Quartz 4

Unit Self-Test

20 min read

Level I Growth and Development — Unit B Self-Test

Module 1: Growth and Development During the Preschool Years

Introduction

Remember that you are being tested on the first section of Chapter 3 in Contemporary Orthodontics, the material on embryonic development of the face, as well as the content of the computer teaching program. This is pages 72-78 of the text in the 4th edition, as well as the pictures on pages 79-81. Read this carefully. It’s not covered in any of the computer teaching programs.

Question 1

  1. ectoderm ✓
  2. mesoderm
  3. endoderm
  4. all three are equally important

Correct

That’s correct. In the formation of the face almost all the tissue, including muscle and bone that elsewhere is derived from mesoderm, is of ectodermal origin.

Question 2

Hemifacial microsomia and related congenital syndromes arise at which of the stages of craniofacial development?

  1. germ layer formation and initial organization of structures
  2. neural tube formation
  3. origin, migration and interaction of cell populations ✓
  4. formation of organ systems
  5. final differentiation of tissues

Correct

That’s right. Hemifacial microsomia is an example of a problem arising early in development from loss of neural crest cells before they migrate into the developing fact. Thalidomide and isotretnoin (Accutane) are drugs that create malformations by this mechanism.

Question 3

Cleft lip and palate arise at which of the stages of craniofacial development?

  1. germ layer formation and initial organization of structures
  2. neural tube formation
  3. origin, migration and interaction of cell populations
  4. formation of organ systems ✓
  5. final differentiation of tissues

Correct

That’s right. Cleft lip and palate arise after the cell populations are in place, at the stage in the second month of embryonic life when organ systems are being formed.

Question 4

The upper lip in an adult is derived from which of the facial processes?

  1. median and lateral nasal
  2. lateral nasal and maxillary
  3. median nasal and maxillary ✓
  4. median nasal, lateral nasal and maxillary

Correct

That’s right. The upper lip is derived from the median nasal and maxillary processes. Although failure of fusion between the median and lateral nasal processes results in a cleft lip, the lateral nasal process forms the outer parts of the nose and contributes little or nothing to the ultimate upper lip.

Question 5

Crouzon’s syndrome and the other malformations due to early closure of craniofacial sutures arise at which of the stages of craniofacial development?

  1. germ layer formation and initial organization of structures
  2. neural tube formation
  3. origin, migration and interaction of cell populations
  4. formation of organ systems
  5. final differentiation of tissues ✓

Correct

That’s right. The characteristic hypertelorism and midface deficiency of Crouzon’s syndrome are due to prenatal fusion of the superior and posterior sutures of the maxilla, along the wall of the orbit. This occurs in fetal life, during the final differentiation of tissues, considerably later than the embryologic origin of clefts and related problems.

Question 6

(A) In normal human infants, the mandible is prominent at birth because (B) like all the structures of the head and face, a high percentage of mandibular growth is completed before birth.

  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. Human newborns have an underdeveloped mandible relative to the rest of the head and face, for which their mothers should be grateful because this facilitates the head’s passage through the birth canal. The mandible grows more than other facial structures in postnatal life and eventually catches up.

Question 7

At what degree of deviation from the normal height-weight standards is special investigation of a child’s status indicated?

  1. <10 percentile or >90 percentile
  2. <5 percentile or >95 percentile
  3. <3 percentile or >97 percentile ✓
  4. <1 percentile or >99 percentile

Correct

That’s right, the general guideline is that children who are below the 3rd or above the 97th percentile should be examined carefully to be sure they represent only normal variation rather than some abnormal condition. Such a child would plot outside the colored area of a chart like the one shown here.

Question 8

How well can you predict the size a child will attain from examining her parents?

  1. 90% accuracy
  2. 67% accuracy
  3. 50% accuracy
  4. 25% accuracy ✓
  5. <10% accuracy, almost unpredictable

Correct

That’s right, there is a correlation between the size of parents and their children, but genetic / hereditary factors explain only about 25% of the variation, so 25% accuracy is about all you could hope for.

Question 9

Compared to an eight-year-old, a normal four-year-old child has a:

(1) relatively larger cranium

(2) relatively longer lower face

(3) more prominent mandible.

