OCCLUSION stuff Flashcards
defn of occlusion
static closed relationship of the cusps or masticatory surfaces of upper and lower teeth
defn of articulation
describes the dynamic sliding contact of upper and lower teeth that takes place during closed grinding movements of the mandible
continuous change from one occlusal position to the next
dfn of OVD and how do we get it
OVD = the amount of separation between maxilla and mandible when the teeth are fully intercuspated ie (MI)
established by:
- natural teeth when there are sufficient tooth contacts determining OVD
- when no contacts present, OVD must be estimated by using RVD - FWS
What is the significance of the S sound
is the closest speaking space and the record blocks should be slightly apart (approx 1mm)
significance of B and M sounds
lips should touch
- if OVD is excessive, will oberve lip strain during these sounds
defn of rvd
the amount of separation between maxilla and mandible when the mandible is in the physiologic rest position
habitual postural position of the mandible when the patient is resting comfortably in the upright position with the condyles in a neutral unstrained position in the glenoid fossa
what is the RVD established by and what factors influence it
established by:
- muscles: balance between elevators (temporalis, masseter, medial pterygoid) and depressors (anterior digastric)
- gravity
short term factors
- head posture (decrease when head tilts forward)
- body position (decrease with supine position due to decreased effect of gravity)
- presence of prosthesis (increase w denture wearing)
- presence of teeth
- stress
long term factors
- age (increases with age due to alveolar growth, lengthening of lower third of face)
- parafunction eg bruxing
defn of CR
a maxillomandibular relationship in which the condyles articulate with the thinnest avascular portion of their respective discs with the complex in the antero superior position against the slopes of the AE
- REPRODUCIBLE
effects of wrong CR
1) poor retention
- denture becomes loose after occlusal contact
- upper denture will become loose bc mucus milked from palatal glands by antero posterior rocking of denture caused by heavy occlusal contact anteriorly
2) unstable dentures
- sliding on ridge
- retching only on occlusion but not at other times because movement of dentures trap mucus at posterior edge or irritates mucosa in postdam area
3) same effect as increased OVD
- trauma to tissues causing pain
- speech problem since speaking space is absent
- clicking while speaking
- TMD
purpose of enamel mod
- provide rest seat
- establish guide surface
- correct discrepancies in occlusal plane
- modify unfavourable survey lines
- create retentive areas
