oral functions Flashcards
masseter origin
zygomatic arch
masseter insertion
lateral surface and angle of mandible
which muscles are tender in pts with Bruxism?
masseter
temporalis
fct of masseter
elevates mandible
testing masseter
one finger IO, other on cheek
temporalis origin
floor of temporal fossa
temporalis insertion
coronoid process and anterior border of mandible
temporalis fct
elevates and retracts mandible
palpating temporalis
digital palpation between superior and inferior temporal lines, just above ear, extending forwards towards the supraorbital region
LP origin
lat surface lat pterygoid plate
LP insertion
inferior - anterior border of condyle
superior - intra-articular disc
LP fct
protrudes mandible and lateral deviation
inferior head functions with the mandibular depressors during openings
testing LP
not accessible to manual palpation - resistance test
MP origin
deep head - medial surface of LP plate
superficial head - tuberosity of maxilla
MP insertion
medial surface of angle of mandible
fct of MP
elevates and protrudes
MP testing
can’t palpate or resistive movement tests - no reliable way of examining
which muscle hit with needle during IDB can cause temp trismus?
MP
how to avoid causing trismus IDB?
contact bone to ensure correct position
movements of TMJ
rotation - initial opening - hinge
translation - wider opening - sliding
- protrusive/retrusive
what happens to the condyles in protrusive movements?
both condyles leave fossa and move forward along the articular eminences
what happens to the condyles in retrusive movements?
both condyles leave the eminences and move back into their respective fossa
Ulf Posselt
graphical recordings in occlusal and sagittal plane and profile radiography
all produced similar shape
max clenching/biting forces
varies between teeth
max between molars (200-700N)
factors affecting max bite force
psychological - fear of tooth fracture muscle mass - bigger muscles = larger forces - Bruxists often hypertrophic muscles - look for facial asymmetry muscle fibre type tooth type and position root area (PD support) nutcracker analogy
what does your predominant muscle fibre type vary depending on?
jaw morphology and diet
max bite force - tooth type and position
greatest bite force generated between 1st molars
position relative to TMJ and muscles (molars are nearer the force generating muscles and the fulcrum - TMJ)
type 1 muscle fibres
slow low forces
type 2 muscle fibres
fast stronger forces
subtypes of muscle fibres
IIA
IIX
IIB
evidence for people with ‘squarer’ jaws
have more type 2 fibres and can generate stronger bite forces
suprahyoid muscles
mylohyoid
digastric
geniohyoid
stylohyoid
infrahyoid muscles
thyrohyoid
omohyoid
sternohyoid
sternothyroid
when the hyoid bone is fixed by contraction of the infra hyoids, which muscles act as jaw depressors?
mylohyoid
geniohyoid
digastric
fct of intrinsic tongue muscles?
alter shape
intrinsic tongue muscles
longitudinal (superior and inferior)
vertical
transverse
fct of extrinsic tongue muscles?
alter shape and position
extrinsic tongue muscles
genioglossus
hyoglossus
styloglossus
palatoglossus
orbicularis oris and buccinator role
help to control food bolus and prevent spillage
dysfunction can be the 1st signs of a stroke
mandibular division of trigeminal nerve
mental auriculotemporal buccal lingual IAN n to mylohyoid
how to avoid ulceration after IDB?
warn pt not to bite lip as will be numb
paraesthesia
abnormal sensation typically tingling or pricking (pins and needles)
favourable prognosis - no complete sectioning of nerve
dysaesthesia
abnormal unpleasant sensation felt when touched, caused by damage to the peripheral nerves
function of gagging reflex
mechanical mechanism - acts to prevent material entering pharynx
what is the gagging reflex?
mechanical stimulation of fauces, palate, posterior tongue, pharynx
contract
similar to vomiting but no ejection of material
what is an oversensitive gag reflex?
a clinical problem
gag reflex neural pathway
stimulus
receptor - glossopharyngeal
sensory neuron - afferent sensorial response from CN9
association neuron
motor neuron - efferent motor response from CN5,9,10,11,12
effector - posterior part of tongue/SP contracts
response
what are also stimulated in the gag reflex?
