Quartz 4

Unit Self-Test

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Level I Growth and Development — Unit C Self-Test

Module 1: Eruption of Permanent Teeth

Question 1

Key differences between dental age 9 and dental age 10 are:

(1) root completion of lower incisors

(2) degree of resorption of primary canines

(3) degree of root formation of canines and premolars

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

Correct

That’s right. At dental age 10, the primary canines show more resorption and the canines and premolars have more root formation than at dental age 9, but the appearance of the lower incisors is very similar at ages 9 and 10. It takes 2 years to complete the roots after an incisor erupts, so the lower incisors are likely to already be complete at age 9.

Question 2

What is the dental age when the roots of all the permanent teeth (except third molars) are completed?

  1. 12
  2. 13
  3. 14
  4. 15 ✓
  5. 16

Correct

That’s right, the roots of all permanent teeth except third molars are completed at dental age 15. The guideline is that it takes two years after eruption for the roots to be completed, and the second molars often haven’t completed their eruption at dental age 12, so root completion wouldn’t be expected at age 14 or younger.

Question 3

Which of the following is not characteristic of the first stage of eruption, dental age 6?

  1. eruption of the first permanent molars
  2. eruption of the mandibular central incisors
  3. eruption of the maxillary central incisors ✓
  4. formation of half the root of the mandibular lateral incisors
  5. formation of less than half the root of the maxillary lateral incisors

Correct

That is correct. The maxillary central incisors erupt a year later than the permanent first molars and the mandibular central incisors, so their eruption isn’t part of dental age 6.

Question 4

With regard to space for the permanent teeth as they erupt, what does the term “incisor liability” mean?

  1. space for incisors normally is less than required ✓
  2. space for incisors normally is only equal to required
  3. if space is a problem, it’s almost always space for incisors that’s the problem.
  4. you’re more likely to get sued if the incisors are involved

Correct

That’s right, incisor liability means that under normal conditions there isn’t quite enough space for the permanent incisors when they erupt, which can lead to temporary crowding even when there’s ultimately enough space.

Question 5

During normal develoment, which of the following is not a source of additional space to overcome incisor liability?

  1. increase in intercanine width
  2. distal movement of the maxillary canine into primate space ✓
  3. distal movement of the mandibular canine into primate space
  4. labial positioning of the permanent incisors
  5. they’re all sources of additional space

Correct

That’s correct, the maxillary canine can’t move distally into a primate space that’s mesial to it, but the other possibilities all help overcome incisor liability.

Question 6

To a dentist, a beautiful smile in the primary dentition reveals large spaces between the primary incisors. Which of the following is not a reason for that attitude?

  1. permanent incisors are likely to erupt in crossbite unless spaces are present. ✓
  2. spacing is required to provide enough space for the permanent teeth
  3. large spaces are better than no spaces
  4. crowding of the permanent teeth is likely even if small spaces are present.
  5. in the absence of spacing, the permanent teeth are more likely to be displaced as they erupt.

Correct

That’s correct. Large spaces between the primary incisors are necessary if there’s to be enough room for the permanent incisors, but the amount of spacing has little or nothing to do with whether the teeth erupt in crossbite.

Question 7

At which dental age is eruption of the first permanent molars completed?

  1. 6
  2. 12
  3. 15

  4. 15 ✓

Correct

That’s right. All the teeth have to continue to erupt after they reach the occlusal plane, to stay in occlusion while the face is growing taller. Eruption doesn’t stop until growth is completed—and even late in life, a tooth is likely to start erupting if its antagonist is lost. So the first molars have to erupt beyond age 15, as long as vertical growth continues.

Question 8

(A) Eruption of the mandibular second molars ahead of the second premolars can be a problem because (B) this decreases the space for the second premolar and may lead to its impaction.

  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. Even though eruption of the second molars ahead of the second premolars is a “normal variation”, it’s unfortunate when space in the dental arches is marginal.

Question 9

At dental age 7, where is the maxillary canine located?

