occlusion Flashcards
3 parts that make up the articulatory/masticatory system
temporomandibular joints, occlusion, muscles of mastication
What are the 3 parts of a cusp?
ridge, cusp tip, slope
Where does the word ‘occlusion’ come from?
occludere is Latin for ‘to close up’
What is the static occlusion?
The occlusion the patient makes when they fit teeth together
How would you ask the patient to show their static occlusion?
swallow and keep teeth together
Other terms for static occlusion
centric occlusion (CO), habitual bite, maximum intercuspation (MIP), intercuspal position (ICP)
What is dynamic occlusion?
the sideways movement of the mandible from a centric position
Other terms for dynamic occlusion
mandibular eccentric movements, lateral excursion
How can occlusal contacts be marked?
articulating paper
How is articulating paper held in the patient’s mouth?
Miller forceps (securely and smoothly grip entire length of paper)
Why are 2 colours of articulating paper used?
To identify occlusal contacts in static and dynamic occlusion
Alternative methods of holding articulating paper that Miller forceps?
Y-type articulating paper holder, fix-clip bite frame (autoclavable)
Disposable equipment that can be used to mark occlusal contacts without needing forceps
bite-check articulating film from microscopy
How can contact artefacts be created?
when thick articulating paper is used (200u) or when teeth are wet
Why should thin articulating paper be used?
minimise contact artefacts and clearly indicate only the small points of true contact
How thin should articulating paper be?
40u
When is it acceptable to use thick articulating paper (200u)?
for dentures
How can teeth be dried before using articulating paper?
using 3-in-1, cotton rolls (must be removed to avoid risk of inhalation)
What can broad and rubbing ICP contacts be associated with?
Occlusal problems such as tooth wear, attrition. (first must exclude it is an artefact)
Appearance of heavy/high contacts with articulating paper
more colour is squeezed out (greatest masticatory pressure)
Term used to describe non-carious lesions that result form attrition
wear facets
Why do heavy contacts (premature contacts) need to be resolved?
Could lead to a fracture, or sensitivity
Which are the supporting cusps to occlusal stability?
Mandibular buccal cusps and maxillary palatal cusps
Which are the non-supporting cusps?
Mandibular lingual cusps and maxillary buccal cusps
What is stable occlusion?
Cusp tips lie in opposing fossa / marginal ridge or tripodization around the fossa
What is tripodization?
3 reciprocal incline contacts (3 points around fossa) which is even better for stabilisation
Which areas of the tooth should occlusal contacts be avoided?
On restored surface and on the border between enamel and restoration
Name of a digital tool used to analyse occlusal forces in place of articulating paper
T scan
Advantage of T scan
shows how much pressure is exerted in each point of contact (red=heavier contact)
Disadvantage of T scan
expensive and 60u thick (not as thin as 40u articulating paper)
What is an infra-occluded restoration?
When the tooth has been grinded down to avoid occluding with opposing tooth
What is the harm with infra-occluded restorations?
the tooth will over erupt to create an instable occlusion
Function of Shimstock foil
a metal foil used to check firmness of occlusal contacts in comparison to how it was before the restoration (e.g. on index teeth - moulds)
Thickness of Shimstock foil
8 microns (u)
How can shimstock foil be used to check a restoration?
Shimstock should be firmly held in place in ICP by both the restoration and adjacent teeth. Shimstock should hold the same with and without the restoration.
What are the shimstock contacts like for anterior teeth?
light contacts - should be kept after restoration
What would you ask the patient to do to check their dynamic occlusion?
Slide their jaw from side to side
Which teeth guide the mandible during lateral excursions of the jaw?
lower canines
What happens in terms of occlusion during dynamic occlusion?
upper and lower canines are in contact which results in posterior teeth disocclusion.
Term used to describe multiple contact relations between maxillary and mandibular teeth (inc canines) in lateral movements
group function
Down to how thin can materials be for the periodontal ligament to detect?
half the thickness of human hair
What is the conformative approach?
restoring the occlusion in harmony with the existing ICP (mark occlusal contacts before and after)
During lateral mandibular movement, which condyle is the working side?
The side the mandible moves towards is the working side.
Name of the angle formed between the sagittal plane and the path of the mandibular condyle during lateral movement
Bennett angle
In which condyle is the Bennett angle formed?
non-working side
How is Shimstock used by the dentist and technician to check the articulator has the same bite as the patient?
To ensure each pairs of teeth (e.g. 17 and 47) have the correct occlusion. Shimstock will hold/pull through for the same pairs of teeth.
