5. Somatic Growth and Development Flashcards
The importance of understanding growth and development
A thorough background in craniofacial growth and development is necessary for every dentist.
Even for those who never work with children, it is difficult to comprehend conditions observed in adults without understanding the developmental processes that produced these problems.
This background is especially important for those dealing with children as it allows the clinician to distinguish normal variation from the effects of abnormal or pathologic processes.
Orthodontia is also known as _____
The specialty deals with the diagnosis, prevention and correction of malpositioned teeth and the jaws.
orthodontics and dentofacial orthopedics
Orthodontists are heavily involved in the development of not just the dentition but the entire _____.
Their treatments are frequently intended to manipulate facial growth for the benefit of the patient.
dentofacial complex
“Growth” and “Development”
Growth and development, though closely related, are not _____.
Since some tissues grow rapidly and then shrink or disappear, a plot of physical growth versus time may include a _____ phase.
The term _____ usually refers to an increase in size or number.
With reference to growth, the term development is used almost always to
refer to an increase in _____.
Development carries an overtone of increasing specialization, so that one price of increased development is a loss of _____.
Growth is largely an _____ phenomenon, whereas development is _____ and behavioral.
synonymous negative growth complexity potential anatomic physiologic
The Pattern of Growth: Changing body proportions occur during normal growth and development
In fetal life, at about the _____ month of intrauterine development, the head takes up almost _____% of the total body length.
After the third month of fetal life, the proportion of total body size contributed by the head and face steadily _____.
The overall pattern of growth thereafter follows this course, with a progressive reduction of the relative size of the head to about _____% of the adult.
third
50
declines
12
The cephalocaudal gradient of growth
At birth, the legs represent about _____ of the total body length, while in the adult, they represent about _____.
There is more growth of the _____ limbs than the upper limbs during postnatal life.
All of these changes, which are a part of the normal growth pattern, reflect the “_____ gradient of growth.”
This simply means that there is an axis of increased _____ extending from the head toward the feet.
one third half lower cephalocaudal growth
The cephalocaudal growth gradient of the face
Not only is there a cephalocaudal gradient of growth within the body, there also is one within the _____.
The _____, being farther away from the brain, tends to grow more and later than the maxilla, which is closer.
face
mandible
Scammon’s curves for growth of the four major tissue systems of the body.
Not all the tissue systems of the body grow at the same _____.
As head size proportion decreases the _____ and skeletal elements grow faster than the _____ and central nervous system.
One reason for gradients of growth is that different tissue systems that grow at different rates are _____ in various parts of the body.
rate
muscular
brain
concentrated
Scammon’s curves for growth
Growth of the neural tissues is nearly complete by _____ years of age.
General body tissues, including muscle, bone, and viscera, show an _____-shaped curve, with a definite slowing of the rate of growth during _____ and an acceleration at _____.
Lymphoid tissues proliferate far beyond the adult amount in late _____ and then undergo involution at the same time that growth of the _____ tissues accelerates rapidly.
6-7 S childhood puberty childhood genital
Predictability and Variability in Patterns of Growth and Development
Predictability
An important aspect of pattern is its _____.
Patterns repeat.
A change in growth pattern would indicate some _____ in the expected changes in body proportions
Variability
Everyone is not alike in the way that they grow
It can be difficult but clinically very important to decide whether an individual is merely at the extreme of the normal _____ or falls outside the normal range.
predictability
alteration
variation
Height and weight charts plotted vs. age
Rather than categorizing growth as normal or abnormal, it is more useful to think in terms of deviations from the usual pattern and to express variability ____.
One way to do this is to evaluate a given child relative to peers on a ____.
Charts of this type are commonly used for ____.
quantitatively
standard growth chart
height and weight
Height and weight charts plotted vs. age
The “normal variability” as derived from large-scale studies of groups of children, is shown by the ____ lines on the graphs.
An individual who stood exactly at the midpoint of the normal distribution would fall along the ____% line of the graph.
One who was larger than 90% of the population would plot above the ____% line
One who was smaller than 90% of the population would plot below the ____% line.
solid
50
90
10
Two ways these charts can be used to determine if growth is normal or abnormal:
Location of an individual relative to the group can be established.
