Longitudinal study of facial growth in relation to skeletal maturation during adolescence

Americun Journd of ORTHODONTICS Volume

49, Nu,mber ‘7, J U IA Y, 1963

ORIGINAL

ARTICLES

Longitudinal study of facial growth in relation to skeletal maturation during adolescence JAGDISH PEARL Denver,

K. VAT-G

BAMBHA,

B.D.S.,

NATTA,

M.S.,

and

M.A.

Cola.

INTRODUCTION MANY investigators in the field of orthodontics have noted the beneficial effect that the rapid rate of growth during adolescence has upon orthodontic treatment. The close relationship between skeletal maturation and sexual development has also been 0bserved.l It is the purpose of this article to implement these observations by relating the growth of the face during the adolescent period to a measure of skeletal development based on hand and wrist s-raps. REVIEW

0~

LITERATURE

Shuttlewort.h,? in his study of sexual maturation and physical growth in girls, concluded that menarche is closely associated with physical size and onset of adolescence. He also showed that while his three different groups of girls. classified by age at first menstruation, have the same increment pattern 01’ growth, the time of menarche is different. The shape of the average height growth curve of the early-menstruating group is similar to the shape of the curve’ of the late-menstruating group but is shifted to the left on the time scale. When the early-maturing group is at the peak of its acceleration in hod>* height, the late-maturing group is just beginning to accelerate. The skeleta.1 maturation as assessed from hand and wrist roentgenograms shows similar pat terns for the two groups. From the Child Denver, Colo.

Research

Supported

in part

Presented 18, 1962.

before

Council

by grants the

Midwestern

from

and

the

Universit,y

Commonwealth Society

of

of Colorado Fund

Orthodontists,

of

New Omaha,

School

of Medicine

York. Neb.,

Sept.

-16 iit

.

In their study on three gronps of girls, C~rcwlicli:’ and latw Siurmous ancl Grealich4 found the limit,ations of using height-\vcigllt-age tables bawd on group averages for assessing the maturational status o F individuals. In these thtw groups the girls with early, average, and late menarches arc distinguished from one another by their mean skeletal ages mwe consistently and more rcgula~~ly than by their weight or weight-height, indices. C:reulich and Simmons fountl a significant correlation .coefficient betwcn chronologic age at mrnarchc ant1 skeletal age i’rom 7 through 17 years and fnrthcr concluded t’rom correlation coefficients that skeletal age and stature are closely related from i years throng11 1 I years while from I:! years through 17 years, the skclctal age: is related somcwhat more closely to weight than to stature. (ienetic diversity and diffcrcnt nutritional status in variolls groups Ilmltc height-weight tables unrcliahle for assrssing the developmental status of the chil(l. 11~ belicvcs that hand films taken OVCI a period of time arc a I~~OIY: efficicwtmeasure of the child’s skeletal dovelopnwnt., from which it is usnally pcr;ssiblc to predict the time when epipliysial fusion will occur and the grolvtli in 1~1~ height xv-ill bc completed. A rcccrlt ilrtiPl0 l)?Hansman ant1 iUarcsli wems to contradict this Gcw.l Howard” ~1s the first to obstr~o that the majority ot’ the children with retarded dwelopmcnt of the jaw and arches, cspeciall~- in preadolescent cases, also showed general retardation of skeletal growth. Hc stressed that no orthodontic case should be subjected to mechanical therapy bcforc t,hc status 01 skeletal growth is cstablishcd. Contrary to these opinions, Rose” i’ound chronologic age and skeletal matnration as assessed by hand and nrist s-ray films to bc an ineffcctivc guide to the growth and dewlopmcnt of the face. He fonnd that stature and body wchight wcrc more satisfactory indicators of facial development. Nore recently Hughes,’ Shrhan, ’ Sassouni,!’ and Krogman,” by discussing individual cases, ha\-e drawn attention to the \-alum of nsing the association lwtwen general body growth and skeletal matm~ation in orthodont,ic trcatmcnt. MATERIBL

