A cephalometric template: Its construction and clinical significance

A cephalometric template: Its construction and clinical signijicance JAMES

E.

D.D.S.,’ Ann

HARRIS, AND

Arbor,

D.D.S.,

ROBERT

E.

M.S..” MOYERS,

LYSLE

JOHNSTON,

D.D.S.,

Prr.D.*”

N&h.

II’7TROI)UCTION

THE University of Michigan Orthodontic Clinic the growth pattern of each patient is considered to be an individual factor which must be studied wit,11 great carp. For this reason, patients are accepted in the clinic when they arcquite young, even though orthodontic treatment may not be initiated for somc~ time. Unfortunately, it is not always possible in practice to accumulate growth records on patients, and an immediate evaluation of present and potentia~l growth factors must be made. Est,imating the level of growth and development of a child at any givcll t imc is a matter of judgment. However, guide lines may be drawn t,o direct the clinician’s observations to critical relationships. To derive these guide lines, the I)cpartmcnt of Orthodontics has for many years c,ooperated with the Univcrsit!: of Michigan School of Education in a program known as the Universit.y 01 Michigan Wementary School Growth Study. One of the results of this project has been the compilation of a set of ccphalometric norms or standards. TIN transformation of tbesc data into a visual form or template suitable for t,ho rapid evaluation of lateral cephalograms by t,he clinician will be presented hcrc from a statist,&& biometric, and clinical viewpoint.

IN

This study ( C-4).

was

l’rwcnted before 2x0. 1960.

supported

by

the

Lakes

Great

United Society

State, q Public of

Hcalt)li

Ortllodontista.

Service Cincinnati.

Grant Ollio,

I)-224 SCI~.

REvIEw

0~

THE

LITERATURE

Since the cephalostat,” the powerful x-ray source, and a constant anodesubject distance came into use, many different ccphalometric analyses have evolved. Most analyses have been based upon the lat,eral cephalogram and represent a wide range of craniofacial landmarks, angles, and planes. This vast accumulation of data has resulted in ratios, indices, profiles, grids, histograms, etc. which may represent single individuals or large, randomly selrct,ed samples. What all anlayses have in common is t,he attempt to relate craniofacial landmarks, in a meaningful way, t,o the occlusion of the teeth. The many craniofacial investigations have been reviewed and summarized by Krogman and Sassouni,14 Bj&k,* Brodie,6 Broadbent, and Salzman,” to name just a few. More specifically, those analyses centered on t.he Boltonnasion-sella reference points (that is, those of Broadbent,* Brodic,? Margolis,‘” Jenkinsl? and Popovich and Graingcrl”) give evidence of the long-continued interest in these cranial base landmarks. The projection of the craniofacial landmarks on a mean occlusal plane in relation to Bolton-nasion was a further refinement added by JenkinsI” The problem of convenient clinical application of growth data has been approached from many directions. A visual template, as suggested by Popovich and Grainger,l” reflecting the parameters of the Burlington, Ontario, cephalometric sample is a most convenient method of comparing individual cephalograms with selected population norms. Tho Burlington template is based upon scattergrams related to the Boltorl-nassiori-sc!ll;l and mean occlusal plane refcrence points. IIATERIAL

The University of Michigan Elementary School Growth Study data consist of the annual collection of dental casts, carpal x-rays, cephalograms, height, weight, etc. The cephalograms (lateral, posteroanterior, and oblique) and models are obtained approximately at, the birthday of the individual. Whenever possible, each child is entered in the cephalometric program upon registration in the elementary school, at 3 to 4 years of age, and examined each year through the twelfth grade. To expand the sample and compcnsatc for students lost from the

