Cephalometrics

Question 1

Why Is the Jefferson Cephalometric analysis a good first line Cephalometric analysis?

Answer 1

Simplified analysis
Not Gender Specific
Not Race specific
Based On Divine Proportion

Question 2

In Jefferson Cephalometric evaluation what is represented by SOr?

Answer 2

Supra Orbitale, the most anterior point of the intersection of the shadow of the roof of the orbit and that lateral contour, intersection of roof of orbit and lateral wall of orbit

Question 3

In Jefferson Cephalometric evaluation what is represented by SI?

Answer 3

Sella inferior the lower most tip of the internal contour of Sella Turcica
○ SOr to SI is known as the Cranial plane

Question 4

In Jefferson Cephalometric evaluation what is represented by ANS?

Answer 4

Anterior Nasal Spine, the anterior tip of the premaxilla on the midsagittal plane

Question 5

In Jefferson Cephalometric evaluation what is represented by PNS?

Answer 5

Posterior Nasal Spine, the most posterior point on the contour of the maxillary bony plate
Can be difficult to locate sometimes by looking for the Base of the Teardrop(pterogo-maxillary fissure)

Question 6

In Jefferson Cephalometric evaluation what is represented by CG?

Answer 6

Constructed Gonion, the intersection of the lines running outside the posterior border of the Ramus and the line running from Menton(M) along the inferior border of the mandible

Question 7

In Jefferson Cephalometric evaluation what is represented by OC?

Answer 7

The occlusal is made with the mid point of the occlusal contacts of the 6’s and the mid points of the 5’s or E’s Occlusal contacts, this is a plane?

Question 8

In Jefferson Cephalometric evaluation what is represented by N?

Answer 8

Nasion Is the superior most aspect of the Nasal bone, it is also the most posterior point of the anterior superior curve of the nasal bone and the junction of the superior aspect of the nasal bone and the Frontal Bone.

Question 9

In Jefferson Cephalometric evaluation what is represented by P?

Answer 9

Pogonion is the most anterior point of the profile of the bony Chin

Question 10

In Jefferson Cephalometric evaluation what is represented by M?

Answer 10

Menton is the most inferior point of the bony chin/most inferior point of the mandibular symphysis

Question 11

In Jefferson Cephalometric evaluation what are the 4 facial planes?

Answer 11

SOr-Si is the cranial plane and represents the angle of the anterior cranial base.
ANS-PNS is the Palatal plane
OC is the functional occlusal plane, common errors include using the traditional occlusal plane
M-CG is the mandibular plane and represents the angular psotion of the mandible

Question 12

In Jefferson Cephalometric evaluation what is represented by Centre T?

Answer 12

Centre T is the constructed convergence point of the 4 facial planes, in an ideal face these planes will align on a single point. If these points do not converge on a single point Centre T will be placed on the point with the smallest distance between the planes as measured vertically.

Question 13

In Jefferson Cephalometric evaluation what is the Anterior Arc and how is it drawn?

Answer 13

The Anterior arc is the method of determining ideal AP position of maxilla, mandible and upper incisor. The anterior arc is drawn with a protractor with the centre of the arc on Centre T and starting with the other side of the arc on N(is usally drawn in Red)

Question 14

In Jefferson Cephalometric evaluation what is the Vertical arc and how is it drawn?

Answer 14

The Vertical arc is an arc drawn, based on the individuals age to determine the ideal vertical relationship. The Vertical arc is drawn with a protractor with the centre of the arc on ANS and the other end of the protractor sitting,
If the patient is above 18 1cm superior to SOr
If the patient is below 18 (0.75 x (pt’s age-4))mm superior to SOr

Question 15

What range of inter incisal angle is considered ideal?

Answer 15

135° is considered ideal with between 120° and 140° being acceptable and is called Div 1 or Division 1

Question 16

What interincisal angle Range is called Division 2?

Answer 16

Division 2 is an interincisal angle greater than 140° and clinically appears as retroclined incisors.

Question 17

What interincisal angle Range is called Division 3?

Answer 17

Division 3 is an interincisal angle Less than 120°

Question 18

What is a Witts Analysis and how is it measured?

Answer 18

A Witts analysis is an analysis used to determine relative maxillo mandibular relationship a line is drawn along the occlusal plane(the midpoint of the occlusal contact of the 6’s and the interincisal contact point) a line is drawn at the perpendicular bisector from point A to the Occlusal Plane, and Another line is drawn at the perpendicular bisector of point B. a linear measurment between these two values are determined. a value of 0mm is ideal for females and for men BO is idealy 1mm anterior to AO given a Wits reading of -1mm.

Question 19

In the Steiner Analysis what is the ideal values for the following and what do these measurements represent:
S-N-A
S-N-B
A-N-B
\+1/NL
-1/ML
Interincisal angle
NL/Ml' (constructed) MMP

Answer 19

SNA 82 +-3 AP maxillary position
SNB 79 +-3 AP mandibular position
ANB 3 +-1 Relative maxillo-mandibular position
Upper incisive mx plane 108° +-5 Proclination of upper central incisor
Lower incisive to mn plane 92° +-5 Proclination of lower central incisor
Interincisal angle 135° +-11 Dental division
Mx mn planes 28° +-4 Inclination of mandible relative to maxilla

Question 20

What is Represented by the Cephalometric point S?

Answer 20

The centre of Sella Turcica, the middle of the pituitary fossa

Question 21

What is represented by the Cephalometric point A?

Answer 21

The point of greatest convexity/most posterior point of the anterior inferior border of the maxilla

Question 22

What is represented by Cephalometric point B?

Answer 22

The point of greatest convexity/most posterior point of the anterior border of the body of the mandible