act in a reciprocal manner
what are the 3 phases of the chewing cycle?
- opening
- closing
- occlusal
describe the chewing cycle
The forward movement of the tongue during the occulsal and initial opening phases creates a contact between the tongue and the hard palate
The contact zone moves progressively backwards, squeezing the processed food through the fauces (‘squeeze-back’ mechanism)
This material accumulates on the pharyngeal surface of the tongue and remains there until swallowing occurs
During the processing of solid foods, the mouth is continuous with the oropharynx
Posterior oral seal may be produced during the ingestion of liquids (liquids are swallowed from the mouth ie. without stage 2 transport)
why are food and liquid swallowed differently
liquid has a seal before it is swallowed, solid food does not
how does the opening phase of the chewing cycle occur
jaw depressor muscles are active
how does the closing phase of the chewing cycle occur
jaw elevator muscles are active
how does the occlusal phase of the chewing cycle occur
mandible is stationary/ teeth joined in IP
why and how does the chewing cycle vary
Hard food e.g. carrot creates a broader stroke than soft food e.g. cheese
Brittle food e.g. carrot needs a narrower cycle
Tough food e.g. meat needs a wider cycle
Chewing gum produces an even broader and wider stroke
what occlusal conditions affect the chewing stroke
worn occlusion, bruxism
malocclusion
in what ways can chewing style be considered when designing prostheses
- if ruminatory mandibular movements, use teeth with cusps to achieve balanced occlusion
- if dentures have evenly flat occlusal surfaces, this is suggestive of vertical mandibular movements
Is it necessary to chew food
- facilitates swallowing
- might improve digestive efficincy in GI tract
minimum chewing with a ‘good’ dentition is sufficient to ensure adequate digestion of most foods
what can deteriorated masticatory performance result in
- avoiding foods that are difficult e.g. green veg, some meats
does masticatory performance correlate or not correlate to occlusal contact area
correlate
is it always neccessary to replace missing teeth
no, this assumes that the other components of the masticatory apparatus are functioning properly
‘do nothing’ is sometimes the best treatment option
how many teeth make up a shortened dental arch
20 healthy units (implants count)
