Proportional profile changes concurrent with orthodontic therapy

Proportional

profile changes concurrent

with orthodontic DONALD Palo

ALDEN

RUDEE,

B.S.,

D.D.S.,

M.S.D.

ARO, Calif.

An understanding scntd to the most be

therapy

of

the

skillful

growth treatment

characteristics procedures

of if

,individual patient ultima.te clinicul result

the

the

is

PS

,is to

achieved. ---Moore.

orthodontists will readily attest to the fact that most persons who seek orthodontic treatment are motivated by the desire for improvement irr facial harmony. This would include harmony of the teeth with each other, of the integumental features of the face, or the esthetic proportion between the teeth and the soft-tissue facial structures. The orthodontist seeks to attain not only these goals but also functional and physiologic harmony of the denture. As his knowledge of biomechanics has increased and as corrective appliances have improved, it is generally accepted that he is able to bring about a.11t hrl desired corrective changes in the esthetic conformity of a patient’s face. The full responsibility for undesirable facial alterations in a patient is often shouldered by the orthodontist when in reality, the changes are a product 01 physiologic development and thus beyond his influence. Conversely, orthodontists take credit for gratifying results following orthodont,ic therapy when these same physiologic factors of growth and development have been the more important factors in molding facial contours. Many investigators endeavor to show the course of normal development OI the skeletal and integumental profiles by longitudinal and serial studies which depict the changes by growth alone. Others show the effects of orthodontic trcatment upon the facial profile exclusive of growth. Of prime importance to the clinician in prognosticating the changing contour of the fact is the cumulative effect of growth, development, and treatment upon the patients who come lo his CLINICAL

l’his thesis, which was given as fication by the American Board and the recommendation of the necessarily represent or express

a partial fulfillment of the requirements of Orthodontics, is being published with Board, but it should be understood that the opinion of the Board.

for cr!rtithe consent it does not,

422

Rudee

office for treatment. It would be most helpful for him to know the relat,ive rctrusion of the lips which accompanies retraction of the incisor teeth and what, the apparent change would be, taking into consideration the changing prominence of the nose and chin. This study represents an attempt to explore the changes which occur in the soft-tissue profile of the face and their interrelationship to concomitant changes in the underlying hard tissue during orthodontic treatment. It is hoped that the findings will provide additional perspective for the employment of “judgmerit’-the sine qua non of sound orthodontic therapy. mvnw

OF

THE

LIIWL~TYJRE

Angle? and his contemporaries”-5 assign much importance to the esthetic objectives of orthodontic treatment but make little attempt to define these objectives other than in broad comparative concepts. Angle holds that although artists have always sought lines and rules for facial measurement which could be used to detect variations from the normal, there is no standard that would have universal application. Attention has been drawn to the quantitative assessment of the human profile, largely because of the introduction of the roentgenographic cephalometer. This instrument permits measurement and evaluation of facial form in a manner that allows for consist,ency of method and a means for universal communication between investigators. Until recently soft-tissue appraisal by means of the cephalometer has been generally neglected for the skeletal and dental structures. RiedelG evaluated the facial profiles of twenty-nine patients by cephalometric appraisal of the underlying structures. Profile tracings of the sample were submitted to seventy-two practicing orthodontists for their evaluation of the esthetics in terms of “good,” “fair,” or “poor.” A surprisingly high level of agreement was found among the judges, and the “good” and “poor” groups showed distinguishable characteristics in their dental and skeletal patterns. In a later study,7 Riedel analyzed the profiles of thirty-one beauty contestants as to facial types and attractiveness by this method and related his findings to cephalometric measurements of the teeth and osseous base. Using a skeletal base line established by the nasal floor, Burstone* measured the integumental profiles of forty subjects by relating certain soft-tissue landmarks to this base and then angularly to each other. He found that desirable or undesirable alterations in facial contour could be effected by alteration of the dentoskeletal framework and that the normal facial pattern could be very greatly influenced by growth and maturation changes. Bash9 compared the quantitative soft-tissue changes in thirty-seven cases treated in accordance with the Tweed philosophy with the changes that occurred in thirty-seven cases treated by the IJniversity of Washington method, using a base line that connected the soft-tissue counterparts of glabella and pogonion. In both groups there was significant straightening of the profile, with no differences in the males but some demonstrable difference in the females. Neger’s’o seventy normal and malocclusion cases were assessed by means of angular mea-

