Unit Self-Test

Level IV Clinical Treatment — Unit C Self-Test

Module 1: Indications for Orthognathic Surgery

Question 1

What is the most frequently used orthognathic surgical procedure at present?

1. Sagittal split, mandibular ramus, advancement ✓
2. Sagittal split, mandibular ramus, setback
3. Mandibular lower border osteotomy, chin augmentation
4. LeFort I osteotomy, maxilla
5. Combined LeFort I osteotomy and sagittal split

Correct

That’s right, the sagittal split mandibular ramus osteotomy for advancement is the most frequently used procedure, simply because mandibular deficiency is the most prevalent problem requiring orthognathic surgery and almost all advancements now are done with a sagittal split. All the other procedures listed here are used routinely at present, however.

Question 2

How far can upper incisors be retracted to correct maxillary dental protrusion?

1. 3 mm
2. 5 mm
3. 7 mm ✓
4. 9 mm
5. 12 mm

Correct

That’s right, the general guideline is that protruding upper incisors can be retracted a maximum of about 7 mm in most circumstances. It’s unrealistic to think they can be retracted a lot more than that, but remember that the envelope of discrepancy provides guidelines. Don’t think that the numbers are precise predictions for individual patients.

Question 3

One approach to a skeletal Class II problem in early adolescence is growth modification. How much improvement in the jaw relationship can be reasonably expected?

1. 3 mm
2. 5 mm ✓
3. 7 mm
4. 9 mm
5. 12 mm

Correct

That’s right, the best estimate is 5 mm of skeletal change. Since the molar relationship must be changed 7 mm to change a typical Class II relationship to a normal Class I relationship, that means some tooth movement in addition to growth modification almost always is required to correct a skeletal Class II problem. Could you correct a 12-mm overjet with orthodontics alone? Perhaps, but with only 5 mm of skeletal change available, it would require 7-mm movement of the teeth.

Question 4

(A) The potential for orthodontic treatment of skeletal Class II problems decreases after adolescence because (B) Tooth movement is much less successful in adults than children, so the incisors can’t be retracted as far.

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 true but the second is false. The potential for orthodontic treatment decreases after adolescence because growth modification to significantly improve the jaw relationship is no longer possible. Tooth movement has about the same potential in adults as in younger patients.

Question 5

(A) More Class III than Class II patients require orthognathic surgery because (B) The position of the mandible can be changed much more with surgery than orthodontics.

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 aren’t related in a cause-and-effect sense. More Class III than Class II patients require surgery, not because surgery can move mandibles further but because both growth modification and tooth movement have less potential to correct Class III problems. Note in the envelopes that the maximum potential of orthodontic treatment for Class II patients is close to the maximum for stable surgical correction. The result: >90% of skeletal Class II patients can be treated with a combination of growth modification and tooth movement if the treatment starts during adolescence. Because the potential for orthodontic Class III treatment is smaller, probably the worst one-third of skeletal Class III patients need surgery for correction.

Question 6

Which of the following are contraindications for orthognathic surgery?

a. diabetes mellitus

b. severe periodontal disease

c. hemophilia

d. paranoid schizophrenia

1. all
2. a, c, and d
3. b, c, and d
4. c and d
5. none if controlled ✓

Correct

That’s right, patients with any of these pathologic conditions can have orthognathic surgery if the underlying condition has been brought under control by adequate treatment. Uncontrolled disease is a contraindication; controlled disease is not. Even hemophiliacs can have orthognathic surgery if the missing clotting factors are replaced, and for some hemophiliacs surgery under those controlled conditions is better patient management than prolonged orthodontic treatment.

Question 7

How do you determine whether orthodontic camouflage was successful?

1. Quantify the quality of the occlusion with PAR scores or a similar occlusal index
2. Evaluate TM joint function with Helkimo’s index or a similar quantitative method
3. Obtain scores on the psychological MMPI test
4. Ask the patient what he or she thinks ✓

Correct

That’s correct. What the patient thinks is the determinant of whether orthodontic camouflage was successful. If the patient thinks things look acceptable, psychosocial problems related to dental and facial appearance will largely disappear, and if the patient doesn’t think they look acceptable, there’s still a problem no matter how good the scores are for occlusion and TM joint function. Scores on psychological tests might provide details of what the psychosocial problem is, but that kind of testing is not necessary to know whether a problem still exists. The primary goal of treatment, after all, was to solve the patient’s problems.

