Quartz 4

Level II unit B unit self test

35 min read

Level II Diagnosis — Unit B Self-Test

Module 1: Facial Form Analysis

Question 1

Which of these are characteristic of skeletal Class II?

  1. Mandibular retrusion
  2. Increased overjet
  3. Long lower face height
  4. Excessive lip prominence
  5. Lip incompetence
  6. 1 and 2 ✓
  7. 3 and 4
  8. 1, 2, and 3
  9. 3, 4, and 5
  10. all the above

Correct

That’s right, mandibular retrusion and increased overjet are characteristic of skeletal Class II. The other three may or may not be present in a child with a skeletal Class II problem, and aren’t characteristic of skeletal Class II.

Question 2

Which of the following are characteristic of skeletal Class III?

  1. large mandible
  2. concave profile
  3. long lower face
  4. maxillary dental protrusion
  5. 1 and 2 ✓
  6. 3 and 4
  7. 1 and 4
  8. 1, 2, and 4
  9. all the above

Correct

That’s right, a large mandible and concave profile are characteristic of skeletal Class III. A long lower face and maxillary dental protrusion (dental compensation for the skeletal discrepancy) often also are present, but they aren’t characteristic of the skeletal problem.

Question 3

Which of the following soft tissue findings do not indicate bimaxillary dentoalveolar protrusion?

  1. lips more prominent than nasal tip
  2. lips touching at rest but forward from soft tissue points A & B
  3. lips separated at rest but not forward from soft tissue points A & B
  4. lips forward from soft tissue points A and B and separated at rest
  5. 1 and 2
  6. 3 and 4
  7. 1, 2, and 3 ✓
  8. 2, 3, and 4
  9. none of the above, they all indicate incisor protrusion

Correct

That’s right, the only correct statement is 4—1,2 and 3 do not indicate excessive incisor protrusion. Incisor protrusion is judged to be excessive only if the lips are forward from soft tissue points A and B and separated at rest. It would be unusual to have lips more prominent than the nasal tip that weren’t indicative of dental protrusion, but that could happen if the nose were small and the lips were large.

Question 4

To which of the following facial characteristics does steepness of the occlusal plane relate?

  1. anterior face height
  2. mandibular retrusion
  3. mandibular protrusion
  4. crowding of incisors
  5. protrusion of incisors
  6. 1 ✓
  7. 1 and 2
  8. 1, 2, and 3
  9. 3, 4, and 5
  10. none of the above

Correct

That’s right, anterior face height is the only one of these characteristics that correlates well with the mandibular plane angle. A steep mandibular plane angle usually is found in patients with excessive anterior face height (long face), and a flat mandibular plane angle usually accompanies a short face. But the mandibular plane angle doesn’t relate in a systematic way to the other characteristics. Note the dramatic difference in mandibular plane angle between a long face patient (left) and short face patient (right).

Question 5

Which of the following can judged in full face examination of a patient?

  1. upper face symmetry
  2. lower face symmetry
  3. vertical facial proportions
  4. relative mandibular protrusion
  5. lip protrusion
  6. 1 and 2
  7. 3 and 4
  8. 1, 2, and 3 ✓
  9. 3, 4, and 5
  10. all of the above

Correct

That’s correct. Upper and lower face symmetry and vertical facial proportions can evaluated from the full face (frontal) view, while mandibular protrusion and lip protrusion must be evaluated from the profile view.

Question 6

When the distance between soft tissue points A and B are considered, which of the following are within the limits of Class I, skeletal normal?

  1. 6 mm
  2. 4 mm
  3. 2 mm
  4. 0 mm
  5. -2 mm
  6. 1 and 2
  7. 3 and 4
  8. 2, 3, and 4
  9. 3, 4, and 5
  10. all of the above ✓

Correct

That’s right, all of these measurements are within the limits of normal, which extend from 6 to -2 mm. Judged from soft tissue landmarks, skeletal Class II is >6 mm, and skeletal Class III is >-2 mm.

Question 7

In which of the following orthodontic clinical conditions would the patient’s facial form play a major role in the ultimate treatment plan?

  1. jaw asymmetry
  2. crowded lower incisors
  3. anterior open bite
  4. spaced and protruding upper incisors
  5. 1 and 2
  6. 3 and 4
  7. 1, 2, and 3
  8. all of the above ✓
  9. none of the above

Correct

That’s right, in all of these conditions the treatment plan would depend in large measure on facial form analysis; that is, the treatment plan easily could be different for identical malocclusions for patients with different facial proportions.

Question 8

Which of the following correctly describe the relationship between facial proportions, esthetics and beauty?