AXD

METHOD

\\‘e studied the skeletal maturation and adolcswnt growth of t,hc face in twent,y-two boys and twenty-eight girls. These snbjects, who were born in lhver of Sort11 Europcall ancestry, were taking part in the longitudinal growth st,ndy at the Child Research Council. The nature of the program has bccrr prwiousl>described in detail by Washburn” and IValdo.12 The time of masimmn facial growth was determined b\- warning the latwal cephalometric roentgenograms taken at yearly intervals from the age of 9 s-cars 9 months to the age of 17 years 9 months. The apparatus used for taking ccphalometric roentgenograms is dcrelopcd on the snmc principles as the Rolton setup at \Yestern Rrscrw I-niversity in Clevelandl” bnt is modified for the space irnd rcqnirements of the Child Rcscnrch Council. Only one dimension-sella-gnathion (SE-GX)-is measured to detcrmincx the time of maximum facial growth during adolescence. One of us (J. K. B.) has previously demonstrated that the time of maximum growth of the face dnr-

J’ig.

1. The

grnogram

sella-gnathion t,o establish the

(SE-Ghr) time of

dimension maximum

measured aircumpuberal

on

the lateral crphalometrir: growth during adolescence.

roent

It was necessary to analyze the data on girls and boy separately, since thrs t imrs OF maximum facial growt,h do not ha\e the same distribution in the twc~ groups. Tables I and II give the yearly incrcmcnt ot’ sella-gnathion in l)o~~ i\nd girls from I) years I) months to 16 years 9 months of age. The rrlatiw incwmcnt growth curre of the sella;gnathion dimension is used t,o tlctcrmine th(~ maximum circumpuheral growth spurt,.‘7 In Tahlc I II t,hc differcnw, in months, Iwtwen the chronologic age and the skeletal age of lwys has hcen listed u11d~~r

484

Bambha

Am.

and Van Natta

Table 1. Yearly

increments

J. Orthodontics JuZ!x/ 1963

of the sella-gnathion

measurement

(expressed

as

mm. x10) in boys Serial nzllnber

Between 9-9 and 10-9

Between 10-9 and 11-9

Between 11-9 and 16-9

Between 18-9 and 13-9

Between 18-9 and 14-9

Between 14-9 and 15-9

Between

and

15-9

16-9

5

1.2

2.7

2.3

4.8

4.2

0.3

0.3

125

2.1

1.1

4.0

5.4

1.6

0.8

1.0

29

1.9

2.4

3.6

4.6

2.7

1.3

0

10

2.0

2.0

2.3

3.9

3.0

2.6

0.6

120

I.5

2.8

3.2

3.7

3.2

2.0

1.4

76

5.6

1.2

2.3

5.9

4.6

0.8

0.9

116

2.9

2.9

4.0

5.1

2.7

1.8

1.2

15

3.0

2.6

2.6

3.7

4.5

3.5

3.0

6 57

2.2 2.6

2.0 2.4

3.8 2.8

4.6 5.0

4.7 6.7

3.7 0.8

0.6 0.6

82

2.1

1.9

2.8

2.1

6.1

3.6

1.5

59

0.9

2.1

1.4

4.0

5.4

4.4

3.4

33

2.0

1.4

2.0

2.6

4.6

2.6

2.6

85

1.0

1.2

3.5

4.0

5.3

2.0

1.8

21

1.4

0.8

2.5

3.6

3.6

2.3

2.2

108 14

2.7 1.4

2.3 1.4

2.2 1.4

1.8 2.3

2.2 3.9

4.6 4.9

2.5 3.0

109

2.3

2.2

1.4

3.1

3.0

5.8

4.4

1.4

2.2

1.6

1.5

1.5

3.8

3.6

126

1.5

3.2

1.8

2.3

1.7

4.6

4.0

66

2.2

2.0

2.0

2.2

4.2

4.2

2.4

96

2.5

1.3

1.7

1.8

2.7

1.3

4.7

11

Figures

in italics represent

the period of a maximum

growth spurt.

