occlusion 2 Flashcards
2 states for examining the occlusion
- dynamic
- static
tools used to mark teeth contacts
- Millers forceps
- fine articulating paper - 40microns
- deally 2 colours – 1 to mark static ICP and 1 dynamic in excursive positions
how to record how teeth meet in occlusion
Dry teeth
place in articulating paper held by Millers forceps
tap together for ICP or move side to side for lateral excursive/forward for protrusion
4 times to mark teeth contacts
- Before
- Preparing a tooth
- Removing a restoration
- After
- Placement of a crown
- Placement of a restoration
why do you mark contacts before you change anything
If the occlusal scheme is good….
- stick to it (conform)
- These are called tripodised contacts and show where the opposing cusps contact (ICP stops)*
- hard to achieve
- more commonly – cusp tip to fossa*
4 components of ICP contacts (static occlusion)
- functional cusps
- non-functional cusps
- fossa
- ICP contacts
functional cusps in ICP contacts (static occlusion)
- Cusps that occlude with the opposing teeth in the intercuspal position
- The palatal cusps of the upper posterior teeth and the buccal cusps of the lower posterior teeth
non functional cusps in ICP contacts (static occlusion)
- Cusps that do not occlude with the opposing teeth in the intercuspal position
- The buccal cusps of the upper posterior teeth and the lingual cusps of the lower posterior teeth
fossa in ICP contacts (static occlusion)
- Depression or concavity on tooth surface
- Functional cusp of a tooth contacts the fossa of the opposing tooth
ICP contacts in static occlusion
- The lingual cusp of an upper molar contacts the fossa of a lower molar
- The buccal cusp of a lower molar contacts the fossa of an upper molar
tap for ICP contacts in static occlusion
- Dry first
way to remember function and non functional cusps
Functional cusps
- Palatal upper
- Buccal lower
Non-functional cusps
- Buccal Upper
- Lingual Lower
buccal cusps occlude….
palatal cusps occlude..
buccal cusps occluding with upper fossa
palatal cusps occluding with lower fossa
maxillary tooth looks more buccally placed than mandibular tooth
problems in static
- Incisor Relationship
- Molar relationship
- Overjet/Overbite
- Cross bites
- Open bites
- Individual tooth contacts
- RCP – ICP slide (freedom in centric)
incisor relationship classified by
angle’s
overbite
Vertical overlap of the incisors
2-4mm normal range
Akerly classification
Ackerly classification for overbite
I
- lower incisors impinge on palatal mucosa
- inflammation of palatal mucosa with the imprine of lower incisal edges
II
- lower incisors incisal edge occlude into palatal gingival crevices of maxillary teeth
- labial splaying of maxillary incisors
- palatal pocket
III
- class II div2 type of incisor relationship
- stripping of the gingiva in relation to palatal surfaces of upper anterior teeth and labial surfaces lower anterior teeth
IV
- lower incisor causing progressive abrasion of palatal surfaces of maxillary teeth
- abrasion of palatal surfaces of upper anterior teeth
- dentine hypersensitivity
overjet
Relationship between the upper and lower teeth in a horizontal plane
crossbite
- condition where one or more teeth may be abnormally malpositioned buccal or lingually or labially with reference to opposing teeth
- posterior
- anterior
anterior open bite
- Lack of vertical overlap of anterior teeth when posterior teeth in full occlusion
- Often due to digit sucking
- Here 3-3
posterior/lateral open bite
- Failure of contact between the posterior teeth when the teeth are in full occlusion
- here From 16-12
why 2 colours articulating paper
Better to use a different colour articulating paper to show canine guidance/dynamic from static
canine guidance
Dynamic
- Mandible moves to the left (working side)
- Contact only between the canines
- No posterior tooth contacts (a space – freeway space)
- This is what’s known as a mutually protected occlusion
Canine roots are strong – adapted to withstand lateral forces
Unlike molar teeth – up and down and grinding cusp action
tooth wear case design for wax up
- ideal
canine guidance
GOLD standard
mutually protected occlusion
gold standard
- Canine guidance
- Posterior disclusion in lateral excursions
- No non-working/working side contacts
