oral functions 3 Flashcards
define ingestion
movement of food from the external environment into the mouth
how does ingestion happen
accomplished by biting (anterior teeth) and / or using “tools” such as cutlery
what role does lips play in ingestion
they provide an anterior oral seal cant control food in the mouth without the muscles around the lips - orbicularis oris - buccinator (prevent spillages)
what is stage 1 transport
moving material from the front of the mouth to the level of the posterior teeth
food is gathered on tongue tip
what happens in stage 1 transport
the tongue retracts
pulling the material to the posterior teeth
(pull back process)
takes about 1 second
associated with the retraction of the hyoid bone and narrowing of the oropharynx
define mechanical processing
some solid foods must be broken down and mixed with saliva before they can be swallowed
what happens to moist solid food like fruit before transport and swallowing
needs to have the fluid removed
what teeth chew the food
premolar and molars
although molars are not always needed - prosthetic dentistry
what happens to some soft foods in mechanical processing
they are squashed by tongue against the hard palate
so the tongue is involved in chewing
what happens to the hyoid bone in chewing
it retracts
what does food processing involve
the co-ordinated actions of the following muscles
> mandibular muscles (also called the muscles of mastication)
> the supra-hyoid muscles
> tongue muscles
> the lips and cheeks
what are the 2 types of tongue muscles
- intrinsic
- extrinsic
what is the function of intrinsic tongue muscles
name these
alters the shape
- longitudinal
- vertical
- transverse
what is the function of extrinsic tongue muscles and name these
alters shape and position
- genioglossus
- hyoglossus
- palatoglossus
- styloglossus
what are the tongues actions in chewing
- controls the bolus
- gathers good and rotates to reposition the bolus on the occlusal table
- the tongue along with the cheeks, keeps the bolus on the chewing surfaces
- the tongue and cheeks act in a reciprocal manner to place the food on the occlusal surfaces of the teeth
- the tongue moves the bolus from side to side of the mouth
- tongue gathers the bolus for transport
what way should patients chew
bilaterally
what is the problem with chewing unilaterally
it is not good for the masticatory system
leads to problems with the masticatory muscles
hypertrophic muscles on one side of the face if chewing unilateral
what happens to the tongue during the occlusal and initial opening phases
the tongue moves froward
this creates a contact between the tongue and the hard palate
what is the squeeze back mechanism
> the contact (created during the occlusal and initial opening phases) moves progressively backwards
squeezing the processed food through the fauces
[pushes the bolus so it is ready to be swallowed]
the material accumulates on the pharyngeal surface of the tongue and remains until swallowing occurs
when is the mouth continuous with the oropharynx
during the processing of solid foods
what may be produced during the ingestion of liquids
posterior oral seals
liquids are swallowed from the mouth without stage 2 transport
watch video on SDEO
what are the phases in the chewing cycle
- opening phase
- closing phase
- occlusal phase
what happens in the opening phase of the chewing cycle
jaw depressor muscles are active
what happens in the closing phase of the chewing cycle
jaw elevator muscles are active
what happens in the occlusal phase of the chewing cycle
mandible is stationary / teeth are joined
what makes the chew cycle different
> different patients according to shape of teeth
different patients according to presence or absence of tooth wear
different foods
is the chewing cycle the same as the fossa envelope
no
the fossa envelope shows the broader movement of the jaw and mandible
what is the chewing cycle shape like when eating brittle food eg carrots
narrower / thinner shape
what is the chewing cycle shape when eating tough food eg meat
broader / wider shape
what does the chewing cycle look like in good occlusion
consistent shape
lines close together
what does the chewing cyclin look like in worn occlusion / bruxism
random
wider shape
what does the chewing cycle look like in malocclusion
no real pattern
what are ruminatory mandibular movements
when the patient chews there is lots of lateral movements
what is the biscuit test
patient eats a biscuit so you can examine how they chew
if the patient has ruminatory mandibular movements, what needs to be considered when designing the denture
the dentures should have teeth with cusps to achieve balanced occlusion (especially when patients have favourable ridge form)
teeth with cusps to ensure the denture is stable when chewing
if the patient has vertical (chopping) mandibular movements, what needs to be considered when designing the denture
the dentures should have cuspless teeth in this case
(occlusal surface which are evenly worn / flat)
this is the case especially in flat atrophic mandibular ridges
if patient has a worn bite they will struggle to eat differently if they have cusps in their new denture teeth
what can the tongue’s movements compromise
the retention and stability of the denture
if you dont leave room for the tongue in the denture design then the denture will rock / be mobile when the denture moves
why is it important to make sure the denture teeth are on the ridge exactly and do not lean lingually or buccally?
