Ortho level 2 unit B module 1 and 2

Question 1

What is normal face asymmetry?

Answer 1

In most people the right side of the face is slightly larger than the left side.

Question 2

When is an asymmetry noticed by people?

Answer 2

When it deviates about 3mm from the midline.

Question 3

How are transverse facial proportions evaluated?

Answer 3

They are divided into a central region and 2 lateral regions on each side. thie 5 regions are usually about the same width.

Question 4

What are the features of a well-proportioned face?

Answer 4

Distance between the eyes is the same as the width of the eye.

Width of the nose is about the same as the distance between the eyes.

Width of the mouth is equal to the interpupillary distance.

Width of the mandible at the gonial angles equals the width across the eyes.

Question 5

How are vertical facial proportions evaluated?

Answer 5

They are seen in both the frontal and lateral views.

3 vertical regions:

Harline to bridge of the nose

Bridge of the nose to the bottom of the nose

Bottom of the nose to the chin. This is further divided into base of nose to mouth, upper to lower part of the mouth, and mouth to the lower chin is the third part.

Question 6

What are the features of good vertical face proportion?

Answer 6

The medieval artists (da Vinci, Durer) who wrote the guidelines for drawing the human face expected the three regions to be the same size. In modern populations the lower third of the face usually is a little (but only a little) longer.

Question 7

What is the ideal anterior tooth display at rest?

Answer 7

At rest, it can be 0 but usually is 2 - 4mm., more in younger children than older ones and less or zero in adults.

Question 8

What is the ideal anterior tooth display when smiling?

Answer 8

100% exposure of the maxillary incisors and possibly a small amount of gingiva.

Minimum for best appearance is 75% exposure of the incisor.

Question 9

What should be noted about the posterior tooth display in a smile?

Answer 9

It is possible to see the maxillary posterior teeth and their relationship to the cheeks should be noted. There should be a small separation between the teeth and the cheeks.

A wide buccal corridor detracts from the appearance of the smile and is an indication that widening the maxillary arch may be indicated in orthodontic treatment.

Question 10

What should the smile arc look like?

Answer 10

Curvature of the lower lip should relate to the contour of the maxillary dentition.

Question 11

Which soft tissue structures show the maxilla?

Answer 11

Base of the upper lip and the nose reflects the position of the anterior maxilla.

Question 12

What soft tissue structure shows the position of the upper incisor?

Answer 12

Position of the upper incisor determines the lip contour at the vermillion border

Question 13

What soft tissue structure shows the mandibular alveolar process?

Answer 13

The contour of the lower lip similarly reflects the contours of the mandibular alveolar process and may be affected by the upper teeth

Question 14

What does a short face/deep overbite look like?

Answer 14

Disproportionately short middle/lower third of the face.

Question 15

What does a long face/open bite look like?

Answer 15

Disproportionately long middle third of the face. Increased display of maxillary gingiva.

An easy way to detect downward-backward rotation of the mandible is to use a mirror handle to demonstrate the mandibular plane angle (image 4). The steeper the angle, the more likely it is that rotation has occurred.

Question 16

What are the critical questions to ask for facial form analysis?

Answer 16

What is the anteroposterior position of each jaw and how do the jaws relate to each other?

What are the vertical facial proportions, especially in the lower 1/3 of the face?

Is the face symmetric?

Are the upper incisors in the center of the face? Are the buccal corridors wide, normal or narrow?

Are the incisors correctly positioned vertically relative to the lips, so that incisor display is optimal?

Do the incisors provide proper lip support, or are they retrusive or protrusive?

Question 17

How is lip position related to inciosr position evaluated?

Answer 17

Lip position and incisor prominence are evaluated by viewing the profile with the patient’s lips relaxed and observing the position of the upper lip relative to a true vertical line through the concavity at the base of the upper lip.

The position of the lower lip is evaluated relative to a true vertical line through the bottom of the concavity between lip and chin.

Protrusive = anterior to the reference line

Retrusive posterior from the reference line.

Question 18

What does incompetent lips tell us about the tooth position?

Answer 18

If the lips are prominent, incompetent (separated at rest by more than 3-4 mm) and strained on closure, the anterior teeth are excessively protrusive.

Question 19

What are the advantages to using cephalometric radiographs for orthodontics?

