Occlusion Flashcards
what is the main cause of TMJ disease pain?
the retrodiscal colateral tissue which is highly vascular and innervated moves too far anteriorly and becomes wedged between the bone and the head of the condyle
what does the Retrodiscal colateral Tissue attach to?
the mandibualr fossa
what muscles are involved in mandibular movements?
Muscles of mastication: temporalis, masseter, lateral & medial pterygoid
Suprahyoid: digastric, geniohyoid, mylohyoid, stylohyoid
what is the function of the temporalis?
retracts and elevates
what is the function of the masseter?
elevates and protracts
what is the function of the medial pterygoid?
elevates, protracts and lateral movement
what is the function of the lateral pterygoid?
depresses, protracts and lateral movement
describe the resting vertical dimension. (2)
mouth slightly open
teeth not in contact - freeway space between
name the types of mandibular movement. (3)
rotation/hinge
translation
lateral translation
how much opening is there in hinge/rotation movements?
20mm - fairly passive
describe translation movements. (3)
Lateral pterygoid contracts and pulls the condyl and articular disc anteriorly
The condyle moves downwards and forwards along the articular eminence
The condyl can also move laterally
name the 3 planes of border movements.
sagittal
horizontal
frontal
describe the ICP stage on posselts envelope. (2)
Tooth positon regardless of condylar position
The maximum interdigitation of the teeth which is comfortable
in what position/stage of poselts envelope are most restoration made in unless the occlusion is reorganised?
ICP
name and describe the E stage on posselts envelope. (3)
edge to edge
Translational movement which Refers to tooth position.
When teeth slide forward from ICP guided by the palatal surface of anterior teeth the incised edges of the upper and lowers will touch and the posterior teeth will either be apart or occluded depending on the type of guidance they have
(E stage)
what type of guidance will a patient have if when teeth slide forward from ICP the incised edges of the upper and lowers will touch and the posterior teeth have space between them?
anterior guidance
(E stage)
what type of guidance will a patient have if when teeth slide forward from ICP the incised edges of the upper and lowers will touch and the posterior teeth occlude?
group function
name and describe the Pr stage on posselts envelope. (4)
protrusion
At this stage the condyl has moved forwards and downwards on the articular eminence
Initially only the incisors and canines will touch
Eventually no teeth will contact
(Pr stage) what is occuring if posteriors touch at this point?
protrusive interference
name and describe the T stage on posselts envelope. (3)
maximum opening
Full translation of the condyle over the AE = mouth wide open
No tooth contacts
name and describe the R stage on posselts envelope.
retruded axis position
This is the most superior anterior position of the condylar head in the fossa
No tooth in contact
name and describe the RCP stage on posselts envelope.
Retruded contact position
The first tooth contact when the mandible is leaving the retruded axis position
Retruded axis position - the most superior anterior position of the condylar head in the fossa
describe the relationship between the ICP and the RCP.
ICP is approx 1mm anterior to the RCP (90% of patients)
what are lateral translation movements also known as?
Bennet movement
describe the bennet movements.
refers to a working side and a non-working side (working side is whichever side the mandible moves to)
what are bennet movements controlled by?
contraction of 1 of the lateral pterygoid muscles
describe the movements of the condyl on the non-working side during bennet movements.
the condyle moves forwards and inwards
describe a working side contact. is this desirable?
tooth contact on the working side in the lateral excursion poison
no its occlusal interference
describe a non-working side contact. is this desirable?
If you had a tooth contact on the non-working side in the lateral excursion poison
no its occlusal interference
define the bennet angle.
The path of the non-working condyle in the horizontal plane during lateral excursion
name the 2 types of occlusion.
Dynamic
Static
how thick is articulating paper?
40 microns
why do we use 2 different colours of articulating paper?
1 to mark static occ
1 to mark dynamic occ
describe how we mark static ICP occlusion.
Dry teeth and tap teeth together on the paper
describe how we mark dynamic occlusion.
Move mandible from side to side and forward whilst biting on the paper
when should we mark tooth contacts?
before altering anything;
i.e. tooth prep or restoration removal
after placing anything i.e. crown or restoration
name the types of tooth contacts we want to achieve. (2)
Tripodised = very difficult to achieve
Cusp tip to fossa = more commonly used
name the part of the tooth that is in contact when in ICP? (1)
Functional cusps - occlude with the opposing fossa
maxilla = palatal
Mandible = buccal
where are the functional cusps in ICP in the mandible and maxilla?
mandible = buccal maxilla = palatal
what problems can we detect in static ICP occlusion? (5)
Incisor relationships
overbite
overjet
crossbite
openbite - anterior or posterior
what are we examining in dynamic occlusion?
guidance; canine or group
protrusion
describe canine guidance.
mutally protected occlusion with only the canines in contact with a freeway space between the other teeth.
no protrusive interference
describe the contacts in protrusion.