  1. Faces with more than moderate disproportions are judged unesthetic
  2. Perfect symmetry is highly associated with beauty
  3. Proportional faces are judged esthetically acceptable under almost all circumstances
  4. If the lips are competent, dental protrusion is considered highly unesthetic
  5. 1 and 2
  6. 2 and 3
  7. 1 and 3 ✓
  8. 2, 3, and 4
  9. all of the above

Correct

That’s right, statements 1 and 3 are correct, 2 and 4 are not. Major facial disproportions (more than moderate disproportions) are considered unesthetic. To draw an unesthetic face, the artist always alters the normal facial proportions. Proportional faces are almost always considered esthetically acceptable, though they may not be considered beautiful. Beautiful faces have slight asymmetries—perfectly symmetrical faces (or dentitions) have an unnatural look. Dental protrusion is not an esthetic problem until excessive lip separation at rest (lip incompetence) occurs.

Question 9

What is meant by the term “orthodontic triage”? It is a way of sorting patients by: (choose the ONE best answer)

  1. Skeletal vs dental problems
  2. retrusive-normal-protrusive lip positions
  3. the degree of mandibular protrusion, from Class II –ClassI-Class III
  4. the severity of their problems and their prognosis ✓

Correct

That’s right, triage refers to the process of sorting patients by the severity of their problems. The word comes from the French “trier” (to sort), and it was first used in medicine to refer to sorting casualties during battle based on priority of treatment. A similar process is used to screen orthodontic patients, separating out those with severe problems that would require complex and prolonged treatment from those with moderate problems that would respond to simpler and shorter treatment procedures. Facial form analysis is a key procedure in orthodontic triage.

Question 10

Which of the following are more likely to be seen in a patient with a purely dental malocclusion than ina patient with a skeletal discrepancy?

  1. bimaxillary dentoalveolar protrusion
  2. excessive lip separation at rest
  3. anterior deep bite
  4. dentoalveolar asymmetry
  5. 1 only ✓
  6. 1 and 2
  7. 1 and 3
  8. 1, 2, and 4
  9. all the above

Correct

That’s right, bimaxillary dentoalveolar protrusion is most likely to be seen in a patient with only dental discrepancies, although it is seen occasionally in skeletal Class II patients. All three of the other characteristics can occur in a patient with no skeletal discrepancies, but are more likely in patients with skeletal discrepancies. Excessive lip separation at rest is most likely in a long face patient whose mandible has rotated down and back; anterior deep bite is most likely in a short face patient; and dentoalveolar asymmetry is more likely when there also is a jaw discrepancy than in a patient with no skeletal problem.

Module 2: Cephalometric Tracing Techniques

Question 1

Which of the following are ways that typical American and European cephs differ?

  1. direction in which the patient faces
  2. vertical orientation of the head
  3. distance from x-ray source to patient
  4. positioning of the ear rods
  5. 1 and 2
  6. 2 and 3
  7. 3 and 4
  8. 1 and 3 ✓
  9. 2 and 4

Correct

That’s right, the direction in which the patient faces (nose to the right in America, to the left in Europe) and the distance from the x-ray source to the patient (greater in Europe) are different. The vertical orientation of the head and the positioning of the ear rods are the same.

Question 2

(A) The major goal of cephalometric analysis is to establish the relationship of the teeth of each jaw to that jaw because (B) correcting these relationships is the primary objective of orthodontic treatment.

  1. A true, B true, A and B related
  2. A true, B true, A and B not related
  3. A true, B false
  4. A false, B true
  5. A and B false ✓

Correct

You’re correct, both statements are false. Establishing the relationship of the teeth to their jaw is one goal of cephalometric analysis, but establishing the relationship of the jaws to the cranial base and to each other also are important goals of the analysis. Correcting the patient’s malocclusion in a way that provides maximum benefit to the patient is the primary objective of orthodontic treatment—the relationship of the teeth to their jaw is just one thing to be considered relative to that primary objective.

Question 3

(A) Creating an image like a lateral ceph from a cone-beam CT image is impossible because (B) the amount of information in a CBCT image is much greater than the information in a standard ceph.

  1. A true, B true, A and B related
  2. A true, B true, A and B not related
  3. A true, B false
  4. A false, B true ✓
  5. A and B false

Correct

That’s correct. The first statement is false—it’s quite possible to produce a “synthetic ceph” from CBCT data—but the second one is true. A CBCT file indeed has much more information than is found in a standard ceph.

Question 4

Why is orienting the patient so the Frankfort plane is level, now the preferred method for taking a ceph?

  1. reproducibility
  2. allows comparison with craniometric data
  3. allows comparison with anthropometric data
  4. correlates with NHP
  5. it isn’t, NHP is preferred ✓

Correct

That’s correct, NHP is preferred in modern cephalometric technique. Although the Frankfort plane correlates with the natural head position, and is the best way to orient your patient if he’s dead, NHP gives you the patient’s real head position in life.

