Occlusion Flashcards
1
Q
describe articular disc and attachments
A
- separates TMJ into super and inferior articular cavities each lined by separate synovial membranes
- articular disc if fibrous extension of the capsule
- runs between the two articular surfaces of the TM joint
- the disc articulates with the mandibular fossa and condyle of mandible
- also attached to condyle medially and laterally by collateral ligaments
- anterior disc attaches to joint capsule and superior head of lateral pterygoid
- posterior portion to mandibular fossa
2
Q
describe capsule of TMJ
A
- fibrous membrane that surrounds the joint
- attaches to the articular eminence, articular disc and neck of the mandibular condyle
3
Q
which part of TMJ is main contributor in pain of TMD
A
- retrodiscal tissue
- vascular and highly innervated (unlike disc itself)
4
Q
muscles involved in mandibular movement
A
- muscles of mastication - involved in depression, elevation, and lateral movements
- mylohyoid elevates hyoid and floor of mouth
- stylohyoid initiates swallowing by pulling hyoid bone posterior superior
- digastric and geniohyoid depresses the mandible and elevates the hyoid
5
Q
temporalis action
A
- elevates mandible closing mouth
- retracts mandible pulling jaw posteriorly
- assists in rotation
6
Q
masseter action
A
- superficial part in action
- elevates the mandible closing the mouth
- assists in lateral movement
7
Q
lateral pterygoid action
A
- superior head positions disc in closing
- inferior head protrudes and depresses mandible and causes lateral movement
- lateral movement caused by unilateral action
8
Q
medial pterygoid action
A
- elevates the mandible closing the mouth
- some lateral movements and protrusion
9
Q
temporalis originates/inserts
A
- originates from the temporal fossa
- condenses into a tendon which inserts onto the coronoid process of mandible
10
Q
massteter originates/inserts
A
- superficial part originates from maxillary process of zygomatic bone
- deep part originates fromzygomatic arch of temporal bone
- both insert onto ramus of mandible
11
Q
lateral pterygoid originates/inserts
A
- superiod head originates from greater wing of sphenoid
- inferior head originates from lateral pterygoid plate of sphenoid
- two heads converge into a tendon which attaches to neck of mandible (condyle)
12
Q
medial pterygoid originates/inserts
A
- superficial head originates from the maxillary tuberosity and pyrimidal process of palatine bone
- deep head originates from medial aspect of lateral pterygoid plate of sphenoid
- both heads attach to ramus of mandible near the angle of mandible
13
Q
two major types of mandibular movement
A
- rotation
- translocation
14
Q
describe rotational movement of mandible
A
- when mouth opened small amount (up to 20mm) the condyle hinges within the articular fossa
- condyle and disc remains within articular fossa
- no downwards or forwards movement
- also known as hinge movement
- rotation of condylar heads around an imaginary horizontal line through rotational centres of condyles
15
Q
name for imaginary horizontal line through rotational centres of condyles
A
terminal hingle axis
16
Q
facebow summary/function
A
- facebow registration used to record terminal hinge axis and distance between the condyles
- records the relationship of the maxilla to the terminal hinge axis of rotation
- allows maxillary cast to be placed in an equivalent relationship on the articulator
- poles of facebow inserted into ear canal as close as we can be to heads of condyle
- measure intercondular distance
17
Q
describe translation of the condyle
A
- lateral pterygoid contracts and the condyle and disc translate anteriorly
- travels downwards and forwards along the incline of the articular eminence
- may also travel laterally
18
Q
planes in which we can see border movements of mandible
A
- saggital plane
- horizontal plane
- frontal plane
19
Q
what does posselts envelope show
A
- border movements of the mandible - extremes of mandibular movement
- in saggital plane
20
Q
reference points on posselts envelope
A
- ICP = intercuspal position
- E = edge to edge
- Pr = protrusion
- T = maximum opening
- R = retruded axis position
- RCP = retruded contact position
21
Q
posselts envelope
describe ICP
A
- intercuspal position
- tooth position regardless of condylar position
- where teeth meet in occlusion during comfortable bite
- best fit of the teeth