surements taken from the Frankfort horizontai plane, as plotted on photographs. and then related to the occlusion in the cases under study. He contradicted T~eed’s’~ assertion that normal face pattern is impossible without normal ocelusion and showed that the straight profile does not necessarily accompany normal occlusion. Ricketts12 recommends three planes of reference for routine clinical use: the facial plane, the A-PO plane, and the esthetic or E plane which is tangent to nose and chin and to which lower face changes and relationships art made. TweedI is one of several investigators who have attempted to designate WYtain osseous and dental criteria by which to establish esthetic and functional objectives. In an analysis of twenty-nine cases treated by Tweed, Wylie”’ tested the correlation of esthetics to tooth position and concluded that the lower incisor angle did not influence profile changes as much as mandibular growth. Holdaway,15 in an attempt to relate skeletal landmarks to esthetic conformity, used the relationship of the lower incisor and pogonion to the N-B plane. He suggested that most pleasing esthetics are achieved when these structures are proportionate and when the most ideal relationship of the apical bases is present. In a longitudinal study of normal hard- and soft-tissue profiles of thirt) subjects, Xubtelny16 used head films from the Bolton study and, in a qualitative approach only, described the changes in nose, chin, lips, and teeth. An extension of this workl? related the changes resulting from treatment, with the conclusion that all parts of the soft-tissue profile do not directly follow the underlying skeletal profile. Bloom18 used head film tracings of ten patients to measure lip and tooth movements by projecting perpendicular lines from the palatal plane. A perpendicular angle from sella-nasion plane was used by Bauml” to determim changes during and after treatment in forty-four cases! and differing respo~w~ by age and sex were noted. In a very comprehensive study by O’Reilly, 2o treatment changes alone were. analyzed in twenty-five cases by serial cephalomrtric head film tracings orientc~tl to eliminate distortions by growth. PrieweZ1 recently summarized one of the apparent goals of orthodontic rc. search-the attempt to design a formula for treatment. The specific phase isolated for consideration in his study was the indication for extraction in treatment planning. The formulation was derived from systems of measuring plastw casts and cephalometric head films. Although some of the systems involved esthetic considerations indirectly (through the selection of a sample). the strnctures that were measured were either dental or osseous. While it is obvious t.llat this “struct,ural” concept of tooth positioning must be a part of case analysis, an evaltmtion of proposed facial change also must be a part of it. Only when sufficient studies of soft-tissue changes have been made in the manner summarized by Priewe will treatment plans reflect the tot,al eraluat,ion of the case. The foregoing investigations have dissected the problem into its va.riou~ parts : treatment alone, growth alone, variations between sexes, measurement (11 soft tissue alone, and gross qualitative appraisal without measurements. A st,udb seemed to be in order that would evaluate quantitatively the facial changes iti

424 Rudee

Am.

J. Orthodontics June 1964

relation to the dento-skeletal changes which occur in an orthodontic with the concomitant effects of growth and treatment. METHODS

AND

patient,

MATERIALS

Measurements used in this study are taken from tracings of cephalometric head films drawn from the files of eighty-five patients in my practice. The group consists of fifty females and thirty-five males, selected on the basis of the following criteria: (1) all cephalograms taken from the same cephalometer, (2) a period of at least 1 year between the first and second cephalograms, (3) all head films recording the teeth in centric occlusion with the lips in repose, (4) all cases selected consecutively, regardless of age or sex, and (5) all cases under active appliance therapy with the edgewise mechanism or the cervical (Kloehn type) traction appliance. The interval between the two head films ranges from 1 year 5 months to 4 years 10 months, with an average of 32 months. The sample includes patients from 6 years 11 months to 22 years 6 months of age. The range is intentionally broad; it is deemed unnecessary to break down the data as to specific age and sex response, since the study is aimed at determining the relationship of changes

Fig. 1. Measurements and on S-N with N registered.