Question 8

Which of the following is not an appropriate surgical approach to a skeletal Class II patient with mandibular deficiency?

1. Surgical retraction of the upper anterior teeth ✓
2. Mandibular advancement
3. Upward movement of the maxilla
4. Simultaneous combination of 2 and 3

Correct

That’s right, retracting the protruding teeth (surgery to do the same thing that orthodontic tooth movement would have accomplished) is not an appropriate surgical approach because it would probably result in a camouflage failure. Mandibular advancement is the solution to deficient mandibular growth. Moving the maxilla up allows the mandible to rotate upward and forward. This improves a skeletal Class II jaw relationship and is indicated, alone or in combination with mandibular advancement, in patients who had too much vertical maxillary growth. If necessary, simultaneous maxillary and mandibular surgery is quite feasible.

Question 9

(A) Computer image prediction is more successful in predicting the probable outcome of growth modification than surgery because (B) Facial changes accompanying growth are inherently more predictable than surgical movement of the jaws.

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 of these statements are false. The truth is just the opposite. Computer image predictions of surgical change are clinically useful, but they can be quite misleading for growing children because growth changes remain largely unpredictable. The effects of treatment in the absence of growth are predictable, and orthognathic surgery is done only after major growth changes are no longer likely.

Question 10

(A) Correcting a malocclusion may require surgery to keep from making a reasonably satisfactory pretreatment facial appearance unsatisfactory because (B) Tooth movement alone to correct the occlusion can make dental and facial esthetics worse.

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. Some patients with an underlying jaw discrepancy don’t have an unacceptable facial appearance before treatment, but they would be moved into the unacceptable category if the incisors were repositioned to bring them into proper occlusion. This girl’s facial appearance would have been damaged by retracting her upper incisors. Computer slide predictions can help patients understand the esthetic implications of treatment choices.

Module 2: Orthodontic Management of Patients with Cleft Lip and Palate

Question 1

A) Surgery to repair a cleft of the secondary palate causes a deficiency of the midface because B) During the surgery bone is placed in the hard palate to close the defect.

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 surgery to repair the palatal cleft involves lifting soft tissue flaps from the palatal halves and suturing the flaps in the midline. No bone is placed in the secondary palate during the repair. This surgery causes scarring of the tissues, which restricts the growth of the maxilla, thus a midfacial deficiency results. The extent of the scarring depends on the quality of the surgery—the less traumatic the surgery, the less the extent of midfacial deficiency.

Question 2

A) Alveolar bone grafting in the mixed dentition is always timed for the eruption of the lateral incisor because B) This tooth is most likely to be present near the cleft site.

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, an alveolar bone graft is generally timed for the eruption of the canine near the cleft site but may also be timed for the eruption of the lateral incisor, if present. Often, however, the lateral incisor near the cleft site is missing or so malformed that it requires extraction, so it is not the most likely tooth to be present near the cleft site.

Question 3

To ensure the proper timing of placement of the alveolar bone graft, it is important for the general dentist to refer a child with an alveolar cleft to the orthodontist at which of the following stages?

1. Soon after birth
2. Once the deciduous teeth have erupted
3. Just as the maxillary central incisors are erupting ✓
4. In the mixed dentition
5. In the permanent dentition

Correct

That’s right, a child with a cleft of the alveolus should be referred to the orthodontist just as the maxillary permanent central incisors are erupting. Referral at this time would ensure that the orthodontist has sufficient time to assess the child’s eruption status. The orthodontist will determine whether there is a viable lateral incisor near the cleft site that would require grafting at that time, or whether the graft could be placed later because the lateral is missing.

Question 4

A) Orthodontic treatment in the patient with a repaired cleft of the lip and palate is generally needed during the primary dentition because B) The collapsed maxillary arch must be expanded as early as possible to ensure stability.

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, generally it is a waste of time to start orthodontic treatment in the primary dentition. Expanding the maxillary arch at this time is not necessary and certainly will not ensure stability of the expansion. A retainer must be used to hold the expansion. An initial phase of orthodontics occurs in the early mixed dentition in conjunction with alveolar bone grafting. Then, there is a second phase of orthodontics once the permanent teeth erupt during adolescence.

Question 5

A) Palate repair in a patient with a cleft of the secondary palate should be delayed until at least age 2 because B) Delaying surgery to the secondary palate allows the tissues to mature and enhances the development of speech.

