Oral Biology Flashcards
1
Q
occlusion definition
A
contact relationships of teeth or equivalent (dentures etc)
2
Q
articulation definition
A
dynamic relationships of teeth when in sliding contact
3
Q
jaw relationship definition
A
positional relationship which mandible bears to maxilla
4
Q
rest/postural position of teeth
A
-teeth = apart
5
Q
what maintains resting/postural position of teeth
A
- minimal muscle activity
- muscle elasticity
6
Q
why is resting/postural position important
A
- remains reproducible/stable throughout life in dentate and edentulous subjects
- important as a reference for full dentures
7
Q
intercuspal position (ICP)
A
- maximal intercuspation/interdigitation between mandibular and maxillary teeth depending on dentition
- curve of wilson and spee
- angles classification etc
8
Q
position of condyles and teeth during retruded contact position/RCP/ligamentous position
A
- condyles retruded in the glenoid fossa
- mandibular teeth 1-2mm posterior to ICP (this = ICP in 10-20% of patients)
9
Q
clinical signif of retruded contact position
A
- symmetrical retrusion
- gives reproducible relationship between maxilla and mandible
- can correct patients bite if incorrect with dentures etc
10
Q
occlusal vertical dimension (OVD)
A
- face height with teeth in ICP
- measured between two arbitrary points
- governed by height of teeth, therefore changes overtime due to wear
11
Q
how is occlusal vertical dimension (OVD) measured
A
between two arbitrary points using a willis gauge
12
Q
rest/postural vertical dimension (RVD)
A
- face height with mandible in rest/postural position
- measured between two arbitrary points
- should not alter signif throughout life
13
Q
what is freeway space (FWS)
A
- space between teeth in rest position
- diff in RVD and OVD
- 2-5mm
14
Q
during lateral excursion which side is the working side
A
-the side teeth move towards
15
Q
during lateral excursion which side is the non working side
A
-the side teeth move away from
16
Q
contact between teeth on working side during lateral excursion and importance
A
- the teeth that touch during movement are called guidance teeth and can either be:
- > canine guidance
- > group function
- important when restoring teeth as you have to stimulate lateral movements
17
Q
contact between teeth on non working side during lateral excursion
A
- teeth do not contact (disclude)
- may contact during cross bite, after extraction or due to upper removable appliances (URA’s)
18
Q
condylar movement at working side during lateral excursion
A
-rotates around vertical axis
-lateral bodily movement
=bennett movement
19
Q
condylar movement at non working side during lateral excursion
A
- moves downwards and forwards and forwards over eminence
- moves medially
- creates bennett angle
20
Q
bennett movement
A
at working side during lateral excursion
21
Q
bennett angle
A
- at non working side during lateral excursion
- describes the PATH of movement
22
Q
balanced occlusion concept
A
- tooth contact during excursions at both working/non working sides
- ideal for F/F dentures (maintains stability and controls cusp shape/tooth position and orientation)
- difficult to achieve because teeth are rarely in contact
- cannot exist in a normal dentate occlusion
23
Q
masticatory efficiency
A
- experimental tests to define capacity to reduce size of food particles by chewing
- eg. test food and serial sieve
- can also use swallowing threshold test (how many times you chew before you swallow)
24
Q
factors affecting masticatory performance
A
- no. of teeth in functioning occlusion
- replacement of teeth (fixed and/or removable prostheses)
- F/F masticatory performance is less efficient (can be improved by implants)
25
muscle used in RCP
temporalis
26
condylar movement for protrusion
-symmetrical on left and right
| =downwards and forwards
27
how is mastication controlled (3)
- voluntary
- pattern generator (happens semi-automatically, generator=programming centre)
- reflex (rapid automatic control)
28
reflex definition
predictable response to a given stimulus
29
eg's of reflexes (6)
- knee jerk reflex
- jaw jerk reflex
- pupillary reflex
- gag reflex
- masticatory- salivary reflex
30
reflex pathway
stimulus -> receptor -> afferent neurone (from periphery to CNS) -> snapse (s) -> efferent neurone (from CNS to periphery) -> effector
-> response
31
stretch reflex and examples
- simple
- mono-synaptic (1 synapse)
- eg:
- >knee jerk reflex
- >jaw jerk reflex
32
knee jerk reflex:
- stimulus
- receptor
- synapse (s)
- effect
- latency
- stretch via patellar tendon tap
- muscle spindle
- 1
- contraction of quadriceps femoris
- 19-24ms
33
reflex latency
=time from stimulus to effect
- conduction time of afferent neurone + conduction time of efferent neurone + synaptic delay (max synaptic delay = 0.2ms per synapse)
- >conduction time depends on the speed of the neurone and the time
34
jaw jerk reflex:
- stimulus
- receptor
- synapse (s)
- effect
- latency
- stretch via chin tap
- muscle spindle
- 1 in V (trigeminal) motor nucleus
- contraction of masseter muscle
- 7-8ms
35
role of jaw jerk reflexes (3)
- tonic (resist gravity/help maintain posture, synapse constantly stimulated due to gravity?)