manner

of recording

them

by superpositioning

of

the

two

tracings

Volume Number

50 6

P1-oportional

profile

dbanges

12 5

within the individual rather than between individuals. Numerous studies reported in the literaturelQy 22-25record the differing rates of growth at various age levels in males and females. However, because the chin area most significantly reflects the differing responses between the sexes, chin response alone is divided into male and female groups. No attempt has been made to esplorc the effects of any particular appliance; my purpose has been merely to correlate hard-tissue changes to soft-tissue changes. The sample does not exclude twrnt yfive cases under cervical (Kloehn type) headgear treatment only. Each head film tracing is constructed as follows : The first head film is traced on acetate tracing film with a fine-pointed pen and includes the soft-tissue profile, sella, nasion, pogonion, the upper central incisor, and the lower central incisor. ,2 line is drawn on the film to connect points sella and nasion (the S-X line), and another line connects nasion and pogonion (the facial plane). The second head film, t,raced similarly on the original tracing, is superimposed on the S-Ii line with point N registered, but without the drawing of a second facial plant. Structures are measured as distances from the facial plane to their most cvertctl anterior point along a perpendicular to the original facial plane (Fig. I ) to produce “before and after” measurements from the facial plane to the tip of the nose, upper lip, lower lip, upper incisor, lower incisor, pogonion, and softtissue pogonion or chin. We consider that movemclnt of a structure anteriorly is a. positive value and that movement in a posterior direction is a negative value. The data are analyzed by accepted statistical metbods.2F The individual -ratios and their range are thought to be more inf’ormativc than a grouping ot t,he individual movements as an average; therefore, means are established onlyfor the ratios that are calculated for hard-tissue-soft-tissue chwngcs. Ratios and correlations are determined for movements between upper lip and upper incisor. Iowcr lip and lower incisor, and lower lip and upper incisor. The rtprcsnion

Fig.

2. Scattergram

illustrating

relation

of

upper

incisor

to upper

lip

movements.

426

Itudee

curve is fitted to the variables of tooth and lip movement by means of the leastsquares method and is shown on the scattergrams in Figs. 2, 3, and 4. It is most difficult to measure accurately with any one base line the changes which occur in the human head, whether from treatment or growth, because of the multiple centers and directions of growth. Several workshops on cephalometrics have been held to establish uniformity of landmarks, procedures, and definitions. Sa1zmannz7 summarized the findings by noting that practically all commonly used landmarks are variable. Therefore, in establishing a base from

Fig.

3. Scattergram

illustrating

relation

of

lower

incisor

to lower

Fig.

4. Scattergram

illustrating

relation

of

upper

incisor

to lower

lip

lip

movements.

movements.

Volume

50

Proportionel

Number6

profile

changes

427

which to measure, it seems more important to designate one that reflects the changes under study, which are apparent to the clinician, than to seek one for a stability and reliability that does not exist. The facial plane chosen as this base line has been a guide for anthropologists and is equally familiar to all orthodontic clinicians and cephalometric analysts. Most important, it parallels all the facial features measured in this investigation and eliminates a degree of error because of the grea.ter ease and certaint) with which its landmarks are located. BergersenZ8 points out that t,hcrc is no significant difference in orientation for superpositioning on S-N as compared wit,11 “R” point. Superpositioning on the facial plane angle to S-N plant permits measurement of the movement of the mandibular symphysis, which intlicatcts the increasing or decreasing prominence of the chin. No control group has been set up, since the literature is rqlete with norma~l growth studiesz+“” and since the validity of the findings is tcstcd by statisticxal correlation.

--

4 l’cragc

Jfnxim

(mm.)

\ Upper incisor Upper lip Lower incisor Lower lip I’ogonion Over-all Male Femalr (‘bin Nose

urn

I

(mm.)

I

Minimu WI ( mm . )

-4.386

+1.3

--10.9

-1.447 -1.238

+3.1

-

-0.7Q53

+4.7 +7.L'

.- 7.7 - 6.1.

10.6671 +O.Q85i

+5.8 +5.X

-

+0.4440

+5.S

+1.261 +2.540

+8.2 +T.6

- R.-l -- 6.8 -

8.0

8.1 4.2

1.1

The individual readings are too extensive t,o reproduce here, but, thc,y ark’ summarized in Tables I and II. A high degree of correlat,ion (r = 0.7265) is shown between the upper incisor and upper lip retraction. This is established b\, an average incisor retraction of 4.38 mm. and an average lip retraction of 1.11 mm. The relationship of the lower incisor measurement t,o the lower lip measur+ ment produces a coefficient of correlation of 0.7004, an average incisor rt+rnctiolI Table II. Summary

of statistical

evaluations Correlation coefficients

IJpper Lower Upper

Central Central Central

: Upper : Lower : Lower

Lip Lip Lip

+0.7265 +0.7004 1-0.4885

’

Standnrd Mean

ratios

+2.93:1 +0.59 +l.OO

dcz:iath 7.624

:1 :1

2.184 4.202

428

Rudee

Am.

