Tooth Wear and Occlusion Flashcards
what makes up the articulatory system
temperomandibular joint
occlusion
muscles of mastication
what is the masticatory system
the articulatory system
describe the design of occlusal surfaces
intricately designed to fit together in occlusion
crucial for effective mastication and proper alignment of the teeth
which cusp has a tuburcle of carabeli in 60% of people
the mesio palatal on upper sixes
describe the occlusion of first molars
upper mesio palatal cusp fits in the central fossa on the lower
what are the most important cusps in relation to occlusion
lower buccal and upper palatal
why is it important that there is precise alignment of cusp tips, ridges and slopes between opposing teeth
to ensure efficient mastication and prevent the undue stress on individual teeth
this alignment plays a crucial role in maintaining the integrity of the articulatory system
which features of occlusal surfaces are the most important in relation to stable occlusion
cusp tips
ridges
slopes
what must be considered when studying occlusion
the close interrelationship between the articulation of the teeth and the muscles of mastication and the temperomandibular joint
what does occlusion mean
how the teeth fit together
what is static occlusion
how the teeth fit together when biting
what is dynamic occlusion
how the teeth fit together when sliding the mandible from side to side
what is jaw function
chewing
what is jaw parafunction
when we clench and grind teeth
what are the other terms to refer to dynamic occlusion
lateral or protrusive movements
eccentric movements
what is jaw protrusion
moving it forward - part of dynamic occlusion
what are the other terms to refer to static occlusion
centric occlusion
habitual bite
maximum intercuspation
intercuspal position
what are mandibulare eccentric movements
the sideways movement of the mandible from a centric position
what is canine guidance
this is when we try to move our jaw from side to side and the only tooth contact area is between canines
what is group function when sliding the mandible
when the canines touch as well as some of the posterior teeth
how do we mark the occlusal contacts
use of articulating papers
describe articulating papers
ink paper in different colours and thicknesses (the thinner the better).
held using miller forceps
ask patient to tap their teeth for static occlusion or slide them for dynamic
leaves dots or lines on the teeth to show where they occlude
what are miller forceps used for
securing the entire length of the articulating papers
why are there different colours of articulating papers
to identify specific tooth contacts and allow comparisons to be made
why do we use miller forceps rather than just holding articulating paper
the paper will crumple and we will not get the occlusal contact of the most posterior tooth if we just hold it
what is the most common holder for articulating paper
millers forceps
describe bite check articulating film
has a disposable holder, allows for no risk of biting the holder, handle holds the film flat so there is no curling
thin film to mark the high points accurately
available in double sided
why do we prefer thin articulating paper over thick
using thin paper minimises contact artefacts and clearly indicates tooth contact and details
why should teeth be dried
to allow articulating papers to mark the teeth
what is the ideal intercuspal position contact
small and discrete
what does it mean if there are broad ICP contacts
there are underlying occlusal problems
what are wear facets
type of non carious lesion that occurs when teeth rub against each other too much
how do patients interact with articulating paper for dynamic occlusion
slide on the paper
how do patients interact with articulating paper for static occlusion
tap the paper
what is a fish eye from articulating paper
this is where the colour has been squeezed out, and indicates a high contact point
this will need to be adjusted as it can cause fracturing
why are high contact points risky in restorations
can fracture the restorations as they are weaker
what is indicated by this picture
heavy occlusal pressure concentrated on the lingual inclinations and lingual cusps
these premature contact areas can lead to cracks in the teeth due to excessive forces on the cusps of the tooth
sensitivity can be due to large contact areas that create pressure on the cusp, leading to a crack.
what are the supporting cusps in occlusal stability (posterior teeth)
mandibular buccal and maxillary palatal
what are the non supporting cusps in stable posterior occlusion
mandibular lingual and maxillary buccal
what is an important note when referencing stable occlusion
cusp must be on a fossa or marginal ridge
if there is a cusp incilne, then it is not stable
cannot have the cusp on the incline
what is tripodisation
this is when the reciprocal incline contacts the antagonist.
there are three points of contact around the cusp
what is the proper definition for receprical incline contacts
each centric cusp contacting an opposing fossa has three reciprocating contact areas
what happens if there is no occlusal contact
the antagonist will over erupt and move to try and find contact
this is fine for stable occlusion but it causes interference in dynamic occlusion
is a single contact point bad
yes, because it allows unwanted tilting and overeruption
what happens if a restoration is overcarved
lack of contact with the antagonist, after a time it will shift to make a more stable occlusal position to reestablish contact
ICP is now stable, mediotrusive contact is interfered with
why is it important to avoid occlusal contacts on tooth restorative interfaces
dental restorative materals, while durable, may not withstand the full force of occlusion over time as well as natural tooth enamel.
excessive pressure can lead to materal fracture or debonding
restorative material is not as strong as enamel
describe T scans
a digital tool used to analyse occlusal forces
provides detailed understanding of the patients bite and how their teeth come together
thin, 60 micron pressure sensor.
usually plots more contact points than usual due to digital artefacts
how do t scans show occlusion
showing how much pressure is exerted in each point of contact
why are flat restorations bad
no contact between the restoration and the antagonist, leading to overeruption of anatagonist tooth and inferene in mesioprotrusion
what is infra occlusion
tooth is out of occlusion
what is shimstock foil used for
checking the firmness of the occlusal contacts in comparison with those on the selected index teeth
no ink, just checks how firm the occlusion is
how does the shimstock check the occlusal contacts
if it pulls out, there is no contact. if it stays, there is
what is shimstock
a metal foil used for occlusal testing
what is the thickness of shimstock
8 microns
describe shimstock foil use in crown preparation
when you fit a crown, both restoration and adjacent teeth should hold shimstock firmly in ICP
describe the shimstock contacts of anterior teeth
light
how to test if crown occlusion is stable
shimstock holds when crowns are not in the mouth and when the crowns are in the mouth
what are the dots on articulation
static occlusion
what are the lines on articulation
dynamic occlusion
describe canine guidance
lower canines guide the mandible during lateral excursions of the jaw
this means the jaw moves to the side, and the contact between the upper and lower canines prevents the posterior teeth from touching
what is posterior teeth disclusion
they are not touching
what is group function occlusion
multiple contact relations between the maxillary and mandibular teeth in lateral movements (including canines)
when is occlusion important
reduce the risk of fracture, wear and failure of the tooth and restoration
describe the link between mechanoreceptors and occlusion
mechoreceptors can detect half the thickness of a human hair, and this should not be disturbed as it is very sensitive.
another reason is to ensure there is correct occlusion
why is amalgam being phased out
bad for the environment (not bad for the patient)
describe ceramic inlays
made in the lab and then cemented on to the patient. it needs to fit the same occlusion or the tooth can fracture
what is bruxism
tooth grinding and clenching - can fracture restorations if they have poor occlusion conformation
what is the conformative approach to restorative dentistry
consideration of the occlusal scheme is made according to the patients existing intercuspal position
new restorations are provided in harmony with the existing jaw relationships
why are dental loupes useful to have
facilitates the removal of excess and reduce the risk of damage to marginal enamel
what should the head tilt angle be for the ergonomic working posture
less than 25 degrees
what are condys
joints that rotate when we move the mandible from side to side