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 false. There is a trade-off between the speech pathologist versus the surgeon and orthodontist regarding the timing of palatal closure. The surgeon and orthodontist would like the surgery delayed to allow sufficient development and maturation of the hard and soft tissues to facilitate the surgical repair and decrease the chance of impaired maxillary growth; however, the surgery is not delayed until at least age 2 years. It is generally performed around one year of age. This is because surgical techniques have improved and the chance of growth problems have decreased. Delaying the surgery does not enhance the development of speech; in fact, speech development is enhanced the earlier the surgery is performed.

Question 6

Which one of the following statements is true about a presurgical infant orthopedic appliance?

1. It is primarily a feeding appliance.
2. It is used before palate repair to mold the maxillary arch.
3. It is used to enhance speech development.
4. It is a pinned appliance.
5. It is used before lip repair to mold the maxillary segments. ✓

Correct

That’s right, a presurgical infant orthopedic appliance is used to mold the maxillary cleft segments restoring symmetry to the arch before the lip is repaired. The appliance is made at the request of the surgeon, and after the lip is repaired, it is removed. It is not a feeding appliance. With proper instructions to the mother, the baby can feed effectively without an appliance. The orthopedic appliance does not enhance speech, and depending on the design, the appliance may or may not be pinned to the maxilla.

Question 7

A) The key to the obliteration of an alveolar cleft is to have the tooth near the cleft site erupt thorough the graft because B) An erupting tooth causes complete remodeling and replacement of bone in the area through which it erupts and this process provides the erupting tooth with sound periodontal support.

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, an alveolar cleft will be successfully obliterated when the tooth near the cleft site, for which the graft placement was timed, erupts through the grafted area and causes complete remodeling and replacement of bone. This eliminates the bony defect and provides the erupting tooth with sound periodontal support.

Question 8

Which of the following is the most likely speech problem to result from maxillary advancement surgery in a patient with a cleft palate?

1. Leakage of air through the nose (hypernasal speech) ✓
2. Labiodental articulation problems
3. Blockage of air passage through the nose—hyponasal speech
4. Lisping

Correct

That’s right, the most likely speech problem to result from maxillary advancement surgery in a patient with a cleft palate is leakage of air through the nose during speech, or hypernasal speech. This occurs because as the hard palate moves forward along with the rest of the maxilla, the soft palate is pulled forward and away from the pharyngeal wall, which requires greater movement of the soft palate and pharyngeal wall to prevent excess air flow through the nose. After surgery to repair a cleft, movement of the soft palate is restricted, and then moving it forward can lead to inappropriate leakage of air.

Question 9

A) For patients who have a cleft of the lip and/or palate the standard of care requires a team approach to the management of their care because B) Team treatment improves efficiency of care (patients do not have to visit several offices) and ensures coordinated 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

That’s right, the current standard of care for patients with a cleft of the lip and/or palate requires that a team approach to treatment is used with the various specialists on the team interacting together to ensure timely, efficient, and coordinated care for the patients. This is important because of the many different treatment needs of these patients.

Question 10

A) Orthognathic surgery for a patient with a repaired cleft of the lip and/or palate is timed for late adolescence when growth is essentially completed because B) The patient is more likely to tolerate surgical treatment at this time.

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, orthognathic surgery for a patient with a repaired cleft of the lip and/or palate is timed for late adolescence when growth is essentially completed because if the surgery is done earlier, before facial growth is completed, the outcome may be negated by later mandibular growth so that a second surgery would be required to correct the discrepancy. Tolerance for surgery is specific to the particular patient and may or may not be an age-related factor.

Module 3: The Best Time for Orthodontic Treatment

Question 1

Which of the following are important considerations in determining the effectiveness of orthodontic treatment?

a. PAR score

b. Appearance of teeth

c. Appearance of face

d. Duration of treatment

1. a and b
2. b and c
3. a, b, and c ✓
4. b, c, and d
5. all of the above

Correct

That’s right, both the quality of the dental occlusion (which can be summarized by the PAR score) and the appearance of the teeth and face are important considerations in determining the effectiveness of treatment. No matter how perfect the dental occlusion, it’s not successful treatment if the patient’s dental and facial appearance isn’t esthetically acceptable. Treatment duration relates to efficiency, not effectiveness.

