Six Keys to Normal Occlusion

Question 1

List the six keys to normal occlusion:

Answer 1

1. molar relation
2. crown angulation
3. crown inclination
4. rotations
5. contact points
6. occlusal plane

Question 2

The distal marginal ridge of the maxillary first molar occludes on the mesial marginal ridge of the mandible second molar. This describes:

Answer 2

Key 1- Molar relation

Question 3

Key 1- Molar relation:

The ____ marginal ridge of the maxillary first molar occludes on the _____ marginal ridge of the mandibular second molar

Answer 3

distal; mesial

Question 4

Key 1- Molar relation describes the relationships between the:

(marginal ridges)

Answer 4

Distal marginal ridge of maxillary first molar; mesial marginal ridge of mandibular second molar

Question 5

In this image what is the arrow pointing to? What does this satisfy?

Answer 5

Distal marginal ridge of maxillary first molar occluding with the mesial marginal ridge of the mandibular second molar

Key 1- Molar relation

Question 6

Key 1- Molar relation:

the ____ cusp of the maxillary first molar must occlude on the _____ of the mandibular first molar

Answer 6

mesiolingual cusp; central fossa

Question 7

According to Key 1- Molar relation, the mesiolignual cusp of the maxillary first molar must occlude:

Answer 7

on the central fossa of the mandibular first molar

Question 8

Key 1- Molar relation describes the relationships between the:

(cusp & fossa)

Answer 8

The mesiolingual cusp of the maxillary first molar must occlude on the central fossa of the mandibular first molar

Question 9

In this image, what are the arrows pointing to? What does this satisfy?

Answer 9

The mesiolingual cusp of the maxillary first molar occluding on the central fossa of the mandibular first molar; Key 1- Molar relation

Question 10

According to Key 1- Molar relation, if the maxillary and mandibular molars are in normal relation, the _____ and _____ enjoy a cusp-embrasure relationship buccally and cusp-fossa relationship lingually

Answer 10

canine; premolar

Question 11

According to Key 1- Molar relation, if the maxillary and mandibular molars are in normal relation, the canine and premolar enjoy a ______ relationship buccally and ______ relationship lingually

Answer 11

cusp-embrasure; cusp-fossa

Question 12

In this image, what is the first arrow pointing to? What does this satisfy?

Answer 12

Canine & premolar enjoy a cusp-embrasure relationship buccally; Key 1- Molar relation

Question 13

The gingival portion of the long axis of each tooth is distal to the incisal portion:

Answer 13

Key II- Crown angulation

Question 14

According to Key II crown angulation:

Answer 14

The gingival portion the long axis of each tooth is distal to the incisal portion

Question 15

What is this image showing?

Answer 15

Key II- Crown angulation: The gingival portion the long axis of each tooth is distal to the incisal portion

Question 16

What is this image showing?

Answer 16

Key II- Crown angulation: The gingival portion the long axis of each tooth is distal to the incisal portion

Question 17

The degree of tip of the incisors determines the among of mesiodistal space they consume:

Answer 17

Key II- Crown angulation

Question 18

Key II- Crown angulation states that the degree of tip of the incisors determines the amount of:

Answer 18

mesiodistal space they consume

Question 19

Key II- Crown angulation states the _________ determines the amount of mestiodistal space they consume

Answer 19

Degree of tip of the incisors

Question 20

(Crown angulation)

+ Reading = _____ tip of the crown

• Reading = _____ tip of the crown

Answer 20

+: distal tip

-: mesial tip

Question 21

Key III =

Answer 21

Crown inclination

Question 22

Would the crown inclination in the following image be positive or negative?

Answer 22

Positive (+7) labiolingual inclination

Question 23

Would the crown inclination in the following image be positive or negative?

Answer 23

Negative (-7) labiolingual inclination

Question 24

Anterior teeth-torque falls under what key?

Answer 24

Key III- Crown inclination

Question 25

According to Key III, the crown inclination should be _____ from canines through second molars

Answer 25

progressively increased

Question 26

What is the ratio of inclination & angulation?

Answer 26

Ratio 4:1

Question 27

What do we mean by saying there should be a ratio of 4:1 for inclination & angulation?

Answer 27

For every 4 degrees of lingual root torque there is 1 degree of mesial root tip

Question 28

For every four degrees of _______ there is 1 degree of _____

Answer 28

lingual root torque; mesial root tip

Question 29

A rotated molar occupies more mesiodistal space & a rotated anterior tooth occupies less mesiodistal space:

Answer 29

Key IV rotations

Question 30

According to Key IV rotations, a rotated molar occupies:

Answer 30

more mesiodistal space

Question 31

According to Key IV rotations, a rotated anterior tooth occupies:

Answer 31

less mesiodistal space

Question 32

In the absence of genuine tooth size discrepancies “ideal” occlusions should have tight contacts:

Answer 32

Key V- Tight contacts

Question 33

Key V- Tight contacts states that in the absence of genuine tooth size discrepancies:

Answer 33

“ideal” occlusions should have tight contacts

Question 34

1. A flat occlusal plane should be a treatment goal
2. Intercuspation of teeth is best when the plane of occlusion is relatively flat

Answer 34

Key VI- Occlusal plane

Question 35

Key VI- Occlusal plane states that a ____ should a treatment goal

Answer 35

flat occlusal plane

Question 36

Key VI- Occlusal plane states that intercuspation of teeth is best when:

Answer 36

the plane of occlusion is relatively flat

Question 37

Key VI- Occlusal plane states that the _______ of teeth is best when the plane of occlusion is relatively flat

Answer 37

intercuspation