- phasic/active (load COMPENSATES FOR LOAD DURING CHEWING, stabilises jaw during vigorous head movements e.g. running)
- clinical (tests integrity of trigeminal nerve)
36
protective reflexes:
- synapse(s)
- stimulus
- eg's
- polysynaptic (greater than 1 synapse) reflexes
- often response to noxious (damaging) stimulus
- eg. limb flexion withdrawal reflex, jaw 'opening' reflexes
37
flexion-withdrawal reflex
- excite nociceptors, gives sensation of pain, one nerve (to biceps) is activated, other (to the triceps) is inhibited
- excitatory neurone to the biceps
- inhibitory neurone to the triceps
38
jaw opening reflexes:
- stimuli
- receptors
- response in sub primates (e.g. cats)
- response in primates (inc. humans)
- intra oral mechanical or noxious and extra oral noxious
- mechanoreceptors and nociceptors
- activation of jaw depressors/openers in cats
- inactivation of jaw closers (inhibiting jaw closing) in humans
39
response and latency of reflex following a gentle tap to tooth
- response = early inhibition (of clenching, inhibits jaw closing)
- latency= approx 10ms
40
response and latency of reflex following harder tap to tooth
- response = early and late reflex (stop clenching, inhibits jaw closing)
- latency= approx 10 and 40 ms
41
response and latency of reflex following painful stimulus to the lip
- response = late reflex (stop clenching, inhibits jaw closing)
- latency= approx 40 ms
42
responses of inhibitory jaw reflexes
- inactivation of jaw closing muscles
- two phases:
- >early (10-30ms)
- >late (40-90ms)
43
role of inhibitory jaw reflexes
- prevent overloading of the masticatory system
| - facilitates opening (to expel noxious material, and to minimise damage to intra-/peri-oral structures)
44
jaw unloading reflex:
- stimulus
- response
- result
- sudden closure following hard biting (e.g. a hard/brittle food breaks)
- inactivation of jaw closing muscles and activation of jaw opening muscles
- teeth do not crash together
45
EMG
- electrodes put onto skin or needles into muscles to measure electrical activity of the muscle
- to stimulate inhibitory response, patient clenches first before applying stimulus (mechanical and noxious can inhibit muscle activity stimulating jaw opening)
46
CMD
=cranio-mandibular dysfunction/disorder
- pain involving masticatory muscles and TMJ joints
- protective reflexes are absent in these patients
47
role of mastication (3)
- breakdown of foodstuffs
- >prepare for swallowing
- >increase surface area for chemical digestion
- >release of chemicals for sense of taste
- stimulation of salivary flow
- growth and maintenance of pro-facial tissues
48
importance of mastication depending on food type:
- very important
- quite important
- not very important
- very important for red meat and vegetables
- quite important for white meat
- not very important for fish, egg, rice, bread and cheese (may speed up absorption)
- >large particles take longer to pass through gut
49
mechanics of ingestion/consumption (separate in most animals, overlap in humans) (4 steps) *important*
- stage I transport (food from lips to cheek teeth, inc. molars and premolars)
- mastication (chewing, except for liquids)
- stage II transport (food from cheek teeth to the back of the tongue)
- swallowing
50
mechanics of mastication (4)
- jaw movements (chewing cycles)
- tongue movements (directing food onto crushing surfaces after it has been displaced due to chewing, crushing food, mixing food and saliva)
- cheek movements (directing food)
- lip movements (accepting food, retaining food via anterior oral seal and directing food)
51
duration of the chewing cycle
0.5-1.2 seconds
52
phases of chewing cycle (and diff. terminologies) (3)
- opening, closing, occlusal phases
- opening, fast closing, power closing phases
- opening, fast closing, slow closing, intercuspal phases
53
at which phases during the chewing cycle does food breakdown occur (2)
- slow closing
| - intercuspal
54
masticatory forces (2)
- physiological chewing forces (70-150N dentate and 4-55N edentulous)
- maximum clenching forces (500-700N between molars, record = 4,345N)
55
normal and abnormal masticatory movement pathways (4)
*use these diagrams when asked to reproduce chewing cycle/phases, DO NOT use envelope of movement as this is extreme movements, whereas the cycle is not*
- tough foods = clockwise, wide oval, open go out to side and close again (quite lateral movement)
- brittle foods = clockwise, thin oval (more vertical movement)
- abnormal = anticlockwise or figure of 8 movements
56
movements of condylar head during opening and closing on working side
- opening = rotates around vertical axis, moves slightly (1-1.4mm) laterally (bennett movement)
- closing = moves medially to normal position in glenoid fossa early on in closing phase, and rotates back to normal orientation
57
movements of condylar head during opening and closing on non working side
- opening = moves downwards, forwards and medially (described by bennett angle)