- maximum intedigitation of the teeth
- can also becalled centric occlusion (CO)
22
Q
posselts envelope
describe E
A
- edge to edge
- tooth position where teeth slide forward from ICP guiding on palatal surfaces of anterior teeth
- incisor edges of upper and lower incisors touch
23
Q
posselts envelope
describe Pr
A
- protrusion
- condyle moves forward and downwards on articular eminence
- only incisors (+-canines) touch
- no posterior tooh contacts
- eventually no tooth contacts
24
Q
posselts envelope
describe T
A
- maximum opening
- no tooth contacts
- mouth wide open
- full translation of condyle over the articular eminence
25
Q
posselts envelope
describe R
A
- retruded axis position
- no tooth contacts
- mostly superior poesterior position of condylar head in the fossa
- terminal hinge axis
26
Q
posselts envelope
describe RCP
A
- retruded contact position
- first tooth contact when mandible is in retruded axis position
- ICP is approx 1mm anterior to RCP in 90% of population
27
Q
ICP-RCP slide
A
- mandible slides forward to achieve ICP
- ICP is approx 1mm aterior to RCP in 90% of population
28
Q
describe lateral translation
A
- mandible moves laterally
- mandible moves to R side = R side is working side, L side is non-workingalso known as bennet movement
- results of contraction of one lateral pterygoid muscle
- mandibular condyles slide along the mandibular fossa
29
Q
bennet angle
A
- angle formed by saggital plane and the path of the mandibular condyle
- during lateral movement when viewed in a horizontal plane
30
Q
describe this diagram
A
- mandibular movements viewed from frontal plane
- ICP is maximum intercuspation
- PP is physiological rest position with no tooth contacts
- divets are a result of canine guidance - lateral movement canines touch but posterior teeth do not - protects posterior teeth from lateral forces
31
Q
A
32
Q
A
33
Q
examining the occlusion
2 types
A
- dynamic occlusion
- static occlusion
34
Q
how to examine occlusion
A
- fine articulating paper
- millers forceps to hold paper
- ideally two articulating paper records - one for dynamic contacts and one for static
35
Q
when to mark tooth contacts
A
- before preparing a tooth or removing a restoration
- after placement of a crown or placement of a restoration
36
Q
tripodised contacts
A
- show where the opposing cusps contact
- ICP stops
- An occlusal scheme characterized by a cusp to fossa relationship in which there are three points of contact about the cusp and opposing fossa with no contact on the cusp tip
37
Q
what does static occlusion measure
A
- incisor relationship
- molar relationship
- overjet/overbite
- cross bites
- open bites
- individual tooth contacts
- RCP
38
Q
static occlusion ICP contacts
functional cusps
A
- cusps that occlude with the opposing teeth in the intercuspal position
- lingual cusps of upper posterior teeth
- buccal cusps of lower posterior teeth
39
Q
static occlusion ICP contacts
non functional cusps
A
- cusps that do not occlude with the opposing teeth in ICP
- buccal cusp of upper posterior teeth
- lingual cusps of lower posterior teeth
40
Q
static occlusion ICP contacts
fossa and contact points
A
- fossa - depression or concavity on the tooth surface
- the functional cusp of a tooth contacts the fossa of the opposing tooth
- lingual cusp of the upper molar contacts the fossa of the lower molar
- buccal cusp of the lower molar contacts the fossa of the upper molar
41
Q
problems in static occlusion
A
- incisor relationship - angles classification
- overbite - vertical overal of the incisors
- overjet - horizontal plane relationship between upper and lower teeth
- crossbite - one or more teeth malpositioned buccal or lingually with reference to opposing teeth
- anterior open bite - lack of vertical overlap of anterior teeth when posteriors in ICP
- posterior/lateral open bite - failure of contact between the posterior teeth when teeth in ICP
42
Q
types of dynamic occlusion
A
- canine guidance
- group function
- protrusion
43
Q
types of dynamic occlusion
canine guidance
A
- when mandible moves towards working side contact is only between the canines
- no posterior tooth contacts
- known as mutually protected occlusion
- due to canines longest and largest roots so can dissipate horizontal forces and protects posterior teeth
- fewer muscles active in canine guidance compared to group function
- gold standard!!!