J. Orthodontics June 1964

of 1.23 mm., and an average lip retraction of 0.79 mm. The coefficient of correlation for the upper incisor retraction to the lower lip retraction is r = 0.4885 (Figs. 2, 3, 4). The average ratio of upper incisor retraction to upper lip retraction is 2.93:l.O; however, several extreme ratios bring the standard deviation to 7.624. The average ratio of lower incisor retraction to lower lip retraction is 0.59 :l.O, with a standard deviation of 2.184. The upper incisor to lower lip ratio is l.O:l.O, with a standard deviation of 4.202. The other structures measured show an interesting constancy and relationship. The average horizontal growth of the nose (2.54 mm.) is about twice that of the chin (1.26 mm.). Skeletal pogonion averages 0.66 mm. of forward positioning, and, as expected, the boys show twice the amount shown by the girls (0.98 mm. and 0.44 mm., respectively). The distribution of the same in Fig. 5 indicates that in approximately one third of the cases upper lip retraction is between equal and one half the distance which the upper incisor moves.

A.

Ratio

Fig. tion

5. A, Distribution of eases for ratio

curves for ratios of upper incisor

of upper to upper

incisor to upper lip retraction.

lip

retraction.

B,

Distribu-

Volume Number

50 6

Proportionul

profile

chan,qe.s 1,2!J

The findings confirm clinical observations concerning the importance of the lip and tooth movement relationship, particularly between the upper lip and the upper incisor. Therefore, most statistical and graphic representrations a,~‘(’ directed to these relationships. DISCUSSION

The primary concern in this study is to assess the relative changes which occur in lip position as the incisors are moved anteroposteriorly. Attention is focused upon (I) the maxillary incisor-upper lip relationship as the most influential factor in orthodonticofacial change; (2) the lower lip-mandibular incisor relationship, and (3) other changes in the profile as a result of nose and chin growth. Although, on the basis of logic as well as clinical experience, a direct causeand-effect relationship would be expected from the positioning of two adjacent structures, the statistical evaluation of these eighty-five cases indicates a VW? high degree of correlation between upper lip and upper incisor movements. Thc~ correlation coefficient of 0.7265 compares favorably with Hasstedt’P 0.545 and O’Reilly’P 0.610. This indicates a very close grouping to the “line of regression“ (Fig. 2). It is interesting to note, however, that in fourteen of our cases there is a negative ratio, which means that as the upper incisor is retracted the upper lip protracts. Although this accounts for 17.5 per cent of the cases, the actual amount of forward lip movement is relatively small. The average ratio of upper lip movement to upper incisor movement is al)proximately 1:3 (Fig. 6) although there are several very high ratios, one being as high as 1:41. These high ratios, together with the negative ratios, are attributed to negligible retraction or forward movement (growth) of the upper lip, even though there is incisor retraction; together they account for 31 per cenl of the total. This seems consistent with Hasstedt’s work and is shown by his strong correlation of upper lip thickening with incisor ret,raction during the period ot active treatment; this relationship disappears when the retention and post,rc tention periods are included. The distribution, as shown in Fig. 5, indicates that although the mean rat,io of upper incisor to upper lip retraction is approximately 3 :l, the mode is bctween 1:l and 2 :l. This means that more cases (28 per cent) have upper lip retraction equal to or one half the distance of the incisor movement than an>’ other single group of ratios. The groups adjacent to the mode! the O:l ratio group and the 3:l ratio group, account for only 14 per cent and 11 prr cent, respectively. It may be very important to know the trend of the mode, for it may indicatcl more clearly what can be expected to occur in the greater number of cases. ‘PEW average upper lip retraction is one third that of the upper incisor, but more lips retract one half the distance or equally. The relationship of the lower incisor is prominent in many systems of cast analysis, 13-15134, 35 so it is only natural that its relationship to facial change

_---Fig. 6. Tracingrorf (2.9:1).