four groups according to the time of the maximum adolescent growth spurt of the face. Similarly, the girls have been divided in live groups in Table IV. In both Tables III and IV the early-maturing subjects show greater gain in skeletal age over chronologic age than the subjects who are in t.he middle. The latematuring subjects show retardation in skeletal maturation over chronologic age. The first question of interest is whether or not there is an association between the variable called “time of maximum facial growth” and the variable called “skeletal age minus chronologic age ” (designated henceforth as SA minus CA). Each child was cross-classified by t,he values of these two variables. The cross-classification figures for girls and boys are shown in Tables V and VI, respectively. Both variables in each table are ordered, with the time of maximum facial growth going from early to late and the SA minus CA going from lags to gains. The Goodman-Kruskal index of association’s between two ordered variables was computed separately for each table. The index is interpreted not with respect to a theoretical distribution, such as chi-square, but with respect to all possible combinations of pairs of individuals chosen at random with replacement from the number of individuals studied. In this study twenty-eight are individuals represented in the cross-classification table for girls; hence, there are W = 784 possible combinations of pairs of individuals. We inspect the

Volume

49

Adolescent

Number 7

Table II. Yearly increments mm. x 10) in girls Serial

Between 9-9 and

number

10-9

1 12 8 86 30 315 104

4.5 2.Y 2.8 3.5 2.5 5.4 1.4 0-.- 0 2.5

99 121 113 so3 JO6 114 9

1.8 2.6 2.6 0.4 2.1 1.4 2.6

110

1.1

2

118

44

2.7 1.5 1.5 0.9 1.9 2.2 1.5 2.0 2.5 1.9 2.2

7

94 105 72 124 112 111 117 107 102 Figures

in italics

represent

facial

and sldetal

Between 11-9 and 12-9

2.2 2.4 4.0 4.1 3.5 3.9 5.4 2.8 3.5 3.3 2.3 1.1 0.9 2.5 4.3 2.0 2.6 2.7 2.1 1.7 2.0 2.8 1.G 2.1 2.3 1.5 2.2 1.9

1.5 1.7 2.5 1.6 2.6 1.2 1.1 4.8 3.9 4.3 4.5 3.6 3.3 5.8 5.7 9.6 8.7 3.5 6.3 2.8 1.9 1.9 2.3 2.0 2.3 2.4 2.1 1.7 period

of

mnturation

)neasurement

of the selba-gnathion

Between 10-9 and 11-9

the

growth

(expressed (IS

Between

Between

Between

lb-9

15-9

14-9

and

13-9

14-9

0.5 1.8 1.3 1.6 0.7 1.1 1.1 0 1.5 1.9 0.9 0 2.4 1.4 2.0 2.7 2.0 3.5 1.8 3. Ia 2.7 4.3 2.5 3.6 4.1 2.5 2.4 2.1 a maximum

and

0.7 1.4 1.7 0.7 1.1 1 .o 0.2 1.5 0.1 cl.9 0 0.9 0.9 0.6

growth

I

-tilt,

and

15-9

I

Betwee?h .15-9 wnd 16-9 0.3

0.3 0 0.4 0.7 1.0 0.6 0.2 0

I) II

0.4 0.9 0.3 0.8 0.4 0.5

0 0 0 11.2 0.4 0.4

0 0 0 0 il.,i

1.5

0.6

(I.7

0.9

0.4

0.3

1.1

1.1

1 .i“

1.7 2.” 2.; ? 2.4 2.3 1.1 1.1 2.5 3.0 2.7

1.0 0 1.8 2.5 1.1 0.3 1.2 1.2 1.6 1.2

0 0 0.2 1.4 0.5 0 1 .i“ 0 0 1.1 _--.-

.

spurt.