  1. not visible, crown formation hasn’t started yet
  2. crown formation beginning just distal to the lateral incisors
  3. crown partially complete, slightly above and distal to the lateral incisors
  4. crown partially complete, very high above and slightly distal to the lateral incisors ✓

Correct

That’s right, the maxillary canines initially are very high above and only slightly distal to the lateral incisor. Their location almost in the floor of the orbit is why they’re sometimes called “eye teeth”.

Question 10

What is the effect of a primary dentition with little or no space between the primary incisors on incisor liability?

  1. decreases it
  2. little or no effect
  3. increases it ✓
  4. unpredictable, primary dentition spacing is unrelated

Correct

That’s right, if there’s little or no spacing in the primary incisor region, the amount of crowding of the permanent incisors when they erupt will increase.

Question 11

At dental age 12, which teeth are expected to be erupting?

  1. maxillary canines and mandibular second premolars
  2. maxillary canines and maxillary second premolars
  3. all four second premolars
  4. maxillary canines and all four second premolars
  5. maxillary canines, all four second premolars and all four second molars ✓

Correct

That’s correct. At dental age 12, the maxillary canines, all four second premolars erupt, and all four second molars erupt. The second molars usually are a bit behind the other teeth, but erupt so close to the same time that they’re part of the age 12 year development.

Question 12

Which of the following are not succedaneous teeth?

  1. central incisors
  2. canines
  3. first premolars
  4. second premolars
  5. first molars ✓

Correct

That’s correct, the first molar is not a succedaneous tooth because it has no primary tooth as a predecessor. Developmentally, the permanent molars can be considered primary teeth that erupt late and last a lifetime.

Question 13

The ugly duckling stage of dental development is characterized by:

  1. duck-bill protrusion of the incisors
  2. upper incisors ducked back toward the lower incisors
  3. spacing of upper and lower permanent incisors
  4. spacing of upper but not lower permanent incisors ✓

Correct

That’s correct, the ugly duckling stage has spaces between the upper incisors, with the upper laterals inclined distally into the canine space. As the canines erupt, these spaces tend to close—but an extreme ugly duckling stage can indicate potential impaction of the canines.

Question 14

(A) When the arches are crowded, lateral incisors usually erupt facially and maxillary canines erupt lingually because (B) teeth tend to erupt on the side where the tooth bud was lying initially.

  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—lateral incisors usually go lingually and canines facially—but the second is true, teeth tend to erupt on the side the tooth buds were lying initially.

Question 15

(A) In a patient with a potential problem in eruption of the maxillary canines, early extraction of the maxillary primary canines should be considered because (B) this increases the chance of the permanent tooth erupting reasonably normally instead of becoming impacted.

  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. Early extraction of maxillary primary canines should be considered when the position of the permanent canines suggests potential impaction.

Question 16

(A) Eruption of the maxillary canine coincident with the maxillary first premolar rarely is a problem because (B) the erupting canine tends to close spaces between the incisors and creates space in that way.

  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 and the second one true. Whether or not there’s incisor spacing, if the canine erupts along with the first premolar, before the second primary molar is lost, it’s likely to be displaced facially, and that’s a problem, because orthodontic treatment will be needed to get it back.

Question 17

Which of the following is not characteristic of dental age 7?

  1. eruption of the maxillary central incisors
  2. eruption of the mandibular lateral incisors
  3. formation of more than half the root of the maxillary lateral incisors
  4. crown formation of maxillary and mandibular canines
  5. approximately half the root formed on maxillary and mandibular first premolars. ✓

Correct

That’s right. At age 7, root formation of first premolars is just beginning, if they are beyond the crown stage at all.

Question 18

How much additional space for the incisors is gained by the normal mechanisms to overcome incisor liability?

  1. the width of one lower incisor
  2. ½ the width of a lower incisor ✓
  3. ¼ the width of a lower incisor
  4. unpredictable, depends on how much was needed and how the child grows.

Correct

That’s correct, the normal mechanisms contribute about 3 mm, or half the width of a lower incisor. If more space than that would be needed to obtain incisor alignment, it probably won’t be forthcoming from normal development alone.