- closing = moves upwards, backwards and laterally and returns to normal position in glenoid fossa late in closing phase
58
movement of condylar head during opening of chewing cycle (working and non working side)
- working side rotates around vertical axis, moves slightly (1-1.4mm) laterally (bennett movement)
- non working sidemoves downwards, forwards and medially (described by bennett angle)
59
movements of condylar head during closing of chewing cycle (working and non working side)
- working side moves medially to normal position in glenoid fossa early on in closing phase, and rotates back to normal orientation
- non working sidemoves upwards, backwards and laterally and returns to normal position in glenoid fossa late in closing phase
60
sequence of muscle activation during opening phase of chewing cycle (3)
mylohyoid -> digastric -> lateral pterygoid
61
sequence of muscle activation during closing phase of chewing cycle (3)
temporalis -> masseter -> medial pterygoid
62
historical perspective on theories of masticatory control
-reflex chain theory (too simple)
63
current theory of masticatory control
-combination of brainstem central pattern generator, cortical (voluntary) and reflex modulation
64
central pattern generator theory of mastication (4 combinations) (long card, break it down)
- peripheral influences -> jaw reflexes -> 'masticatory' muscle motor neurones -> 'masticatory' muscles
- peripheral influences -> central neural pattern generator (pons) -> 'masticatory' muscle motor neurones -> 'masticatory' muscles
- peripheral influences -> higher centres (e.g. cerebral cortex) -> central neural pattern generator (pons) (*this stage can be skipped out*) -> 'masticatory' muscle motor neurones -> 'masticatory' muscles
65
stages of ingestion
- food into front of mouth
- transport?
- >no (spit out)
- >yes (stage I transport to posterior teeth)
- tranpsort?
- > no (chew)
- > yes (stage II transport to back of tongue, bolus formation)
- ready for swallowing?
- >no (bolus formation continues)
- >yes (swallow)
66
swallowing frequency
- approx 500-2500 per day
- depends on activity:
- >25% while eating
- >65% when awake
- >10% when asleep
67
seals involved in 'command' swallow (2)
- applies to swallowing liquids
- >anterior oral seal (lips)
- >posterior oral seal (tongue-soft palate)
68
phases of 'command' swallow (3)
1. oral
2. pharyngeal
3. oesophageal
69
describe oral phase of 'command' swallow (3)
- tongue (stabilised and raised to hard palate)
- soft palate (raised, nasopharyngeal seal, importance of cleft palate repair)
- lower airway protected (breathing stopped, larynx raised)
70
describe the pharyngeal phase of 'command' swallow (4)
- tongue (backwards)
- pharyngeal constrictors (squeezed)
- upper oesophageal sphincter (cricopharyngeus, opens)
- lower airway protected (epiglottis is down and vocal cords are closed)
71
oesophageal phase of 'command' swallow (5)
- primary peristalsis (moves bolus)
- lower oesophageal sphincter opens
- secondary peristalsis (reflex response to debris, cleansing- more for solids than liquids)
- sphincters close
- respiratory system (airway re-opens and breathing resumes)
72
describe peristalsis
- unidirectional wave of muscle contraction in a tubular organ (oesophagus, intestine, ureter)
- powerful (normally gravity assisted, but can swallow upside down)
- diff to other GI movements (e.g. segmentation is not unidirectional)
73
diff between peristalsis in oesophagus and in intestine
- eosophagus = wave of contraction above food bolus
| - intestine = wave of contraction above food bolus AND wave of relaxation below food bolus
74
diff between solid & liquid swallow
- liquid = swallowed from the mouth and has distinct oral phase
- solid = stalled from mouth and/or oropharynx, has an oro-pharyngeal phase
75
diff between adult and infant swallow
- adult = teeth together, jaw/tongue stabilised by jaw closing muscles, tip of tongue stable behind incisors
- infant = gums apart, jaw/ tongue stabilised by facial muscles, 'tongue thrust' (anterior open bite = cause or effect)
76
type of muscles that control swallowing
- mainly skeletal muscle (motor neurone control)
| - some smooth muscle (autonomic control)
77
reflex swallowing pattern
- sensory nerves -> higher centres (eg. cerebral cortex) -> swallowing centre (brainstem) -> swallowing muscle motor neurones -> swallowing muscles
- can go from sensory nerves to either of the 2nd-5th stages
- reflexes go straight to 5th step from sensory nerves
78
voluntary swallowing pattern
- higher centres (eg. cerebral cortex) -> swallowing muscle motor neurones -> swallowing muscles
- >involves CNS
79
description of reflex swallowing sensory nerves (3)
- mechanoreceptive (back of mouth/pharynx)
- water sensitive (epiglottis)
- chemoreceptive (mouth)
80
gag reflex
- stimuli = mechanical at the back of mouth/oropharynx (rarely food, usually dental impressions)
- CNS determines whether the stimuli are for swallowing or gagging, then produces one response or surpasses the other