classification values of the two variables for each of the 784 pairs of girls and put the results of this inspection into one of three categories. In the first category, marked same, we put the pairs in which the order of variables is the same (that is, the pairs in which the girl with the later time of maximum facial spurt also has the larger value of SA minus CA j . In the second category, marked different, we put the pairs in which the order of variables is different (that is, the pairs in which the girl who has the later time of maximum facial spurt also has the lower value of SA minus CA). For example, if one girl of the pair had values showing that the adolescent growth spurt of the face occurred between the ages of 10 years 9 months and 11 years 9 months and SA-CA = 24 months and the other girl had values showing the adolescent growth spurt betwet>n 12 years 9 months and 13 years 9 months and SA-CA = 12 months, this pair would go into the category marked diiljrerent. In the third category, we put t,hs pairs of individuals for whom either of the variables has the same valne (t,hat

Table ISI. Dif’ermce in months of skeletal; crqe mi~~us ch,wnologic G~‘Pof tiwenty-two boys u,t the ages of 12, 14, mail 16 ye~m, sepurnterl ill f0ut. ~jro~trps according to time of maximum circum~mberal growth. qmrt Serial

number

/ Group

5 125 29 10 120 7G 11 6

Gro~p 15 6 57 82 59 33 85 21 Group

11

Maximum circtcmpubwal occwring between ages 13 4 (i 3 0 0 6 II. Maximtbm circumpubd ooccrring between ages -9 -6 -12 -9 -9 -9 -3 0

III.

Maximum

ages

of

of

-15 -12 -13 -24 -12 -12 occurrin,g -21

years

growth of lb-9

circumpuberal between

Group IV. Maximum 96

14

/

I.

occloring

108 14 109 11 126 66

years

circzcmpzcheral between ages of

and

16

I

spurt

years

of fmr

13-9

9 IO 14 0 :: 0 9 growth spurt 13-9 and 14-9 -8 6 -8 -14 -6 -12 9 -; growth spurt 14-9 and 15-9 -18 -12 -22 -28 -21 -9 growth spud 15-9 and 16-9 -21

14 16 24 6 3 6 12 of

face

-7 12 0 -S 4 -9 9 -9 of

fnoc -2.4 -12 -2 I -1X -18 -15

of

face -24

is, both individuals have the same time of maximum facial spurt or the same skeletal age class). We ignore this third category in computing the index. The index is the ratio of the difference between the number in the sanae category and the number in the diferent category to the total number in both categories. If the number in the different category is greater than the number in the same category, the index will bc negative, as we find in this study. For girls, the computed index for time of maximum facial growth with SA minus CA at age 10 is -.66; with XA minus CA at age 12, it is -37; and with SA minus CA at age 14, it is -.95. For boys, the computed index is -.98 at age 12, -.95 at age 14, and -.96 at age 16. The index can take on only values from -1 to +1 with 0 indicating lack of association; thus, we can conclude that for these girls the association between time of maximum facial spurt and SA minus CA becomes stronger as we go

from age 10 to age .I& That means as the skeletal m;lturation lags increasingly ht%ind the chronologic age, the age of maximum circumpuheral growth increases I)l’oport,ionatcl~. The interpretation of an index of association is as t’ollows. I‘sing the index -0.95 for time of maximum favinl growth with 88 minus (‘-1 at age 14 For girls as an example, there are 41% pairs out 0E 78-t possible pairs which can 1~ placed in cithcr the SCZWM? category or the cliff~rcnt category. The\

Maximzmt cticumpubera~. ovcurring between ages 24 24 (~~roup II. Nazimum circumpubcrnl occurring bctuqcacn ages 0 --18 s 0 6 Group III. Max6mttm circumpubernl t&up

I.

occurrin,g

hetwccn

agrs

growth

of

of

of

11-9

IV.

Bfn.ximum

occurring -9 -1s

Grozlp

V.

