PRS02 - Lecture 6 - Occlusion Flashcards
What is the TMJ?
Articulation between the condyle (mandible) and the squamous portion of temporal bone
What is 2 movements of the TMJ (function)?
Rotation - lower joint compartment
Sliding - upper joint compartment (articular disk sits ontop of condyle)
What are the 4 muscles of mastication?
Masseter
Temporal
Medial pterygoid
Lateral pterygoid
What are the 2 classifications of occlusion?
Static
Dynamic
What are the 4 classifications of static occlusion?
Class I - Accepted ideal relationship
Mesiobuccal cusp of U6 lies in the buccal groove of L6
U3 lies distal to the L3
Lower incisaledge lies on or below the cingulum plateau of the palatal surface of upper incisors
Class II division I
Mesiobuccal cusp of U6 lies mesial to the buccal groove of L6
U3 lies mesial to L3
Lower incisal edges are palatal to cingulum plateau of the palatal surface of upper incisors
Upper incisiors are proclined or of average inclination (with increased overjet)
Class II division II
”
Upper incisors (and usually lowers) are retroclined - with minimal overjet (although it maybe increased)
Class III
Mesiobuccal cusp of the U6 lies distal to the buccal groove of the L6
U3 lies distal to the contact point between the L3 and L4
Lower incisal edge meet anterior to the cingulum plateua of the palatal surface of upper incisors
Define the term “overjet” (3)
Horizontal distance between the upper and lower incisors in occlusion
Measured at the tip of the upper incisors
Most people its a positive overjet (but it can be edge to edge or reversed)
Define the term “overbite” (3)
Vertical distance between the tips of upper and lower incisors in occlusion
Ideally - the lower incisors contact the middle third of the upper incisors
However - there maybe excessive overbite, ncomplete overbite, anterior open bite
What type of curve is indicated in the picture?
Curve of Monson (Wilson)
What type of curve is indicated in the picture?
Curve of Spee
What are the 2 dyanmic relationships?
Intercuspal position (ICP) - position of maximum intercuspation of teeth -> not necssarily reproducable
Retruded contact position - most retruded position of the mandible when the teeth are together -> reproducible
What are the 4 directions in which the mandible can move from ICP?
Retrusive - backward movement -> RCP
Protrusive - forward movement (guided by incisors)
Left lateral
RIght lateral
Define working and non-working sides during left and right lateral (2)
Working side - side towards which the mandible moves
Non-working side - opposite side towards which the mandible moves
What is occlusal interference?
Contact between teeth in one of the movements of the mandible that free slding movement of the mandible is interupted
What is occlusal harmony? (2)
Absence of occlusal interference
Allows free movement of teeth in all movements/excursions without damage to resotrations or teeth
What is occlusal vertical dimension (OVD)? (1)
Relationship between the mandible and maxilla with teeth in ICP