case exhibiting

average

rat,io of upper incisor

t,o upper

lip rehaction

should be assessed. This study shows a marked correlation of lower lip retraction to lower incisor retraction, with a coefficient of 0.7004, which again compares well to Hasstedt’s3” 0.518 and O’Reilly’szO 0.557. It is doubtful that the general mandibular growth would alter this figure, as the averages show that both the mandibular incisor and the lower lip retract while both pogonion and chin move anteriorly. There are the same number of negative ratios as for the maxillary relationships, and again they are usually involved with some of the smallest linear changes (0.5 mm. or less). The grouping of the lower incisor-lower lip ratios is much closer than for the upper incisor-upper lip ratios, the average being approximately 0.6 :l. This indicates, roughly, that the lower lip retracts an average of 1 mm. for every 0.6 mm. of lower incisor retraction. It may seem paradoxical that the lower lip moves to a greater degree than the underlying and supposedly governing lower incisor, but an explanation may be found in the influence of the upper incisor on the lower lip. The direct influence of both the upper and lower incisors on the lower lip could ensure retraction of that lip, even if one incisor or the other exhibits little change for a specific case. A coefficient of correlation of 0.4885 between the upper incisor and the lower lip does not reveal a highly significant relationship, but it does com-

I~olunLe a0 N1LilLhOl~ 6

l’ty~portional,

profile

changes

43 1

pare with O’Reilly’s figure of 0.481, and the average ratio of I:1 indicat,es the direct proportion of movement when it occurs. Perhaps the facial e&&s sought by those using formulas for positioning the lower incisor, which I Adquist”” suggests may be only indirectly related to lower incisor position, in fact, indirectly relates to upper incisor changes which reflect a higher degree of lowtll* lip change than that occasioned by the lower incisor. In 1907, without the ben(+it of cephalometric and statistical evaluation, Angle2 stated essentially the S~IU~~ thing: “. . . it is the upper teeth, not the lower, that establishes the CYWV~ot’ 1Il(’ lower lip.” With the compilation of statistics from this study, it was hoped that a pr(‘diction graph would permit an estimation of expected changes in lip prominencc~ from a calculated objective of tooth position. Consequently, a curve was fittetl to the interrelated variables, as expressed in Figs. 2, 3 and 4: to serve this pun’posr as well as to establish the general trend of relationship. The‘ esl)cc*tcJcl amount of tooth retraction is read on the abscissa; by- reading up to its illtclysection with the “line of regression,” the expected lip rc>twction is reatl across t,o the ordinate. This might be considerably more reliable, however, if thcl standard deviation which determines the extent of variation of the sample t’r’o~~ this line were not so large. The over-all facial profile cannot be properly cvaluatcd without taking the nose and chin into consideration. Labial changes effected by orthodontic pr(~cedures affect the appearance of the general profile only in relation to the pr”portional changes in size of these immediately adjacent structures. Many serial cephalometric studies2”s soy3i demonstrate clearly the progressivck growth of the mandible and, though a cross-sectional study such as this is .pron~‘ to a wider range of measurements, it sholys an average growth of 0.6 mm. This is comparable to the 0.57 reported bp Stoner and associat&‘s and the 1.a“1 nut. rcport,ed by Thurston.“g Proportionate differences between male and femalt~ p;~Gents were anticipated, with the growth in males averaging twice that, in Crmales. The twent,v-seven cases that indicat,c a mandibular rrtrusion are at,tribuM I 11 cxither a bite opening evinced by treatment or a tipping of the 9-X plant* U~OII which the second tracing is oriented. Even more significant, however, is the> fact that on the average, the soft-tissue chin grew twice as much as pogonion. This lack of proportional thickening of soft tissues of the fa.cial profile is confirmc:l by other investigators, but neither Suhtelny’” nor RitchieA” noted it in the c11i11 as the>- did in the upper face. h’asal growth has not received much attention in quantitativtl studicas. bui t,hosr that have been published show no disagrccmcnt, in cont,ent. Nanera an11 Subtelny~’ show the same consistent growth of skeletal and soft-tissue NIIIIponents as Ritehi@” and Baum. I9 Measurements taken of the sample in our stud! show grpatcr horizontal linear changes in Cc nose pronrinencc than for an> ot,hcr structure measured except upper incisor rctrnction. The average or’ 2.5 mm. anterior positioning is twice the average for the chin. This can vt’r)- IKt.erially affect the profile if one considers that the average of 1.3 mm. uppc~ lil) retraction becomes an average of 4 mm. when rc>latcd to thca tip o-f the now. ifs nearest structure for reference.