Table I dlales

Ages

Femnles

4

20

22

6 8 10

25 32 20

21 ?I4 22

12 14

20 2‘2

21 20

16

21

20

22.9

23.0

Mean

l)rOgrank, c*cy~lialometric series also have been init iatcd on students in t,he lal(ll* grades. Thus, the cephalograms used in this st lids rt~prc~scnt a misc>cl longit Lldinal and cross-sectional scrics. All c~epha.lograms were selected with only onch rcquircmcnt, the accu rat (a tracing of landmarks. No attempt has been made to define normal or abnormal growth or occlusion. On the contrary, we are interested only in describing all ~l!r;~ayc: population of Ann Arbor school children through the examination o! their statistical parameters of craniofacial growth. Table I shows the apt’ an11 ws distribution of the sample.

l’hc demonstration and measurement of growth on a c@alogram requires a coordinate system if both direction and qnantitation of growth are to 1~~itlrestigated. Many investigators (for example, Scott,lS Broadbent,* and Brodie’ i have indicated the downward and forward growth of the bones of the face conk1~~1 to the cranial base, a relatively stable area in the selected age categori(as of 4 to Iti years. It is for this reason that the Bolton-nasion-sella-oriented coordinate system was selected to emphasize the growth vrrtors of the facial lan& marks as compared to the cranial base. The present investigation started with the accumulated lateral cephalomrtric~ tracings of the Nichigan sample, utilizing the Popovich and Grainger” sehemc~ of landmarks and orientation (Fig. 1 and Table II). Through the three summers of the program, three dental students and one graduate dentist”* traced anti measured 111~cephalograms used in this study. Kach individual was carefull! trained in the Burlington set of measurements, and donblc determinations wcw t\latl~ for all measurements on every fifth cephalogram traced. An analysis oi varianccb was made to test any significant dift’erence between the means of tllc. IWO sots ol’ mc‘asurements, and none were demonstrated 1)~ the ’ ‘t ” scow m~+lloci

Table II h,rlington 1. SOP

--9

2. 3. 4. 3.

* -4 3 -4

NOZ’ c, s;, (22 -

6. 1’: 7. Bo 3. 1 *This set of of a population m.raswrmerbis. **Drs. Nygaard.

Daniel

measurements

1

(angular)

1. A\

-4

BOSR

(S,

&! Ptm, A?

(angular) (linear) (linear) (linear)

B? N:1 1

-9 -3 -3 i -+ -t 3

8, HoNa s1 13o~:a H, 13, R,

\ N: 1 ( 1-, ! /Y2,

(linear) (linear) (linear

2. 3. 4. 5. t;. 7. x.

i

--+ -9 --f

j

A 1: 11, ,’ ;a, x, .I30

/

i%ij

I %A,

.cranial at

facial Burlington,

Ball)ach,

Lysle

constructions Ontario, Johnston,

used by the will be referretl

I.uiversity of Toronto in the st.u(f\ to in this paper m the A’~vlin~~tc~~

Richard

(all

Oles

(‘lass

of

1961)

and

Dr.

Vilwr,e

at the 0.01 per cent level of confidence. Thr Rurlington set of rtlc’asurcment,s np plied to our cephalograms was, then, the raw lnaterial from which WP co11 strutted the template. The present consideration of the data collected and derived from this cepha lometric analysis of Ann Arbor school children is a graphic description of the population parameters. Such a description will serrr two purposes: P’irst, it wil! indicate the homogeniety and character of our sample. Second, it will help in

a

(A.)

Plane

(B.)

Cl Fig. 1. Orientation jections of various

of the landmarks

s2

Ptm, Plane

mean oeclusal plane to to mean occlusal plane

Bolton-nasion

(-4)

and

perpendicular

pro-

(B).

the construction of a simple graphic device or “template ” to compare population norms with single case histories directly on the cephalogram. The representation of cephalometric data on a two-dimensional template is vastly complicated by one basic geometrical fact: It takes a minimum of two

mcasurrments to fix the position of a point, (swh as A, K, etc.) on a plane. This difficulty, of course, can be circumvented by the USC OF scat~tergrams and 1)) clependcncc upon an “ efficient, unbiased estimate ’ ’ for their int,crpret,atioir. Kathchr than rely upon this technique, we sclect,ed wrtain gcwmetrically rtq~rotlucihle Burlington measurements and then augmented these hg a series of nw determinations in order t,hat the final derivation of the trmplatr might he WI.tirol\- mathematical (Fig. 1, 2, and 7 and Table II 1.

