Ortho: Cephalometric Anatomy Tracing & Analysis

Lateral cephalometric radiograph

--> side of the head

Posterior-anterior cephalometric radiograph

--> front of the head

What are the two main types of cephalometric radiograph?

Lateral Cephalometric Radiograph

What cephalometric radiograph do we use in our ortho class?

They are for analysis of the patient's skeletal, dental, and soft tissue

pattern

--> Landmarks are primarily, but not always, anatomic structures

What are the purpose of identifying landmarks on a cephalometric radiograph?

False

T/F: Landmarks on a cephalometric radiograph are always anatomical structures

cephalometric tracing

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

Porion (Po)

Highest point of the ear canal

-Most superior point of the external auditory meatus

-Immediately distal to the condyle

What landmark is this?

Orbitale (Or)

Lowest point of the floor of the orbit

Most inferior point of the external border of the orbital cavity

What landmark is this?

Sella (S)

Center of the pituitary fossa (sella turica) of the sphenoid bone

What landmark is this?

Nasion (Na, N)

Most anterior point of the intersection between the nasal bone and the frontal bone

What landmark is this?

Basion (Ba)

Most inferior posterior point of the occipital bone

Also the anterior margin of the foramen magnum

What landmark is this?

Anterior Nasal Spine (ANS)

The tip of the anterior nasal spine

What landmark is this?

Posterior Nasal Spine (PNS)

The tip of the posterior nasal spine

The most posterior point of the hard palate

What landmark is this?

A point

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

What landmark is this?

B Point

The most posterior point in the concavity along the anterior border of the symphysis

What landmark is this?

Pogonion (Pog)

The most anterior point on the mid-sagittal symphysis

What landmark is this

Gnathion (Gn)

The midpoint between the most anterior and inferior point of the bony chin

What landmark is this?

Menton (Me)

The most inferior point of the symphysis

What landmark is this?

Gonion (Go)

The most convex point along the inferior border of the body of the mandible

What landmark is this?

Ramus Point

The most posterior point of the border of the ramus

What landmark is this?

Articulare (Ar)

The intersection of the mandible with the temporal bone

Not an anatomic structure

What landmark is this?

Condylion (Co)

The most superior point of the condyle

Should be immediately anterior to Porion

What landmark is this?

Constructed Gonion

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

What landmark is this?

Tip of the nose

The most anterior point of the nurse of the nose

Pronasale

What landmark is this?

Upper lip

The most anterior point on the curve of the upper lip

What landmark is this?

Lower lip

The most anterior point on the curve of the lower lip

What landmark is this?

Soft tissue Pogonion

The most anterior point on the curve of the soft tissue chin

What landmark is this?

Symphysis

The internal and external aspects of the symphysial border

Used to superimpose the mandible

What landmark is this?

Inferior alveolar nerve IAN)

The inferior alveolar nerve canal

Used to superimpose the mandle

What landmark is this?

Lower Third Molar Bud (L8)

The developing lower third molar crown

Used to superimpose the mandible

What landmark is this?

U6

The upper first molar

What landmark is this?

L6

The lower first molar

What landmark is this?

U1

The upper central incisor

What landmark is this?

L1

The lower central incisor

What landmark is this?

They provide a quantitative guide for understanding the patients malocclusion

They help guide your diagnosis and treatment plan

What is the purpose of cephalometric measurements?

Angle: measured in degrees

Distance: measured in mm

What are the two types of measurements that you can obtain from a cephalometric radiograph?

This means we have to calibrate our measurements so that we can compare them to the actual patient

This is what the ruler is for

A cephalometric radiograph is rarely the same size as the patients head, and is often magnified.

What does this mean?

True

T/F: On a cephalometric radiograph, angle measurements are the same regardless of the magnification or the size of the object being measured

Actual measurement=

(actual ruler/ceph ruler) X ceph measurement

What is the distance-measurements formula we use when measuring distance on a cephalometric radiograph?

True

T/F: When analyzing the measurements from the ceph, your well-trained eye and clinical judgement should always trump the "Norms"

Cranial base to maxilla

Cranial base to mandible

Maxilla to mandible

The skeletal cephalometric analysis often compares 3 relationships.

What are they?

