Oral functions - feeding

Question 1

What is ingestion

Answer 1

movement of food from the external environment into the mouth

Question 2

how is ingestion achieved

Answer 2

by biting (anterior teeth) and/or using ‘tools’ (cutlery, cups etc)

lips provide anterior oral ‘seal’

Question 3

what happens after ingestion

Answer 3

material is moved from the front of the mouth to the level of the posterior teeth

(stage 1 transport)

Question 4

how is material moved from the front of the mouth to the level of the posterior teeth

Answer 4

• 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

Question 5

What happens after stage 1 transport

Answer 5

mechanical processing

Question 6

why does mechanical processing occur?

Answer 6

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

Question 7

how is mechanical processing achieved

Answer 7

foods chewed (or masticated) by premolar and molar teeth

soft foods squashed by tongue against hard palate

Question 8

What muscles act in a co-ordinated manner to process food

Answer 8

• mandibular muscles
• supra-hyoid muscles
• tongue muscles
• lips and cheeks

Question 9

How does the tongue act in chewing

Answer 9

• 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

Question 10

how do the cheeks and tongue keeps the bolus on the chewing surfaces

Answer 10

act in a reciprocal manner

Question 11

what are the 3 phases of the chewing cycle?

Answer 11

1. opening
2. closing
3. occlusal

Question 12

describe the chewing cycle

Answer 12

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)

Question 13

why are food and liquid swallowed differently

Answer 13

liquid has a seal before it is swallowed, solid food does not

Question 14

how does the opening phase of the chewing cycle occur

Answer 14

jaw depressor muscles are active

Question 15

how does the closing phase of the chewing cycle occur

Answer 15

jaw elevator muscles are active

Question 16

how does the occlusal phase of the chewing cycle occur

Answer 16

mandible is stationary/ teeth joined in IP

Question 17

why and how does the chewing cycle vary

Answer 17

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

Question 18

what occlusal conditions affect the chewing stroke

Answer 18

worn occlusion, bruxism

malocclusion

Question 19

in what ways can chewing style be considered when designing prostheses

Answer 19

• 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

Question 20

Is it necessary to chew food

Answer 20

• facilitates swallowing
• might improve digestive efficincy in GI tract

minimum chewing with a ‘good’ dentition is sufficient to ensure adequate digestion of most foods

Question 21

what can deteriorated masticatory performance result in

Answer 21

• avoiding foods that are difficult e.g. green veg, some meats

Question 22

does masticatory performance correlate or not correlate to occlusal contact area

Answer 22

correlate

Question 23

is it always neccessary to replace missing teeth

Answer 23

no, this assumes that the other components of the masticatory apparatus are functioning properly

‘do nothing’ is sometimes the best treatment option

Question 24

how many teeth make up a shortened dental arch

Answer 24

20 healthy units (implants count)

Question 25

do you need to replace absent molar teeth

Answer 25

only if their absence causes problems

Question 26

does SDA provide sufficient occlusal stability

Answer 26

yes

Question 27

does SDA provide satisfactory comfort and appearance

Answer 27

yes

Question 28

are chewing or comfort enhanced by provision of RPDs for people with SDA

Answer 28

no

Question 29

what is a common reason for people prefereing not to have a denture

Answer 29

intolerance to lower dentures

Question 30

why is the maximum bite force reduced in complete denture wearers

Answer 30

• biting load carried by mucosa of residual ridge

- support area reduced (mucosa vs PDL)

Question 31

how can you design dentures to increase bite forces

Answer 31

supporting them on teeth or implants

Question 32

what are the options for replacing missing teeth

Answer 32

Mucosa-supported prosthesis (complete or partial)

Tooth-supported prosthesis (removable or fixed)

Bone supported prosthesis (implants)

Question 33

what is a cantilever bridge

Answer 33

a pontic connected to a retainer at one end only

Question 34

when are cantilever bridges not recommended

Answer 34

when occlusal forces on the pontic will be heavy

Question 35

what are cantilever bridges used for

Answer 35

to replace single teeth and only one retainer is used to support the bridge

Question 36

What is an adhesive bridge/ resin bonded bridge/ maryland

Answer 36

• an immediate, adhesive bridge

- quick, non-destructive, aesthetic and durable

Question 37

why do we want forces to be distributed and not foccussed in one area

Answer 37

to avoid resorption