  1. 1 only ✓
  2. 1 and 2
  3. 2 and 3
  4. 1 and 3
  5. all of the above

Correct

That’s right, compared to an eight-year-old, the four year old has a relatively larger cranium, but the face is shorter and the mandible less prominent, because the face grows faster than the cranium between ages four and eight.

Question 10

(A) The growth curve for the mandible follows the neural growth curve because (B) all the facial structures are close enough to the brain to be influenced by its growth curve.

  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 mandible doesn’t follow the neural growth curve, so the first statement is false, but it’s true that the facial structures are close enough to the brain to be influenced by its growth curve. In fact, the growth curves for the maxilla and mandible fall in between the neural and general body curves.

Question 11

At age 12, girls are typically:

  1. smaller and less developed than boys
  2. smaller but more developed than boys
  3. larger but less developed than boys
  4. larger and more developed than boys ✓

Correct

That’s right. Girls reach their adolescent growth spurt earlier than boys, and at age 12 they’re typically both bigger and more developed. The males end up bigger because they continue growing for a longer time.

Question 12

Complete recovery from low birth weight, so that the individual ends up close to the mean for the population in height and weight as an adult, is:

  1. quite likely ✓
  2. often happens but frequently does not
  3. possible but unlikely
  4. quite unlikely, growth deficit usually persists

Correct

That’s correct. In the absence of other problems, it’s quite likely that a child who was born prematurely and therefore has a low birth weight will ultimately completely catch up with his or her peers.

Question 13

Complete recovery from a growth deficit caused by chronic illness such as growth hormone deficiency, so that the individual ends up close to the mean for the population in height and weight as an adult, is:

  1. quite likely
  2. often happens but frequently does not
  3. possible but unlikely
  4. quite unlikely, growth deficit usually persists ✓

Correct

That’s right. A child who is successfully treated for a chronic growth-inhibiting condition usually moves closer to the growth norms, but the growth deficit usually persists. The longer the problem was present, the less the chance that the child will achieve normal height and weight.

Question 14

(A) Severe acute illness affects a child’s growth status only temporarily because (B) rapid catch-up growth usually occurs after the illness.

  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 and they’re related. Even though growth stops during the acute illness, a subsequent period of rapid catch-up growth usually brings the child back to his or her previous status.

Question 15

Severe growth inhibition due to a highly stressful social environment is:

  1. frequently observed
  2. unusual but not uncommon
  3. rare but possible ✓
  4. never happens directly, effect secondary to malnutrition

Correct

That’s correct, psychologic and emotional factors can affect growth, but severe growth inhibition (fortunately) is rare even though it is possible. Subtle effects may be relatively common.

Question 16

(A) Chronic malnutrition does not affect growth in the same way as chronic illness because (B) the energy available to an individual is preferentially directed toward growth.

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

Correct

That’s right, both statements are false. Chronic malnutrition affects growth remarkably similarly to chronic illness. Energy is available for growth only after the organism’s other needs for survival have been met.

Question 17

Influences on the ultimate height of an individual include:

(1) racial/ethnic origin

(2) rural vs urban setting

(3) number of children in the family

  1. 1 only
  2. 1 and 2
  3. 1 and 3
  4. 2 and 3
  5. 1, 2 and 3 ✓

Correct

That’s correct, not only racial/ethnic origin but also rural vs urban setting and number of children in the family are influences on an individual’s ultimate height. Urban children and members of smaller families tend to be bigger, perhaps because more resources are available to them.

Question 18

The term “secular trend” in growth and development refers to:

  1. the world-wide trend toward earlier development ✓
  2. the unpredictability of changes over time
  3. the increase in the age at menarche observed in many countries
  4. the way growth charts quickly go out of date

Correct

That’s correct, a secular trend is one that is related strongly to time. In growth and development, there has been a strong world-wide trend toward earlier development. Earlier (not later) sexual maturation is only one example of this.

Question 19

An average child from your practice in some future year, whose growth is plotted on a growth chart based on 1965 data, is likely to appear:

  1. advanced ✓
  2. average
  3. retarded
  4. no way to predict because of the secular trend

Correct

That’s correct, the average child now is bigger at the same age than the average child of the 1960s and this trend toward faster growth and development seems to be continuing, so the old growth chart would make an average child look advanced. Most people are pleased to be told their child is above average, which perhaps accounts for the popularity of old growth charts.