432 Rudee

Am.

J. Orthodorttics June 1964

CONCLUSIONS

The hard- and soft-tissue profiles of the face undergo alterations in size and proportion as a direct result of growth and development as well as orthodontic treatment. Linear changes in prominence of the nose and chin are no less than those of lip retraction which result from orthodontic movement of the incisor teeth, so that the resulting facial changes are shared by both contributing factors. No finite conclusions can be drawn from the averages of the various measurements, as the range’ is broad enough that combinations of the extremes, if applied to any one case, give exaggerated results or nullify each other to give a negligible change. Until further experimentation can calibrate some of the unknowns and variables, our conclusions are limited to the positive statistical significance of correlated tooth movement to lip movement on a broad dispersal of proportion. SUMMARY

1. Cephalometric head films of eighty-five treated cases are analyzed by measuring the anteroposterior changes which occur in certain skeletal and softtissue structures. 2. A statistical evaluation is employed to correlate the movement of the upper and lower incisors with movement of the upper and lower lips. The coefficients of correlation are as follows: Upper incisor to upper lip, 1: = 0.7265 Lower incisor to lower lip, r = 0.7004 Upper incisor to lower lip, r = 0.4885 3. Ratios are compiled to relate the amount of movement of these same related structures, and the averages are as follows: Upper incisor to upper lip, 2.9 :1 Lower incisor to lower lip, 0.59 :1 Upper incisor to lower lip, 1 :l 4. Although tooth and lip movements resulting from orthodontic treatment influence the facial profile, equal concern must be given to the role of concurrent growth as it affects the prominence of the nose and chin. 5. In this investigation, the average amount of upper lip retraction is approximately equal to the average amount of the forward chin growth and only half the average forward growth of the nose. 6. Predictions might be made from the graphs, using the “line of regression” to plot the expected lip retraction, but tempered with the knowledge that the range of possible results is broad enough to thwart precision. GLOSSARY Chin-The Coefficient figure cating

most everted point of the chin tangent to a line drawn of correlation-The comparative measure of association in the range of 0 to 1, 0 indicating no relationship a perfect relationship.

parallel which between

to the facial is represented series and

plane. by a 1 indi-

Proportional

4 33

profile changes

lower--The most everted point of the lower incisor tangent to a line drawn parallel to the facial plane. In&or, upper-The most everted point of the upper incisor tangent to a line drawn parallel to the facial plane. Line of regression-The trend or direction of the association between series of measurements which is expressed in a scatter diagram as a straight line. Lip, lower--The most everted point of the lower lip tangent to a line drawn parallel to the facial plant. Lip, upper-The most everted point of the upper lip tangent to a line drawn parallel to thp facial plane. Xasion-The frontonasal suture which appears on the rorntgenogram as an irregular notczh on the profile outline of the frontal and nasal bones. Xose-The most everted point of the nose tangent to a line drawn parallel to the facial plane. Pogonion-The most anterior point located on the curvature of the sgmphgsis of the mandible. Hella-The center of the bony crypt occupied by the hypophysis cerebri. Standard deviat,ion-The root-mean-square of the deviation from the arithmetic mean. The equivalent, of one standard deviation in a normal distribution will include 68.27 per cent, of the sample, two standard deviations will include 95.45 per cent, and three standard deviations will include 99.73 per cent of the case3.

Incisor,

REFEREXCES 1. hloore, A. W.: Observations on Facial Growth and Its Clinical Significance, AX J. OKTHODONTICS 45: 399, 1959. 2. Angle, R. H.: Malocclusion of the Teeth, ed. 7, Philadelphia, 1907, 8. S. White Iknta.l Mfg. c’o., Chap. 3. 3. Wuerpel, El.: On Facial Balance and Harmony, Bngle Orthodontist 7: 81, 1937. 4. Case, c. s.: A Practical Treatise on the Techniquesand Principles of Dental Orthopedia. and Prosthetic Correction of Cleft Palate, Chicago, 1921, C. S. Case Company, chap. 15. 5. Simon, 1’. W.: Fundamental Principles of a Systematic Diakmosis of Dental Anomalies. Boston, 1926, The Stratford Co., pp, 160-161. 6. Riedel, 1~. A.: Esthetics and Its Relation to Orthodontic Therapy, Anr. J. ORTIIODOKTICS 22:

168,

7. Riedel,

1950.