A general guideline is that a child who falls outside the range of ____% of the population should receive special ____ before being accepted as just an extreme of the normal population.
Growth charts can be used to follow a child over time to evaluate whether there is an unexpected change in growth pattern.
Pattern implies ____.
For the growth charts, this means that a child’s growth should plot along the same percentile line at all ____.
If the ____ position of an individual relative to his or her peer group changes, especially if there is a marked change, further evaluation is indicated.
97
study
predictability
ages
percentile
Influences of growth variability outside the normal experience
Growth of a boy who developed a medical problem that affected growth, plotted on the male chart.
Note the change in pattern (crossover of lines on the chart) between ages ____.
This reflects the impact of serious illness beginning at that time, with ____ after age 13 but a continuing effect on growth.
10 and 11
partial recovery
Distance Curves vs. Velocity Curves
Growth can be plotted in either ____ at any age (the black line) or the amount of ____ in any given interval (the maroon line, showing the same data as the black line).
A curve like the black line is called a “____ curve,” whereas the maroon line is a “____ curve.”
Plotting velocity rather than distance makes it easier to see when ____ and decelerations in the rate of growth occurred.
Note the acceleration of growth at adolescence, which occurred for this individual at about age 14.
height or weight change distance velocity accelerations
Timing as a source of variability
Another major concept in physical growth and development is that of timing. Variability in growth arises in several ways:
1) Normal variation
2) Influences outside the normal experience (e.g., serious illness)
3) ____ effects
Variation in timing arises because the same event happens for different individuals at different times- the ____ of different individuals can be set differently.
Variations in growth and development because of timing are particularly evident in human ____.
timing
biologic clocks
adolescence
Growth velocity curves for early-, average-, and late maturing girls
Growth effects because of timing variation can be seen particularly clearly in girls with the onset of ____ (menarche).
Menstruation is an excellent indicator of the arrival of sexual maturity.
Sexual maturation is accompanied by a spurt in ____.
The earlier the adolescent growth spurt occurs, the more ____ it appears to be.
The onset of menstruation (menarche) (M1, M2, and M3) comes after the ____ of growth velocity.
menstruation
growth
intense
peak
Velocity curves for four girls with quite different times of menarche, replotted using menarche as a zero time point.
Although age is usually measured chronologically as the amount of time since birth or conception, it is also possible to measure age ____, in terms of progress toward various developmental markers or stages.
Timing variability can be reduced by using ____ age rather than chronologic age as an expression of an individual’s growth status.
It is apparent that the growth pattern in each case is quite similar, with almost all of the variations resulting from ____.
biologically
developmental
timing
Hand Wrist Radiograph
A reliable assessment of skeletal age must be based on the ____ status of markers within the skeletal system.
The ossification of the bones of the ____ was for many years the standard for skeletal development.
A radiograph of the hand and wrist provides a view of some 30 small bones, all of which have a predictable sequence of ossification.
maturational
wrist and hand
Hand Wrist Radiograph
Although a view of no single bone is diagnostic, an assessment of the level of development of the bones in the wrist, hand, and fingers can give an accurate picture of a child’s skeletal development status.
To do this, a hand-wrist radiograph of the patient is compared with ____ radiographic images in an atlas of the development of the hand and wrist.
standard
Graves and Brown: The timing of peak height velocity
Appearance of the ____ and the hooking of the hamate > PHV > Capping of the ____ middle phalanx, the capping of the first ____, and the capping of the radius
ulnar sesamoid
third
proximal phalanx
Ossification stages of the sesamoid bone of the first metacarpal
A. Absence of calcification
B. Onset of calcification
C. Definite calcification
TAKE A LOOK
Epiphysis stages of the proximal phalanx of the thumb
A. Pre-capping (widening) B. Capping C. Fusion onset D. Fusion in progress E. Fusion complete
TAKE A LOOK
A closer look at capping
The epiphyses becomes ____ (wider) than the metaphyses.
