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75 Cards in this Set

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Growth
increase in size, number, complexity

must always maintain functional equilibrium
Development
involves differentiation & specialization = loss of potential
Intramembranous Ossification
mesenchymal cells differentiate directly into osteoblasts, which deposit bone matrix within CT

No cartilage intermediate

Includes:
flat bones of the cranial vault

Mx and Md bones of the jaws
endochondral ossification
occurs by formation of a cartilaginous model that is gradually replaced by bone

Includes:
long bones
base of the skull
Mandibular condyles
How does bone grow at the periosteal surface?
Apposition
Longitudinal studies
a group is examined over a long period of time to obtain data for studying growth rates & variability

Advantage:
small sample size
comparison standards
can observe variability

Disadvantage:
Long duration
What are the advantages to a longitudinal studies
small sample size
can derive comparison standards
can observe variability among individuals
What are the disadvantages to a longitudinal studies
Long duration
Cross Sectional Studies
Large # of people of different ages are examined on one occasion to obtain info about growth at a particular age

Advantage:
Short duration

Disadvantage:
Only can estimate average growth rates
Cannot study individual variation
What are the advantages to a cross sectional studies
Short duration
What are the disadvantages to a cross sectional studies
Can only estimate the average growth rates

Cannot study individual variation
Mixed longitudinal studies
A hybrid combination of cross-sectional and longitudinal studies

Get the both of both by obtaining subjects in different age groups for a shorter period of time

Allows you to look at variability because you are not estimating averages
Anthropometry
involve measuring skulls of living people to study growth patterns

Can be either cross sectional or longitudinal
cephalometric radiology
advantage = allows direct measurement of skeletal dimensions

disadvantage = produces a 2D representation of the 3D structure

Can be either cross sectional or longitudinal
distance curve / cumulative curve
plots size as a function of age

how big you were at what age

Can be derived from cross section and longitudinal studies
velocity curve / incremental curve
plots amount of growth as a function of time

how fast you grew within a certain time frame

Easier to see phases like pubertal growth, peak velocities

Derived from longitudinal studies only
Which graphic interpretation can only be derived from longitudinal studies?
Velocity curves
Vital staining
uses dyes to stain mineralized tissues

lines of incremental growth can be observed later

Ex: alizarin red stains for appositional growth of bone

tetracycline stains - can determine at what age the tetracycline was given
radioactive tracers
label any metabolite that becomes incorporated into tissues

detects areas of rapid growth
implant radiology
strictly to study growth in humans

metal pins are implanted in bones

provide a reference point so that you can determine the relative positions of one bone to another
cephalocaudal gradient of growth
structures located closer to the head grow less and finish growth first
Scammon’s Growth Curves
neural growth stops at 6-7 yrs

genital growth begins at puberty age

general body growth shows a sigmoidal curve, slow during childhood, accelerated at puberty

lymphoid tissues grow rapidly in childhood and then begins to involute at puberty

md growth follows more similarly to body growth than the mx
What is the general body growth curve according to Scammon
general body growth shows a sigmoidal curve, slow during childhood, accelerated at puberty
What is mandibular growth curve according to Scammon
md growth follows more similarly to body growth than the mx
How do you find out if a person is at the extreme end of the normal variation?
You have to compare standards of growth derived from longitudinal studies

Compare child to his peers on standard growth chart

Compare height, weight, skeletal, dental development
Normal height growth
measurement that falls within one standard deviation around the mean (68%)

normal range of one standard deviation falls bt the 16th and 84th percentile
adolescent growth spurt
begins earlier in female

lasts about 2 – 2.5 yrs in both males and females
Menarche
always comes after the peak velocity of the growth
Which has more variation, weight or height?
Weight
adolescent weight spurt
average age in girls is 12 and boys is 14

peak velocity for weight spurts lags behind peak velocity of height by about 3 months
Which peak velocity lags?
peak velocity for weight spurts lags behind peak velocity of height by about 3 months
What are most variations in growth attributed to?
Timing

same events happen at different times in diff people

late bloomers grow slower, but longer, and their growth usually surpasses the early bloomers
Chronologic age
not a good indicator of growth status because of timing and variability

measure age biologically by studying developmental markers instead
What is the best way to indicate growth status
measure age biologically by studying developmental markers
What do girls growth curves look like after menarche
girls’ growth curves are very similar to e/o
morphologic age
based on height compared to his peers

useful from late infancy to early adulthood
sexual age
development of secondary sex characteristics

only for adolescent growth

ask the age of menarchy and the peak velocity occurred right before it

menarchy is the key marker for sexual age
What is the key marker for sexual age
menarchy
skeletal age
assess the development of cervical vertebra or wrist bones

peak growth of the mandible occurs bt CVMS 2 and 3
dental age
Can use eruption age and crown calcification to root completion
What is the major difference b/t the growth theories?
where the control of bone growth is

Sutural - genetics control growth
Primary Cartilage - cartilage controls growth
Functional Matrix - growth due to functional needs
Sutural Growth Theory
genetics is what controls osteogenesis

sutures are the dominant commanding structures that directs growth

pressure created by formation of new bone at sutures tends to push bones apart, and bone would form in between those pushed apart spaces.