Question 5

Which of the following are characteristics of a good cephalometric landmark?

  1. marks the position of specific teeth
  2. relates the position of a tooth to the jaw
  3. can be identified accurately on a ceph
  4. represents a known part of one of the major functional units
  5. 1 and 2
  6. 2 and 3
  7. 3 and 4 ✓
  8. 1 and 3
  9. 2 and 4

Correct

That’s correct, a good cephalometric landmark can be identified accurately on a ceph, and represents a known part of one of the major functional units. Landmarks aren’t restricted to the teeth, and no single landmark can relate one thing to another.

Question 6

Which landmark is found at the junction of the fronto-nasal suture?

  1. Sella
  2. Nasion ✓
  3. Pogonion
  4. Gonion
  5. Menton

Correct

That’s correct, it’s nasion. Nasion is defined as the anterior point of intersection of the nasal bone and frontal bones, which of course is the fronto-nasal suture. It represents the anterior end of the cranial base and is a key point in establishing the length and inclination of the cranial base.

Question 7

Which landmark is at the base of the contour above the chin?

  1. point B ✓
  2. pogonion
  3. gnathion
  4. menton
  5. gonion

Correct

That’s right, it’s point B. Point B indicates the anterior part of the bony base of the mandibular dentition, and is located at the innermost point on the contour of the mandible between the incisor tooth and bony chin.

Question 8

How do you locate the landmark S (sella)?

  1. junction of anterior and posterior clinoid processes
  2. 5 mm distal from anterior wall of depression in sphenoid bone
  3. 5 mm mesial from posterior wall of depression in sphenoid bone
  4. center of the space created by the depression in the sphenoid bone ✓
  5. junction of ethmoid and frontal bones

Correct

That’s right, the point S is the center of the space (called sella turcica) created by the depression in the sphenoid bone in which the pituitary gland is located. The normal variations in the shape of sella turcica make it impossible to be consistent in measurements based on the position of the bony constituents of this region, but the center of the space can be located with acceptable accuracy.

Question 9

How do you find the landmark PNS?

  1. trace the superior and inferior surfaces of the anterior nasal spine and mark its tip
  2. follow the external contour of the maxilla downward toward the upper incisor, and mark the depth of this concave line
  3. trace posteriorly along the roof of the mouth to the end of the bony outline, and mark the end of the palatal bone contour ✓
  4. trace anteriorly along the base of the nose, and mark the height of contour
  5. trace the bony chin, following the external contour of the bone upward toward the incisor, and mark the depth of this concave line

Correct

That’s right, PNS is located at the posterior end of the palate, and is best located by tracing posteriorly along the roof of the mouth to the end of the bony contour.

Question 10

(A) Creating a digital model of a ceph instead of a tracing requires more landmarks because (B) otherwise there is not enough information for the computer to add the lines needed to simulate a tracing.

  1. A true, B true, A and B related ✓
  2. A true, B true, A and B not related
  3. A true, B false
  4. A false, B true
  5. A and B false

Correct

That’s right, the statements are true and related. In digitization, additional landmarks are need to outline the cranial base, add the soft tissue profile, and refine the display of the maxilla, mandible and teeth.

Question 11

Which of the following lines is not used in establishing vertical facial proportions?

  1. S-N
  2. N-Me ✓
  3. ANS-PNS
  4. occlusal plane
  5. Go-Gn

Correct

That’s right, N-Me is a measure of face height, but it’s not used to establish vertical proportions. The orientation of the other 4 lines to each other does help to establish vertical proportions.

Question 12

Which of the following statements usually would not correctly describe a patient with a long face?

  1. open bite
  2. maxilla rotated down anteriorly ✓
  3. mandible rotated down anteriorly
  4. increased anterior face height
  5. they’re all correct

Correct

That’s right, in a long face patient the maxilla is much more likely to be rotated down posteriorly rather than anteriorly, but the other characteristics are present. Note that the tracing for this severe long face patient shows the palatal plane almost parallel to the true horizontal line, so there’s no maxillary rotation at all for him.

Question 13

Which of the following measurements would be most useful in establshing the a-p position of the mandible relative to the cranial base?

  1. SNA
  2. SNB ✓
  3. ANB
  4. Gonial angle
  5. N-Me distance

Correct

That’s correct, of these chacteristics SNB would be the most useful in establishing the a-p position of the mandible relative to the cranial base.

Question 14

To compare whether an upper incisor had erupted too much, which of the following characteristics would be most useful?

  1. Max incisor-SN angle
  2. distance from incisal edge to NA line
  3. distance from incisal edge to ANS-PNS line
  4. Max incisor-palatal plane angle
  5. distance from root apex to ANS-PNS line ✓

Correct

That’s right, the distance from the root apex to the palatal plane (ANS-PNS line) would be the best indicator of excessive eruption of the upper incisor. For the lower incisor it would be the distance of the root apex from the mandibular plane (Go-Gn). Angular measurements wouldn’t work, and the distance from the root apex is a better indicator than distance from the incisal edge.