Only the incisors and canines tough, no posterior contacts
what problems can we detect in dynamic occlusion? (1)
occlusal interferences - may produce mandibular deviation
name the types of occlusal interferences.
Working side: the interference is usually posterior in the direction of travel of the mandible
Non-working side: the interference is on the posterior on the opposite side from the movement
Protrusive: any posterior contact during protrusion
Why should we avoid posterior contacts/interferences? (2)
Teeth are NOT designed to absorb lateral forces
(normal = down the long axis)
muscles are always active, no rest = painful, enlarged muscles, TMJ problems
what pathology can arise from poor occlusion/occlusal movements? (3)
bruxism
tooth wear
occlusal trauma
name the two types of bruxism.
eccentric
centric
describe eccentric bruxism - what can this cause?
Parafunctional movements of the mandible from side to side which cause occlusal trauma
Involuntary, rhythmic, spasmodic or function gnashing
describe centric bruxism. - what is this associated with?
Parafunctional clenching (pressing and clamping) of the teeth and jaws.
Associated with nervous tension and physical effort
what are the clinical signs of bruxism? (8)
Toothwear - lose the anatomy of the teeth
Tooth mobility and widened PDL from occlusal trauma (not perio)
Fractured restorations
Pain and stiffness of the TMJ and muscles
Tooth migration
Headache
Earache
name the types of tooth wear.
Abrasion
Attrition
Erosion
Abfraction
describe occlusal trauma.
Injury resulting in tissue changes within the attachment apparatus i.e. the perio ligament, alveolar bone, cementum, as a result of occlusal force
name and describe the types of occlusal trauma that occur in a healthy periodontium. (2)
Primary:
When there is trauma and movement of an intact periodontium with no periodontitis (no inflammation and loss of attachment)
Secondary:
When there is trauma and movement of a reduced but healthy peridontium (no inflammation and loss of attachment)
define fremitus.
Fremitus is when there is palpable/visible movement of a tooth subjected to occlusal forces
how can we assess movement of teeth only?
Place your index finger on the tooth i.e. the central and ask the patient to tap their teeth together
when assessing occlusion what should we examine? (6)
Incisor relationship Guidance Overjet/bite ICP contacts Occlusal interference- Working/non-working/protrusive contacts Pathology
what must we do before recording the occlusion?
mount the casts on an average value articulator.
what is the bennet angle and the condylar guidance set to on an average value articulator?
BA = 15
C guidance = 30
what do we need to take before mounting a maxillary cast?
Facebow transfer
what do we need to take before mounting the mandibular cast?
take an Interocclusal registration
describe how to take a facebow registration.
Assemble the face vow on the patient by sliding the bite fork arm through the clamp marked #2
Fit the earpieces into the ears
Tighten the centre wheel
Raise or lower the bow so that the pointer aligns with the anterior reference point
Once aligned, tighten the #1 and #2 clamps
Once face bow is in place;
Ensure that the bow is parallel to the inter pupillary line/floor
Loosen the finger screw on the measuring bow, slide open the bow and remove the face bow from the patient
Detach the measuring bow from the transfer jig by loosening the finger score
Disinfect the apparatus
when do we use an ICP interocclusal registration?
conformative approaches
when do we use an RCP interocclusal registration?
use when taking a reorganised approach
what ways can we take an interocclusal registration in ICP? (4)
Recording ICP with no material
Recording ICP with wax wafer
Recording ICP with registration paste
Recording ICP using a record block
When would we take an interocclusal registration in ICP using no material?
ICP is obvious and many teeth are in contact
When would we take an interocclusal registration in ICP using a registration paste?
used when the ICP is not obvious
When would we take an interocclusal registration in ICP using a record block?
used when there’s a free end saddle and cannot hand articulate
what happens if we use too much wax/registration paste when taking an interocclusal registration in ICP?
Increases OVD and restorations will be too high.
define the conformative approach.
the provision of restorations in harmony with the existing jaw relationships
when can we not use the conformative approach? (4)
(When do we not place restorations in ICP)
When an increase In vertical height is required to make space for restorations
When a tooth/teeth are significantly out of position i.e. over erupted, tilted, rotated
A significant change in appearance is wanted
There is a history of occlsually related failure or fracture of existing restorations: multiple fractures seen.