motor (secretory) visceral nerves of the salivary glands and lacrimal gland
nerves involved in gagging reflex
trigeminal 5 glossopharyngeal 9 vagus 10 accessory 11 hypoglossal 12
afferent sensory neurons
carry a message into CNS
efferent motor neurons
carry message away from CNS
interneuron
connect one neuron with another
RPDs and gag reflex
retaining mesh in posterior part - facilitate attachment of acrylic extension
- indicated when post-dam can’t be tolerated by pt (gag reflex) - allows it to be adjusted more easily
reduces weight of large metal connector
alginates and gag reflex
take U behind pt - push up at back first so excess doesn’t run down throat
distract pt
reduce temp of water - use fast setting alginate
nose breathing
don’t want alginate behind post-dam of pt
U imp sitting up
Bell’s palsy
unilateral
motory disorder
any type of facial paralysis that does not have any other associated causes e.g. tumours, trauma, salivary gland inflammation
signs of Bell’s palsy
inability to wrinkle brow
drooping eyelid - can’t close eye/blink
can’t puff cheeks
drooping mouth - food stuck in cheek
causes of Bell’s palsy
infections (HSV/cold sores)
otitis media (inflammation middle ear)
diabetes
trauma
toxins
temp by infiltration of LA to facial nerve branches
- LA given too far distally and parotid gland penetrated
- avoid - position above contralateral premolars
facial nerve branches
temporal zygomatic buccal mandibular cervical
trismus after IDB
hit MP
facial nerve palsy after IDB management
pts may feel something is wrong but be unable to identify exactly what problem is, usually operator who notices specific changes
inform and reassure pt - transitory and reversible
protect eye with loose pad - cornea protected until protective blink reflex returns
recovery often in v short time (within 1hr)
how to prepare mouth for over dentures?
good if few remaining teeth
decoronation - keep roots and PDL
can use precision attachments
- either do RCT and use space for attachment
- if elderly pt decoronation may not reach pulp - GI lining as cap
- help with support
advantages of overdentures
PD mechanoreceptors allow finer discrimination of
- food texture
- tooth contacts
more precise control of mandibular movements and levels of fct loading - less likely to break dentures with accidental occ overload
psychological benefit - prevent feeling of total loss of natural teeth - more acceptable to pt
makes eventual transition to complete dentures more acceptable
good as resorbed alveolar ridge if no teeth - so keep teeth to prevent resorption. Potential of implants in future
loss of PD mechanoreceptors influences:
control of jaw fct
precision of magnitude
direction
rate of occ load application
loss of PD mechanoreceptors in complete dentures
conventional complete dentures don’t carry enough sensory info to restore necessary natural feedback pathways for motor fct
inherently unstable during normal jaw movements
joint receptors
joint position (mouth open/closed) joint movement (opening/closing) - info useful in controlling jaw movements e.g. chewing
dysphagia
difficulty swallowing - food stuck in oesophagus
causes of dysphagia
stroke - may be one of first symptoms brain injury MS GORD tumours
detecting a stroke
compare sensorial and motor responses from both sides of face and oropharynx - stroke unilateral
nociceptors
free nerve endings
high thresholds
respond to intense (noxious) stimuli - usually associated with pain
- myelinated (Ad fibres):noxious mechanical and heat stimuli
- unmyelinated (C-fibres)
nociceptors carry several types of receptor proteins, responsive to diff noxious stimuli
dental pulp, muscles, joints, mucosa, PDL
“sensitivity”
orofacial tissues v sensitive
receptors have low thresholds for activation
but not all regions equally sensitive
general senses
touch
proprioception
temp
pain
facial skin and mucosa (mouth, pharynx) - mechanoreceptors, thermoreceptors, nociceptors
sensory abilities in these regions similar
special senses
taste - oral chemoreceptors
smell - nasal chemoreceptors
mechanoreceptors
low thresholds (0.5mN) - senses of touch, pressure adaptation to constant stimulus slowly and rapidly adapting types a sensory receptor that responds to mechanical pressure or distortion
role of PD mechanoreceptors
v sensitive - enable us to assess direction of forces applied to teeth contribute to oral functions - mastication (food consistency) - salivation - interdental discrimination
proprioception
self-sense
awareness of position and orientation of body parts
served by various proprioceptors
- joint
- muscle - muscle spindles, Golgi tendon organs
- PD receptors
found in diff points in mouth
interdental discrimination
ability to gauge extent of mouth opening co-ordination of masticatory movements monitoring size of food particles detection of 'high' spots TMJ, muscle and PDL receptors
PDL can detect materials between teeth down to 1/2 the thickness of a human hair - remember when placing/adjusting Rxs
Shimstock
metal foil for occlusion testing
8 microns thick
2 point discrimination example - polo mint
have taste buds and olfaction of mint
have experience of tasting polo - facilitates the correlation
acquire format of mint - compress it against the hard palate with tongue
- mechanoreceptors can identify format (hole)
- 2 point discrimination of both tissues
nociceptors - primitive response of mint
smell
olfactory epithelium
- millions of olfactory sensory cells
- cilia project down into mucus layer produced by Bowman’s glands
odor molecules dissolved in mucus - stimulates receptor sites on the cilia
nerve signals - olfactory bulb - brain
where are taste buds located?