Question 19

Dental age 11 is characterized by eruption of:

  1. mandibular canine and all first premolars ✓
  2. maxillary canine and all first premolars
  3. mandibular canine and mandibular first premolars
  4. mandibular canine and maxillary first premolars
  5. all canines and mandibular first premolars

Correct

That’s right. At dental age 11, the mandibular canines and all four first premolars erupt at about the same time. The maxillary canines erupt a year later, at dental age 12.

Question 20

In a child whose dental age is 8 years at chronologic age 6 years, what would you expect her dental age to be at chronologic age 12?

  1. 10
  2. 12
  3. 14 ✓

  4. 14

  5. no way to predict

Correct

That’s right, a child whose dental development is two years ahead of her chronologic age at 6 is likely to still be two years ahead when she’s 12. Children tend to stay in the same developmental percentile channel.

Module 2: Process of Tooth Eruption

Question 1

Almost all tooth eruption occurs during which stage of tooth development?

  1. initiation
  2. histodifferentiation
  3. morphodifferentiation
  4. growth ✓
  5. attrition

Correct

That’s correct. Eruption doesn’t start until the growth stage has been reached. It occurs mostly during the growth stage, but because very slow eruption persists throughout life, a small amount of eruption also occurs during the attrition stage (and occurs to some extent in response to loss of occlusal enamel to attrition).

Question 2

How far does a permanent first molar have to erupt after it first comes into occlusion?

  1. 10 mm or more ✓
  2. 4-5 mm
  3. 1-3 mm
  4. none, eruption ends when the tooth reaches occlusion

Correct

That’s right. Face height normally increases 20 mm or more between age 6, when first molars first come into occlusion, and age 18 when the growth rate declines to the very slow adult level. So both upper and lower first molars each have to erupt 10 mm or more to maintain occlusal contact as the jaws grow. If they didn’t continue to erupt, they would appear to submerge into the gingiva as the other teeth erupted past them—which happens occasionally to a tooth that becomes ankylosed.

Question 3

When a tooth is mechanically blocked from erupting, its root may become distorted in form. What is the descriptive term for such a root?

  1. macerated
  2. dilacerated ✓
  3. encapsulated
  4. commiserated
  5. eviscerated

Correct

That’s right. A severely curved tooth root is called dilacerated. This is the result of trauma or a souvenir of mechanically-blocked eruption. Trauma while the root is still forming can displace the apex. When the crown can’t move toward the oral cavity because a path cannot be cleared, root formation continues and the root apex moves away from the mouth. If it hits a bony wall like the wall of the maxillary sinus or the lower border of the mandible, a curve in the root is formed.

Question 4

During the post-emergent spurt stage of eruption, when does active eruption occur?

  1. mostly from early morning to noon
  2. mostly from noon to late afternoon
  3. mostly from late afternoon to midnight ✓
  4. mostly from midnight to early morning
  5. no influence of time of day

Correct

That’s right. Active eruption occurs mostly in the evening, beginning in late afternoon or early evening and ending around midnight. There is little or no net eruption from early morning until the next evening, and usually the tooth loses some of the ground it gained the previous evening during the next 18 hours—but it starts the next day’s eruption from a higher point, so there’s some net gain each day.

Question 5

How is eruption controlled after a tooth comes into occlusion?

  1. tongue-lip pressures against the teeth ✓
  2. biting force
  3. level of circulating growth hormone
  4. all the above
  5. none of the above

Correct

That’s right, the experimental evidence suggests that light force of long duration is the controlling element for post-emergent eruption, and this probably comes from tongue-lip pressures against the teeth while the jaws are separated during sleep. Biting force is heavy force of long duration, so it has the wrong characteristics. The level of growth hormone may play a role indirectly, since it relates to the amount of skeletal growth after a tooth comes into occlusion, but its direct role on blood flow no longer applies.

Question 6

What is the most important initial diagnostic sign of primary failure of eruption?