- No protrusive interferences
- Teeth slide edge-edge, no posterior contacts too
group function
- Mandible moves to the left (working side), multiple teeth in contact on the left
- many lines marked from paper - not just canine
- Bilateral group function frequently seen in toothwear, aging pts
protrusion
Condyle moves forwards and downwards on articular eminence
- Only incisors +/- canines touch
- No posterior tooth contacts – undesirable deflective contacts
problems in dynamic
Occlusal Interferences
- Undesirable tooth contacts that may produce mandibular deviation during closure to ICP or may hinder smooth passage to and from ICP (Schillingberg 1997)
3 types of occlusal interference
- working side
- non-working side
- protrusive
working side contact
occlusal interference
Should just see line of canine guidance and nothing else posteriorly
-
Line of upper left 7 indicates a posterior contact that is not wanted
- similar cusps contacting
non-working side contact
occlusal interference
Mandible moving to right so see blue line on right canine – only marking on that side
-
Ideally want no lines at all on opposing side
-
But upper left 6 has a line
- not desirable
-
But upper left 6 has a line
protrusive interference
“any posterior contact during protrusion”
- As condyle moves downwards and forwards over articular eminence get teeth sliding into edge-edge*
- Should be space posteriorly – no contacts
why avoid posterior contacts
- Teeth are designed to absorb heavy forces in the direction of the long axis of the tooth
- Lateral forces to molar teeth – not designed to withstand
- Most teeth are not designed to absorb significant lateral forces generated by occlusal interferences
- Musculature gets a rest as less activity if not undesirable posterior contacts
- Tired, pain, uncomfortable, enlarged, TMJ problems
- Occlusal trauma and undesirable tooth movements
- E.g. fremitus
pathologies due to occlusion (3)
- bruxism
- toothwear
- occlusal trauma
2 types of bruxism
- Eccentric side to side
- Centric
centric bruxism
Clenching: The pressing and clamping of the jaws and teeth together. Frequently associated with acute nervous tension or physical effort
eccentric bruxism
side to side
- The parafunctional grinding of teeth
- An oral habit consisting of involuntary rhythmic or spasmodic or functional gnashing, grinding or clenching of teeth in other than chewing movements of the mandible which may lead to occlusal trauma
issue of bruxism
added strain on joint, muscles and teeth
clinical signs and symptoms of bruxism
- Toothwear
- shortened crowns, lose anatomy
- Fractured restorations
- Tooth migration
- Tooth mobility (Often in absence of periodontal disease)
- Muscle pain and fatigue
- Headache
- Earache
- Pain and stiffness in the TMJ and surrounding muscles
tooth wear types (4)
- abrasion
- attrition
- erosion
- abfraction
multifactorial
often just classified as mild/moderate/severe (but keys exist - Smith and Knight)
tooth wear index - smith and knight
0
- no loss of enamel surface characteristics
1
- loss of enamel surface characteristics
2
- buccal, lkngual and occlusal loss of enamel, exposing dentine for less than 1/3 surface
- incisal loss of enamel
- minimal dentine exposure
3
- buccal, lingual and occlusal loss of enamel, exposing dentine for more than 1/3 of surface
- incisal loss of enamel
- substantial loss of dentine
4
- buccal, lingual and occlusal complete loss of enamel, pulp exposure or exposure of sencondary dentine
- incisal pulp exposure or exposure of secondary dentine
occlusal trauma
Could be due to undesirable posterior contacts
-
lateral forces on teeth
- Cause system to be disjointed/annoyed -> tooth movement
Injury resulting in tissue changes within the attachment apparatus, including periodontal ligament, supporting alveolar bone and cementum, as a result of occlusal force(s)
- Primary
- intact periodontium
- Secondary
- reduced periodontium
Fremitus
- palpable or visible movement of a tooth when subjected to occlusal forces
fremitus
palpable or visible movement of a tooth when subjected to occlusal forces
examination checklist for occlusion
- Incisor relationship
- Guidance
- Overjet/overbite
- ICP contacts
- Working/non-working/Protrusive contacts
- Pathology – tooth wear