around base and sides of papillae
- few taste buds in centre of tongue
senses involved in taste
gustatory receptors - nerves olfactory receptors salivary glands stimulated - increase taste past experiences mechanoreceptors - texture thermoreceptors - temp
thickening response
sucrose and fructose thickeners in drink
provide quenching taste
why many pts prefer soft drinks
smell and taste
smell stimulates salivary glands - so smelling disorders often affect taste
infection of nasopharnyx - loss of olfactory sense (anosmia) may be associated
pts have difficulty discerning between taste and olfaction - interchange terms
motor innervation of tongue
palatoglossus - CN10
all other intrinsic and extrinsic tongue muscles - CN12
anterior 2/3 tongue sensory innervation
general - lingual nerve CN5
special - chords tympani CN7
posterior 1/3 tongue sensory innervation
general and special - CN9
area innervated by internal laryngeal nerve CN10
special sensory nerves
taste
general sensory nerves
touch pressure heat cold etc
the feeding sequence
ingestion
stage 1 transport
mechanical processing
stage 2 transport
ingestion
external env into mouth
biting (anteriors) / tools (cutlery)
lips provide anterior oral ‘seal’ - orbicularis oris
stage 1 transport
move material from front of mouth to level of posterior teeth
food gathered on tongue tip
tongue retracts, pulling material to posterior teeth (about 1sec)
associated with retraction of hyoid bone and narrowing of oropharynx
mechanical processing
break down, mix with saliva moist solid foods e.g. fruit need fluid removed before transport and swallowing mastication by premolars and molars some foods (soft) are 'squashed' by tongue against HP coordinated actions of many muscles - mandibular muscles - suprahyoids - tongue muscles - lips and cheeks
stage 2 transport
moving food into oropharynx
tongue gathers bolus for transport
forward movement of tongue during occlusal and initial opening phases creates a contact between the tongue and HP
contact zone moves progressively backwards, squeezing the processed food through the fauces ‘squeeze back mechanism’
material accumulates on pharyngeal surface of tongue, stays there until swallowing occurs
processing of solid foods
mouth continuous with oropharynx
when is a posterior oral seal produced?
ingestion of liquids
they are swallowed from the mouth i.e. without stage 2 transport
tongue actions in chewing
controls and transports bolus within mouth
gathers food and rotates to reposition bolus on occlusal table
along with cheeks keeps bolus on chewing surfaces
- tongue and cheeks act in a reciprocal manner “tongue pushing and cheek pushing” cycles
tongue moves bolus from side to side of the mouth and gathers it for transport
chewing cycle phases
occlusal phase - ICP
opening phase - jaw depressor muscles are active
closing phase - jaw elevator muscles are active
how can you avoid hyper/hypotrophic muscles?
advise pt to chew bilaterally
variations in chewing cycles?
tough food e.g. meat has wider cycle than brittle foods e.g. carrot
occlusal conditions also has an effect on the chewing stroke
gum very broad stroke
consider chewing style when designing prostheses
balanced articulation
ruminator mandibular movements - use teeth with cusps to achieve a balanced occlusion (esp where pts have a favourable ridge form)
if dentures have evenly worn/flat occlusal surfaces - suggests vertical (chopping) mandibular movements - esp in flat atrophic mandibular ridges could use cuspless teeth
consider tongue movements when designing prostheses
inaccurate placement of L posterior teeth - could interfere with tongue’s movements - will compromise retention and stability of denture
- if teeth inclined lingually will bite tongue while chewing
- if teeth inclined buccally will bite cheek while chewing
chewing performance
is it necessary to chew food?
- mechanical breakdown of food in mouth
= facilitates swallowing
= might improve digestive efficiency in GIT
“min chewing with ‘good’ dentition sufficient to ensure adequate digestion of most foods” - don’t need max
deteriorated MP can lead to dietary restrictions - avoiding foods that are ‘difficult’ e.g. green veg, some meats
but no clear evidence that poor mastication causes malnutrition in people with GIT disorders esp with modern foods and methods of preparation
what does masticatory performance correlate with?
occlusal contact area
occlusal contact area vs occlusal surface area
occlusal contact area usually smaller than the total occlusal area unless a lot of toothwear
min teeth
20 teeth considered the min for acceptable:
- masticatory fct
- aesthetics
- maintenance of OH
but other tx options may be appropriate here
SDA
“a dentition where most posterior teeth are missing”
can be good as compliance with L dentures v poor esp with FES
only replace molars if absence causing problems
provides sufficient occ stability, satisfactory comfort and appearance
chewing and comfort were not greatly increased by RPD
no of people who might have a fct SDA falls with age
biting forces and complete dentures
biting forces reduced in complete denture wearers
biting load carried by mucosa of residual ridge
- not designed to bear masticatory loads
- why bone gets resorbed below it - better to utilise teeth
support area reduced (mucosa vs PDL)
bite forces can be increased by supporting dentures on teeth or implants
when are cantilever bridges not recommended?
