Chu Alignment

Question 1

What are 4 things seen on the occlusal surfaces of the teeth?

Answer 1

Grooves, sulci, cusps, cusp ridges

(Sulcus is a broad depression or valley on occlusal surface of posterior teeth.)

Question 2

The occlusal table is what % of the buccolingual dimension of the tooth?

Answer 2

50-60%. (It is the area within the cusps tips. Masticatory forces are applied to the occlusal table. It is positioned within the confines of the root.)

Question 3

Where is the bucco-occlusal line?

Answer 3

It is drawn through the buccal cusp tips of the mandibular posterior teeth. It divides the inner and outer aspects of the buccal cusps.

Question 4

Where is the linguo-occlusal line?

Answer 4

It is drawn through the lingual cusp tips of the maxillary posterior teeth. It divides the inner and outer aspects of the lingual cusps.

Question 5

Where are the central fossa lines?

Answer 5

Drawn through the central developmental grooves of maxillary & mandibular posterior teeth.

Question 6

What is inclination?

Answer 6

In the facio-lingual dimension. You can have TOOTH inclination or ROOT inclination. (These will be opposite)

Question 7

What is angulation?

Answer 7

The tooth or root position In the mesio-distal dimension.

Question 8

What is the angulation of all teeth?

Answer 8

All teeth have a mesial crown angulation and distal root angulation.

Question 9

What is the inclination of facial and lateral incisors?

Answer 9

Facial inclination

Question 10

Canines and premolars have their crown and root in the same plane in the ________ dimension.

Answer 10

bucco-lingual

Question 11

Maxillary posterior teeth have a slight inclination toward what side?

Answer 11

Buccal

Question 12

Mandibular posterior teeth have a slight inclination toward what side?

Answer 12

Lingual

Question 13

What are 4 reasons to understand root angulation?

Answer 13

1) Tells you where to point x-ray 2) Tells you the direction of occlusal forces along long axis of tooth 3) Orthodontic force control 4) Implant placement

Question 14

Where are the facial and lingual heights of contour for the anterior teeth?

Answer 14

Facial & lingual are in cervical 1/3

Question 15

Where are the facial and lingual heights of contour for posterior teeth?

Answer 15

Facial = cervical 1/3, lingual = middle 1/3

Question 16

What is the convexity of the facial and lingual heights of contour? What is the exception?

Answer 16

0.5mm, except lingual of mandibular posteriors which is 1.0mm

Question 17

What are the two categories of contact areas?

Answer 17

Facio-lingual contact area; inciso-cervical contact area

Question 18

What are 3 functions of contact areas?

Answer 18

1) Stabilize arch (prevent rotation, mesial drift)
2) Prevent food impaction (prevents food from being forced through the contact area)
3) Protect interproximal gingival tissue

Question 19

How do contact areas change over time?

Answer 19

The area increases with age. It also becomes more cervical as you move from anterior to posterior teeth.

Question 20

In what dimension is the contact area centered for anterior teeth?

Answer 20

The contact area is centered facio-lingually.

Question 21

Where is the contact area for posterior teeth? Why is this significant?

Answer 21

More towards the buccal than the lingual. It creates a “sluiceway” or an area for food to escape.

Question 22

For maxillary and mandibular anterior teeth, looking occlusally, which embrasure is larger, facial or lingual?

Answer 22

The lingual embrasure is larger. (Remember this is the same for maxillary and mandibular anteriors.)

Question 23

For maxillary and mandibular anterior teeth, looking facially or lingually, which embrasure is larger, the gingival or incisal?

Answer 23

The gingival embrasure is larger. (This is the same for maxillary and mandibular anteriors.)

Question 24

Looking at the occlusal surface of the maxillary premolars, which embrasure is larger, buccal or lingual?

Answer 24

Lingual

Question 25

Looking at the occlusal surface of the mandibular posteriors, which embrasure is larger, facial or lingual?

Answer 25

Lingual

Question 26

Where is the interproximal contact area localized compared to the central fossa line? (Is it more buccal or more lingual?)

Answer 26

Localized buccal to the line

Question 27

What is the benefit of having lingual embrasures that are larger?

Answer 27

It allows food to be displaced lingually. The tongue can then return the food to the occlusal surface easily.