The cranial base stops growing early to mirror early cessation of brain growth

Excellent reference plane for the growth of the rest of the face

Why do we use the cranial base as a reference plane for cephalometric radiographs?

Frankfort Horizontal (FH)

Porion to Orbitale

What reference line is this?

Cranial base reference line

"Natural head position"

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

What is the purpose of measuring the Frankfort Horizontal (FH)?

Sella Nasion (SN)

Sella to Nasion

Cranial base reference line

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

What reference line is this?

Mandibular Plane (MP)

Tangent line to lower border of the mandible

Three definitions

1. Me-Go

2. Me-Constructed Go

--> This is what the American Board of Orthodontics uses

3. Go-Gn

What reference line is this?

Downs Occlusal Plane

Downs Vs. Ricketts Occlusal Plane landmark

Which one is this?

Point 1: Molar occlusal contact

Point 2: Bisection of the overbite

Ricketts's Occlusal Plane

Downs Vs. Ricketts Occlusal Plane landmark

Which one is this?

Point 1: Molar occlusal contact

Point 2: 1st premolar occlusal contact

E-Plane

Tip of Nose to Soft Tissue Pogonion

Lip protrusion reference plane

Heavily affected by nose and chin size

What reference line is this?

SNA- Sella-Nasion vs Nasion-A Point

What landmark is this?

Porion to Orbitale

What two landmarks create the Frankfort Horizontal reference line?

Sella to Nasion

What two landmarks create the Sella-Nasion (SN)

1. Me-Go

2. Me-Constructed Go

3. Go-Gn

What are the 3 definitions of the mandibular plane (MP) reference line?

Tells you about the AP position of the maxilla

What does the Sella-Nasion vs Nasion A-Point (SNA) reference line tell you?

Protrusive maxilla (too big)

The normal SNA angle measurement is 82.0 ±3.5.

If the SNA angle measurement is GREATER than the normal value, what does this tell you about the maxilla?

Well positioned Maxilla

The normal SNA angle measurement is 82.0 ±3.5.

If the SNA angle measurement is within the range of the normal value, what does this tell you about the maxilla?

Retrusive Maxilla (too small)

The normal SNA angle measurement is 82.0 ±3.5

If the SNA angle measurement is LESS than the normal value, what does this tell you about the maxilla?

Tells you about the AP position of the mandible

What does the Sella-Nasion vs Nasion B-Point (SNB) reference line tell you?

Retrusive Mandible

The normal SNB angle measurement is 80.9±3.4

If the SNB angle measurement is LESS than the normal value, what does this tell you about the mandible?

Well positioned Mandible

The normal SNB angle measurement is 80.9±3.4

If the SNB angle measurement is within the range of the normal value, what does this tell you about the mandible?

Protrusive Mandible

The normal SNB angle measurement is 80.9±3.4

If the SNB angle measurement is GREATER than the normal value, what does this tell you about the mandible?

Tells you about the AP skeletal classification

Nasion-A Point vs Nasion-B Point (ANB) is the difference between SNA-SNB

What does this tell you?

Class II

The normal value of ANB is 1.6±1.5

If SNA-SNB value is GREATER than the normal value, what angle classification is this?

Class III

The normal value of ANB is 1.6±1.5

If SNA-SNB value is LESS than the normal value, what angle classification is this?

Class I

The normal value of ANB is 1.6±1.5

If SNA-SNB value is within the limits of the normal value, what angle classification is this?

FMA

Frankfort Horizontal vs. Mandibular Plane

What reference line is this?

Tells you about the vertical angulation of the mandible

What does the FMA (Frankfort Horizontal vs. Mandibular Plane) reference line tell you?

High Angle/Dolicofacial/ Hyperdivergent

The normal FMA value is 23.9±4.5.

If the FMA value is GREATER than the normal value, what does this tell you about the mandible?

Low Angle/Brachyfacial/ Hypodivergent

The normal FMA value is 23.9±4.5.

If the FMA value is LESS than the normal value, what does this tell you about the mandible?

Normal Angle/Mesofacial/ Normodivergent

The normal FMA value is 23.9±4.5.

If the FMA value is within the limits of the normal value, what does this tell you about the mandible?