The epiphysis, prior to epiphyseal fusion, overlaps the ____ (capping), depicting tiny hornlike structures at both ends of the epiphysis.
larger
metaphyses
Fishman: The timing of peak height velocity
Capping of the distal phalanx of the third finger occurs less than 1 year before PHV > PHV > Capping of the ____ of the third finger occurs just after PHV
Capping of the middle phalanx of
the ____ occurs less than 1⁄2
year after PHV
middle phalanx
fifth finger
Cervical Vertebral Maturation (CVM) method for the detection of the peak in mandibular growth
A, Diagrammatic drawings and descriptions of the stages.
B, Stage 2, indicating that peak grow that adolescence is still a ____ or so ahead.
C, Stage 3, which on average is less than ____ prior to peak growth.
D, Stage 4, typically a ____ or so beyond peak growth.
E, Stage 5, more than ____ beyond the peak of the growth spurt, probably with more ____ than anteroposterior growth remaining.
F, Stage 6, more than ____ beyond peak growth (but in a patient with a severe skeletal problem, especially excessive ____ growth, not necessarily ready for surgery-the best way to determine the cessation of growth is serial ____ radiographs).
year year year 1 year vertical 2 years mandibular cephalometric
Measurement Approaches for Studying Physical Growth
Craniometry
Craniometry has the advantage that rather precise measurements can be made on ____ skulls; it has the important disadvantage for growth studies that, by necessity, all these growth data must be ____.
Cross-sectional means that although different ages are represented in the population, the same individual can be measured at only one point in ____.
Anthropometry
This the measure skeletal dimensions on ____ individuals.
Various landmarks established in studies of dry skulls are measured in living
individuals simply by using ____ points overlying these bony landmarks.
This produces ____ data: repeated measures of the same individual.
dry
cross-sectional
time
living
soft tissue
longitudinal
Measurement Approaches for Studying Physical Growth: Cephalometric Radiology.
This approach can combine the advantages of ____ and anthropometry.
It allows a ____ measurement of bony skeletal dimensions, since the bone can be seen through the soft tissue covering in a radiograph, but it also allows the same individual to be followed over ____.
Growth studies are done by superimposing a tracing or digital model of a later cephalogram on an earlier one, so that the changes can be measured.
craniometry
direct
time
Measurement Approaches for Studying Physical Growth: Three-Dimensional Imaging.
Computed axial tomography (CAT or more commonly, CT) Cone beam CT (CBCT) Magnetic resonance imaging (MRI) Three-dimensional photography
• CBCT has less \_\_\_\_ exposure and less \_\_\_\_ than CAT ○ Similar \_\_\_\_ • MRI ○ Great for showing \_\_\_\_ in more detail than hard tissue ○ Advantage: no \_\_\_\_ exposure at all
radiation
cost
information
soft tissue
radiation
Adolescence
Adolescence is a sexual phenomenon, the period of life when ____ is attained.
It is the transitional period between the juvenile stage and adulthood.
Secondary sexual characteristics appear, the adolescent ____ takes
place, ____ is attained, and profound physiologic changes occur.
All these developments are associated with the maturation of the sex organs and the accompanying surge in secretion of ____.
This period is particularly important in dental and orthodontic treatment because the physical changes at adolescence significantly affect the ____.
Major events in dentofacial development that occur during adolescence include the exchange from the mixed to the ____ dentition, an acceleration in the overall rate of facial growth, and ____ growth of the jaws.
sexual maturity growth spurt fertility sex hormones face and dentition permanent differential
The cascade of endocrine signals controlling sexual development
The first events of puberty occur in the ____.
Releasing factors from the ____ are carried via the pituitary portal circulation to the ____ gland, where they initiate the release of ____ hormones.
These in turn stimulate cells in the testes, ovaries, and adrenals, which secrete the steroid ____.
Each of the three steps in the control process results in an ____ of the control signal.
brain hypothalamus pituitary pituitary gonadotropic sex hormones amplification
Growth curves for the maxilla and mandible shown against the background of Scammon’s curves.
The growth of the jaws is ____ between the neural and general body curves.
The mandible follows the ____ body curve more closely than the maxilla.
____ growth is unaffected by the events of adolescence, since it is essentially complete by age 6 or 7.
The acceleration in general body growth at puberty, which affects the jaws, parallels the dramatic increase in development of the ____.
