Orthodontics- Cephalometric Anatomy, Tracing, and Analysis

cephalometric tracing

The process of identifying landmarks and creating a line drawing of the radiograph is called ......

porion

which anatomical landmark:

- Highest point of the ear canal

- Most superior point of the external auditory meatus

- Immediately distal to the condyle

orbitale

which anatomical landmark:

- Lowest point of the floor of the orbit

- Most inferior point of the external border of the orbital cavity

sella

which anatomical landmark:

- Center of the pituitary fossa (sella turcica) of the sphenoid bone

nasion

which anatomical landmark:

- The most anterior point of the intersection between the nasal bone and the frontal bone

basion

which anatomical landmark:

- Most inferior posterior point of the occipital bone

- Also the anterior margin of the foramen magnum

anterior nasal spine

which anatomical landmark:

- The tip of the anterior nasal spine

posterior nasal spine

which anatomical landmark:

- The tip of the posterior nasal spine

- The most posterior point on the hard palate

A point

which anatomical landmark:

- Deepest point of the curve of the maxilla, between anterior nasal spine (ANS) and the dental alveolus

B point

which anatomical landmark:

- Most posterior point in the concavity along the anterior border of the symphysis

pogonion

which anatomical landmark:

- Most anterior point on the mid-sagittal symphysis

gnathion

which anatomical landmark:

- Midpoint between the most anterior and inferior point on the boney chin

menton

which anatomical landmark:

- Most inferior point of the symphysis

gonion

which anatomical landmark:

- Most convex point along the inferior border of the body of the mandible

ramus point

which anatomical landmark:

- Most posterior point on the border of the inferior ramus

articulare

which anatomical landmark:

- Intersection of the mandible with the temporal bone

- Not an anatomic structure

condylion

which anatomical landmark:

- Most superior point of the condyle

- Should be immediately anterior to Porion

constructed gonion

which anatomical landmark:

- The intersection of the mandible and the line that bisects the angle formed by Menton-Gonion and Articulare-Ramus Point

tip of nose

which anatomical landmark:

- Most anterior point of the curve of the nose

- Pronasale

upper lip

which anatomical landmark:

- Most anterior point on the curve of the upper lip

lower lip

which anatomical landmark:

- Most anterior point on the curve of the lower lip

soft tissue pogonion

which anatomical landmark:

- Most anterior point on the curve of the soft tissue chin

symphysis

which anatomical landmark:

- The internal and external aspects of the symphysial border

- Used to superimpose the mandible

IAN

which anatomical landmark:

- The inferior alveolar nerve canal

- Used to superimpose the mandible

quantitative

the cephalometric analysis measurements provide a .... guide for understanding the patient's malocclusion

skeletal; dental; soft tissue

cephalometric analysis Measurements can be taken in three categories:

1. ....

2. ....

3. ....

AP; Vertical

cephalometric analysis ±Measurements can be taken in two dimensions:

1. ....

2. ....

ceph ruler

- To calculate a distance measurement, you must use a ratio to account for magnification

- We do this using the .....

actual measurement

..... = (actual ruler/ceph ruler) x ceph measurement

Cranial base to mandible

Skeletal cephalometric analysis often compares three relationships:

- Cranial base to maxilla

- ......

- Maxilla to mandible

frankfort horizontal

which reference plane:

- Porion to Orbitale

- Cranial base reference line

- "Natural head position"

- Should be parallel to the floor when the patient "looks off into the horizon"

sella nasion

which reference plane:

- Sella to Nasion

- Cranial base reference line

- According to Bjork, the cranial base grows along the Sella Nasion line

mandibular plane

which reference plane:

- Tangent line to lower border of the mandible

Three definitions:

- Me-Go

- Me-Constructed Go (This is what the American Board of Orthodontics uses)

- Go-Gn

Downs occlusal plane

which reference plane:

- Point 1: Molar occlusal contact

- Point 2: Bisection of the overbite

ricketts occlusal plane

which reference plane:

- Point 1: Molar occlusal contact

- Point 2: 1st premolar occlusal contact

E plane

which reference plane:

- Tip of Nose to Soft Tissue Pogonion

- Lip protrusion reference plane

- Heavily affected by nose and chin size

SNA

What skeletal measurement:

- Sella-Nasion vs Nasion-A Point

- AP relationship between the cranial base and the maxilla

- Tells you about the AP position of the maxilla

protrusive maxilla

an SNA greater than to norm indicates a ....