Fig.

2. Coordinat,e

system

DEFINITION

OF

derived

to determine

-I> IS, and

c points.

LAXDMARKS

The subscripts attached to the listed landmarks refer to various projections of these points used in their measurement. This will be clarified by suhsryucnt illustrations (Figs. 2 and 3) of the methods employed. For the purpose OFthis study, the definitions of the craniofacial landmarks arc as follows: anterior

1. B point-A nasal spine

2. B point-A infradentale and

midline landmark and prosthion.

midline pogonion.

3. C point-The eondyles, measured

landmark

representing

the

deepest

point,

on the

concavity

Ix~twc~cll

representing

the

deepest,

point

on the

concavity

I&wrscbn

on the

outline

of

mean of the most distal parallel to the mean occlusal

point (Bo)-A “midline” point upward curvatures of the two retrocondylar 5. P point-The mean of the most distal deciduo& molars. 4. Bolton

in the

6. : point-The deciduous molars. 7. Mran occlusal

mean plane

of

the

most

distal

(XOP)-A

plane

points plane.

the

representing the mean fossde. points 011 the (‘rowns

of of

points

of

construatrd

ou

the at

crowns an

angle

two

the

of

nxtndilmk~r

highc~st

point*

the

uppw

rcw,rrd

thr

loner

sc~c*on~l

38 degrees

from

BO-Na.

8. Nasion

(Na)-The

intersection

of

the

internasal

suture

with

the

naaofrontal

suture.

9. Natural occlusal of the buccal segments, 10. I’TX--The 11. THE

S--The

most midpoint

plant (NOP)-A plant constructed with cmpllasis placed upon premolars

through and first

inferior

portion

of tlrc pterygomaxillary

of sella

turcica,

as determined

the interdigitating molars.

cusps

fissure.

l)y inspection.

TEMPLATE

The arrangement of the data contained in the finished template is such that, first bawd for purposes of description, it may be divided into two parts-The

No

x,: 4yrs

e8 It, BO

(A)

.I2 “14 “16

Bo

Bo Fig. 3. Model for determining regression lines points. B, Regression line that best fits mea,n point, indicating range of standard deviations.

for growth of A, B, points. C, Construction

or e points. A, of-box around

Mean mean

upon a scheme of orientation utilizing Bolton point, naison, and sella (Fig. X,B) and the second consisting of a set of relationships centered around the OCC~US~ ljlane (Fig. 8,A). In the first part the following constructions and measurements were cnlployed in the analysis of each cephalometric tracing. A line was drawn conncrt-ing Bolton point and nasion (Fig. l,il). Another line was then constructed, forming an angle of 38 degrees with Bo-Na. This line represents the mean of the natural occlusal planes in the Burlington st,udy, and was used also as the base line here. From this mean occlusal plane (MOP), a perpendicular line was thcil drawn through sella (S), dividing Bo-Na into two segments-Bo-S, and S,-Sa (Fig. I,B) , Additional perpendicular lines were drawn from the mean ocdusal plnne to condylion (C) and the pterygomaxillary fissure (PTM) . In order to fix the positions of A, B, and e precisely, perpendicular lines were drawn from Bo-Na so as t,o pass through These points (Fig. 2). Thus, A, B, and e points could then be related mathematically to the cranial base. li’or esample,to locate A point, one measurement was taken from A to A, (s, ‘I ant.1 a second was made from A, to S, (x,) . By means of vernier calipers, the followin, 1~measurements were then taken : l.Bo 2. Bo 3. c, 4. s, 5.A 6. A, 7.B 8. B, 9. c 10. e-1

