Oral Biology: Occlusion

Question 1

What is occlusion?

Answer 1

Contact relationships between teeth:

• within arches
• between arches

Question 2

What factors does occlusion consider? (7)

Answer 2

1) contact points
2) arch form
3) tooth alignment
4) cross bites
5) intercuspal position
6) molar relationships
7) incisor relationships

Question 3

A contact point is a stagnation area. What does this pose an increased risk for?

Answer 3

Caries

Question 4

What is a contact point critical for? (2)

Answer 4

1) food displacement during mastication
2) arch alignment/stability

It is therefore important to restore a contact point.

Question 5

What is an approximal surface?

Answer 5

The approximal surfaces are those surfaces whcih form points of contact between adjacent teeth

Question 6

Which arch is normally longer than it’s opposing arch?

Answer 6

Upper arch overlaps lower arch

Question 7

Where do the buccal cusps of the upper dentition meet on the lower dentition when teeth are occluded?

Answer 7

Upper buccal cusps are buccal to lower buccal cusps

Question 8

What does each upper tooth contact with? (2)

Answer 8

Each upper tooth contacts with its lower antagonist and it’s distal neighbour

Question 9

What is tooth alignment determined by?

2

Answer 9

1) path of eruption

2) forces exerted on the teeth by: teeth, soft tissues, and other factors like thumb sucking

Question 10

Describe the “neutral zone” in tooth alignment

Answer 10

the “neutral zone” is the sense of equilibrium between forces exerted on a tooth

Question 11

Which dental treatment makes the neutral zone clinically important?

Answer 11

Denture construction

Question 12

Which anatomical features of which teeth are described by Angle’s Classification?

Answer 12

Relationship between the MB cusp of the upper 6’s and the MB groove of the lower 6’s

Question 13

What is the definition of an overbite in relation to incisor relationships?

Answer 13

An overbite is an upper tooth overlap in the vertical plane

Question 14

What is the definition of an open bite?

Answer 14

No overbite, upper and lower teeth do not contact

Question 15

What is the definition of an overjet?

Answer 15

upper tooth overlap in the horizontal plane

Question 16

What is the definition of a reverse overjet?

Answer 16

Lower teeth overlaps upper teeth in the horizontal plane

Question 17

What does Incisor Classification relate to?

Answer 17

Relates to where the lower incisor tip meets the cingulum plateau of the upper incisor

Question 18

Describe a Class I incisor relationship

Answer 18

The lower incisor edges occlude with or lie immediately below the cingulum plateau of the upper central incisors

Question 19

Describe a Class II division I incisor relationship

Answer 19

The lower incisor edges occlude with or lie posteriorly to the cingulum of the upper central incisors

Question 20

Describe a Class II division II incisor relationship

Answer 20

The upper central incisors are retroclined

Question 21

Describe a Class III incisor relationship

Answer 21

Lower incisor edges lie anterior to the cingulum of the upper incisors (upper teeth lie posteriorly to lower incisors)

Question 22

Will molar and incisor relationships correlate with each other in a patient?

Answer 22

No, molar and incisor relationships may be different in a patient

Question 23

Which direction do upper molar occlusal surfaces face?

Answer 23

Buccally

Question 24

Which surfaces do molar occlusal surfaces face?

Answer 24

Lingually

Question 25

What does the ‘Curve of Wilson’ refer to?

Answer 25

It refers to the curvature in a frontal pane through cusp tips of both right and left molars

Question 26

What defines a bilateral cross bite?

Answer 26

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)

Question 27

What is a unilateral cross bite?

Answer 27

a lateral misalignment of dental arches on one side only

Question 28

Define the intercuspal position

Answer 28

position of the jaws when the maxillary and mandibular teeth are in maximum intercuspation (also referred to as centric occlusion)

Question 29

What is the ‘Curve of Spee’?

Answer 29

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”

Question 30

Describe Class I of the angle’s classification?

Answer 30

The mesio-buccal cusp on the upper first molar occludes with the buccal groove of the lower first molar

Question 31

Describe Class II of the Angle’s classification?

Answer 31

The mesio-buccal cusp of the upper first molar occludes anterior to the buccal cusp of the lower first molar

Question 32

Describe Class III of the Angle’s Classification?

Answer 32

The mseio-buccal cusp of the upper first molar occludes posterior to the buccal groove of the lower first molar