Question 20

Which of the following is not typical of physical growth in the preschool years?

  1. cranial growth is well advanced
  2. lymphoid tissue is beginning to shrink ✓
  3. mandibular deficiency is decreasing
  4. sexual development is very slow

Correct

That’s correct, lymphoid tissue tends to grow very rapidly during the preschool years. It doesn’t begin to shrink until sexual development starts at the beginning of adolescence.

Module 2: Primary Tooth Eruption and Exfoliation

Question 1

Which of the following is the most common eruption sequence in the mandibular arch in the primary dentition?

  1. Central incisor, lateral incisor, canine, first molar, second molar.
  2. Central incisor, lateral incisor, first molar, second molar, canine.
  3. Central incisor, lateral incisor, first molar, canine, second molar. ✓
  4. Lateral incisor, central incisor, canine, first molar, second molar.

Correct

That’s right; in the mandibular arch the central incisor erupts first and is followed by the lateral incisor. The next tooth to erupt is the first primary molar which appears to be out of sequence skipping the canine. The canine then erupts and is followed by the second molar.

Question 2

The eruption of the primary dentition is usually complete by:

  1. 12-18 months of age.
  2. 18-24 months of age.
  3. 24-30 months of age. ✓
  4. 30-36 months of age.

Correct

That’s right; the eruption of the primary dentition is usually complete by 24-30 months of age with the eruption of the maxillary second primary molar.

Question 3

A mother has brought her 2 year old daughter in for a new patient dental examination. During the health history the mother states that her daughter has a fever, diarrhea and been irritable for the last two days. Your examination reveals that the mandibular first primary molars are erupting. Which of the following should you recommend to the mother?

  1. Seek medical care to investigate the fever and diarrhea. ✓
  2. Reassure her that the symptoms are due to teething and not serious
  3. Have her apply topical anesthetic gel to the soft tissue around the erupting teeth.
  4. Prescribe a systemic antibiotic.

Correct

That’s right; you should counsel the mother to seek medical care to investigate the cause of the fever and diarrhea. One should not dismiss the symptoms as being related to teething. The use of topical anesthetics around the erupting teeth may provide some relief of local symptoms, but this ignores the potentially serious systemic symptoms. The prescription of antibiotics is unwarranted, however, because a diagnosis of the systemic problem has not been made and the cause of the fever and diarrhea are not known. Unless there is a specific indication for antibiotics, their use may also lead to the development of antibiotic resistance.

Question 4

Which of the following conditions are associated with delayed eruption of primary teeth?

  1. Hypophosphatasia
  2. Hyperpituitarism
  3. Cherubism
  4. Hypothyroidism ✓

Correct

That’s right; the congenital and juvenile forms of hypothyroidism are associated with the delayed eruption of primary and permanent teeth, and the delayed exfoliation of primary teeth. The other three conditions are associated with early loss of primary teeth.

Question 5

A mother brings in her 13-month-old son to see you because no primary teeth have erupted at this time. What would be your advice to the mother concerning the eruption of the teeth?

  1. No current intervention, this is within acceptable normal limits ✓
  2. Suspect an underlying condition inhibiting eruption
  3. Obtain radiographs to investigate whether the teeth are present
  4. Both 2 and 3

Correct

That’s right; at the age of 13 months the eruption of the primary teeth is delayed but still within acceptable normal limits. However by 18 months of age the majority of children have some erupted primary teeth. In an 18-month-old with no erupted primary teeth options 2 and 3 would be appropriate.

Question 6

Which of the following is correct with respect to ankylosed primary teeth?

  1. Diagnosis is confirmed radiographically in the majority of cases
  2. The mandibular first molar is the most commonly affected tooth ✓
  3. A single tooth is most commonly involved
  4. Maxillary teeth are more commonly involved than mandibular teeth

Correct

That’s right; the mandibular first primary molar is the most commonly involved primary tooth. Mandibular teeth are more often involved than the maxillary teeth and it is not uncommon to have multiple ankylosed primary teeth in the same patient. In the majority of cases no evidence of fusion between the root and the alveolar bone is apparent on radiographs.