+ -+ -3 + 4 -+ --f -+ + +

Na s, Bo-Na S, (on Bo-Na plane) Bo-Na S, (on Bo-Na plane) Bo-Na S, (on Bo-Ka plane)

: : : : : :

XL s, y1 y2 %, x2

Rlcans (x) were then obtained for all measurements in each of the age-sex groupings, and standard deviations (u) from t,he means were calculated. (:rowt,h vectors for A, B, and e points were obtained by fitting a line to the mean points of each age-sex grouping by way of a regression analysis for two variahlcs, both of which are subject to errorI (Fig. 3,d and B). Generally, if there is a linear regression, for the mean y when ?i is given, the formula may be written as follows : /.q.x = A + B (s - ??) B is the slope of the line, or the amount that /~y.x changes when S changes I~>one unit, The formula for B (b) which determines the direction of growth 01 A, B, and -e points was, then as follows :

b=

zx,\i, - 2X,X:\‘, N --v$q - (ZX,)” N

mm 4.00 1.

4~~~

2.50I

4

6

8 IO 12 14 16 AGE

Fig. 4. Regression analysis of mean points on line.

applied

to means

4 of A,

B, or e points

6

8

I

I

I

IO 12 14 I6 AGE

at 4 through

16. Placement

In order to represent an area into which a certain per cent of A, B, and e points may fall at a given age, rectangles were constructed around each mean point on the regression line (Fig. 3,C). In the placement of the rectangles around the various A points, for example, the width of the box is equal to 2.aa1 and the length is equal to 2.uaaz. Thus, the area represented is 2 gal. 2aa2. (Fig. 3,C). The variability of the standard deviations reflected the character of our sample, their respective values tending to become larger in the higher age groups. To normalize this variability, regression analyses were performed on the various values. The procedure may be represented in graph form (Fig. 4). The data obtained for the first portion of the template were combined and organized into a clinically usable spatial arrangement. Figs. 5 and 6 demonstrate the presentation of these data on vinyl plastic overlays through the use of the photographic silk-screen process. The data so far discussed are presented in the center and on the right-hand side of the overlay. The second portion of the template, dealing with relationships on or around the natural occlusal plane, was derived in a manner not unlike the first. Grouped among the routine determinations made on all cephalograms in the growth study were two measurements relating e with A and e with B. These measurements were obtained by projections of ei < A, and B perpendicular to the mean occlusal plane (Fig. 7). It may be noted, however, that the 38 degree mean occlusal plane is a guide line derived from a Canadian population (Burlington) and does not represent the growth of any given individual on a lateral cephalogram. For any given case, the mean of 38 degrees and the natural occlusal planes may show a distinctly different angulation. When grouped together, however, the mean of all natural occlusal planes in the Michigan study was 37 degrees from BoNa. Thus, for purposes of measurement, averages derived from the mean occlusal plane would differ from those measured on the natural occlusal plane by only 0.02 per cent and could be applied clinically to t,he natural occlusal plane of a cephalogram.

NAY _,_._

Ceohakmetric Univ.

-\,,11 ‘-..

Standards of Mich.

Ages:

Growth

OecLUSAL -~.-_--

PLAM

4-16 Years Study

Na

s

Bo Cephafometric Univ.

Standards of Mich

Ages:

Growth

4-16 Years Study

E’ig. 7. Determinatiou mean occlusal plane.

of

measurements

based

on

natural

occlusal

pla~lc

aud

projected

on

The angulation of the upper and lower incisors to the natural occlusal plane, along with their horizontal overjet, was determined for the ages of 4 to 6 (deciduous dentition) and 8 to 16 (permanent dentition) (Figs. 5 and 6). The data contained in the second portion of the template were arranged in the manner shown in Figs. 7 and 8,8, and on the left-hand side of the plastic overlay. DISCUSSION

