Occlusion

Question 1

Each tooth opposes two teeth in occlusion, except …… & ……..

Answer 1

Mandibular central incisor & Maxillary 3rd molar

Question 2

Each tooth in the Max. arch occludes with …….

Answer 2

its counterpart & the one distal to it

Question 3

Each tooth in the Mand. arch occludes with …..

Answer 3

its counterpart & the one mesial to it

Question 4

When the arches come together, the posterior teeth contact, and the anterior are …..

Answer 4

just out of contact

* There is overbite & overjet

Question 5

The Max. canine occludes in …….

The Mand. canine occludes in …..

Answer 5

• The buccal embrasure between the Mand. canine & first premolar
• The lingual embrasure between the Max. canine & lateral incisor
• Note that: occlude here doesn’t mean contact

Question 6

Define:

1. Supporting cusp

2. Guiding cusp

Answer 6

1. The cusps that occlude in the opposing fossae or marginal ridges. Responsible for supporting forces of occlusion
2. The cusps that are not in contact, but outside the occluding area

Question 7

The guiding inclines are …….

Answer 7

the inclines of the guiding cusps, from the cusp tip towards the center of the tooth (e.g the lingual incline of the buccal cusps of the Max. molars)
* They make contact with the Functional outer Aspect (FOA) of the opposing functional cusps

Question 8

What are the areas of contact in a posterior tooth in occlusion??

Answer 8

1. FOA of the holding cusp contacting the guiding incline of the opposing guiding cusp
2. Occlusal slope of the holding cusp contacting the occlusal slope of the opposing holding cusp
3. The guiding incline of the guiding cusp contacting the FOA of the holding cusp in the opposing

Question 9

The Max. posterior tooth holding cusp occludes in ………., except for the ML cusp of Molars which occlude in …….

Answer 9

• the distal marginal ridge of the counterpart, and the mesial marginal ridge of the one distal to it
• ML occludes in the central fossa of the coutnerpart
• • Reverse the order for the Mand. teeth
• see p. 742 if not clear

Question 10

The distal cusp of the Mand. molar occludes in ……… of the counterpart

Answer 10

distal triangular fossa of the counterpart

* Note that: the DB cusp of the Mand. molars occlude in the central fossa of the counterpart

Question 11

The gliding cusps of the Max. posterior teeth oppose the facial embrasure between …… & …… except for MB of molars which oppose …… & the DB cusp of the 1st molar which oppose …….

Answer 11

the counterpart & the one distal to it

• buccal groove of the counterpart
• DB groove of the Mand. 1st molar

Question 12

The DB cusp of the Max. 2nd molar opposes ……

Answer 12

the facial embrasure between the second & third Mand. molars

Question 13

The gliding cusps of the Mand. posterior teeth oppose the lingual embrasure between …… & …… except for the DL cusp of molars which oppose ……..

Answer 13

counterpart & the tooth mesial to it

* the lingual groove of the Max. counterpart

Question 14

The lingual surface of the Max. incisors is like …….. & the incisal 2 mm of the labial surface of Mand. incisors is like ……..

Answer 14

gliding slope

FOA

Question 15

The Mand. central incisor labioincisal angle opposes ……..

Answer 15

the mesial marginal ridge of the Max. central & its lingual fossa

Question 16

The Mand. lateral incisor labioincisal angle opposes …..

Answer 16

the distal marginal ridge of the Max. central & the mesial of Max. lateral, plus the lingual fossa

Question 17

The Max. central opposes ………., the lateral opposes ….., while the canine opposes ……

Answer 17

The Mand. central & lateral
The Mand. lateral & canine
The embrasure between the Mand. canine & 1st premolar

Question 18

What is Angle classification of occlusion?

Answer 18

1. Class I: MB cusp of Max. 1st molar is in MB groove of Mand. 1st molar. Max. canine is in facial embrasure between Mand. canine and 1st premolar
2. Class II: MB cusp of Max. 1st molar is anterior to MB groove of Mand. 1st molar. Same for Canine. Called Distocclusion
3. Class III: MB cusp of Max. 1st molar is posterior to the MB groove of the Mand. 1st molar. Same for the canine. Called Mesiocclusion

Question 19

Angle class I is considered malocclusion. T/F?

Answer 19

True

• Anterior crowding may be present. Normal occlusion is not classified by Angle. Class I also called neutrocclusion
• In Class II, the Mandible is micrognathic, while in Class III, it is prognathic

Question 20

The side, to which the mandible moves during function is called ……., while the other side is called …….

Answer 20

working side (functional side)
non working side (balancing side)

• Note that: functional cusp is called supporting/holding/occluding cusp
• Remember: Mand. is moving, the Max. is stationary! see note p. 745 for cusp pathways

Question 21

Protrusion of the Mandible is caused by the coordinated function of ……

Answer 21

lateral pterygoid muscle

* The condyles move forward & downward on the articular eminence

Question 22

Movement of the mandible laterally to the left is caused by contraction of ……..

Answer 22

right lateral pterygoid muscle

Question 23

Describe the condyle movement during lateral excursion

Answer 23

1. The condyle rotates on the working side. During this movement, the gliding and holding cusps move through the embrasures & grooves of the opposing teeth, and cusps don’t become tip to tip
2. On the non working side, the condyle moves forward, downward & medially on the eminence, hence, the cusps move anterior & lateral (diagonally). Teeth on this side don’t contact (due to downward movement) p. 746

Question 24

Describe the condyle movement during the lateral protrusive movement

Answer 24

1. Working side: condyle rotates with forward & downward movement.
2. Non working side: condyle moves anteriorly, downward & medially. Cusp movement similar to pure lateral movement, except the oblique line points more anteriorly (i.e less angle from the central area of the arch)
   * see p. 747 if not clear