Answer 19

The radiographic view makes it possible to directly view the relationship of the jaws to each other and to the cranial base.

Serial cephalometric radiographs make it possible to evaluate both growth changes and the response to treatment in a way that was not possible previously.

Question 20

How are cephalometric radiographs made in the US differ from the radiographs made in Europe?

Answer 20

Patients look to the right in the american ceph. Patient looks to the left in european ceph.

American radiograph is often more magnified because the x-ray source is closer. (important when considering serial radiographs)

Question 21

What information is important to see on a cephalometric radiograph?

Answer 21

The relationship of the cranium/cranial base to the jaws and the teeth to their own jaws.

Question 22

What are cephalometric radiographs compared to in the Down’s analysis?

Answer 22

The patient’s measurements are compared to normal values from cephs of a small group of individuals with ideal dental occlusion.

The “normal” values are obtained based on racial and ethnic group because the normal values change between these groups.

Templates are created from the data and the landmarks are superimposed on the patient’s cephalometric radiographs and this can be used for a diagnosis. This has been digitized and a computer program can be used to quickly generate as many linear and angular measurements as needed.

Question 23

What has digitizing cephalometric analysis done to tracings?

Answer 23

More landmarks are used.

Computer program can be used to quickly generate as many linear and angular measurements are desired.

Question 24

How are cephalometric radiographs standardized?

Answer 24

Patient is put into a headholder with ear rods which controls the distance from the x-ray source to the head and from the head to the imaging device. This also controls the a-p, veritcal, and transverse position of the head.

Getting the head level via the ear rods. Then this is arranged around the frankfurt plane which goes from the superior external auditory meatus and the inferior margin of the orbit.

Question 25

What are the 5 main structures with landmarks on them that are used for cephalometric analysis?

Answer 25

Cranial base

Maxilla

Mandible

Max/mand dentition

Question 26

What are the criteria that define a cephalometric landmark?

Answer 26

It can be identified accurately on a cephalometric film

It represents a known part of one of the five major functional units

Question 27

What are the landmarks for the cranial base?

Answer 27

The sella turcica and the nasion.

The sella turcica is on the posterior end of the cranial base whereas the nasion is the anterior end of the cranial base.

Question 28

Where is the nasion located?

Answer 28

At the anterior-superior point at the junction of the nasal and frontal bones.

Question 29

What are the landmarks for the maxilla?

Answer 29

Anterior nasal spine: Front end of the maxilla, and is located at the tip of the anterior nasal spine

Point A: Another landmark associated with the anterior maxilla, located at the innermost point of the contour of the premaxilla between the anterior nasal spine and the incisor tooth.

Posterior nasal spine: Indicates the posterior end of the maxilla, and is located at the tip of the posterior spine of the palatine bone, at the junction of the hard and soft palates

Question 30

What are the landmarks for the mandible?

Answer 30

5 important landmarks for the mandible:

Point B: Bony base of the mandibular dentition, located at the innermost point on the contour of the mandibular dentition. Between incisor tooth and the bony chin.

Pogonion: The most anterior point on the contour of the chin.

Menton: The most inferior point on the mandibular symphysis

Gnathion: The center of the inferior contour of the chin halfway between the pogonion and the menton

Gonion: Indicates the angle of the mandible, and is located at the center of the inferior contour of the mandibular angle.

Question 31

What are the landmarks of the max/mand dentition?

Answer 31

Upper incisor

Lower incisor

Upper molar (U6)

Lower molar (L6)

Question 32

How is landmark S traced?

Answer 32

Draw the contour of the bone including the concavity and the line along the floor of the anterior and posterior cranial base. It is in the middle of the concavity

Question 33

How is landmark N traced?

Answer 33

Draw a line that follows the outer surface of the nasal and frontal bones past the junction. Then draw a suture between the bones. Identify point Na as the place where these lines intersect.

Question 34

How is the ANS traced?

Answer 34

It is at the tip of the anterior nasal spine.

Question 35

How is point A traced?

Answer 35

It is the junction between the skeletal maxilla and the maxillary dentoalveolar process. It is the innermost contour of the premaxilla between the anterior nasal spine and the incisor.

Question 36

How is the PNS traced?

Answer 36

It is on the back end of the bony palate. The point where the hard palate ends and the soft palate begins.