44
Q
types of dynamic occlusion
group function
A
- multiple teeth in contact when mandible moves to working side
- bilateral group function frequently seen in toothwear
- any contact more posterior than mesio-buccal cusp of 1st molar is not desirable - increased amount of force placed due to proximity to fulcrum
45
Q
types of dynamic occlusion
protrusion
A
- condyles move forwards and downwards on articular eminence
- only incisors +/- canines touch
- no posterior tooth contacts
46
Q
problems in dynamic occlusion
A
- occlusal interferences - undersirable tooth contacts may produce mandibular deviation during closure to ICP or may hinder smooth passage to and from ICP
- working side contact- working side contact when mandible moves towards working side
- non working side contact - interference on non working side
- protrusive interference - any posterior contact during protrusion
47
Q
dynamic occlusion
why avoid posterior contacts
A
- molar teeth do not like lateral forces
- teeth are designed to absorb heavy forces in the direction of long axis of tooth - not significant lateral forces
- muscles get a rest during canine guidance - can develop TMJ problems etc if posterior contacts
- can cause occlusal trauma and undesirable tooth movements
48
Q
occlusion pathology
A
- bruxism
- toothwear
- occlusal trauma
49
Q
occlusion pathology
bruxism signs and symptoms
A
- toothwear
- fractured restorations
- tooth migration
- tooth mobility
- muscle pain and fatigue
- headache
- earache
- pain and stiffness around TMJ
- hypertrophy of masseter
50
Q
occlusion pathology
toothwear
A
- smith and knight toothwear index to classify
- often just classified as mild/moderate/severe
- often multifactorial
- abrasion
- attrition
- erosion
- abfraction
51
Q
occlusion pathology
occlusal trauma
A
- results in tissue changes within attachment aparatus - PDL, alveolar bone, cementum
- primary - intact periodontium
- secondary - reduced periodontium
- fremitus - palpable or visible movement of a tooth when subjected to occlusal forces
52
Q
examination of occlusion check list
A
- incisor relationship
- guidance - canine or group function
- overjet/overbite
- ICP contacts - tap teeth together on articulating paper
- working/non-working/protrusive contacts
- pathology
53
Q
A
54
Q
A
55
Q
What does this show
A
Group function
56
Q
What does this show
A
Protrusion
57
Q
What does this show
A
Working side contact/interference
58
Q
What does this show
A
Non working side contact/interference
59
Q
overview of mounting casts on articulator
A
- ARCON: articulating condyle on lower member which is anatomically correct as condyle on mandible
- average value and semi-adjustable available
- average value: bennet angle set at 15degrees and condylarguidance angle at 30
- semi adjustable allows you to set bennet and condylar guidance angles
- diagnostic casts are most effective mounted on semi-adjustable: can see full range of mandibular movements for occlusal diagnosis and evaluation
60
Q
function of facebow transfer
A
- to mount maxillary cast onto articulator
and then occlusal registration to mount mandibular cast
61
Q
how to record a facebow registration
A
- mark anterior reference point: 43mm above incisal edge of 12 ideally (using reference plane locator) roughly pos of infraorbital foramen
- bite registration using bite fork
- assemble earbow and transfer jig
- fit measuring bows earpieces tightly into patients ear and tighten centre wheel on bow
- raise or lower bow so pointer aligns precisely with anterior reference point
- once aligned tighten clamps 1 and 2 ensuring bow is parallel to interpupillary line/flooe
62
Q
how to record a facebow registration
bite registration
A
- bite registration paste applied to bite fork
- bite fork arm to the right and locating notch facing up
- firmly seat to record cusps of maxillary teeth and check its parallel to pts coronal and horizontal planes
- align dental midline with locating notch
63
Q
how to record a facebow registration
assembling earbow and transfer jig
A
- loosen centre wheel to allow earbow to open/close
- make sure finger screws 1 and 2 are nice and loose
- numbers 1 and 2 facing towards you and reference pointer to the right of the patient
- attach the vertical shaft to the measuring bow and tighten finger screw on earbow
64
Q
facebow transfew
what have we recorded so far
A
- the relationship of the maxilla to the hinge axis of rotation of the mandible
- we can now mount the maxillary cast in an equivalent relationship on the articulator
65
Q
facebow transfer
mounting the lower cast
A