Question 7

A mother brings her daughter (5 yr 10 months old) to see you. The mother is concerned about the eruption of the lower incisors, as she now has “two rows of teeth”. On examination you see that the lower central incisors are erupting lingual to the primary central incisors, which have not exfoliated. What would be your advice to the mother?

  1. The primary central incisors should be extracted at this appointment.
  2. Consider a removable appliance to move the permanent teeth labially.
  3. 1 and 2
  4. No intervention required at this time, the primary centrals should exfoliate in time and the permanent centrals should move facially. ✓

Correct

That’s right; no intervention is required at this time. As the permanent central incisors erupt further, tongue forces usually will move them forward and stimulate the exfoliation of the primary teeth. Extraction of the primary central incisors or the use of an active appliance is not required at this time.

Question 8

Which of the following is not commonly associated with the ectopic eruption of a mandibular permanent lateral incisor?

  1. Impaction of the central incisor ✓
  2. Shifting of the mandibular dental midline
  3. Incisor crowding
  4. Early loss of the ipsilateral primary canine

Correct

That’s right; impaction of the permanent central incisor does not commonly occur in these situations but the other things do. As you recall the central incisors erupt before the lateral incisors and would not become impacted if the lateral incisor erupts ectopically. Ectopic eruption of a mandibular permanent lateral incisor commonly results in early loss of the primary canine on the same or ipsilateral side. Once the primary canine is lost, the incisors are free to move laterally resulting in a shift of the mandibular dental midline. This scenario is usually a sign of an underlying crowding problem in the mandibular arch.

Question 9

Which permanent tooth is most likely to erupt ectopically?

  1. Maxillary lateral incisor
  2. Mandibular canine
  3. Mandibular second premolar
  4. Maxillary first molar ✓

Correct

That’s right; although ectopic eruption of all these teeth can occur, the maxillary first molar is the tooth most likely to do so. When it erupts ectopically the maxillary first molar usually resorbs the distal surface of the primary second molar.

Question 10

Approximately what percentage of ectopically erupting maxillary first permanent molars self-correct and do not require intervention?

  1. 1/3
  2. 1/2
  3. 2/3 ✓
  4. 3/4

Correct

That’s right; approximately 2/3 of ectopically erupting maxillary first permanent molars will self correct and do not require intervention. This would imply that in an age appropriate child, after the initial diagnosis, a period of observation of 3-4 months is recommended to see if self correction occurs.

Question 11

(A) The apparent submergence of an ankylosed primary tooth is misleading because (B) what really happens is that the ankylosed molar stops erupting while the adjacent teeth continue to erupt.

  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 and related. Submergence is a misleading term since the ankylosed tooth stops erupting while the adjacent teeth continue to erupt.

Question 12

Which of the following is most likely to indicate underlying pathology affecting the eruption process?

  1. Eruption of the maxillary right but not the left central incisor ✓
  2. Accelerated eruption (3 months) of both maxillary central incisors
  3. Delayed eruption (3 months) of both maxillary central incisors
  4. All are equally important signs of potential pathology

Correct

That’s right; a deviation of sequence or symmetry in eruption may indicate underlying pathology and is a more important sign than symmetric acceleration or delay.

Module 3: Development of Occlusion in the Primary and Transitional Dentition

Question 1

Primate spaces in the primary dentition are usually located:

  1. In the maxillary arch between the canine and first molar
  2. In the maxillary arch between the lateral incisor and canine ✓
  3. In the mandibular arch between the canine and lateral incisor
  4. In the mandibular arch between the first and second molar

Correct

That’s right; in the maxillary arch the primate spaces are between the lateral incisors and canines while in the mandibular arch they are between the canines and first molars.

Question 2

In the maxillary arch, which of following facilitates the eruption of the larger incisors to replace the primary incisors?

  1. Labial eruption path of the permanent incisors ✓
  2. Primate spacing between the primary canine and first molar
  3. Expansion of the midpalatal suture
  4. Increase in arch length due to growth in the tuberosity region

Correct

That’s right; in the maxillary arch, gaining space for eruption of the larger permanent incisors is facilitated by their facially directed eruption, which increases arch length and circumference. The maxillary primate space also helps their eruption, but it is located between the canine and lateral incisor, not the canine and first molar. Midpalatal suture expansion and growth in the tuberosity are important aspects of maxillary growth but they play a minimal role in the eruption of the permanent incisors.