SN-MP

Sella-Nasion vs. Mandibular Plane

What reference line is this?

Tells you about the vertical angulation of the mandible

What does the SN-MP (Sella-Nasion vs. Mandibular Plane) reference line tell you?

High Angle/Dolicofacial/ Hyperdivergent

The normal SN-MP value is 32.9±5.2.

If the SN-MP value is GREATER than the normal value, what does this tell you about the mandible?

Low Angle/Brachyfacial/ Hypodivergent

The normal SN-MP value is 32.9±5.2.

If the SN-MP value is LESS than the normal value, what does this tell you about the mandible?

Normal Angle/Mesofacial/ Normodivergent

The normal SN-MP value is 32.9±5.2.

If the SN-MP value is within the limits of the normal value, what does this tell you about the mandible?

Y-Axis

Frankfort Horizontal vs. Sella-Gnathion

What reference line is this?

Tells you about the vertical angulation of the mandible

What does the Y-Axis (Frankfort Horizontal vs. Sella-Gnathion) reference line tell you?

High Angle/Dolicofacial/ Hyperdivergent

The normal Y-Axis value is 59.2±7.8

If the Y-Axis value is GREATER than the normal value. What does this tell you about the mandible?

Low Angle/Brachyfacial/ Hypodivergent

The normal Y-Axis value is 59.2±7.8

If the Y-Axis value is LESS than the normal value. What does this tell you about the mandible?

Normal Angle/Mesofacial/ Normodivergent

The normal Y-Axis value is 59.2±7.8

If the Y-Axis value is within the limits of the normal value. What does this tell you about the mandible?

U1-SN

Sella-Nasion vs Long axis of U1

What reference line is this?

Tells you about the angulation of the upper incisors

What does the U1-SN (Sella-Nasion vs Long axis of U1) reference line tell you?

Proclined Upper Incisors

The normal value of U1-SN is 103.8±5.5

If the value of U1-SN is GREATER than the normal value, what does this tell you?

Retroclined Upper incisors

The normal value of U1-SN is 103.8±5.5

If the value of U1-SN is LESS than the normal value, what does this tell you?

Well angulated upper incisors

The normal value of U1-SN is 103.8±5.5

If the value of U1-SN is within the limits of the normal value, what does this tell you?

L1-MP (IMPA)

Mandibular Plane vs Long Axis of L1

What reference line is this?

Tells you about the angulation of the lower incisors

What does the L1-MP (Mandibular Plane vs Long Axis of L1) reference line tell you?

Proclined lower incisors

The normal value of of L1-MP 95.0±7.0

If the L1-MP value is GREATER than the normal value, what does this tell you about the lower incisors?

Retroclined lower incisors

The normal value of of L1-MP 95.0±7.0

If the L1-MP value is LESS than the normal value, what does this tell you about the lower incisors?

Well angulated lower incisors

The normal value of of L1-MP 95.0±7.0

If the L1-MP value is within the normal limits of the normal value, what does this tell you about the lower incisors?

U1-NA

Nasion-A Point to the upper incisors

What landmark is this?

Tells you about the horizontal position of the upper incisors

What does the U1-NA (Nasion-A Point to the upper incisors) reference line tell you?

Protruded upper incisors

The normal value of the U1-NA is 4.3±2.7.

If the U1-NA value is GREATER than the normal value, what does this tell you about the upper incisors?

Retruded upper incisors

The normal value of the U1-NA is 4.3±2.7.

If the U1-NA value is LESS than the normal value, what does this tell you about the upper incisors?

Well positioned upper incisors

The normal value of the U1-NA is 4.3±2.7.

If the U1-NA value is within the limits of the normal value, what does this tell you about the upper incisors?

L1-NB

Nasion-B Point to the lower incisors

What landmark is this?

Tells you about the horizontal position of the lower incisors

L1-NB (Nasion-B Point to the lower incisors) what does this reference line tell you?

positive

U1-NA-->

If U1 is anterior to NA, the measurement is _____

negative

U1-NA-->

If U1 is posterior to NA, the measurement is _____

postive

L1-NB

If the L1 is anterior to NB, the measurement is _______

negative

L1-NB

If the L1 is posterior to NB. the measurement is _______