Growth And Development

Question 1

At what age do females and males reach PHV (peak height velocity)?

Answer 1

Females = 11.9 years

Males = 14.0 years

Question 2

At what age does girls and boys initiate adolescence?

Answer 2

Girls = 9.4 years

Boys = 11.2 years

Question 3

What is the mild-childhood growth spurt? When does it typically occur?

Answer 3

The increase in growth velocity that occurs in some, but not all, children several years before adolescence.

Occurs between 6.5 and 8.5 years of age.

Question 4

True or false… the mid-childhood growth spurt more often occurs in girls than boys.

Answer 4

False… it tends to occur more frequently in boys than girls

Question 5

Which skeletal (Hand) indicators are most closely associated with peak height velocity?

Answer 5

PHV in males and females occurs slightly after the appearance of the ulnar sesamoid and the hooking hooking of the hamate, and slightly before capping of the third middle phalanx, the capping of the first proximal phalanx, and the capping of the radius.

Question 6

Which skeletal indicators (cervical vertebrae) are most closely associated with peak height velocity?

Answer 6

PHV occurs between cervical vertebral maturation stage CS3 (concavities on the inferior borders of the second and third vertebrae, and both the third and fourth vertebrae are either trapezoid or rectangular horizontal in shape) and CS4 (concavities on the inferior borders of the second, third, and fourth vertebrae, and both the third and fourth vertebrae are rectangular horizontal in shape).

Question 7

What are three conclusions that are drawn from the equilibrium theory of tooth position?

Answer 7

The forces (produced naturally or by orthodontic appliances) extorted on the crowns of teeth are sufficient to cause tooth movements

Each tooth may have more than one stable state of equilibrium

Even small forces (3-7 grams), if applied over a long enough period can cause tooth movements.

Question 8

What are the primary factors involved in the equilibrium theory of tooth position?

Answer 8

Pressures of the lips, cheeks, and tongue

As well as the eruptive forces produced by metabolic activity within the periodontal membrane.

Extrinsic pressures, such as habits and orthodontic forces, can alter dentoalveolar equilibrium provided that they are sustained for at least 6 hours each day.

Question 9

Which, the maxilla or mandible, contributes the most to class 3 malocclusions?

Answer 9

The mandible

Question 10

Do third molars play a role in determining crowding?

Answer 10

Although third molars have been related with crowding, most contemporary studies show little or no relationship.

The NIH determined that there is little to no justification for extracting third molars solely to minimize present or future crowding of the lower anterior teeth.

Question 11

True or false… anterior growth of the mandible significantly contributes to mandibular incisor crowding as it pushes the incisors in the the lower lip.

Answer 11

False. Although incisor compensation to back-ward mandibular rotation has been demonstrated, crowding as a result of anterior growth displacements remain to be established. However, changes in lower incisors crowding have been shown to be related to VERTICAL growth.

those who undergro greater inferior growth displacements of the mandible, and associated greater eruption of the lower incisors, show greater crowding than those who undergo less vertical growth and less eruption.

Question 12

How much should the maxillary and mandibular incisors and molars be expected to erupt during adolescence? (Between ages 10-15)

Answer 12

Maxillary first molars 5-6mm

Maxillary central incisors
4.5-5mm

Mandibular molars
3-5.5mm

Mandibular incisors
2.5-4.5

Males showed greater eruption than females

Question 13

How do untreated maxillary and mandibular intermolar widths change during childhood and adolescence?

Answer 13

Increases 7-8mm between age 5 - age 8. Then an additional 1-2mm between age 8 and age 12.5.

Question 14

During the transition from the deciduous to permanent incisors, mandibular intercanine width increases approximately ___. Maxillary intercanine width also increases, approximately __. Mandibular intercanine widths decrease slightly after the emergence of the permenent canine.

Answer 14

3mm

1.5 - 2mm

Question 15

True or false.. maxillary intermolar widths were significantly smaller in subjects with Class 2 division 1 malocclusion than subjects with Class 2 division 2.

Answer 15

True

The narrow maxillary arch of division 1 subjects was apparent at 7 years of age and persisted through age 15.

Question 16

class 2 division 2 malocclusion have __ and __ maxillary arches, whereas class 2 division 1 have __ and ___ maxillary arches

Answer 16

Short and wide

Long and narrow

Question 17

True or false.. growth spurts do NOT occur in the AP position of either the maxilla or mandible

Answer 17

True. In other words, the chin does not undergo an anteriorly-directed growth spurt. However, the vertical aspects of both maxillary and mandibular growth exhibit adolescent spurts with peaks.

Question 18

True or false.. peak maxillary growth velocities are usually attained more than 6 months before peak mandibular velocities. The maxilla tends to peak before PHV, whereas the mandible peaks after PHV.

Answer 18

True

Question 19

Approximately __% of 10-year-olds are classified as prognathic or retrognathic, changing to orthognathic by age 15.

Answer 19

30%

Question 20

Approximately __% of those who are orthognathic at 10 years of age become either prognathic or retrognathic at age 15.

Answer 20

30%

Question 21

Between ages __ and ___, fore every 1mm the maxillary width increased, the mandibular width increased ___.

Answer 21

12 and 18

0.7mm

Question 22

__ and ___ displacement of the glenoid fossa should be expected to occur along with growth of the sphenoid-occipital synchondrosis, elongation of the posterior cranial base, and associated displacement of the temporal bone.

Answer 22

Inferior and posterior

Question 23

The distance between the glenoid fossa and nasion increases ___mm between 12 and 20 years of age.

Answer 23

7.5mm

Question 24

The condyle grows __ and slightly __, whereas the gonion drifts ___ and ___ in approximately equal amounts

Answer 24

Superiorly
Posteriorly

Superiorly
Posteriorly

Question 25

The closure of the mid palatal and transverse sutures can begin as early as ___ years of age but can be delayed in some individuals into the late ___.

Answer 25

15

20s or early 30s

Midpalatal sutures show evidence of growth through 16 years of age infemales and 18 years of age in males.

Question 26

True or false… even though sutures start closing in adults, only relatively small portions of the sutures exhibit true fusion

Answer 26

True

Question 27

The cranial base lengths (SN, BaN, BaS) and mandibular lengths (Ar-Go, Go-Gn, Ar-Gn) attained their maximum lengths between ages __ and __, after which they shortened slightly

Answer 27

29 and 39