  1. 1st molars failing to erupt after eruption path is cleared
  2. 1st and 2nd molars failing to erupt after eruption path is cleared ✓
  3. failure of the roots to form after crown formation is complete
  4. failure of the affected teeth to respond to orthodontic force
  5. submergence of the affected teeth

Correct

That’s correct, the primary diagnostic sign of primary failure of eruption is failure of 1st and 2nd molars to erupt even though an eruption path has been cleared for them. If first molars fail to erupt, the problem may be just ankylosis; if other posterior teeth in the same quadrant also fail to erupt, it’s probably primary failure. In primary failure, second premolars often also are affected. It’s true that the affected teeth may appear to submerge over time, and that they do not respond to orthodontic force, but these are best thought of as confirmatory rather than initial diagnostic signs.

Question 7

What controls the rate of pre-emergent eruption?

  1. the rate of bone resorption over the tooth ✓
  2. the rate of root formation
  3. the rate of formation of new tissue at the root apex
  4. the amount of force generated by the eruption mechanism

Correct

That’s right, the rate at which obstacles to eruption are removed, not the rate at which new tissue forms or the amount of force from the eruption mechanism, is what controls pre-emergent eruption. Normally, an eruption path is formed, and then the eruption mechanism moves the tooth along that path so that the crown stays close to the area where bone, primary tooth roots or gingiva are being resorbed. Failure of a tooth to follow along a cleared eruption path indicates either mechanical failure of eruption (ankylosis) or primary failure of eruption (abnormal PDL, eruption mechanism doesn’t work).

Question 8

(A) If a tooth becomes ankylosed and fails to erupt, it appears to submerge because (B) the alveolar bone grows past it and may eventually cover it over.

  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 correct but the second is false. Alveolar bone forms in response to eruption of a tooth, so if a tooth becomes ankylosed, no bone forms in that area, and there is likely to be a long-term alveolar defect. If an ankylosed tooth is totally covered over, it’s by soft tissue only.

Question 9

Which of the following is the major mechanism of post-emergent eruption after a tooth comes into occlusion?

  1. shortening of collagen fibers in the PDL ✓
  2. contractile fibroblasts in the PDL
  3. pressure from proliferating cells at the root apex
  4. blood pressure / flow in the PDL

Correct

That’s right, maturation and shortening of collagen fibers in the PDL is now thought to be the major mechanism of post-emergent eruption. The other possibilities cannot be totally ruled out but are not supported by experimental evidence.

Question 10

During the crown formation stage of tooth eruption, the direction of eruption is:

  1. anterior
  2. posterior
  3. a and c
  4. no eruptive movements occur ✓

Correct

That’s correct. The tooth enlarges during crown formation, but movement toward the occlusal plane doesn’t start until root formation begins, and there are no anterior or posterior movements during crown formation.

Question 11

The eruption of a mandibular molar is best described relative to the:

  1. cranial base
  2. occlusal plane
  3. core bone of the maxilla
  4. core bone of the mandible ✓

Correct

That’s right. An erupting mandibular tooth moves relative to the cranial base, occlusal plane and maxilla, but eruption is defined as movement of a tooth relative to its jaw. For a mandibular molar, of course that’s the mandible.

Question 12

How does the prognosis for the unerupted teeth in primary failure of eruption compare to the prognosis for an unerupted tooth that is mechanically obstructed?

  1. worse ✓
  2. about the same
  3. better
  4. impossible to predict

Correct

That’s right, the prognosis is worse. If a mechanical obstruction is removed, there is a chance that unerupted teeth will erupt on their own, and if not, they can be pulled into position orthodontically. But when the eruption mechanism fails, there is an abnormality of the periodontal ligament that makes teeth impossible to move orthodontically. The only option in primary failure of eruption is to eventually replace the unerupted teeth with some type of prosthesis.

Module 3: Physical Growth at Adolescence

Question 1

The earlier you mature sexually, the _______ you will be as an adult.

  1. shorter ✓
  2. taller
  3. heavier
  4. lighter

Correct

That’s right. Early sexual maturation means earlier closure of the epiphyses of the long bones, so the earlier you mature, the shorter you’ll be, and vice versa.