A table of means and standard deviations and a “template” representing the geometric construction of this table may be used in attempts to describe the character of a population sample. Since the template is only a graphic presentation of selected statistical measurements applied to a selected sample, it will reflect necessarily the limitations of the statistical system. In general, the standard deviations reflect the character of the various measurements (Table III) : 1. Those measurements where little change was expected (S,-PTM) demonstrated rather constant standard deviations. 2. Measurements of rapidly growing structures (A - BoNa) were reflected in a general increase in the range around the mean. 3. Measurements of structures where there was a reduction of linear distances (e - S,) were represented by an increasing or fluctuating standard deviation. 4. Angular measurements were more variable than linear measurements. It should bc recnllcd that the third category was exemplified by the relationship of e to A point, 1 to NOP (angular), and 1 to 1, all dental landmarks reflecting not only bony growth but the entire de&l development. Hence, the greater variability is rrlatcd to the eruption of teeth, the mixed dentition, etc.

The seemingly large variance observed between -II --+ K, (linear) values ~c‘fi~ls i It(k ncgativc sign sometimes attached to the ant,cropostcrior relationship of thrs~~ landmarks. It, is not ohservcd in the mean bccaust~ of summation ; hc~ncc. SHIV l)ortionatcly, it is not rrlatively greater than the other ranges. Our statistical model reflects the heterogeneity of most American school children. Therefore, all forms and degrees of malocclusion, early and lat,e ma-. turers, variable racial and ethnic backgrounds, et,c. may be observed. Our sample is biased by the role and location of the University School Systems, with most of the children coming from highly educated, upper-income families. The statistical analysis of our total sample of 321 cephalograms was applietl separately to fourteen age-sex divisions, averaging 23 boys and 22.0 girls for each group. Since we are interested in examining the growth attainment, for each cephalometric landmark at each age by sex, this grouping of samples is necessary. Each landmark, for each sample, was rcprcsentcd by a mean and b>~ a standard deviation. Attention should be called to the differences in the growth rates t,hrongh the age periods during craniofacial growth, with far greater activity evident in the facial landmarks. Tanner,lg Bayer and Bayley,l k’rogman,l-’ and Harris” have noted this phenomenon in the long bones as well as in the craniofacial complex. Sex differences may be noted not only in the expected total amount of growfh of the various craniofacial landmarks but also in the timing of the indicated growth spurts. Growth increments were characterized by periods of increase, periods of decrease, and plateaus reflecting the differences in timing between tltc male and the female. Nasion, sella, condylion, Bolton point, and the pterygomaxillary fissure werr. by definition, a part of the coordinate system and hence were readily charted on their growth axes by perpendicular incremental markings along the appropriate axis. A, B and e points, however, are only coordinate points located in relatiorr to the Bolton-se%a-nasion axis. The direction of growth of these points as determined by a regression analysis for two independent variables suggests a projcction of t,he A and B points into later agn ca.tegorics and they were in rlos11 nSgreemcnt with the Burlington Ontario scatterprams. Again, the value of choosing the cranial base as the foundation for a coordinat,e system was emphasized by the vectors of growth of the A, B, and P regression analyses. The downward and forward growth of the facial comple:x as visualized by Broadbent, Popovich,16 etc. through the use of scattergrams is substantiated by these regression analyses. The statistical analysis of the data collected and presented here is only a preliminary step in a long-range program of study of the correlation and factorial analysis of the growth of the various craniofacial components. The template, then, is a simple statistical representation of the growtll curves of an Ann Arbor school population. The potential usefulness of this dcvice in the reading and interpretation of a single child? cephalogram will be in direct relationship to the care with which it is applied. As WylieZO has pointed out, there is always danger of a “too strict use of cephalometric studies in individual case analysis, prognosis, and treatment. ” With these admonitions in mind, hmv-

deviations

[3.9] [5.0] [2X] [2.5] [1.9] [1.8] [3.4] [2.1] [2.5] [3.0] 13.51 [LO] [3.2] [2.6] [2.7] 11.81

[5.3] [7.2] [2.5] [2.1] [2.2] [1.6] [3.8] 12.91 [1.9] [2.5] 12.71 [2.6] [2.3] [2.2] [1.9] [1.6]