SNB

What skeletal measurement:

- Sella-Nasion vs Nasion-B Point

- AP relationship between the cranial base and the mandible

- Tells you about the AP position of the mandible

Protrusive mandible

an SNB greater than to norm indicates a ....

ANB

What skeletal measurement:

- Nasion-A Point vs Nasion-B Point

- ANB=SNA-SNB

- This means ANB can be negative!!!!!

- AP relationship between the maxilla and the mandible

- Tells you about the AP skeletal classification

class 2

an SNB greater than to norm indicates ....

Wits

What skeletal measurement:

- Distance between A point and B point measured along the occlusal plane

- AP relationship between the maxilla and the mandible

- Tells you about the AP skeletal classification

class 2

an Wits greater than to norm indicates ....

FMA

What skeletal measurement:

- Frankfort Horizontal vs. Mandibular Plane

- Vertical relationship between the cranial base and the mandible

- Tells you about the vertical angulation of the mandible

dolicofacial

an FMA greater than to norm indicates ....

SN-MP

What skeletal measurement:

- Sella-Nasion vs. Mandibular Plane

- Vertical relationship between the cranial base and the mandible

- Tells you about the vertical angulation of the mandible

dolicofacial

an SN-MP greater than to norm indicates ....

Y-axis

What skeletal measurement:

- Frankfort Horizontal vs. Sella-Gnathion

- Vertical relationship between the cranial base and the mandible

- Tells you about the vertical angulation of the mandible

dolicofacial

an y-axis greater than to norm indicates ....

U1-SN

What dental measurement:

- Sella-Nasion vs Long Axis of U1

- AP relationship between the cranial base and the upper incisors

- Tells you about the angulation of the upper incisors

proclined upper incisors

an U1-SN greater than to norm indicates ....

L1-MP

What dental measurement:

- Mandibular Plane vs Long Axis of L1

- AP relationship between the body of the mandible and the lower incisors

- Tells you about the angulation of the lower incisors

proclined lower incisors

an L1-MP greater than to norm indicates ....

U1-NA

what distance measurement:

- Nasion-A Point to the upper incisors

- AP relationship between the cranial base, maxilla, and the upper incisors

- Measured from the incisal edge of the upper incisor to Nasion-A Point along a perpendicular line

- If U1 is anterior to NA, the measurement is positive

- If U1 is posterior to NA, the measurement is negative

- Tells you about the horizontal position of the upper incisors

protruded upper incisors

an U1-NA greater than to norm indicates ....

L1-NB

what distance measurement:

- Nasion-B Point to the lower incisors

- AP relationship between the cranial base, mandible, and the lower incisors

- Measured from the incisal edge of the lower incisor to Nasion-B Point along a perpendicular line

- If L1 is anterior to NB, the measurement is positive

- If L1 is posterior to NB, the measurement is negative

- Tells you about the horizontal position of the lower incisors

protruded lower incisors

an L1-NB greater than to norm indicates ....

U lip to E-plane

what soft tissue measurement:

- Upper lip to E-Plane

- Distance from the most protrusive point on the upper lip to E-Plane along a perpendicular line

- If U Lip is anterior to E-Plane, the measurement is positive

- If U Lip is posterior to E-Plane, the measurement is negative

- Tells you about upper lip protrusion

protrusive upper lip

an U lip to E-plane greater than to norm indicates ....

L lip to E-plane

what soft tissue measurement:

- Lower lip to E-Plane

- Distance from the most protrusive point on the lower lip to E-Plane along a perpendicular line

- If L Lip is anterior to E-Plane, the measurement is positive

- If L Lip is posterior to E-Plane, the measurement is negative

- Tells you about lower lip protrusion

protrusive lower lip

an L lip to E-plane greater than to norm indicates ....