**these sutures are both sites of growth AND centers of growth
Site of growth
where the growth occurs

Ex: condyles and sutures
Center of growth
location at which independent growth occurs under its own genetic control

a growth initiator that pushes apart

Ex: craniofacial synchondroses
Primary Cartilage Theory
cartilage is what does the growth while bone merely replaces it

condyles is what controls the growth of the mandible

Growth of the Nasal Complex results in the maxillae growing down and forward
Experimental evidence against sutures being growth centers
sutures fail to grow after being transplanted to other location

when sutures are pushed or pulled, they are reacting rather than acting independently

theory about sutures being control centers of growth is FALSE.
Experimental evidence against condyles being growth centers
mandibular condyle will grow very little or none at all when transplanted

theory about the condyles being control centers of growth is FALSE.
Is the mandibular condyle a center of growth?
no

If the mandibular condyle fractures, there is 75% chance that normal growth will NOT be affected
Is the nasal septum a center of growth?
yes

removal of it, or damage to it will always affect growth of the maxillae causing under-development (Class-III occlusion)
Functional Matrix Theory
Function dictates growth of the craniofacial complex

growth is mediated by the soft tissues/functional matrix that embeds the hard tissues

growth is mediated by the soft tissues

Proof:
Growth of the cranial vault is a direct response to the growth of the brain.

25% of condylar fractures results in deficient growth of the mandible.

Thumb-sucking can cause changes in the oral structures causing open bite and narrowed palatal vault
Which theory is the most accurate?
it’s multi-factorial involving intrinsic factors, epigenic factors, and environmental factors
endosteal and periosteal deposition & resorption
side w/ the applied pressure gets resorbed

side w/o the pressure gets deposition
Which growth mechanism is the principle used in the movement of teeth in orthodontics
endosteal and periosteal deposition & resorption


side w/ the applied pressure gets resorbed

side w/o the pressure gets deposition
If ortho wire pulls a tooth mesially, which side resorbs bone?
Mesial side w/ pressure absorbs bone

Distal side w/out pressure deposits bone
cortical drift
cortical plate will increase in thickness when bone is deposited
and decrease in thickness when bone is resorbed

imbalance of deposition & resorption causes the cortical bone to shift
What causes the cortical bone to shift?
imbalance of deposition & resorption
relocation
apposition and resorption processes that cause shifts in the relative bone position (cortical drift)
remodeling
adjust the size & shape of the area to the new relationship, to the new physiological loading
displacement
separate movement of the whole bone by some physical force that carries it away from contacts with other bones

Primary and Secondary Displacement
primary displacement
growth of a structure is affected by that same structure’s own growth & enlargement

takes place in the opposite direction of the vector of bone growth

Ex: maxilla moves down & forward due to its own Nasal Complex growing up and back
What kind of displacement is occurring when the maxilla moves down and forward due to the Maxilla's Nasal Complex growth up and backwards?
Primary displacement
secondary displacement
growth of a structure is affected by the growth of other bones surrounding it

can be additive (deposition) or subtractive (resoprtion)

Example = displacement of Nasomaxillary Complex is caused by growth of the middle cranial fossa
What kind of displacement is occurring there is displacement of Nasomaxillary Complex caused by growth of the middle cranial fossa?
secondary displacement
Where is bone deposited?
inner surface of the V
Where is bone resorbed?
outer surface of the V
V-principle
V will eventually enlarge and move away from its apex due to deposition in the inner surface and resorbtion on the outer surface of the V
Where is bone deposited in the mandible?
bone is deposited on the lingual surfaces
Where is bone resorbed in the mandible?
resorbed on the buccal surfaces
What does growth of the condyles cause?
Primary displacement

causes anterior displacement of the chin down & forward
What does growth of the cranal base cause?
Secondary displacement

causes anterior displacement of the chin down & forward
How does the chin move down & forward?
Primary displacement of condyles

Secondary displacement of cranial base
Where is the least amount of change occuring in mandibular growth?
Anterior surface of Bony chin
Where is there deposition in the Maxilla?
Oral cavity side
Where is there resorption in the Maxilla?
On the nasal side
What causes the Maxilla to move down and forward?
Primary displacement of nasal complex

Secondary displacement of cranial base