Question 2

Which of the following are part of the burden of treatment in orthodontics?

a. Posttreatment pain

b. Travel time to the office

c. Comments about having to wear braces

d. Interest on money borrowed to pay for treatment

1. a and b
2. b and c
3. a, b, and c
4. b, c, and d
5. all of the above ✓

Correct

That’s right, all the annoyances, inconveniences, and economic costs of treatment are part of its burden. The noneconomic costs of treatment have to be considered along with the monetary cost when treatment efficiency is evaluated.

Question 3

(A) The best time to stop preadolescent growth modification treatment is when the jaw relationship has been corrected because (B) Continuing treatment beyond that point would make things worse, not better.

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 these statements are false. No matter when it starts, the best time to stop growth modification treatment is toward the end of adolescent growth, when little growth remains. For a younger patient, unless treatment is continued, growth in the original pattern will wipe out much or all of the improvement.

Question 4

Which of the following are reasons why the adolescent growth spurt is the preferred time for most orthodontic treatment?

a. Crooked teeth are more apparent after all the permanent teeth erupt.

b. The rate of growth declines sharply after the adolescent spurt.

c. Only one stage of treatment is needed.

d. Adolescents are, in general, more cooperative than younger children.

1. a and b
2. b and c ✓
3. a, b, and c
4. b, c, and d
5. all of the above

Correct

That’s right, adolescent treatment is preferred because the rate of growth declines sharply after the adolescent spurt, which means that further growth will not undo the treatment effect, and only one stage of treatment is needed because the permanent teeth are available after adolescence. Both effects make the treatment most efficient then.

It’s true that crooked teeth are often more apparent after the maxillary canines erupt, but that isn’t a factor in the timing of treatment relative to adolescence. Unfortunately, adolescents often are less cooperative than younger children, so adolescent treatment generally is preferred in spite of this, not because of it.

Question 5

What is the major reason for delaying orthodontic treatment until after the adolescent growth spurt?

1. Unpredictable growth in a syndromic patient
2. Class II due to a long face condition
3. Class III due to mandibular excess ✓
4. Slowly erupting permanent teeth that aren’t available until later

Correct

That’s right, the major reason for delaying treatment is excessive mandibular growth, because this often continues well beyond the adolescent growth spurt and can cause relapse after adolescent treatment. The other conditions listed in this question might or might not lead to delayed treatment, but they aren’t the major reason for delay.

Question 6

Preadolescent expansion to correct dental crowding usually involves what sort of appliance?

1. Fixed jackscrew to widen the maxilla ✓
2. Lingual arch to move incisors forward
3. Functional appliance to hold mandible forward
4. Removable expanders to widen both arches
5. All of the above

Correct

That’s right, early expansion usually involves a jackscrew appliance to widen the upper arch by opening the midpalatal suture, which is followed later by a complete fixed appliance in both arches. A lingual arch is used much more to maintain space than to throw incisors forward. Functional appliances to guide growth are irrelevant in treatment of crowding/protrusion problems. Removable expanders are possible, but removable appliances to move teeth are so much less effective than fixed appliances that they are rarely used now.

Question 7

Which of the following criteria should a patient meet to become a candidate for serial extraction starting at age 8?

a. Lack of space for alignment of lateral incisors

b. >9 mm crowding in both arches

c. Normal facial proportions

d. Fixed appliance treatment available later

1. a and b
2. b and c
3. c and d
4. a, b, and c
5. all of the above ✓

Correct

That’s right, an 8-year-old child isn’t a candidate for serial extraction unless all these criteria are met. The rule on starting serial extraction, which usually involves extraction of primary canines so lateral incisors can erupt, is simple: “If in doubt, don’t!”

Early extraction of primary canines in a child who doesn’t meet the criteria can greatly complicate appropriate treatment later. But for the limited number of children who do meet all the criteria, serial extraction can be effective and reasonably efficient treatment. So once all doubt has been removed, it’s perfectly acceptable.

Question 8

In a patient with a moderate space discrepancy, which of the following are criteria for placement of a lingual arch to maintain space during the early mixed dentition?

a. Loss of primary molar to caries

b. Spontaneous loss of one or both primary canines

c. Posterior crossbite

d. Anterior open bite

1. a and b ✓
2. b and c
3. c and d
4. a, b, and c
5. All the above

Correct

That’s right. Early treatment, consisting of a lingual arch to maintain space, is needed for a child with moderate crowding who loses a primary molar to caries or one or both primary canines spontaneously (which can happen as the permanent laterals erupt). Neither posterior crossbite nor anterior open bite are indications for a lingual arch at an early age.