- interocclusal registration can be used to mount the mandibular cast in relation to maxillary cast (already mounted using facebow transfer)
- two choices of interocclusal registration:
- ICP intercuspal position (conformative approach)
- RCP retruded contact position (reorganised approach)
66
Q
what to use for ICP registration and when
A
- wax or registration paste when ICP not obvious to technicial
- no material when plenty of tooth contacts and ICP is obvious to technician, intercuspal is obvious, multiple tooth contacts when pt bites together
- record block if free end saddles and casts cannot be hand articulated
67
Q
what to use for ICP registration and when
wax
A
- when enough teeth and bite in ICP is obvious you dont need wax
- use when ICP not obvious to technician
- if too much wax used and lower cast is mounted like this - OVD will be increased and restoration will be high in bite when placed
- when using wax ensure it is thin and cusp tips are visible
68
Q
what to use for ICP registration and when
registration paste
A
- when ICP will not be obvious to technician
- silicone paste that sets quickly
- a small amount is needed - too thick and will increase OVD
- occlusal contacts must be visible through material
69
Q
registration position options
A
- ICP registration WITHOUT OVD increase = conformative approach (simple)
- ICP registration WITH OVD increase = reorganised approach (not simple)
- RCP registration with or without OVD increase = reorganised approach (not simple)
70
Q
conformative approach
A
- ICP registration without OVD increase
- provision of restorations in harmony with the existing jaw relationships
- means that the occlusion of the new restoration is provided so occlusal contacts of the other teeth remain unaltered
71
Q
conformative approach difficulty with triposides contacts
A
- tripodised contacts show where when opposing cusps contact
- difficult to reproduce accurately
- if one of the point is heavier or lighter than the other - either teeth move and/or increased risk of unintended CR/CO slide
- introduces some level of instability
- instead should attemp to create flat landing spots for the opposing cusps to contact
72
Q
when do we not use the conformative approach
A
- an increase in vertical height is needed to make space for restorations
- tooth/teeth significantly out of position - overerupted, tilted or rotated etc
- significant change in appearance is wanted
- history of occlusal related failure or fracture of existing restorations
73
Q
reorganised approach
A
- RCP with or without OVD increase/ICP with OVD increase
- not simple - postgrad level
- plan to provide new restorations to a different occlusion
- occlusion is defined before the work is started
- provide restorations which change the occlusion but are well tolerated by the patient
74
Q
why do reorganised approach/RCP registration
A
- ICP is non-existent or no use
- you need space to place restorations
- RCP is reproducible position of the andible independent of the teeth
75
Q
interocclusal record in RCP iverview
A
- pt guided to a terminal hinge closure where initial tooth contact occurs (RCP)
- most reliable techniques: bimanual manipulation and chin point guidance
- RCP record taken at slightly increased OVD just prior to this initial tooth contact - the mandible is rotating about its terminal hinge xis
76
Q
RCP registration material
A
- must use a registration medium
- may use an anterior jig
- wax, paste or record block
- take your registration just before the teeth contact in ICP
77
Q
describe retruded arc of closure
A
- RCP initial tooth contact can occur at any point on the retruded arc of closure
- between R (retruded axis/terminal hinge axis) and RCP
78
Q
RCP to ICP slide
A
- if initial contact is on posterior teeth then there is likely to be a slide from RCP to ICP - as pt tries to achieve maximum intercuspation of teeth
- in 10% pts RCP and ICP are the same
- 90% of patients will slide to achieve maximum intercuspation
RCP usually infero-posterior to ICP by 0.5-2mm
79
Q
guidance options when restoring anterior teeth
A
- copy existing guidance - simple, conformative, most often
- change guidance - not simple, reorganised, less often
- a mutually protected occlusion has canine guidance
- group function can be changed to canine guidance
80
Q
occlusion checklist
A
- TMJ function and MOM activity
- incisor and molar relationships
- open and/or cross bites
- guidance
- wear facets/severity of tooth wear
- restoration #
- occlusal contacts
- deflective contacts
- working/non-working side contacts
- mount casts on average value or semi-adjustable articulator and review all of the above
81
Q
A