Question 2

Orthodontic growth modification during adolescence is aimed at:

  1. accelerating mandibular growth
  2. retarding maxillary growth
  3. retarding mandibular growth
  4. accelerating maxillary growth
  5. producing differential growth between maxilla and mandible ✓

Correct

That’s right. In order to correct jaw discrepancies, differential growth is needed. That might involve accelerlating or retarding the growth of either jaw.

Question 3

The first step in the endocrinology of adolescence is:

  1. increased secretion of hypothalamic releasing factors ✓
  2. increased secretion of pituitary gonadotrophins
  3. increased secretion of estrogen
  4. increased secretion of testosterone

Correct

That’s right. Increased secretion of hypothalamic releasing factors is the first step in the endocrinologic cascade that leads to adolescence.

Question 4

The biologic purpose of the endocrinologic sequence is to:

  1. amplify the initial hypothalamic signal ✓
  2. modulate the initial hypothalamic signal
  3. compensate for the initial hypothalamic signal
  4. make the control circuitry redundant for greater safety in use

Correct

That’s right. The cascade serves as an amplifier, allowing the very small signal produced by only a few cells in the hypothalamus to control a large system.

Question 5

Maximum growth velocity for mandible in boys occurs at which stage?

  1. stage I
  2. stage II
  3. stage III ✓
  4. stage IV
  5. unpredictable

Correct

That’s right. The adolescent growth spurt for the mandible coincides with the spurt in height, so it occurs at stage III just as the height spurt does.

Question 6

At which stage of sexual development in girls does pubic hair first appear?

  1. stage I ✓
  2. stage II
  3. stage III
  4. stage IV
  5. indeterminate, pigmentation may be delayed

Correct

That’s right. Pubic hair begins to form at the first stage of sexual development in girls, at the same time breast buds are noticed.

Question 7

The “fat spurt” early in puberty in boys leads temporarily to a more feminine fat distribution pattern because (B) cells in the testis that produce estrogens are stimulated at this early stage before those that produce androgens.

  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. Estrogen release by cells in the testis (and adrenal cortex) leads to the fat spurt and the temporary feminine fat distribution.

Question 8

Which of the following is not a major player in the endocrinology of adolescence?

  1. hypothalamic releasing factors
  2. pituitary gonadotrophins
  3. male and female sex hormones
  4. adrenocorticotrophins ✓

Correct

That is correct. Adrenocorticotrophins are important before, during and after puberty, but they are not major players in the endocrinologic cascade that leads to adolescence.

Question 9

What of the following is not true concerning effects on adolescent growth?

  1. slender body (ectomorphic), later growth spurt
  2. heavy body (endomorphic), earlier growth spurt
  3. colder climate, earlier growth spurt ✓
  4. spring-summer, faster growth rate
  5. all are true

Correct

That’s right. All other things being equal, the adolescent growth spurt comes earlier in children who live in a warmer climate, not a colder one.

Question 10

In girls, which of the following is not an indicator of peak growth velocity?

  1. noticeable breast development
  2. axillary hair
  3. pigmented, curled pubic hair
  4. menstruation ✓

Correct

Noticeable breast development, axillary hair and curled pubic hair are all seen at stage II of adolescence, when growth velocity peaks. Menstruation doesn’t occur until growth velocity is declining.

Question 11

Which of the following indicates that a boy is beyond the peak of the adolescent growth spurt?

  1. fine “peach fuzz” on upper lip
  2. pigmented hair on upper lip
  3. hair on upper lip and chin ✓
  4. recent rapid growth in height

Correct

That’s right. The appearance of hair on the upper lip and chin is a good indicator that a boy is well beyond the peak of the adolescent growth spurt. He’s approaching if not in stage 4. Peach fuzz and pigmented hair on the upper lip are indicators of early and late stage 3, respectively. Recent rapid growth in height tells you he’s in the growth spurt but not where.

Question 12

(A) Early maturing boys reach puberty before late maturing girls because (B) the individual variation in when puberty starts is greater than the average differences between the sexes.