Module 3: Cephalometric Superimposition

Question 1

What is the major purpose of preparing cephalometric tracings so that they can then be superimposed?

  1. allows multiple registrations
  2. makes it possible to observe growth changes
  3. makes it possible to observe treatment changes
  4. makes landmarks visible
  5. reduces the amount of information that is displayed ✓

Correct

That’s right, the major purpose is the reduce the amount of information to a manageable level. If you try to superimpose the two cephs themselves, almost everything becomes just a blur. The other things listed as possible answers are a function of the information reduction produced by making tracings.

Question 2

(A) Cranial base superimpositions are on the S-N line registered at N because (B) N does grow forward relative to the central part of the cranial base.

  1. A true, B true, A and B related
  2. A true, B true, A and B not related
  3. A true, B false
  4. A false, B true ✓
  5. A and B false

Correct

That’s right, the first statement is false but the second one is true. The cranial base superimposition is on the S-N line at S, so that forward growth of nasion will not affect the apparent forward growth of the facial structures below it.

Question 3

What would be the apparent effect on facial growth of superimposing on the posterior part of the cranial base and registering on a point there that was distal to and below S (Basion, for example)?

  1. make growth look more forward and less downward ✓
  2. make growth look less forward and more downward
  3. make it look like less facial growth occurred
  4. make it look like the face grew upward and not forward at all
  5. effect would be unpredictable because the posterior cranial base grows away from S

Correct

That’s right, the effect would be to make the facial growth look more forward and less downward, because the registration point would be below S. Sometimes you will see superimpositions on the Ba-N line registered at Ba or other lower points, especially if the presenter wants to show how some type of treatment made the jaws grow forward.

Question 4

(A) In a mandibular superimposition you should superimpose posteriorly on the inferior alveolar canal instead of just using the mandibular plane (Go-Gn) because (B) Go can be significantly affected by surface remodeling.

  1. A true, B true, A and B related ✓
  2. A true, B true, A and B not related
  3. A true, B false
  4. A false, B true
  5. A and B false

Correct

That’s correct, the statements are true and related. As you learned previously, the surface of the mandible undergoes significant remodeling during growth. Studies based on implants in the mandible have shown that the best superimposition is on the lingual contour of the mandibular symphysis anteriorly (but changes in Gn relative to it usually are small), and on the inferior alveolar canal posteriorly, where changes in the location of Go can be surprisingly large. Note the changes in the position of Go in this superimposition.

Question 5

Which of the following are seen clearly in a maxillary superimposition?

  1. remodeling of the anterior palate
  2. upward or downward movement of PNS
  3. increase in distance of maxillary teeth from the palatal plane
  4. forward or backward movement of incisors relative to their supporting bone
  5. 1 and 2
  6. 2 and 3
  7. 3 and 4 ✓
  8. 1, 2, and 4
  9. all of the above

Correct

That’s correct, vertical or a-p movement of the teeth relative to the maxilla can be visualized in a maxillary superimposition, but you register on the lingual contour of the palate and keep the palatal plane (ANS-PNS) level, so changes in either of those cannot be seen.

Question 6

Which of the following could not be a correct interpretation of superimpositions from a patient being treated for a Class II problem?

  1. shortening of the body of the mandible
  2. transversel tipping of the maxillary incisors
  3. increase in mandibular plane angle
  4. downward growth of the maxilla
  5. 1 and 2 ✓
  6. 2 and 3
  7. 3 and 4
  8. 1, 2, and 4
  9. all of the above

Correct

That’s right, the mandible may not grow during a period of treatment, but shortening of the mandibular body would not occur, and of course you can’t see transverse movements of the incisors in a lateral ceph. An increase in the mandibular plane angle and downward growth of the maxilla are often observed.

Question 7

If the maxilla rotated down posteriorly during treatment, which of the following would you expect not to see in a set of cranial base, maxillary and mandibular superimpositions?

  1. downward-backward rotation of the mandible
  2. major retraction of the maxillary incisors
  3. increase in mandibular plane angle
  4. increase in anterior face height
  5. downward movement of the gonial angle area
  6. 1
  7. 2 ✓
  8. 3
  9. 4
  10. 5

Correct

That’s correct, retraction of the maxillary incisors almost surely would not be seen because the maxillary rotation would tend to move them anteriorly relative to the cranial base. Downward-backward rotation of the mandible, an increase in the mandibular plane angle, an increase in anterior face height, and downward movement of the gonial angle area all would be expected.

Question 8

Which of the following could not be correct interpretations of superimpositions from a patient being treated for a long face Class II problem with premolar extractions and Class II elastics?