Question 9

Why is it recommended to start comprehensive (fixed appliance) treatment for Class I crowding/protrusion just before the second primary molars are lost?

1. The uncooperative phase of adolescence starts then.
2. The adolescent growth spurt usually occurs then.
3. Freeway space decreases at that point.
4. Leeway space is lost when the second primary molars are lost. ✓

Correct

That’s right. In patients with moderate crowding, maintaining the leeway space (the difference in size between second primary molars and second premolars) provides valuable space for aligning the other teeth, often enough that further arch expansion is unnecessary.

The growth spurt doesn’t affect the dentition. Uncooperative behavior isn’t a good answer to this question, even though it’s true that adolescence makes behavior less predictable and often less pleasant for authority figures (which includes the dentist, unfortunately). Freeway space (the difference between the intercuspal and postural positions of the mandible) doesn’t change when 2nd primary molars are lost.

Question 10

What percentage of the patients treated in the clinical trial of early vs late Class II treatment showed a favorable response, in terms of an improvement in the jaw relationship?

1. 25%
2. 50%
3. 75% ✓

4. 90% of those who cooperated

Correct

That’s right, about 75% of the children showed a highly favorable or favorable response, as evaluated by a reduction in the ANB angle that measures the difference in prominence of the upper and lower jaws.

There is no way to be sure precisely how cooperation influenced this number, except that it is not the only reason for failure to respond. You can’t take for granted that whatever the growth modification approach, it would have succeeded if the child had cooperated.

Question 11

In randomized clinical trials of early vs later Class II treatment, after comprehensive phase 2 treatment for both the previously treated and untreated children, how do the PAR scores compare?

1. Much lower in the previously treated group
2. A little lower in the previously treated group
3. About the same ✓
4. A little higher in the previously treated group
5. Much higher in the previously treated group

Correct

That’s right, after phase 2 treatment, PAR scores (which reflect how well the teeth are aligned and how well they fit together) were remarkably similar in the previously treated and untreated Class II children, both in mean scores and in the percentages with excellent/good/disappointing results. PAR scores are like golf scores, lower is better; so for all the groups, there was a similar improvement in occlusion with treatment.

Question 12

Which of the following now are considered valid reasons for early Class II treatment?

a. Unusually severe problems

b. Evidence of major social problems from teasing, etc.

c. Tissue damage from the bad bite

d. Maternal anxiety about waiting for treatment

1. a and b
2. b and c
3. c and d
4. a, b, and c ✓
5. all of the above

Correct

That’s right. Unusually severe problems, major social problems, and the presence of tissue damage from the malocclusion are now considered valid reasons for early Class II treatment. Maternal anxiety isn’t. Orthodontics as a form of psychotherapy for mothers is not good treatment for the mother or the child.

Question 13

Which of the following are problems with early treatment to restrain excessive mandibular growth?

a. Minimally effective

b. Any effect tends to be lost to continued growth

c. Treatment has to be continued until the late teens

d. Early orthognathic surgery is a better alternative

1. a and b
2. b and c
3. c and d
4. a, b, and c ✓
5. all of the above

Correct

That’s right, problems with early treatment to restrain excessive mandibular growth are that it’s minimally effective, doesn’t work very well. Any effects it does achieve tend to be lost to rebound growth unless the treatment is continued for a decade or more, well into the late teens, and even then it may not work.

But early orthognathic surgery isn’t a better alternative. Excessive growth is likely to continue even after surgery if it is done too soon, so the surgery has to wait, often until the late teens, until growth finally slows to adult levels.

Question 14

Why is it so important for a maxillary deficient child to start treatment early?

1. Above about age 8, forward displacement of the maxilla becomes impossible. ✓
2. It is much easier to move the upper incisors forward just as they are erupting.
3. Only quite young children can be persuaded to cooperate with wearing a face mask.
4. It isn’t—waiting until the adolescent growth spurt is the most efficient approach.

Correct

That’s right, it’s important to start this treatment early because the window of opportunity to produce skeletal change closes about age 8. After that, the sutures of the maxilla become so interdigitated that displacing it forward is no longer possible.

Moving the upper incisors forward is not the goal of treatment, skeletal change is. Older children can be persuaded to wear a face mask, it just doesn’t work as well or often at all. For most problems waiting until the adolescent growth spurt is the most efficient approach to treatment. Maxillary deficiency is the prime exception to that rule.