Lymphoid ____ also occurs at this time.
intermediate general neural sexual organs involution
Timing of Puberty
There is a great deal of individual variation, but puberty and the adolescent growth spurt occur on the average nearly ____ earlier in girls than in boys.
Orthodontic treatment must be done earlier in ____ than in boys to take advantage of the adolescent growth spurt.
Because of the considerable individual variation, ____ boys may reach puberty ahead of slow-maturing girls.
It must be remembered that age is only a crude indicator of where an individual stands developmentally.
2 years
girls
early-maturing
chronologic
Timing of Puberty
The stage of development of ____ provides a physiologic calendar of adolescence that correlates with the individual’s physical growth status.
Not all the secondary sexual characteristics are readily visible but most can be evaluated in a normal ____ examination, such as would occur in a dental office
secondary sexual characteristics
fully clothed
The three stages of adolescence in females
The first stage occurs at about the beginning of the physical ____, is the appearance of ____ and early stages of the development of ____.
The peak velocity for physical growth occurs about ____ after the initiation of stage I, and coincides with ____ of development of sexual characteristics.
At this time, there is noticeable ____ development.
Pubic hair is darker and more widespread, and hair appears in the ____ (axillary
hair).
growth spurt breast buds pubic hair 1 year stage II breast armpits
The three stages of adolescence in females
The third stage in girls occurs ____ years after stage II.
It marked by the onset of ____.
By this time, the growth spurt is all but ____.
At this stage, there is noticeable broadening of the ____ with more adult fat distribution, and development of the ____ is complete.
1 to 1.5 menstruation complete hips breasts
The four stages of adolescence in males
Puberty begins later and extends over a longer period of about ____ compared with 3 1⁄2 years for girls.
In boys, ____ stages in development can be correlated with the curve of general body growth at adolescence.
5 years
four
The four stages of adolescence in males
STAGE I
The initial sign of sexual maturation in boys usually is the “____ spurt.”
The maturing boy gains ____ and becomes almost chubby, with a somewhat feminine fat distribution.
This probably occurs because ____ production by the Leydig cells in the testes is stimulated before the more abundant ____ cells begin to produce significant amounts of testosterone.
During this stage, boys may appear ____ and somewhat awkward physically.
fat weight leydig sertoli obese
Stages II and III of adolescence in males
At stage II, about ____ after stage I, the spurt in height is just beginning.
There is a redistribution and relative decrease in subcutaneous ____, pubic hair begins to appear, and growth of the ____ begins.
The third stage occurs ____ months after stage II and coincides with the ____ in gain in height.
Axillary hair appears and facial hair appears on the ____ only.
A spurt in muscle growth also occurs, along with a continued decrease in
subcutaneous fat and an obviously harder and more angular body form.
Pubic hair distribution appears more adult but has not yet spread to the ____ of the thighs.
The penis and scrotum are near ____.
1 year fat penis 8 to 12 peak velocity upper lip medial adult size
The four stages of adolescence in males
FOURTH STAGE
Stage IV for boys occurs anywhere from ____ months after stage III and is more difficult to ____.
At this time, the spurt of growth in ____ ends.
There is facial hair on the ____ and the upper lip, adult distribution and color of pubic and axillary hair, and a further increase in muscular strength.
15 to 24
pinpoint
height
chin
Sex hormones and growth in height
The earlier the onset of puberty, the smaller the ____, and vice versa.
Growth in height depends on ____ bone growth at the epiphyseal plates of the long bones and ____ impact endochondral bone growth is two ways.
First, the sex hormones stimulate the ____ to grow faster, and this produces the adolescent ____.
But the sex hormones also cause an increase in the rate of skeletal ____, which for the long bones is the rate at which cartilage is transformed into ____.
The acceleration in maturation is even greater than the acceleration in growth so the cartilage is used up faster than it is ____.
Toward the end of adolescence, the last of the cartilage is transformed into bone, the ____ close, and growth in height stops.
adult size endochondral sex hormones cartilage growth spurt maturation bone replaced epiphyseal plates