  1. anterior displacement of the maxillary incisors
  2. forward growth of the mandible
  3. eruption of the first molars in both arches
  4. decrease in anterior face height
  5. 1 and 2
  6. 2 and 3
  7. 1 and 4 ✓
  8. 1, 2, and 4
  9. all of the above

Correct

That’s right, anterior displacement of the maxillary incisors and a decrease in anterior face height almost couldn’t happen with this treatment plan. The maxillary extractions and Class II elastics both would favor pulling the maxillary incisors back, and the elastics would elongate posterior teeth and prevent a decrease in anterior face height. Forward growth of the mandible and eruption of the first molars would be quite likely to occur.

Question 9

Which of the following are correct interpretations of these superimpositions from a patient being treated for a long face Class II problem?

  1. retraction of upper and lower incisors
  2. forward growth of the mandible
  3. downward and forward growth of the maxilla
  4. eruption of the first molars in both arches
  5. 1 and 2
  6. 2 and 3
  7. 3 and 4
  8. 1, 2, and 4 ✓
  9. all of the above

Correct

That’s right, the upper and lower incisors were retracted relative to the maxilla and mandible respectively, the mandible grew forward (and also downward), and the first molars erupted in both arches—but the position of the maxilla was quite stable. It didn’t grow downward and forward as might have been expected.

Question 10

For this patient being treated for a Class III problem, which of the following is not a correct interpretation of the superimpositions?

  1. forward movement of the maxilla
  2. forward displacement of the maxillary teeth relative to the maxilla ✓
  3. downward movement of the maxilla
  4. downward-backward rotation of the mandible
  5. stable position of mandibular teeth

Correct

That’s right, all of the other things happened, but the maxillary teeth did not move forward relative to the maxilla. For a patient like this one, moving the maxilla forward wthout displacing the maxillary teeth was a highly desirable outcome, because she had a skeletal maxillary deficiency. Rotating the mandible downward also moves the chin back, which helps to correct a forward position of the mandible (so long as face height does not increase too much).

Question 11

Which of the following are correct interpretations of this cranial base superimposition in a patient being treated for posterior crossbite with a maxillary expansion appliance?

  1. major transverse expansion occurred
  2. not possible to evaluate the crossbite correction
  3. vertical position of the maxillary molars maintained
  4. vertical position of the mandibular molars mainained
  5. 1 only
  6. 2 only
  7. 1 and 3
  8. 1, 3, and 4
  9. 2, 3, and 4 ✓

Correct

That’s right, the other 3 statements are correct, but it’s not possible to evaluate changes in the transverse plane of space in a lateral ceph, so there is no way to know from the ceph how much (if any) transverse expansion occurred.

Module 4: Space Analysis and Its Interpretation

Question 1

In doing a space analysis, what is the significance of observing a skeletal Class III relationship?

  1. incisor position assumption is violated ✓
  2. tooth size correlation assumption is violated
  3. molar repositioning assumption is violated
  4. no significance, it makes no difference to space

Correct

That’s right. In a Class III patient, as in a Class II patient, the incisor position is likely to change, thus changing the space available. Usually the lower incisor moves lingually in a child with a Class III growth pattern, decreasing the available space.

Question 2

In space analysis, how do you account for the change in first permanent molar position that may occur during the transition to the permanent dentition?

  1. measure the distance from lower buccal cusp to upper groove
  2. measure the distance from upper buccal cusp to lower groove ✓
  3. measure the size difference between upper and lower premolars
  4. subtract the average mesial movement from space available

Correct

That’s right, the correct procedure is to measure the distance the lower molar would have to move forward to obtain a Class I relationship, which is the distance from upper buccal cusp to lower groove.

Question 3

Cephalometric analysis shows that in your patient, the lower lip is slightly behind the E line. Your interpretation is

  1. slight protrusion
  2. normal lip position ✓
  3. slight retrusion
  4. severe retrusion, the lip should be in front of the E line

Correct

That’s right. The lower lip normally is slightly behind the E line, although the E line can be affected by the size of the nose or chin and should not be the sole judge of lip position.

Question 4

Why do prediction tables based on tooth size correlations work better for Caucasian than other population groups?

  1. Caucasian teeth are more predictable
  2. upper lateral incisor variation is less in Caucasians
  3. lower premolars are extremely variable in Orientals
  4. published tables are based largely on data from Caucasians ✓

Correct

That’s right. There’s no reason to think that the teeth of other racial groups are less predictable, but the size relationships are somewhat different. Ideally, a prediction table would be available for each specific population group, but these specialized tables simply don’t exist.

Question 5

In space analysis, why is the prediction formula different for the maxillary and mandibular teeth?