65.0 73.2 8.7 25.8 26.3 27.5 123.4 3.3 44.4 46.5 76.1 24.2 42.6 13.9 2.1 15.0

[4.2] [7.0] [2.1] [2.5] [2.1] 11.51 13.01 [1.2] [2.0] [2.2] [3.0] [4.5] [1.6] [2.5] [2.4] 11.81

[2.1] 18.51 [2.5] [2.2] [Z.2] [1.9] [4.4] [2.1] [3.0] [3.3] [5.5] [4.3] [2.7] [3.1] [2.7] [1.9]

6

deviations”

63.1 73.1 8.8 26.1 27.3 27.6 127.2 4.4 43.4 47.1 76.6 23.2 43.6 13.4 1.2 15.1

are shown in brackets.

65.4 55.4 6.5 25.2 27.7 27.8 117.8 2.7 39.7 45.2 69.0 24.8 36.6 13.0 2.1 14.2

1. NOP+1 2.NOP+7 3. c, -+ s, 4. Hz +PTM 5,s-+A, 6.e,+B, 7.Bo+Na &l-+1 9. A-+BoNa (x,) 10. A,-+ 8, (x,) 11. B -iBoNa (yl) 12. B, -+ S, (~2) 13. e+BoNa (q) 14. r-3 s, (z2) 15. A, 3 B, 16. Bo + S,

"Standard

63.6 75.2 6.5 26.9 28.8 28.3 122.3 3.8 42.6 47.4 72.6 24.8 39.2 13.2 1.5 15.2

1. NOP--,l 2.NOP-+7 3. c,s2 4. S?+PTM 5.3+A, 6.<+Bz 7.Bo+Nn 8.1 +i 9. A+ BoNa (x,) 10. A, -+ S, (x,) 11. B +BoNa (yl) 12. B,-+ S, (~2) 13. e +BoNa (q) 14. e+ s, (z,) 15. A, +B, 16. Bo + s,

4

Nean values and standard

M~~aswwnents

Table III.

56.0 73.8 9.0 26.1 25.8 26.8 126.5 3.9 47.1 45.4 78.2 24.1 46.1 13.6 2.7 15.3

54.9 72.3 8.7 28.1 26.3 26.9 131.8 4.8 48.7 47.8 80.7 24.1 47.8 14.7 1.1 15.5 [2.5] [5.5] [2.7] [2.1] [1.4] [1.8] [1.4] [1,9] [2.5] [4.2] [3.4] [5.5] [3.3] [4.4] [2.6] [1,9]

[3.0] [5.8] [3.1] [2.7] [2.2] [2.4] [4.2] [2.2] [2.6] [4.1] 14.11 [5.5] [3.5] [3.7] [2.8] [2.1]

8

Girl5

Boys

54.3 73.4 10.0 27.2 25.5 26.6 131.0 5.2 49.4 45.8 81.2 24.0 49.5 13.5 2.4 16.2

52.2 72.1 10.2 28.6 26.1 26.5 135.2 5.3 51.1 47.9 83.7 23.9 50.4 14.8 1.9 16.3

(years)

[4.6] [7.2] [3.4] [2.9] [1.4-j [1.8] [3.8] 12.51 [l.Sj [3.9] [2.9] [5.0] [2.4] [4.0] [2.9] [LO]

[3.8] [7.3] [2.0] [2.2] [2.5-j [2.6] 14.81 [2.3] [2.7] [4.4] [4.1] 13.51 [5.0] [5.3] [2.7] [2.4]

10

Age

56.7 73.i 11.0 28.1 26.0 27.2 133.3 4.9 52.7 45.8 85.1 23.5 50.8 10.4 2.9 16.3

53.0 70.4 11.9 28.1 25.7 26.4 136.9 5.2 54.2 48.1 89.4 24.4 54.9 14.7 1.9 16.3 [3.61 [8.0] [2.1] [4.0] [1.5] [2.3] [3.8] [2.6] [2.1] [4.0] [4.7] [4.8] [3.2] [5.1] L3.11 [2.3]

