7. Study Models and Occlusion Flashcards
1
Q
Define ‘occlusion’
A
- the way the teeth of the upper and lower jaws meet and move over each other in function
2
Q
Define ‘static occlusion’
A
- a patients occlusion at rest (when not eating)
- patient may be biting together (intercuspal position) or more relaxed with teeth apart (rest position)
3
Q
Define ‘intercuspal position’
A
- position of maximum intercuspation of teeth
- if you close teeth into where bottom and top normally fit together
- clench back teeth this is ICP
- fundamental position in orthodontics and restorative dentistry as to not interfere with normal occlusion with filling etc
4
Q
Define ‘rest position’
A
- teeth are slightly separated by a couple of mm
- teeth usually only in contact for short time each day
- completely relax in seated position and let jaw hang
5
Q
Define ‘normal bite’ as in no crossbite or scissorbite
A
- normally upper arch is wider than lower so palatal cusps of upper posteriors contact central fossa of lowers and buccal cusps of lowers fit into central fossa of uppers
6
Q
Define ‘crossbite’
A
- lower jaw is slightly wider than upper so buccal cusps of upper molars and premolars contact central fossa of lowers and lingual cusps of lowers contact central fossa of uppers
7
Q
Define ‘scissorbite’
A
- upper jaw significantly wider than lower jaw so teeth don’t contact
8
Q
Define ‘functional cusp’
A
- cusp that bites into central fossa of opposing posterior tooth in intercuspal position
- usually palatal cusp of upper teeth and buccal cusp of lowersDefi
9
Q
Define ‘working side’
A
- when jaw moves side to side to chew food
- the side it moves towards is working
- can depend on where the food is moved in chewingDefi
10
Q
Define ‘non-working side’
A
- the side which food is not moved to when you chew
11
Q
Define ‘guidance teeth’
A
- teeth that make contact as patient slides lower jaw to working side and back again
- important for making crowns/bridges because if they’re for guidance teeth they’ll do more work and wear faster
12
Q
Define ‘overjet’
A
- horizontal overlap of upper and lower incisors
- measured in mm with ruler from most prominent tooth
13
Q
Define ‘overbite’
A
- vertical overlap of upper and lower incisors
- measured in mm using ruler or by % coverage of lower incisors as ruler is hard in mouth
14
Q
To assess overbite by % coverage of lower incisors, you …
A
- estimate how much of the height of the lower incisors is covered by uppers
- in ICP
15
Q
Define ‘Class I incisal relationship’
A
- lower incisal edges occlude with or lie immediately below cingulum plateua of upper central incisors
16
Q
Define ‘Class II div 1 incisal relationship’
A
- lower incisor edges lie posterior to cingulum plateau of upper central incisors
- for div 1, upper incsiors are proclined and overjet is generally larger
17
Q
Define ‘Class II div 2 incisal relationship’
A
- lower incisal edges lie posteriorly to the cingulum plateau of upper central incisors
- for div 2, upper incisors are retroclined and overjet is generally minimal/decreased
18
Q
Define ‘Class III incisal relationship’
A
- lower incisor edges lie anterior to cingulum plateua of upper central incisors
- overjet is reduced/reversed
19
Q
Define ‘class I molar relationship’
A
- mesiobuccal cusp of upper 6 occludes buccal groove of lower 6
- upper 6 is in half in groove of lower 6, half behind
20
Q
Define ‘class II molar relationship’
A
- upper 6 is a full tooth in front of Class I
- half upper 6 in groove of lower 6 and half is in front
21
Q
Define ‘class III molar relationship’
A
- upper 6 is a full tooth distal to lower 6 and Class I
- here if canines were also Class III, they would be behind the lower 4s
22
Q
If a tooth was in between classes, how are they referred?
Use 2 1/4 for example
A
- use fractions to refer to difference from type 1
- if a tooth was 1/4 of a tooth width away from being class 1 but was moving towards a 2 position, it would be 1/4 unit of Class II