  1. it isn’t, the same formula works
  2. different formula required because the correlation coefficients are different for the two arches
  3. different formula required because the correlations are different for the two arches ✓
  4. different formula required because the method is different for the upper from the lower arch

Correct

That’s right; the correlations themselves are different even though the method and the correlation coefficients are the same.

Question 6

During the mixed dentition, which is the preferred method of measuring space available for the permanent teeth?

  1. measure the width of each tooth individually and sum the numbers
  2. measure the intercanine and intermolar widths and sum the numbers
  3. form a wire to the ideal catenary curve and measure its perimeter
  4. measure the length of arch segments from first molar to first molar ✓

Correct

That’s right, measuring the length of arch segments is preferred. A catenary curve from molar to molar is another possibility but is probably less accurate. Intermolar and intercanine widths cannot provide space available, which is a perimeter measurement. Measuring the teeth individually isn’t possible until they erupt and would give you space required, not space available.

Question 7

In doing a space analysis, what is the significance of observing a skeletal Class II relationship?

  1. incisor position assumption is violated ✓
  2. tooth size correlation assumption is violated
  3. molar repositioning assumption is violated
  4. no significance, it makes no difference to space

Correct

That’s right. In a Class II patient, the incisor position is likely to change, thus changing the space available. Usually the lower incisor moves facially in a child with a Class II growth pattern.

Question 8

Which of the following is not a frequent cause of error in space analysis?

  1. inaccurate measurements of space available
  2. inaccurate measurement of incisor width
  3. incorrectly trimmed dental casts
  4. they’re all important causes of error ✓

Correct

That’s right; they’re all important causes of error.

Question 9

Which of the following is not a valid method for calculating the space required for the unerupted permanent teeth?

  1. radiographic evaluation
  2. tooth size correlation
  3. jaw size-tooth size correlation ✓
  4. radiographic plus tooth size correlation

Correct

That is correct. Jaw size-tooth size correlation is not a valid way to predict how much space is required, but the others are valid methods.

Question 10

If your patient has protrusive lips as judged from facial form analysis, how would that affect your interpretation of space analysis results?

  1. patient has more space than the analysis indicators
  2. patient has less space than the analysis indicates ✓
  3. space may increase as incisor becomes more protrusive
  4. space may increase as molar moves forward less than it would otherwise

Correct

That’s right. In a child with protrusive incisors, space analysis tends to overestimate the amount of space, because some space may be needed to reduce the protrusion.

Question 11

Which of the following is not a factor to consider in interpreting the results of space analysis?

  1. skeletal classification
  2. dental classification
  3. incisor position
  4. dental arch growth ✓
  5. they all must be considered

Correct

That’s right. A valid assumption of the mixed dentition analysis is that there is no significant growth of the dental arches anterior to the mesial of the first permanent molars, so growth in this area does not have to be considered. Skeletal classification, dental classification and incisor position are all key variables in mixed dentition analysis.

Question 12

Which of the following is a way that Class I molars are achieved in a child who is skeletally Class I but has flush terminal plane primary molars?

  1. distal shift of the upper molar
  2. mesial shift of the lower molar ✓
  3. differential forward growth of the upper jaw
  4. restriction of mandibular growth

Correct

That’s right, mesial shift of the lower molar, due to tooth movement and/or differential forward growth of the lower jaw, is the only one of these items that could lead to achievement of Class I molars. Upper molars don’t shift distally during normal development, and both forward growth of the upper jaw and restriction of mandibular growth would make things worse, not better.

Question 13

(A) The size of the unerupted mandibular canine and premolars can be established better from the size of the maxillary than the mandibular incisors because (B) there is an excellent correlation between the size of the upper incisors and the lower canines/premolars.

  1. A true, B true, A and B related
  2. A true, B true, A and B not related
  3. A true, B false
  4. A false, B true
  5. A and B false ✓

Correct

That’s correct, both statements are false. There isn’t a good correlation between the size of upper incisors and other teeth because upper lateral incisors are so variable in size. That’s why the size of both upper and lower canines/premolars can be estimated better from the size of the lower incisors.

Question 14

(A) During the mixed dentition, space available for the permanent teeth often is less than the space required because (B) the primary incisors are significantly smaller than the permanent incisors that replace them.

  1. A true, B true, A and B related
  2. A true, B true, A and B not related ✓
  3. A true, B false
  4. A false, B true
  5. A and B false

Correct

That’s right, both statements are true but they’re not related. Crowding has multiple causes, and the size difference between primary and permanent incisors is not a major one.

Question 15

Which of the following is not a key assumption in mixed dentition space analysis?

  1. There is a high correlation between the size of anterior and posterior teeth.
  2. Jaw growth occurs primarily in the tooth bearing area of the jaws. ✓
  3. The patient fits the reference population group.
  4. The incisors will not move facially or lingually during further growth.
  5. Repositioning of the molars during the premolar exchange is predictable.