-24 -34 -24 -33 Maximum occzkrring

-9 -24 -9

and

of

~&VI-

IO-9

spurt II-9

of

,fuw

sp’urt 12-9

of

face

spwt

of

fact

0 r>

0 3 12 -6 0 6 (I -8 0 0 -3 -20 Grokcp

spurt

9-9 and 26 21 grou>th 30-9 o,utZ 9 0 6 1 :! 12 grodh

circumpuberccl

growth

betw~c% agrs of

12-g

/Uld 113.9

-6

circumpuberal between

ages

of

- 12 “4 30 -9 --27 growth spurt 13-9 nnrl 14-9 -6 --24 --I2

-$

-1-k 20 s -4 -9 of

face

-10 -18 -17

488

Bambha

Am. J. Orthodontics July 1963

and Van Natta

Table V. Twenty-eight girls cross-cZlassified by time of maximum skeletal age minus chronologic age Time of maximum facial spurt (years)

Skeletal age minus chronologic 44 and below

-83 to -10 SA

Between 9-9 ana 10-9 Retween 10-9 and 11-9 Between 11-9 and 12-9 Between 12-9 and 13-9 4 Between 13-9 and 14-9 1 Total 5 Index of association = -.66

-9 to +9 CA

at

CA

=

(months)

10 to 33

64 and above

4

5

1

10

12

1

1

6

2 17

minus

CA

at CA

1 z

-ii-

3

1

2

10

12

1

2

6

1 4

1 -i-K

minus

CA

at CA

3 =

14

11-9

years

4

5

1

12

1

10

13-9

2

4

6

:: -a-

6

15

2

1

12-9

Index of association

3 28

-i

2

14-9

2 5

2

10-9

Total

*3 28

13 years

1

SA

2

1

3 SA

Total

IO years

2

Between 9-9 and 10-9 Between 10-9 and 11-9 Between 11-9 and 12-9 Between 12-9 and 13-9 3 Between 13-9 and 14-9 1 Total 4 Index of association = -.87 Between 9-9 and Between 10-9 and Between 11-9 and Between 12-9 and Between 13-9 and

minus

age

facial spurt and

-5

2

R -ix

= -.95

proportion of these 418 pairs which are in the same category is .02 and the proportion in the different category is 0.97. The difference between these proportions is the index of association -0.95. Why does the index become larger as chronologic age goes from 10 to 14 for girls and remain the same as chronologic age goes from 12 to 16 for boys?

T-olume Number

49 7

facial grodh

Adolescent

and

skeletal

maturation

48:)

examination of the frequencies listed in Table V shows that while the girls with time of maximum facial growth falling in the two earliest classes shifted to gains in SA minus CA by age 14, and the girls with maximum facial growt,h between 12-9 and 13-9 shifted also toward the gain side of t,he continuum, the girls with the latest time of maximum facial growth (between 13-9 and 14-91: did not shift toward the gain side. This explains the stronger association between the two variables at age 14 than at age 10. It was not possible to examine thr dist,ribution at age 16 for girls, since some of the girls in the study arc not

An

Table VI. !l’wenty-two

boys cross-classified by time of maximum skeletal age minus chronologic age Time of maximum facial spurt (years)

Between 12-9 Between 13-9 Retween 14-9 Between 15-9 Total Index

and

13-9

and

14-9

and

15-9

and

16-Q

of

association

Skeletal age -64 and below

-23

to -10

SA

minus

Total Index

and

13-9

and

14-9

and

15-S

and

16-9

of

association

Total Index

of

to +9

at

CA

1 1

(months)

10 to $3

=

12 years

s 6

-T

- 1

ic

minus

CA

at

CA

=

14 years

5

1

2

7

2

ti

8

4

1

6

1

T =

1

-7

-G-

E

Gj-

T

-.95 minus

(:A

at

CA

:=

16 yc~u~s .> .I

14-9

7

I

association

-G-

1 _-. ‘W M..

