AOM 2

Question 1

How is the vertical jaw relationship measured

Answer 1

Frankfurt plane and mandibular plane
Meet at Frankfurt-Mandibular Plane Angle at external occipital protruberance

Lower anterior face height: Total anterior face height
LAFH: TAFH

Question 2

Frankfurt plane

Answer 2

Lower orbital rim to superior border of external auditory meatus

Question 3

Mandibular plane

Answer 3

Lower border of mandible

Question 4

Lower anterior face height

Answer 4

Base of nose (sub nasale) to inferior aspect of chin (soft tissue menton)

Question 5

Average FMPA

Answer 5

27 +/-4

Question 6

Average LAFH to TAFH

Answer 6

55%

Question 7

Long facial type

Answer 7

LAFH to TAFH proportion > 55%
FMPA>31
Steep inclined mandibular plane
Backward mandibular growth
Anterior open bite tendency

Question 8

Short facial type

Answer 8

LAFH to TAFH <55%
FMPA<23
Parallelism of jaws
Forward mandibular growth rotation
Deep overbite tendency

Question 9

When does mandibular displacement occur

Answer 9

Transverse skeletal variation
Occurs where inter-arch width discrepancy causes U and L posteriors to meet cusp to cusp
Mandible forced to deviate to one side to achieve intercuspal position

Question 10

Mandibular displacement on closure

Answer 10

Cusp to cusp contact -> manidble displaces ->centric occlusion
Associated with unilateral posterior crossbite

Question 11

Facial asymmetries

Answer 11

Dental cause:
Displacement of normal mandible due to unilateral cross bite
True mandibular asymmetry:
Hemi-mandibular hyperplasia
Condylar hyperplasia

Question 12

Crowding causes

Answer 12

Small jaws, normal teeth
Large teeth (macrodontia)

Question 13

Spacing causes

Answer 13

Large jaws, normal sized teeth
Small teeth