Correct

That’s right, the key assumption is that jaw growth does not occur in the tooth bearing areas of the jaw, so the statement that it does is incorrect.

Question 16

What is suggested by a unilateral Class II molar relationship in a child who is skeletal Class I?

  1. loss of space in the upper arch ✓
  2. loss of space in the lower arch
  3. Class III growth pattern with uprighting of the lower incisors
  4. eruption along a wider perimeter

Correct

That’s right, a Class II molar on one side in a child who is skeletal Class I suggests space loss in the upper arch.

Module 5: Ackerman-Proffit Classification

Question 1

(A) The Angle classification ignored the possibility of excessive protrusion of the teeth that compromised esthetics because (B) Angle believed that everyone had the potential to have 32 teeth in ideal occlusion without an esthetic problem.

  1. A true, B true, A and B related ✓
  2. A true, B true, A and B not related
  3. A true, B false
  4. A false, B true
  5. A and B false

Correct

That is correct. Angle strongly opposed the extraction of teeth for orthodontic purposes, and justified the protrusion that aligning crowded teeth could produce by insisting that the patient looked best that way, whatever they might think.

Question 2

Which of the following terms are inappropriate to use within the original Angle classification system?

  1. incisor crowding
  2. deep bite
  3. posterior crossbite
  4. skeletal Class III
  5. 1 and 2
  6. 3 and 4
  7. 1, 2, and 3
  8. 2, 3, and 4 ✓
  9. all the above

Correct

That’s right. The Angle system recognizes incisor crowding as a deviation of tooth position from the line of occlusion, but does not include descriptions of vertical, transverse or skeletal relationships.

Question 3

How does the addition of protrusion to the characteristics considered in classification affect the way crowding is measured?

  1. requires lip prominence to be considered
  2. requires cephalometric analysis
  3. requires adjustment of arch length discrepancy
  4. 1 and 2
  5. 2 and 3
  6. 1 and 3
  7. all the above
  8. none of the above ✓

Correct

That’s right, adding a consideration of protrusion to the classification system has no effect on how the amount of crowding is measured. The effect is on the interpretation of arch length deficiency or spacing, not on how the space analysis itself.

Question 4

Which of the following characteristics of malocclusion would be most likely to be associated with a pitch of the maxilla down posteriorly?

  1. anterior open bite ✓
  2. anterior deep bite
  3. posterior crossbite
  4. posterior open bite
  5. all are equally possible

Correct

That’s right, if the maxilla is pitched down posteriorly, the mandible also is likely to rotate down and back, and anterior open bite is likely. Pitch is not related to crossbite. Pitch in the other direction would be associated with anterior deep bite, and perhaps (though that is unlikely) with posterior open bite.

Question 5

(A) The Ackerman-Proffit classification scheme uses five characteristics of malocclusion because (B) the five-characteristic scheme is quite compatible with computer data base management and computerized diagnosis.

  1. A true, B true, A and B related
  2. A true, B true, A and B not related ✓
  3. A true, B false
  4. A false, B true
  5. A and B false

Correct

That’s correct, both statements are true but they have no cause-effect relationship. Five characteristics are the smallest number that allow a complete description of the malocclusion. Almost any scheme could be used in a computer data base.

Question 6

Which of the following types of malocclusion is most likely to be associated with a roll of the maxilla to the left?

  1. posterior crossbite
  2. anterior deep bite
  3. anterior open bite
  4. crowded incisors
  5. all are equally likely ✓

Correct

That is correct. A roll discrepancy is perceived as a tilt of the dentition relative to the inter-commisure and inter-ocular lines, but does not necessarily affect the dental occlusion at all, i.e., a patient with a roll to the left could have ideal occlusion as perceived from examination of dental casts (unless they were carefully oriented on an articulator). The patient also could have any type of malocclusion, depending on factors other than the roll.

Question 7

What is the greatest risk of an inadequate classification that confuses analogous and homologous patients?

  1. important aspect overlooked
  2. esthetic outcome jeopardized
  3. risk of not obtaining ideal occlusion
  4. improper treatment plan ✓
  5. they’re all equally important risks

Correct

That’s right, the greatest risk of a classification that confuses analogous with homologous problems is that an improper treatment plan will be selected. The improper treatment plan could relate to any or all the other risks listed here.

Question 8

In the first step in Ackerman-Proffit classification, which of the following are major items for evaluation?

  1. facial proportions
  2. tooth-lip relationships
  3. occlusal relationships
  4. skeletal vs dental relationships
  5. 1 and 2 ✓
  6. 2 and 3
  7. 3 and 4
  8. 1, 2, and 4
  9. all the above

Correct

That’s right. The first step is to consider facial proportions and tooth-lip relationships. Occlusal relationships and skeletal vs. dental relationships are considered in steps 3-5, using both clinical and radiographic data.