this can lead to tongue or cheek biting
use a wax knife to ensure they are straight
what do patients need to have to control the denture when incising an apple
have neuromuscular control of the denture
patient controls the denture by pushing the tongue to the hard palate to stabilise the denture
raising the tongue = good thing
if this didn’t happen then the denture would wobble when biting the apple
important to watch how patient walks when they enter / checking their medical history to make sure they dont have a neuromuscular disorder or they will have issues wearing a denture
what is needed to ensure adequate digestion of most foods
minimum chewing with a good dentition is sufficient
what does mechanical breakdown of food in the mouth allow
facilitates swallowing
might improve digestive efficiency in the GI tract
what can deteriorated masticatory performance result in
dietary restrictions
avoiding foods that are difficult such as green veg and some meats
there is no clear evidence that poor mastication causes malnutrition in people with GI tract disorders especially with modern foods and methods of preparation
so if a person is able to eat in a reasonable way they should be okay healthwise
what is the shortened dental arch (SDA)
20 teeth is considered the minimum for acceptable
> masticatory function
> aesthetics (premolar to premolar)
> maintenance of oral hygiene
need to have 20 health units (either natural teeth or implants or sound restored teeth)
what is the concept behind the shortened dental arch
- absent molar teeth are only replaced if their absence gives rise to problems
- SDA provides sufficient occlusal stability
- SDA provides satisfactory comfort and appearance
- chewing and comfort were not significantly enhanced by the provision of RPDs
what must attention be given to for a shortened dental arch to exist
maintaining the health of the remaining teeth
patient must be a good, regular attender who keeps good control of their oral hygiene
what age group does a functional SDA not work well for
elderly
the number of people who might have a functional SDA fails dramatically with age
what are reduced in complete denture wearers
biting forces are reduced
complete dentures = mucosa borne support (mucosa of residual ridge)
this is not designed to bear masticatory loads or to tolerate forces
what do patients lack in complete dentures
lack proprioception
no PDL in complete dentures
how can bite forces be increased in dentures
supporting the dentures on teeth or implants
not everyone can tolerate the surgery of implants or meet the cost
what are the 3 types of prosthesis that can be used to replace missing teeth
- mucosa supported prosthesis
- tooth supported prosthesis
- bone supported prosthesis
what can be given to a patient in mucosa supported prosthesis
- complete denture
- RPD
what can be give to a patient in tooth supported prosthesis
- RPDs
- fixed (‘bridges’)
what can be given to a patient in bone supported prosthesis
- implants
what are problems associated with acrylic partial dentures
> not used long term
not well supported and causes resorption of bone where forces are applied
use gingivally approaching claps that may cause gingival recession on the gingival margin
what is included in a fixed-fixed bridge
all ceramic
- abutment teeth
- retainer
- pontic
what is a cantilever bridge
used in tooth supported prosthesis
a pontic connected to a retainer at one end only
used to replace single teeth
only one retainer is used to support the bridge
not recommended when occlusal forces on the pontic will be heavy
what is an adhesive bridge / resin bonded bridge
an immediate temporary adhesive bridge is appropriate followed by a permanent bridge once the tissues have settled
quick
non-destructive / conservative of tooth tissues
aesthetic
durable (good life span)
has wings on the palatal aspects of abutment teeth
nothing on labial / buccal surfaces
how is the occlusal load transmitted to the bone in mucosa borne support
via the oral mucosa
not recommended
how is the occlusal load transmitted to the bone in tooth borne support
via rests and PDL
recommended
what are implants
bone supported prosthesis
screws / fixtures that will bare the forces
fixed so dont need to be removed for cleaning
