Maxillary, Mandibular Cranial Growth

Question 1

Scammon’s Growth Curve

Answer 1

Max and mand growth tends to follow the gernal growth curve, w/ mandible slower than max

neural finished early w/ growth of brain

genital development comparatively late

lymphoid tissues almost double of adult size around 9-10 yrs of age

Question 2

Maxillary Growth

Answer 2

Predominant enlargement is posterior and superior, displaced downward and forward
*Intramembranous growth

Deposition of tuberosity - causes arch elongation to allow teeth to fit in

Palate is depository, nasal floor is resorptive (relocates palate inferiorly, inc nasal airway)

Question 3

Midpalatal suture

Answer 3

closes around 8, may be opened into adolesence
Opened w/ rapid palatal expansion
Opened some w/ quad helix
Used for cross bite, possibly crowding, and Class III

Used for children w/ too narrow of maxilla

Question 4

V principle of growth

Answer 4

as palate expand and as deposition occurs on the alveolar ridge, the overall bone widens

Question 5

Mandibular Growth

Answer 5

• endochondral in condylar region
• intramembraneous at other growth sites

displacement of the mand downward and forward leads to predomin trend of growth of posterior and superior

Deposition of bone on posterior of ramus, resorption on anterior of ramus

Tuberosity growth: pos direction, allows for tooth eruption

Chin button growth: depository on chin, resorptive at B point

Question 6

Mandibular Growth - Condylar Growth

Answer 6

Condyle is a growth site, not growth center

growth occurs as a result of other factors

The condyle is therefore ADAPTIVE

Question 7

Symphyseal Sutures

Answer 7

closes during 1st year -> hard to expand mandible, Schwartz appliance (expands by uprighting teeth)

Question 8

Timing of Mandibular Growth (Males v females)

Answer 8

Males: growth rate dec during childhood, inc during adolescence, and attained a max of 3.1 mm/yr at 14.3 yrs old

Females: constant rate of condylar growth during childhoot (2-2.7 mm/yr), smaller adolescent peak (2.3 mm/yr), at approximately 12.2 yrs and rapid deceleration after the peak

Question 9

Late Mandibular Growth

Answer 9

either mandible displaces distally (TMJ disturbances)

Upper incisors flare (causes spaces)

Lower incisors displace distally (most common, lower incisors crowd)

Question 10

Mandibular rotation

Answer 10

Overall Forward Rotation

• dec of 3-4 degrees mandibular plane angle (4-adult)
• causes post incisor movement and dec in arch length
• short face type: more rotation than average (square jaw, low MPA, square gonial angle
• long face type: jaw rotates backward and down (high MPA, anterior open bite)

Question 11

3 planes of space for maxilla and mandible

timing of completed growth

Answer 11

Width completes first - mostly prior to adolescent growth spurt, intercanine width basically complete at 12

Length completes second - females: 14-15, males: 18

Height completes last: females: 17-18, males: early 20’s

Question 12

Adult Facial Growth

Answer 12

Facial growth continues throughout life

longer and narrower face

Question 13

How to alter growth

Answer 13

“Headgears” are typically used to retrain anterior max movement or to distalize permanent molars to correct a class II

“Functional” appliances in Class II cases are typically used to inc anteroposterior dimension of the mandible

Question 14

Effects of Thumb Sucking

Answer 14

Increase Overjet

Decrease Overbite

Question 15

Fontanelles of Newborn Skull

Answer 15

Sphenoid, Anterior, Mastoid, Posterior

Question 16

Growth of the Brain Case

Answer 16

Cranium grows b/c brain grows
Age 5, 90% of growth of cranial vault completed
Growth is sutural and appositional

Frontal, Ethmoid, Sphenoid, Temporal, Parietal, Occipital