-.98

” r,

16-S

7

7

1X-Q

15-9

Total

1

1 r =

23 and above

5

SA Between 13-S and Between 13-S and Between 14-Q and Between 15-S and

CA

-9

-age

6

SA Between 12-Q Between 13-9 Between 14-S Hetween 15-S

chronologk

minus

facial spurt a,;71d

1

1

7 s

5

6

1 -2=

1 T -.96

10

4

-i-

E

!-et 16 )YVllX of agr. Iio~~evcr, one nould expect the iIi&x to lwve buck toward zwo if the pub&al action underlping facial growth and skeletal maturation C;~LISCS a shift toward the gain side of the SA minus (-:A scale of the girls lvith the latest maximum facial growth. Table PI shows that thcrc was \-cry littlc shifting in SA minus CA from chronologic age l:! to 16 among these boys. The pract,icnl importance of this to a11 orthodontist is not immediately al)parent. The foregoing measurements describe the population of fifty children and cannot be generalized to others in a direct ~a!-. The mathematical theory necessary for the gcncralization cf the results is now bring worked out 1,. Goodman and Kruskal and should appear in the literature shortly. An orthodontist would like to know if a single hand and wrist, s-ray >lsscssment taken at a particular age can indicate to him the time of maximum circumpubcral facial growth. With this goal in mind, WC examined the data on tift,cen girls at CA = 10 years, CA = 12 years, and CA = 14 years and the data for eighteen boys at CA = 12 years, CA = 14 years, and CA = 16 years. A multiple comparison rank sum test was nscd at each chronologic age to determine whether shifts in the SA minus CA assessment OCCLW between three groups with different times of maximum circumpuheral facial growth. Specifically. it was Table VII.

Nkeletal aye minus claronologic age for fifteen

Bctwecn 10-9 and 11-9 RL4 minus

CA )

Rank

Between

88

minus

11-9

and

CA /

1.2-9 Rank

girls

(K

Retwcm

/ 8A minus

= lb-9

CA /

2, and

‘n = 5) 13-3

Rank

Age 10 -18

(1) 0 0

6 8

(‘-3) (6) (9) (10)

(2, 6)

-8 -.'3 0 0 0 T, = 23 Not

(3, 7) (6, 9) (6, 9) (6, 9)

-31 -33 -21 -38 -. 9

(1) (2) (3) (4) (5)

T, xz 15 Significant

significant

Age lb 0 6 9

(3.5) (6.5)

-12 -. 9

(8)

12 12

(9.5) (9.5)

0 3 6 18

T, =

(1,

3 .5 )

(2, 5.5) (3.5, 8) (5, 9) (6.5, 10)

Significant

-2 0 --_I0’ -12 -9 -6 ‘I“, = 19 Not significant

(1) (“1 (3.5) (5.5) (7,

-14 -9 -8 -8 -6 ‘I’< = 20 Not significant

(2)

Age 14 6 12 12 12 21

(3.5) (8) (8) (8) (10)

-15

-3 1; 9 9 T, = li.5 Significant

(1,

1)

(2, 7) (3.5, 8) (5.5, 9.5) (5.5, 9.5)

(3) (4.5) (4.5) (6)

II 3 4 ti ti 1s

(7.5) (7.5) (9.5) (9.5) (11) (1%)

(6.5) (6.5) (9) (10) (11) (14)

tlosircd to test, whether the group with cwl- maximum facial growth had larger. Yaluw of SA minus C!h and the group with late maximum facial growth Ililt smaller values than the middle group. The test requires groups of equal size, so fi\r girls wcrc chosen at, random from amon, 0’ the t~vc~lw girls in lli(c mitl~ll~~ group ( 11 wars 9 months to If! years 9 months) and five girls wcrc ~*1ms~~11 from among the six girls in the late group (12 years !) months to IS ~IYIYS !I months). Similarly, six hops were sclcctcd at random t’ronr among t IIC SPY*LII boys in the early group ( 12 years 9 months to 13 years 9 months? ilIlt six l)o\Y wwc chosen at, random from among the eight boy in the midtlh~ group C1:: years 9 mont,hs to 1-I years 9 months). The disad~antagr OF not using all th:! available information is offset by the quick 2nd easy c0nlpUtiltio~l newswry fcit* the test. Tables VII and VIII present the information. The data at, each chrotl~llogic age are from the same fifteen girls and, similarl,v, the data for tl:c saniv cightrcn boys are used at each chronologic age. The valuc~~of SA minus (‘:I for girls iI1 thp early group and in the middle recoup aw t*ilnk(‘tl f~(>nl Io\\.~~st 10

49 2 Bambha and Van Natta

Am.