[Y.S] [5.0] [1.4] [2.4] [1.5] [1.7] [4.4] El.81 12.11 [5.7] [3.8] [7.4] [2.7] [4.3] [2.7; [1.5]

18

-------__ 2.0 13.01 16.1 [2.5]

------_-2.6 [2.8] 15.4 11.81

[4.5] [6.2] [2.7] [2.7] -------__ 135.1 [3.74] 4.8 Cl.21 56.6 [3.4] 47.3 [4.4] 89.6 [4.8] 24.7 [7.3]

58.7 71.1 12.6 28.3

4.6 [2.7] 17.6 [1.9]

[5.6] 72.4 [5.3] 13.0 [2.3] 30.2 [2.6] -----_-__ --------142.2 [5.5] 4.4 [1.7] 60.5 [4.0] 48.2 [5.0] 96.7 [5.7] 24.7 [6.7] 5i.0

16

60.3 [5.8] 69.9 [4.5] 12.4 [2.3] 28.6 12.51 --------------_-134.0 [4.4] 3.9 [1.2] 54.8 [3.5] 46.7 [3.2] 88.5 [5.4] 24.3 [3.9]

60.3 [7.6] 72.8 [5.2] 10.8 [3.5] 29.1 [2.5] ----- -----------_ 139.0 [4.5] 4.0 [l.O] 57.4 [2.9] 46.2 [5.0] 91.2 [3.4] 23.4 [S.S] --------------_-2.4 [2.8] 16.8 [2.1]

14

I

I

mm.

aeg"c'~s

mm.

depws

Norms: Age 8 appli to an Angle CI.n, Divisign-1” B.

A.

Fig.

8. Template

schematically

applied

to

Angle

Class

II,

Division

1 malocclusion.

ever, the template may be used to indicate the general growth attainment. of a child in relation to his peers and, perhaps more important, disproportionate growth in the craniofacial complex. The primary purpose of the template, thell, is the rapid cephalometric analysis of an individual against the background of like subjects, a starting point for further investigation. CLINICAL

APPLICATION

Many orthodontic conditions, having widely divergent causes and needing varying methods of treatment, may present superficially a similar clinical appearance. For example, Figs. 8 and 9 demonstrate the application of the growth template to the cephalograms of two children, bot,h of whom have Class II, Division 1 malocclusions. In Fig. 8, note the conformation of the craniofacial landmarks to the norms of the template. Such conformation would serve to direct t,hc clinician’s attention toward muscular or dental problems, thumb- and lip-sucking, early loss of deciduous molars, etc. In Fig. 9 a Class II, Division 1 malocclusion is again observed. However, t,his patient’s cephalogram, when compared to t,hc template, demonstrates a definite skeletal disharmony. B point is considerably posterior to ,4 point, wllih condylion is ant,crior to it,s age norm. Thus, there is definite evidence of a normal maxilla and a disproportionately small mandible. In this case, the orthodontist’s t,hinking would be directed toward the correct,ion of a malocclusion with an underlying skeletal disharmony.

to an Angle Cl. II, Division 1 Skeletal -4.

Fig. 9. Template schematically skeletal foundation.

B.

applied

to Angle

Class II, Division

1 malocclusion

with

The template, then, is used not so much for diagnosing the existence of a malocclusion, which may be better observed clinically or from study casts. Rather, it is designed to indicate the degree of harmony of the craniofacial complex and the site of any disharmony which underlies a given malocclusion. In the two clinical cases shown other cephalometric studies should and would be utilized. Nevertheless, the template will give us an immediate sense of direction, a meaningful set of guideposts to help us visualize the whoZe craniofacial complex.

