Oral Biology: Occlusion Flashcards
What is occlusion?
Contact relationships between teeth:
- within arches
- between arches
What factors does occlusion consider? (7)
1) contact points
2) arch form
3) tooth alignment
4) cross bites
5) intercuspal position
6) molar relationships
7) incisor relationships
A contact point is a stagnation area. What does this pose an increased risk for?
Caries
What is a contact point critical for? (2)
1) food displacement during mastication
2) arch alignment/stability
It is therefore important to restore a contact point.
What is an approximal surface?
The approximal surfaces are those surfaces whcih form points of contact between adjacent teeth
Which arch is normally longer than it’s opposing arch?
Upper arch overlaps lower arch
Where do the buccal cusps of the upper dentition meet on the lower dentition when teeth are occluded?
Upper buccal cusps are buccal to lower buccal cusps
What does each upper tooth contact with? (2)
Each upper tooth contacts with its lower antagonist and it’s distal neighbour
What is tooth alignment determined by?
2
1) path of eruption
2) forces exerted on the teeth by: teeth, soft tissues, and other factors like thumb sucking
Describe the “neutral zone” in tooth alignment
the “neutral zone” is the sense of equilibrium between forces exerted on a tooth
Which dental treatment makes the neutral zone clinically important?
Denture construction
Which anatomical features of which teeth are described by Angle’s Classification?
Relationship between the MB cusp of the upper 6’s and the MB groove of the lower 6’s
What is the definition of an overbite in relation to incisor relationships?
An overbite is an upper tooth overlap in the vertical plane
What is the definition of an open bite?
No overbite, upper and lower teeth do not contact
What is the definition of an overjet?
upper tooth overlap in the horizontal plane
What is the definition of a reverse overjet?
Lower teeth overlaps upper teeth in the horizontal plane
What does Incisor Classification relate to?
Relates to where the lower incisor tip meets the cingulum plateau of the upper incisor
Describe a Class I incisor relationship
The lower incisor edges occlude with or lie immediately below the cingulum plateau of the upper central incisors
Describe a Class II division I incisor relationship
The lower incisor edges occlude with or lie posteriorly to the cingulum of the upper central incisors
Describe a Class II division II incisor relationship
The upper central incisors are retroclined
Describe a Class III incisor relationship
Lower incisor edges lie anterior to the cingulum of the upper incisors (upper teeth lie posteriorly to lower incisors)
Will molar and incisor relationships correlate with each other in a patient?
No, molar and incisor relationships may be different in a patient
Which direction do upper molar occlusal surfaces face?
Buccally
Which surfaces do molar occlusal surfaces face?
Lingually
What does the ‘Curve of Wilson’ refer to?
It refers to the curvature in a frontal pane through cusp tips of both right and left molars
What defines a bilateral cross bite?
a lateral misalignment of dental arches on both sides (where buccal aspect of lower molars sit more buccally than the buccal aspects of upper molars)
What is a unilateral cross bite?
a lateral misalignment of dental arches on one side only
Define the intercuspal position
position of the jaws when the maxillary and mandibular teeth are in maximum intercuspation (also referred to as centric occlusion)
What is the ‘Curve of Spee’?
The curve of spee is the curvature of the mandibular occlusal plane beginning at the premolars and following the buccal cusps of the posterior teeth. Important consideration in orthodontics as a “flat or mild curve of spee is essential to an ideal occlusion”
Describe Class I of the angle’s classification?
The mesio-buccal cusp on the upper first molar occludes with the buccal groove of the lower first molar
Describe Class II of the Angle’s classification?
The mesio-buccal cusp of the upper first molar occludes anterior to the buccal cusp of the lower first molar
Describe Class III of the Angle’s Classification?
The mseio-buccal cusp of the upper first molar occludes posterior to the buccal groove of the lower first molar