J. Orthodontics July 1963

highest; then the values of SA minus CA for girls in the middle group and in the late group are ranked from lowest to highest. Similarly, the values of SA minus CA for boys in the early group and in the middle group are ranked together; then the values for boys in the middle group and in the late group are ranked together. Ranks are shown in parentheses. Ties, when they occur, are assigned a mean rank for their group. In every case, T, is the sum of the first column of ranks for the middle group and T, is the sum of the ranks for the late group. Steel’” has tabulated exact probabilities for this sum-of-ranks statistic, and we compare T, and T, with the tabulated value. If the computed value is smaller than the tabulated value, then the groups are significantly different. The test on the eighteen boys shows the values for groups to be different at the three chronologic ages studied, so that the magnitude of the SA minus CA does indicate the time of maximum circumpuberal facial growth. The evidence for the girls is not so clear-cut. There is no evidence of a shift in SA minus C-4 between the early and middle groups at age 10 or between the middle and late groups at ages 12 and 14. SUMMARY

AND

CONCLUSION

The present study consists of longitudinal data on skeletal maturation and facial growth during adolescence in twenty-eight girls and twenty-two boys being followed at the Child Research Council as part of the physical growth study. This study shows an association between the skeletal maturation and the facial growth during adolescence at the two extremes. The individuals who tend to mature early with advanced skeletal age have an early adolescent facial growth spurt, whereas the children with retarded skeletal maturation tend to mature later. There is a large group in the middle which shows plenty of variation. An attempt has also been made to predict the time of maximum facial growth during adolescence. It should be pointed out that while the statistics demonstrate the general trend, there is enough individual variation to make the orthodontist’s prediction on a given patient less than perfect! REFERENCES

1. Hansman, Charlotte F., and Maresh, Marion M.: A Longitudinal Study of Skeletal Maturation, Am. J. Dis. Child. 101: 305-321, 1961. 2. Shuttleworth, F. K.: Sexual Maturation and the Skeletal Growth of Girls Age Six to Nineteen. Monographs of the Society for Research in Child Development. Vol. III, No. 5, Washington, 1938, National Research Council, pp. l-56. 3. Greulich, W. W.: Some Observations on the Growth and Development of Adolescent Children, J. Pediat. 19: 302-318, 1941. 4. Simmons, K., and Greulich, W. W.: Menareheal Age and the Height, Weight and Skeletal Age of Girls 7 to 17 Years, J. Pediat. 22: 518-548, 1943. 5. Howard, C. C.: Growth Ossification of Bone Centres as Correlated With General Growth Stages, INT. J. ORTHODONTIA 22: 888-894, 1936. Study of Facial Areas From Proflle Roentgenograms and 6. Rose, G. J.: A Quantitative the Relationships to Body Measurements, AM. J. ORTHODONTICS 39: 59-61, 1953 (Abst.). 7. Hughes, B. 0.: Dental Development and the Child as a Whole, Ana. J. ORTHODONTICS 44: 565574, 1958.

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Trauslntell Into Treatment, .\v. h. Shehan, II. L.: Indiridual Diagnosis and Case Analysis J. ORTIIWONTWS 43: 416-428, 1957. !1. Sxsxouni ) \‘.: Diagnosis and Treatment Planning Via Rorntg~,Ilo~ral)hi(~ Celhalomet ry. .\?.I. .I. ~K’~IiOI)ONTICS 44: St:~:b$ti::, 1!68. 10. Krogman, \V. M.: The Meaningful lnterprctatiou 01‘ Gtcrwth nn