Question 37

How is point B traced?

Answer 37

It is the junction between the skeletal mandible and the mandibular dentoalveolar process. It is the innermost contour of the anterior mandible between the incisor and the bony chin.

Tracing the contour of the mandibular symphysis allows it to be located easily as the innermost contour.

Question 38

How is pogonion found?

Answer 38

It is the most prominent point on the anterior chin.

Question 39

How is gnathion found?

Answer 39

Gnathion is the point on the anterior inferior contour of the chin halfway between pogonion and menton

Question 40

How is menton found?

Answer 40

Most inferior point on the bony chin.

Question 41

How is the mandibular gonial angle (gonion) traced?

Answer 41

Follow lower border of the mandible posteriorly and up the posterior surface of the ramus. Center of the curvature is the gonial angle point.

Mild asymmetry leads to 2 shadows of the lower border of the mandible and so trace both sides using a solid line for one and a dotted line for the other. Go is the midpoint between the 2 shadows.

In severe asymmetry measure both separately.

Question 42

How is the orbitale traced?

Answer 42

The most inferior point on the lower border of the orbit.

If both orbits can be seen separately trace Or as the midpoint between.

Question 43

What other structures can be traced in the mandible?

Answer 43

Inferior alveolar canal and the unerupted 3rd molar if present.

Question 44

How are the anterior teeth traced?

Answer 44

Locate accurately the facial surface of the crowns of the upper and lower incisors, the inclination of the roots of the incisors, and the position of the upper and lower first molars.

Orient your tooth template to accurately represent the axial inclination of the incisor and the position of the tooth’s facial surface. Then use the template to draw in the outline of the incisors.

Question 45

How are the posterior teeth traced?

Answer 45

Molars are bilateral structures and by convention we trace the tooth on the left side which is the side closest to the film when the radiograph was taken.

For the first molar first trace the sides of the second molar.

Question 46

How is soft tissue profile acheived and what is done with it?

Answer 46

Add outline of soft tissue profile from the bridge of the nose to the chin.

Question 47

How are soft tissue tracings used?

Answer 47

Adding reference lines

Making measurements

Superimposing it on another tracing.

Question 48

What landmarks would digitizing add to the tracing we do?

Answer 48

Points along the cranial base

Points to mark the posterior maxilla instead of just the orbital rim

A point at the mandibular condyle and another where the shadow of the zygomatic arch crosses the upper mandibular ramus

A series of points along the curvatures of the soft tissue profile

Additional points to define the incisor positions instead of just the tips

Points to mark the mesial and distal contact points of the molars.

Question 49

What are the 5 horizontal reference lines used in cephalometric analysis?

Answer 49

1: S-N line to show the inclination of the cranial base
2: true horizontal which is drawn perpendicular to the true vertical through the lower border of the orbit.
3: ANS - PNS palatal plane
4: Fucntional occlusal plane drawn along the occludign surfaces of the posterior teeth
5: Go-Gn, the mandibular plane

Question 50

What angle should the 5 reference lines used in cephalometric analysis have?

Answer 50

They should move towards a meeting point posteriorly

Question 51

How are antero-posterior jaw relationships investigated using point A and point B and the nasion?

Answer 51

A line is drawn down from the nasion and then point A and B are evaluated relative to it. Point A should be 2mm anterior to the nasion (0 - 4mm are ok). Point B should be 2mm behind the line downwards from the nasion with (-4 - 0mm are ok).

The difference between A and B should not be more than 4mm though.

Question 52

What landmarks and angles are used together to evaluate a-p relationships?

Answer 52

A N and B.

The ANB angle is smaller in patients with normal jaw relationships

S N A and B. The SNA and SNB angles could be measured to indicate whether the maxilla/mandible were in the wrong position.

Move the true vertical line to point A and examine the position of the upper incisors relative to the line. Same with point B for lower incisors. Ideally the incisor line should be slightly anterior.

Question 53

How far forward can lower incisors protrude relative to the mandible?

Answer 53

The lower incisor can be 2mm more forward than Pg but should not be a great deal more prominent than the chin.

Question 54

how is incisor angulation measured?

Answer 54

Maxillary incisors = their angle from the SN line.

Mandibular incisors = their angle from the Go-Gn line.