  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. On the average girls reach puberty two years ahead of boys, but there’s at least a five year spread in the normal distribution for both sexes, so the early maturing boys easily can reach puberty before the late maturing girls.

Module 4: Patterns of Facial Growth

Question 1

Growth pattern of the face refers to:

  1. proportional relationships during growth
  2. changes in proportional relationships during growth ✓
  3. the rate of growth of the components of the head and face
  4. all of the above

Correct

That’s right, growth pattern refers to the way proportional relationships in the face change during growth, not to the proportional relationships themselves or to the rate of growth of the components.

Question 2

The major characteristic of a Class I skeletal relationship in a profile view is:

  1. cranial, facial and dental structures in a nearly straight line ✓
  2. facial and dental structures straight but prominent to the cranium
  3. cranial and facial structures in a nearly straight line, teeth can be anywhere
  4. maxilla forward relative to mandible
  5. mandible forward relative to maxilla

Correct

That’s correct. In a Class I (normal) relationship, the cranium, maxilla, maxillary teeth, mandibular teeth and mandible are in a nearly straight line.

Question 3

The major characteristic of a Class II skeletal relationship is:

  1. cranial, facial and dental structures in a nearly straight line
  2. facial and dental structures straight but prominent to the cranium
  3. cranial and facial structures in a nearly straight line, teeth can be anywhere
  4. maxilla forward relative to mandible ✓
  5. mandible forward relative to maxilla

Correct

That’s right. In a Class II relationship the maxilla is forward relative to the mandible. This can occur because the maxilla grew normally while the mandible grew less than normal, or because the maxilla grew too much, or any combination of deficient mandibular and excess maxillary growth.

Question 4

The major characteristic of a Class III skeletal relationship is:

  1. cranial, facial and dental structures in a nearly straight line
  2. facial and dental structures straight but prominent to the cranium
  3. cranial and facial structures in a nearly straight line, teeth can be anywhere
  4. maxilla forward relative to mandible
  5. mandible forward relative to maxilla ✓

Correct

That’s right. In a Class III relationship the mandible is forward relative to the maxilla. This can occur because the mandible grew normally while the maxilla grew less than normal, because the mandible grew too much, or any combination of deficient maxillary and excess mandibular growth.

Question 5

For which of the following is the adolescent growth spurt least prominent?

  1. weight
  2. height
  3. lower jaw length
  4. upper jaw length ✓

Correct

That’s right. Because the maxilla is influenced by the neural growth curve, it has less response to the adolescent growth spurt that particularly affects general body growth than the mandible and weight / height.

Question 6

What would you expect to happen to the a-p position of the lower incisors in response to a Class II growth pattern?

  1. forward (facial) movement ✓
  2. little or no movement
  3. backward (lingual) movement
  4. vertical change more probable than a-p change

Correct

That’s correct. If the maxilla grows forward more than the mandible in a Class II growth pattern, often the lower incisors partially compensate by moving forward (facially).

Question 7

What would you expect to happen to the a-p position of the upper incisors in response to a Class III growth pattern?

  1. forward (facial) movement ✓
  2. little or no movement
  3. backward (lingual) movement
  4. vertical change more probable than facio-lingual change

Correct

That’s correct. In response to a Class III growth pattern the upper incisors would tend to tip forward, moving facially. In a skeletal Class III patient, the forward movement of the upper incisors and the backward movement of the lower incisors both reduce the relative protrusion of the lower teeth. This is a classic example of dental compensation for a skeletal discrepancy. In Class III or Class II patients, the dental occlusion is often better than the jaw relationship at the end of growth for this reason.

Question 8

In a child with end-to-end permanent first molars at age 10 and a mild Class II growth pattern, what is the most likely molar relationship at age 12?

  1. Class I
  2. end-to-end ✓
  3. Class II
  4. Class III

Correct

That’s correct. With a mild Class II growth pattern it is unlikely that the end-to-end permanent molars would make the normal shift to Class I, and most probably they would stay end-to-end. If the Class II growth pattern was really severe, they could move to Class II. Transition to Class III would require a severe Class III growth pattern.