Question 3

In the primary dentition, the terminal plane of the mandibular second primary molar is located behind the terminal plane of the maxillary second primary molar. What is the molar classification for this patient?

  1. Mesial step terminal plane
  2. Flush terminal plane
  3. Distal step terminal plane ✓
  4. Class III terminal plane

Correct

That’s right; the classification would be distal step, because the lower molar is distal relative to the upper molar. The preferred relationship is a mesial step relationship where the terminal plane of the lower molar is mesial to the terminal plane of the upper molar.

Question 4

In the primary dentition which of the following relationships is most common?

  1. Mesial step terminal plane ✓
  2. Flush terminal plane
  3. Distal step terminal plane
  4. Class III terminal plane

Correct

That’s right; mesial step terminal plane occurs in 49% of children while flush terminal plane occurs in 37% and distal step terminal plane occurs in 14%.

Question 5

The early mesial shift occurs at the time of the:

  1. Exfoliation of the primary canines
  2. Eruption of the first permanent molars ✓
  3. Exfoliation of the primary buccal segments
  4. Eruption of the second permanent molars

Correct

That’s right; the early mesial shift occurs at the time of the eruption of the first permanent molars or approximately 6 years of age. As the permanent molars erupt they drift forward closing the primate spaces, especially in the lower arch. The late mesial shift occurs with the exfoliation of the primary buccal segments in the late mixed dentition.

Question 6

  1. Too small to help patients attain a Class I molar relations
  2. A crucial part of the early mesial shift
  3. Larger in the maxillary arch than the mandibular arch
  4. Due to differences in the size of posterior primary and permanent teeth ✓

Correct

That’s right; leeway space is primarily due to the difference in the combined mesial distal widths of the primary canine, first molar, second molar and the permanent canine, first premolar and second premolar. The three primary teeth are wider than the permanent teeth. Leeway space is a crucial part of the late mesial shift which helps patients attain a class I molar relationship. The leeway space is larger in the mandibular arch (5mm) than the maxillary arch (3mm).

Question 7

What percentage of patients with a flush terminal plane relationship in the mixed dentition will develop into a Class I molar relationship in the permanent dentition?

  1. 25
  2. 40
  3. 60
  4. 75 ✓

Correct

That’s right; 75% of patients with a flush terminal plane relationship in the mixed dentition will develop into a class I molar relationship in the permanent dentition. This occurs due to the late mesial shift and differential mandibular growth.

Question 8

In the maxillary arch the incisor liability is approximately:

  1. 3 mm
  2. 4 mm
  3. 5 mm
  4. 6 mm
  5. 7 mm ✓

Correct

That’s right; because the maxillary permanent incisors are bigger than their primary predecessors by slightly more than 7mm, so that amount of additional space must be gained in some way. The additional space needed to align the permanent incisors is called the incisor liability.

Question 9

The profile of a newborn infant can best be described as:

  1. concave
  2. straight
  3. convex ✓
  4. any of the above due to birth molding

Correct

That’s right; the profile of a newborn infant is quite convex because of the relative underdevelopment of the mandible at the time of birth.

Question 10

What is the chance that a child with a distal step relationship of the primary molars will self-correct to Class I permanent molars?

  1. Extremely small ✓
  2. 10%
  3. 75%
  4. very likely

Correct

That’s right; the chance of spontaneous correction of a distal step relationship is extremely small, much less than 10%.

Question 11

The mandibular arch form of a newborn infant is:

  1. ovoid
  2. V-shaped ✓
  3. trapezoidal
  4. square

Correct

That’s right; the mandibular arch form is rather V-shaped, which is noticeably different than the ovoid maxillary arch.

Question 12

In a child, a lack of primate spaces in the dentition should be interpreted as:

  1. supernumerary teeth are likely to be present
  2. spacing in the arch is likely to occur long term
  3. crowding of the permanent teeth is likely to occur ✓
  4. child is evolutionarily advanced

Correct

That’s right; a lack of primate spaces strongly suggests that crowding of the permanent teeth will occur.

Graph View