1. A visual representation of the growth patterns of selected facial landmarks may be demonstrated graphically when related to the cranial base. 2. The construction of growth vectors, usually done by the estimation of scattergrams, may be accomplished by proper geometric construction and subsequent strict mathematical treatment. 3. A growth template may be employed conveniently as an init,ial step in directing thought and inquiry toward a final, carefully considered diagnosis. 4. The use of nonclinical representative school population parameters to describe “average” or “normal” occlusion and skeletal growth permits the comparison of a patient’s individual growth to that of his peers. 5. The necessity of deriving two templates-one for the male and the other for the female-indicates the significant differences between the growth timing and total attainment of the two sexes.

REFEREYCFS I

I,. M., and Bayley, Nancy: Growth Diagnosis, Chi~~ago, 1959, IJnivrrsity of (‘hicagu Press. Hjiirk, Arnc: Cephalometric X-ray Investigations in l)vntistry, Internat,. I). J. 45: T I,\, 1954. Bjiirk, Srne: The Face in Profile, Svensk tandlak. tirlskr. 40: IN, 1917. Broadbent, B. H.: The Face of the Normal Child, Angle Orthodontist 7: %I0 IWC. Broadbent, B. H.: Bolton Standards and Technique in Orthodontic Prar:&e, Ar1gl6~ Ort,hodontist 7: 208, 193i. Brodie, A. 0.: Appraisal of Present Concepts in Orthodontia, Angle Orthodontist 20: 24, 1950. Brodie, 9. G.: The Behavior of the Cranial Base and Its (‘omponents as RevealelI II\Serial Cephalometric Roentgenograms, Angle Orthodontist 25: 144, 1955. Brodie, H.: On the Growth Pattern of the Humau Heat1 From the Third Month to t11tb Eighth ‘Year of Life, 9m. J. Anat. 68: 209, 1941. Brodie, A. G.: Facial Patterns-a Theme on lrariation, Angle Orthodontist 16: 75, 194ri. Craig, (Cecil, Director of Statistical Laboratory and Professor of Mathematics, l’niversitg of &lichigan: Personal Communication. Harris, J. E.: ,4 Cephalometric Analysis of Mantlibular Growth Rate: :\a~. ,r. 0~1.~1~ YON’ClCS 48: Nl, 1962. Jenkins, D. H.: Analysis of Orthodontic Deformity Employing I.ateral Cephalostat it, Radiography, AM. J. ‘OKT~IO~)ONTICS 41: 143, 1955, Krogman, W. M.: The Problem of “Timing ” in Facial Growth, With Special Refereucv t,o the Period of the Changing Dentition, A&l. J. OR’lYIODOiYTIi!S 37: 253 1!)51. Krogman, W. M., and Sassouni, Liken: A Syllabus in Roentgenographic (Ifephalomctry. Philadelphia, 1957, Philadelphia Center for Research in Child Growth. Margolis, H. I.: A Basic Facial Pattern and Its Application in (~‘linical Orthodontic+, AM. J. ORTHODONTICS SC ORAL SUKC. 33: G81, 1947. R. M.: One (:omnrunit,v’s Orthodontic Problem, In Mopers. l’oporich, F., and Grainger, R. E., and Jay, Philip (editors) : Orthodontics in the Mid-(‘rntury. Ht. Louis. 1959. Tills C. V. Shsbg Company, pp. 192-215. Ct~l)llaloulr~tril~s, Philadelphia, 1961, .I. 1:. Walzmaunl, J. A. (editor) : Roc,lltgpnogral,lli(, Lippincott Company. Scott, J-. H.: The Growth of the Human Face. Proc. Roy Sot. Med. 47: 91, 1954. Tanner, 3. >I.: Growth at Adolescense, Oxford, 1955, Blackwell Scientific Publicationr. IVylie, W. L.: Present Beliefs in the Practicability of (~‘ephalometric Studies in Jn,li vidual Case Analysis, Prognosis and Treatment. AlI. ;r. oRlW,l~OSTICS 32: MC;, l’l4~;.

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