Question 9

In a child with Class I permanent first molars at age 10 and a Class III growth pattern, what is the most likely molar relationship at age 12?

  1. Class I
  2. end-to-end
  3. Class II
  4. Class III ✓

Correct

That’s correct. With a Class III growth pattern, molars that were already Class I at age 10 (when many children with a normal growth pattern are still end-to-end) would be carried toward Class III, and that’s the most probable molar relation after 2 more years of Class III growth.

Question 10

(A) A Class I malocclusion rarely becomes a Class III malocclusion during growth because (B) a Class II growth pattern rarely occurs in a Class I patient.

  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 false, B false

Correct

That’s right. Both statements are true but they’re not related. Class I rarely becomes Class III because Class III growth pattern rarely occurs in a Class I patient. A Class II growth pattern would turn Class I into Class II, not III.

Question 11

What is the chance that a child with a Class II skeletal pattern would spontaneously grow out of it and become Class I as an adult?

  1. less than 10% ✓
  2. 10-20%
  3. 20-40%
  4. about 50%
  5. totally unpredictable - no way to know

Correct

That’s right. Spontaneous correction of a skeletal Class II or Class III pattern rarely occurs. The general rule is “constancy of the pattern”, meaning that whatever the growth pattern is, it’s unlikely to change (but of course unlikely things do happen, they just don’t happen very often). The chance of spontaneous correction of a skeletal Class II or Class III is considerably less than 10%, in fact probably closer to 1%.

Question 12

(A) In a child with a skeletal open bite growth pattern, positive overbite can be present because (B) increased eruption of incisors would compensate for the open bite tendency.

  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 false, B false

Correct

That’s right, increased eruption of incisors could compensate for a skeletal open bite growth pattern, maintaining positive overbite even though the mandible was growing downward away from the maxilla.

Module 5: Maturational Changes

Question 1

Which of the following signals the end of growth in height?

  1. closure of epiphyseal plates of femur and tibia ✓
  2. closure of epiphyseal plates of humerus and radius
  3. fusion of cervical vertebrae
  4. all three are equally important

Correct

That’s correct. The long bones of the legs can’t grow significantly longer after their epiphyseal plates close.

Question 2

One of your 55-year-old patients commented that he used to be 6 feet tall, but now he’s only 5”11”. What would you think was the most likely cause?

  1. resorption of bone in the hips
  2. resorption of bone in the knees
  3. curvature of the cervical spine
  4. compression of cervical vertebrae
  5. compression of intervertebral discs ✓

Correct

That’s right, aging men and women are likely to notice a loss of one or two inches in height, and the usual cause is compression of intervertebral discs. Resorption of bone in hip or knee joints is unlikely to lead to noticeable height loss, and vertebrae don’t get compressed (in the absence of severe trauma). Spinal curvature is a possible but unlikely cause of height loss.

Question 3

Which of the following is not associated with increasing age?

  1. 1-2 mm forward growth of the mandible
  2. 1-2 mm lengthening of the mandibular ramus
  3. widening of the nose
  4. decreased prominence of the nasal tip ✓
  5. increased prominence of the nasolabial fold

Correct

That’s right. With increasing age the nose almost always becomes more, not less prominent. It widens as well as growing forward and downward, and the nasolabial fold (the vertical fold along the sides of the nose) deepens. Slow forward growth of the mandible and lengthening of the ramus also usually occur.

Question 4

(A) In patients who have been treated orthodontically for a skeletal problem like a deficient mandible, some return of the original condition is likely long after treatment was completed because (B) the slow growth that occurs in adults tends to be in the same pattern that produced the skeletal problem initially.

  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 two statements are true and related. Even though facial growth during adult life is very slow, if the upper jaw grows more than the lower jaw, there will be a partial return of the original jaw relationship in a patient previously treated to correct mandibular deficiency—and that pattern of growth is likely in a patient who had deficient mandibular growth in childhood and adolescence.

