what is the first part of the feeding sequence
ingestion
what is ingestion
movement of food from the external environment into the mouth
how is ingestion accomplished
by biting with your anterior teeth and/or using ‘tools’ such as cutlery, cups etc.
what do lips provide in the feeding sequence
provide an anterior ‘seal’
what is the second part of the feeding sequence
transport
what is stage 1 transport
Stage I transport is moving material from the front of the mouth to the level of the posterior teeth.
what are the steps to stage 1 transport
- Food is gathered on the tongue tip
* The tongue retracts, pulling the material to the posterior teeth. PULL BACK PROCESS
what is after transport
mechanical processing
what happens in mechanical processing for solid foods
Some solid foods must be broken down and mixed with saliva before they can be swallowed
what happens in mechanical processing in moist solid foods
Moist solid foods such as fruit have to have fluid removed before transport and swallowing
how is food generally chewed/masticated
Generally food is chewed/masticated by premolar and molar teeth however, some soft foods are ‘squashed’ by the tongue against the hard palate
what muscles are involved in food processing
the ‘mandibular muscles’
the supra hyoid muscles
the tongue muscles
the lips and cheeks
how does the tongue control bolus
It gathers food and rotates to reposition the bolus on the occlusal table
what is the tongues role in chewing
the tongue plays a key role in controlling and transporting the bolus within the mouth.
what do the tongue and cheeks work together to do
The tongue and the cheek act in a reciprocal manner to place the food on the occlusal surfaces of the teeth. ‘tongue pushing’ (red) and ‘cheek pushing’ (blue) are observed during chewing.
what are the tongue movements during chewing
The forward movement of the tongue during the occlusal 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 – the so called ‘squeeze-back’ mechanism.
This material accumulates on the pharyngeal surface of the tongue and remains there until swallowing occurs.
During processing of solid foods, the mouth is continuous with the oropharynx
A posterior seal may be produced during the ingestion of liquids (liquids are swallowed from the mouth without stage II transport
what are the 3 phases of the chewing cycle
opening phase
closing phase
occlusal phase
what is the opening phase
the jaw depressor muscles are active
what is the closing phase
jaw elevator muscles are active
what is the occlusal phase
mandible is stationary, teeth are joined. In the ICP
how does the chewing cycle differ from person to person
it is a narrower chewing cycle for brittle foods such as carrots and a wider one for tougher foods such as meat.
what should be considered when designing prostheses
chewing style
if the patient performs ruminator mandibular movements what kind of teeth should be used
use teeth with cusps to achieve balanced occlusion (especially when patients have favourable ridge form).
if the dentures have occlusal surfaces which are evenly worn, what is this suggestive of
vertical (chopping) mandibular movement
what type of teeth should be used for vertical mandibular movement
In this case, especially in flat, atrophic mandibular ridges, cuspless teeth might be used.
why is it important to consider tongue movement when designing prosthesis
inaccurate placement of the mandibular teeth might interfere with tongue’s movements and will compromise the retention/stability of the denture as if the tongue does not have enough room it will hit the denture. You want the teeth to be on the ridge.
what is the tongue important for in dentures
The tongue is important in controlling the denture. Some patients can use their tongue to control their denture while they eat incisally, this is called neuromuscular control
what does mechanical breakdown of food in the mouth result in
facilitates swallowing
might improve digestive efficiency in GI tract
what does masticatory performance correlate with
occlusal contact area
when is it not necessary to replace missing teeth
the other components of the masticatory apparatus are functioning properly
what is the shortened dental arch
20 teeth is considered the minimum for acceptable masticatory function, aesthetics, maintenance of oral hygiene. However other treatment options may be appropriate here as well.
when are absent molar teeth replaced
Absent molar teeth are only replaced if their absence gives rise to problems. SDA provides sufficient occlusal stability
what should be paid attention to if a patient has an SDA
If a SDA does exist then particular attention must be given to the possibility of simply maintaining the status quo rather than providing an RPD as there is a intolerance especially to lower dentures.
how does dentures effect biting forces
Biting forces are reduced in complete denture wearers
what is biting load carried by in complete dentures
Biting load carried by mucosa of the residual ridge and this is not designed to bear masticatory loads.
how can biting forces of complete dentures be increased
by supporting dentures on teeth or implants
what aerate classifications of prosthesis
mucosa supported
teeth supported
bone supported
what are mucosa supported prosthesis
complete or partial
e.g acrylic partial denture
what are tooth supported prosthesis
removal PD e.g cobalt chrome
fixed bridges
what are bone supported prosthesis
implants
what is a cantilever bridge
has a pontic connecter to a retainer on one end only
It is used to replace single teeth and only one retainer is used to support the bridge
when are cantilever bridges not recommended
Not recommended when occlusal forces on the pontic are heavy
what are 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 and durable (good life span)
What happens in stage II transport
forward movement of the tongue during the occlusal and initial opening phase creates a contact between the tongue and the hard palate - this CONTACT ZONE MOVES PROGRESSIVELY BACK IN WHAT IS CALLED THE SQUEEZE BACK MECHANISM
material accumulates on the pharyngeal surface of the tongue