R.

A.:

An

Analysis

of

Dentofacial

Relationships,

AM.

J. ORTHOWNTICS

43:

103.

195i.

8. Burstone, C. .J.: The Integumental Profile, Ax. J. ORTHODONTICS 44: 1, 1958. 9. Bash, V. P.: S Quantitative Method of Describing t,he Soft Tissue Profile, Unpublishpci Mast,er’s Thesis, University of Washington, 1958. 16. ?;eger, M.: A Quantitative Method for the Evaluation of the Soft, Tissue Facial Profiles, *%M. J. ORTHODONTICS 45: 738, 1959. 11. Txeed, C. H. : Evolutionary Trends in Orthodontics, Past, Present and Future, At%. .I, ORTHODONTICS 39: 81, 1953. 12. Ricketts, R. M.: Foundation for Cephalomet,ric Communication, ADZ. J. ORTHODONTICS 46: 330,

13.

1960.

14.

Tweed, nosis, Wylir,

15.

Holdaway,

25:

C. H.: The Frankfort-Mandibular Treatment Planning and Prognosis, W. L.: The Mandibular Incisor-Its 32,

Incisor Angle Role

Angte (FMIA) Orthodontist 24: in Facial Esthetics,

in Orthodontic Nag121, 1954. Angle Orthodontist

1955.

R. A. : Changes

in Relationship

of

Point,s

A and

B, hmxr, J. ORTHCDONTICS

43;

3, 1956.

Rubtelny, J. D.: A Longitudinal Study of Soft Tissue Facial Struct,ures and Their ProflIts Characteristics Defined in Relation to Underlying Skeletal Structures, Abr. .J. ORTIIODONTICS 45: 481, 1959. 17. Subtelny, J. D.: The Soft Tissue Profile, Growth and Treatment, Changes, Angle Ortlnl. dontist 31: 105, 1961.

16.

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J. Orthodontics June 1964

18. Bloom, L. A.: Perioral Profile Changes in Orthodontic Treatment, AM. J. ORTHODONTICS 47: 371, 1961. 19. Baum, A. T.: Age and Sex Differences in the Dento-Facial Changes Following Orthodontic Treatment and Their Significance in Treatment Planning, BM. J. OHTHODONTICS 47: 355, 1961.

29. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31.

@Reilly, W. C.: Proportional Changes of Hard and Soft Tissue Profiles as a Result of Orthodontic Treatment, Master’s Thesis, University of Washington, 1957. Priewe, D. E.: An Evaluation of Cephalometric Analysis and Extraction Formulas for Orthodontic Treatment Planning, AK J. ORTHODONTICS 48: 414, 1962. Schulz, J. D.: A Serial Cephalometric Study of Children at Twelve and Sixteen Years of Age Having Excellent Occlusions, Master’s Thesis, University of Washington, 1955. Baum, A. T.: A Cephalometric Evaluation of the Normal Skeletal and Dental Pattern of Children With Excellent Occlusions, Master’s Thesis, University of Washington, 1956. Lundell, L. C.: A Serial Cephalometric Analysis of the Skeletal and Denture Patterns of Children With Excellent Occlusions, Master’s Thesis, University of Washington, 1955. Hellman, M.: Development of Face and Dentition in Its Application to Orthodontic Treatment, AM. J. ORTHODONTICS & ORAL SURG. 26: 424, 1940. Arkin, H., and Colton, R.: Statistical Methods, ed. 4, New York, 1960, Barnes and Noble, Inc. The Research Workshop on Cephalometrics, AM. J. ORTHODONTICS 46: Salzmann, J. A.: 834, 1960. Bergersen, E. 0.: A Comparative Study of Cephalometric Superimposition, Angle Orthodontist 31: 223, 1961. Broadbent, B. H.: The Face of the Normal Child, Angle Orthodontist 7: 209, 1937. Brodie, A. G.: On the Growth Pattern of the Human Head From the Third Month to the Eighth Year of Life, Am. J. Anat. 68: 209, 1941. Changes in the Human Face Brought About by Development, INT. J. Hellman, M.: ORTHODONTIA

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