Question 5

Which of the following are typical aging changes in the facial soft tissues?

a) flattening of the nasolabial fold

b) widening of the vermilion border of the lip

c) increased display of the upper incisors

d) increasing tightness of the cheeks

  1. a only
  2. b only
  3. c and d
  4. all the above
  5. none of the above ✓

Correct

That’s right, none of these changes occur in typical aging of facial soft tissues. The nasolabial folds deepen rather than flattening, the vermilion border of the lip narrows instead of widening, there is less display of the upper incisors, and the cheeks become looser rather than tighter.

Question 6

(A) Girls may become concerned about the fullness of their lips in their 20s because (B) lip growth may continue beyond adolescence and eventually lead to a need for lip reduction.

  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 one is false. Lip fullness is maximal at about age 16, and decreases after that. If a girl is concerned about lip fullness in her 20s, almost always it’s concern about loss of fullness, not excessive fullness.

Question 7

Relative to the upper incisors, which movements are characteristic of aging lips?

  1. forward

  2. upward

  3. backward

  4. downward

  1. 1 and 2
  2. 1 and 4
  3. 2 and 3
  4. 3 and 4 ✓

Correct

That’s right, relative to the teeth the lips move backward (closer to the teeth as the lip becomes thinner) and downward (as the facial soft tissues loosen and sag down relative to all the hard tissues of the face).

Question 8

On the average, how much of the upper incisor is displayed when the lips are at rest in a patient who is over age 60?

  1. none, the lower incisors show but the uppers don’t ✓
  2. 1 mm
  3. 2 mm
  4. 3 mm
  5. 4 mm or more

Correct

That’s right, by age 60 the upper incisors are not visible when the lips are at rest, while on average the lower incisors have about 3 mm exposure.

Question 9

For best facial appearance in a normal adult, which of the following would be the most desirable change in the position of the incisors relative to the upper lip during orthodontic treatment or prosthodontic replacement?

(1) upper and lower incisors down

(2) upper and lower incisors forward

(3) upper and lower incisors up

(4) upper and lower incisors back

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

Correct

That’s right, bringing the incisors forward provides more lip support and contributes to “filling up the bag”. Moving them down improves the visibility of the upper incisors and provides a more youthful appearance. For most patients, backward and upward movement would make the patient look older.

Question 10

By what age would you expect to see wear on permanent teeth in a patient on a primitive hard / abrasive diet?

  1. age 8 ✓
  2. 10
  3. 12
  4. 16
  5. 20

Correct

That’s correct. Wear would be noted on the permanent teeth within 2 years of the time they erupted, so already at age 8 the first permanent molars and probably the incisors would show wear.

Question 11

Aging changes in the dental pulp typically make the pulp chamber:

  1. shorter and wider
  2. shorter and narrower ✓
  3. longer and wider
  4. longer and narrower

Correct

That’s right. As you get older, the pulp chamber typically becomes narrower as dentin fills in the sides, and shorter as dentin is added across the upper part of the chamber.

Question 12

(A) Lengthening of the clinical crown of teeth usually occurs by passive eruption because (B) retraction of the gingiva is necessary to completely expose the clinical crown.

  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. Retraction of the gingiva in children and adolescents, which is described as passive eruption, usually is less important in obtaining exposure of the clinical crown than active eruption in concert with vertical growth of the jaws.

Question 13

What is the best description of the relationship between 3rd molar eruption or impaction and late crowding of lower incisors?

  1. almost always 3rd molars are the cause of late incisor crowding
  2. often but not always 3rd molars are to blame
  3. perhaps a little effect from 3rd molars but not the major cause ✓
  4. 3rd molars are too far away to have any effect on incisor position

Correct

That’s right. Several lines of evidence indicate that 3rd molars are not a major contributor to incisor crowding, but some studies suggest that they may be a minor contributor.

Question 14

(A) Late crowding of lower incisors usually accompanies late forward growth of the mandible because (B) the forward growth increases tongue pressure on the incisors and tips them facially.

  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 true and the second one is false. Late crowding of lower incisors accompanies forward growth of the mandible because the growth increases lip pressure that tips the incisors lingually, shortening arch perimeter and causing crowding.

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