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
posselts envelope
describe R
* retruded axis position
* no tooth contacts
* mostly superior poesterior position of condylar head in the fossa
* terminal hinge axis
26
posselts envelope
describe RCP
* 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
ICP-RCP slide
* mandible slides forward to achieve ICP
* ICP is approx 1mm aterior to RCP in 90% of population
28
describe lateral translation
* 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
bennet angle
* angle formed by saggital plane and the path of the mandibular condyle
* during lateral movement when viewed in a horizontal plane
30
describe this diagram
* 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
32
33
examining the occlusion
2 types
* dynamic occlusion
* static occlusion
34
how to examine occlusion
* fine articulating paper
* millers forceps to hold paper
* ideally two articulating paper records - one for dynamic contacts and one for static
35
when to mark tooth contacts
* before preparing a tooth or removing a restoration
* after placement of a crown or placement of a restoration
36
tripodised contacts
* 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
what does static occlusion measure
* incisor relationship
* molar relationship
* overjet/overbite
* cross bites
* open bites
* individual tooth contacts
* RCP
38
static occlusion ICP contacts
functional cusps
* cusps that occlude with the opposing teeth in the intercuspal position
* lingual cusps of upper posterior teeth
* buccal cusps of lower posterior teeth
39
static occlusion ICP contacts
non functional cusps
* cusps that do not occlude with the opposing teeth in ICP
* buccal cusp of upper posterior teeth
* lingual cusps of lower posterior teeth
40
static occlusion ICP contacts
fossa and contact points
* 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
problems in static occlusion
* 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
types of dynamic occlusion
* canine guidance
* group function
* protrusion
43
types of dynamic occlusion
canine guidance
* 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
types of dynamic occlusion
group function
* 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
types of dynamic occlusion
protrusion
* condyles move forwards and downwards on articular eminence
* only incisors +/- canines touch
* no posterior tooth contacts
46
problems in dynamic occlusion
* 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
dynamic occlusion
why avoid posterior contacts
* 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
occlusion pathology
* bruxism
* toothwear
* occlusal trauma
49
occlusion pathology
bruxism signs and symptoms
* toothwear
* fractured restorations
* tooth migration
* tooth mobility
* muscle pain and fatigue
* headache
* earache
* pain and stiffness around TMJ
* hypertrophy of masseter
50
occlusion pathology
toothwear
* smith and knight toothwear index to classify
* often just classified as mild/moderate/severe
* often multifactorial
* abrasion
* attrition
* erosion
* abfraction
51
occlusion pathology
occlusal trauma
* 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
examination of occlusion check list
* incisor relationship
* guidance - canine or group function
* overjet/overbite
* ICP contacts - tap teeth together on articulating paper
* working/non-working/protrusive contacts
* pathology
53
54
55
What does this show
Group function
56
What does this show
Protrusion
57
What does this show
Working side contact/interference
58
What does this show
Non working side contact/interference
59
overview of mounting casts on articulator
* 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
function of facebow transfer
* to mount maxillary cast onto articulator
and then occlusal registration to mount mandibular cast
61
how to record a facebow registration
1. mark anterior reference point: 43mm above incisal edge of 12 ideally (using reference plane locator) roughly pos of infraorbital foramen
2. bite registration using bite fork
3. assemble earbow and transfer jig
4. fit measuring bows earpieces tightly into patients ear and tighten centre wheel on bow
5. raise or lower bow so pointer aligns precisely with anterior reference point
6. once aligned tighten clamps 1 and 2 ensuring bow is parallel to interpupillary line/flooe
62
how to record a facebow registration
bite registration
* 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
how to record a facebow registration
assembling earbow and transfer jig
* 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
facebow transfew
what have we recorded so far
* 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
facebow transfer
mounting the lower cast
* 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
what to use for ICP registration and when
* 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
what to use for ICP registration and when
wax
* 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
what to use for ICP registration and when
registration paste
* 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
registration position options
* 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
conformative approach
* 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
conformative approach difficulty with triposides contacts
* 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
when do we not use the conformative approach
* 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
reorganised approach
* 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
why do reorganised approach/RCP registration
* 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
interocclusal record in RCP iverview
* 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
RCP registration material
* 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
describe retruded arc of closure
* 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
RCP to ICP slide
* 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
guidance options when restoring anterior teeth
* 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
occlusion checklist
* 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