when occ forces on the pontic will be heavy
“food keeps getting stuck in cheek and ear infection”
otitis media has temporarily damaged facial nerve so buccinator and orbicularis oris not fct properly
swallowing phases
buccal phase (voluntary) pharyngeal phase (involuntary) oesophageal phase (involuntary)
swallowing fcts
feeding fct - process by which accumulated food bolus is transported through the lower pharynx and oesophagus to the stomach
protective fct - prevents ingested material from entering the L airway
why is swallowing potentially dangerous?
‘foodway’ crosses the ‘airway’
swallowing liquids
no stage 2 transport
liquids gathered on tongue, anterior to pillars of fauces
mouth separated from pharynx by posterior oral seal
liquid ‘bolus’ propelled through oro and hypopharynx, then into oesophagus
swallowed from mouth proper - oral seal
swallowing solid bolus
chewed food accumulates on the pharyngeal part of the tongue and vallecula (oropharynx)`
no true posterior oral seal
bolus then propelled from tongue through the hypopharynx and then into the oesophagus
swallowed from oropharynx - no oral seal
similarity when swallowing solids and liquids
both are moved rapidly through the hypopharynx past the laryngeal inlet
tongue movements in swallowing
forward movement of tongue during occlusal and initial opening phases creates a contact between the tongue and hard palate
contact zone moves progressively backwards, squeezing the processed food through the fauces
swallowing events
propulsion of food
prevention of reflux
protecting the airway
phases - durations of swallowing
durations of masticatory sequence components vary to different extents with food consistency
swallowing forces
strong enough to move a bolus ‘uphill’ as well as ‘downhill’
preventing reflux
elevation of SP
tongue (sides) contacts pillar of fauces
tongue (dorsum) contacts posterior pharyngeal wall
UOS - reflux from oesophagus into pharynx
LOS - reflux from stomach into oesophagus
airway protection
upward and forward movement of larynx closure of laryngeal inlet - aryepiglottic muscles - epiglottis adduction of vocal folds stop breathing 'apnoea'
conditions affecting the tongue
tongue tie
partial atrophy
tongue stud
xerostomia and speech
impedes speech
difficulty in pronouncing words
dysphasia (aphasia)
specific language disorder
damage to particular parts of brain
- Broca’s area, Wernicke’s area
dysarthria
difficulty speaking - caused due to NM defects of the muscles used in speech
lesions in descending neural pathways, CNs, vocal muscles, NM jcts
odynophagia
pain on swallowing
oral causes of language and speech defects
malocclusions loss of teeth and denture related CL/P tongue-related dry mouth
denture-related language and speech defects
problems mostly from restricted tongue space
denture base plate too thick
artificial teeth not set properly
material used in denture doesn’t affect speech
denture-related language and speech defects - pronouncing th/s/sh
position of the tongue for pronouncing sounds th/s/sh
if polished surface of denture correctly shaped so tongue can form narrow channel in the middle for pronouncing (s) sound
but if excessive thickening of the plate laterally - prevents close adaptation of the tongue to the palate so s becomes sh
denture-related language and speech defects - wrong occlusal planes
problem pronouncing f, v, ph - labio-dental (fricative) sounds
dentures can’t interfere with tongue/lip/cheek movement
lips of U incisors should touch vermillion border of lip during fricative sounds
speech assessment when replacing missing teeth
assess tone of lips and cheek by asking fundamental Qs
- indicates fct relationship of lips and tongue to dentures in speech
music
aerodigestive tract and facial tissues produce vocal sounds and also contribute to playing wind instruments
embouchure
the position and use of lips, tongue and teeth in playing a wind instrument
vary - instruments and individuals
IO mouthpieces wind instruments
single reed - clarinet, sax
double reed - oboe, bassoon
EO mouthpieces wind instruments
piccolo, flute
trumpet, horn, trombone, tuba
SH instruments
ask about instruments
wind - may have special needs in respect to the retention of an appliance and placement of teeth
factors that vary between high and low notes
position of mouthpiece relative to teeth mouth opening (gape) relation of jaws position of hyoid bone position of dorsum of tongue
trumpet mouthpiece
usually centred on lips
tends to move all front teeth backwards