Question 9

Which of the following is not a possible explanation of Class I molars in a child who has excessive face height?

  1. distal position of the maxilla
  2. mesial shift of the lower molar
  3. large mandible
  4. excessive eruption of the maxillary teeth ✓

Correct

That’s right, excessive eruption of the upper teeth would not compensate for the excess face height and downward-backward rotation of the mandible, but the other three things could.

Question 10

Which of the following is most likely to be associated with anterior open bite?

  1. increased distance from nose to upper incisor
  2. increased distance from lower lip to chin
  3. increased distance from nose to chin ✓
  4. increased distance from condyle to chin

Correct

That’s right, if anterior face height is increased, it is likely that the patient will have anterior open bite. An increased distance from nose to upper incisor, indicating excessive eruption of the maxillary anterior teeth, would decrease the chance of open bite. The other two are not related to open bite.

Question 11

On clinical examination, in assessing whether incisor protrusion is excessive, exactly what do you look for?

  1. protrusion of the upper incisor relative to the lower
  2. protrusion of the upper incisor relative to the maxilla
  3. protrusion of the lower incisor relative to the mandible
  4. protrusion of the lips
  5. separation of the lips at rest
  6. 1 only
  7. 2 and 3
  8. 4 and 5 ✓
  9. 2, 3, 4, 5
  10. all of the above

Correct

That’s right, the lips are the key to judging whether incisor protrusion is excessive. Incisor protrusion is measured by the relationship of the upper incisor to the maxilla and the lower incisor to the mandible, but the judgment as to whether this amount of protrusion is excessive is based on whether the lips are both protruded and separated at rest so that they are strained when brought together.

Question 12

What is the characteristic that would be most useful in distinguishing a skeletal from a dental posterior crossbite?

  1. transverse relationship of upper to lower molar
  2. maxillary intermolar width
  3. mandibular intermolar width
  4. width of palatal vault ✓
  5. width of gonial angles

Correct

That’s right. The key measurement for assessment of skeletal crossbite is the width of the maxilla at the height of the palatal vault, which often is narrow. The width of the gonial angles is less relevant because it’s not as closely related to the dental occlusion. Intermolar width tells you nothing about whether a crossbite is skeletal or dental.

Question 13

Which of the following is least likely to produce Class II malocclusion?

  1. maxillary dentition positioned upward relative to maxilla ✓
  2. maxillary dentition positioned anteriorly relative to maxilla
  3. maxilla positioned anteriorly relative to cranial base
  4. mandible retrusive relative to cranial base
  5. mandibular dentition retrusive relative to mandible

Correct

That’s right, moving the maxillary teeth upward relative to the maxilla tends to produce Class III, not Class II malocclusion because the mandible would rotate up and forward. All the other relationships increase the tendency toward Class II.

Question 14

Which of the following are characteristics of skeletal deep bite?

  1. excessive vertical overlap of the upper and lower incisors
  2. short posterior face height
  3. short anterior face height
  4. low mandibular plane angle
  5. 1 and 2
  6. 1 and 3
  7. 2 and 3
  8. 3 and 4 ✓
  9. 1, 3, and 4

Correct

That’s right. Short anterior face height and a low mandibular plane angle are characteristics of skeletal deep bite. Long, not short posterior face height is the skeletal characteristic, and of course the dental relationship is irrelevant in determining the skeletal condition. That’s true even though too much vertical overlap of the incisors is likely in a patient with a skeletal deep bite jaw relationship.

Question 15

Which of the following is least likely to produce a Class III malocclusion?

  1. maxillary dentition posteriorly positioned relative to maxilla
  2. maxilla posteriorly positioned relative to cranial base
  3. mandibular dentition anteriorly positioned relative to mandible
  4. mandible prominent relative to cranial base
  5. mandible rotated to steep mandibular plane angle ✓

Correct

That’s right, rotation of the mandible downward and backward decreases the its prominence in the a-p plane of space, and is more associated with Class II than Class III malocclusion. The other relationships increase the tendency toward Class III.

Question 16

Which of the following are likely to be noted in a patient with a severe yaw of the maxillary dentition to the right?

  1. maxillary midline to the right of the facial midline
  2. buccal posterior crossbite on the right
  3. Class II molar relationship on the left
  4. anterior open bite
  5. 1 and 2
  6. 3 and 4
  7. 1, 2, and 3 ✓
  8. 1, 2, and 4
  9. all the above

Correct

That’s right. A severe yaw to the right definitely would bring the maxillary midline to the right, and is likely to produce buccal crossbite on the right and a Class II molar relationship on the left side as the dentition is rotated forward on that side. Anterior open bite is not related to yaw.

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