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Craniofacial morphometry by photographic evaluations
Craniofacial morphometry by photographic evaluations Virgilio F. Ferrario, MD," Chlarella Sforza, MD, b Alessandro Miani, MD, and Gianluca Tartaglla, DDS
Milano, hal)' Frontal and lateral oriented profile photographs of 108 healthy young adults (57 men and 51 women) were taken, and a standardized protocol was used to quantitatively describe the depicted craniofacial soft tissue structure, the relationships among facial structures, and head posture relative to the ground. Pictures were taken in two body positions, standing and sitting. The male faces were, on average, wider and longer than the female faces, in both frontal and lateral views, with greater differences in the mouth and chin regions. Both sexes were generally symmetrical. Persons who were asymmetric compensated for their appearance by changing head posture relative to the ground, so that in the frontal plane, the interpupillary axis and the occlusal plane were parallel to the ground. Measurements can be employed in computer graphic reconstructions used in orthognathic, maxillofacial, and plastic surgery. In the standing position, the Frankfurt plane was directed upward and forward, with a mean angle of 130 relative to the ground. In seated subjects, it was more nearly horizontal (5 ~ in the men, 8 ~ in the women). This result confirms the need for a careful reevaluation of standard cephalometric and photographic protocols. (AMJ ORTHOD DENTOFAC ORTHOP 1993;103:327-37.)
T h e evaluation of cranofacial morphology is an indispensable tool in clinical practice and in research, and can be achieved with different approaches. Radiographic cephalometrics and photographic systems are the most suitable and therefore the most commonly used. Not only can they provide points and landmarks for measurements, but they can also offer an analytical and complete evaluation of the unique craniofacial aspect of the person who is being investigated. Cephalometrics plays a major role in most of the studies dealing with growth changes; it is indispensable in clinical practice, where it is employed to aid in treatment planning, in careful monitoring of therapeutic procedures and in the final evaluation of results, t Photographic analyses are inexpensive, do not expose the patient to potentially harmful radiation, and could provide better evaluation of the harmonic relationships among external craniofacial structures, including the contribution of muscles and adipose tissue. 2 However, the lack of morphologic balance among different skeletal components can often be masked by compensatory soft tissue contributions? 5
From the Laboratorio di Anatomia Funzionale dell'Apparato Stomat~natico, Istituto di Anatomia Umana Normale, Facolt.~ di Medicina e Chirurgia, UniversitY, degli Studi, Milano, Italy. 'Professor of Human Anatomy. bAssociate Professor of Human Anatomy. Copyright 9 1993 by the American Association of Orthtxlontists. 0889-5406193151.00 + 0.10 811134030
Moreover, photography can be readily used to assess the posture of the head and the face and to compare these with the relationships existing among different craniofacial structures. To date, such mensurational assessments have been accomplished mostly with radiographic analyses. 69 Until recently, photographic analyses have been almost disregarded by researchers and dentists as "unmeasurable" tools. Photographs are widely used for documentation in the dental profession, but they are usually analyzed from a qualitative point of view only. t~ Quantitative evaluation is seldom performed, probably because of the lack of carefully standardized techniques, both in taking the pictures and in their evaluation. Once such techniques have been standardized, photographic analysis might usefully supplement conventional x-ray analysis. I' The purpose of this study is to derive some objective measurements of craniofacial soft and hard tissues from a group of healthy young adults by using a standardized photographic technique of the craniofacial complex. Measurements could then be used as a database for the determination of useful reference values and their ranges of normality, if this technique is valid. MATERIALS AND METHODS --Sample Fifty-one female and 57 rnale subjects ages 20 to 27 years (mean 22 ycars) were selccted from a group of 160 healthy northern Italian (white) dental students. 327
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The following criteria were required for the selection: I. Bilateral Angle Class I first permanent molar relationship 2. Absence of moderate or severe clinical mandibular disorders (no TMJ sounds, no tenderness to palpation of the TMJ or the masticatory muscles, no painful limitations of mandibular movements) 3. Absence of moderate or severe musculoskeletal disorders of the craniocervical region 4. No current orthodontic treatment 5. Absence of anterior or lateral crossbite Subjects entering this study were already selected for a wider protocol, aimed at the definition of some electromyographie and kinesiographic criteria of normal function. All subjects were photographed, using a precise standardized technique for frontal and lateral views of the face. The following 16 points were located by careful inspection (i) a~ad/or palpation (p) and traced on the face of each subject, with a black eye pencil: Median points (on the midsagittal plane): soft tissue nasion (the innermost point between the forehead and nose) (i/p); nasal apex (i); soft tissue subnasale (i); upper lip (at the boundary between skin and vermilion border) (i); lower lip (i); and soft tissue pogonion (the most prominent point on the chin) (i). Lateral (left and right) points: supraorbital foramen (p); infraorbital foramen (p); soft tissue orbitale (infraorbital margin) (p); tragus (i): soft tissue gonion (i/p). The right and left acromial prominences were palpated and indicated with adhesive red marks. All points were located and traced by the same operator.
Photographic technique Five pictures were taken for each subject: two frontal and three right side as follows: Frontal standing, in rest position Frontal standing, clenching a Fox plane between teeth u Lateral standing, in rest position Lateral standing, clenching a Fox plane Lateral sitting, in rest position In all photographs taken in the standing position, subjects stood 2.55 meters from the camera, which was mounted on a tripod, leveled, with the optical axis of the lens horizontal and the film plane vertical. The subjects stood with bare feet, looking straight into a mirror mounted at eye level on the wall, so that they could see the reflected image of their eyes. They were then asked to assume and maintain a "natural and normal" erect posture of head and shoulders, with both arms hanging free beside the trunk. Thi~ should correspond to Broca's "natural head position. ''~~ Two mirrors were used: one frontal and one lateral. In the frontal views, the mirror was replaced by the camera. In the sitting right-side photograph, the subject was seated with the head unsupported and looking into the..mi~or mounted at eye level. On each photograph, a reference line was drawn between two markers placed 10 cm apart. The line was placed parallel
American Journal of Orthodontics and Dentofacial Orthopedics April 1993
to the ground with a small spirit level. This allowed careful control of magnification and of position of the subject relative to reference planes. All the photographs were taken with the same camera, Praktica MTL 5B, lens Pentacon Auto 2.8/135 M e , using llford HPS 135 (ISO 400/27 ~ films. They were developed and printed by the same operator, employing consistent and rigorously controlled procedures. Final magnification was • 0.62.
Digitized points and measurements A set of standardized points was then traced on all the prints by the same operator as shown in Figs. 1 (frontal photographs, 24 points) and 2 (lateral photographs, seven points). In the frontal photographs, the left and right acromial prominences (ACI and ACr) were also traced. The Fox plane was used on both lateral and frontal photographs to register the position of the occlusal plane relative to other facial structures and reference planes. The lateral and frontal points were digitized by means of a semiautomatic image analyzer (MM 1201, Summagraphics Co., Fairfield, Conn.) interfaced with an AT computer (Olivetti M380, Olivetti, Ivrea, Italy). By using a pa'ogram developed for this purpose, the x-y coordinates of these points were used to reconstruct each facial feature or landmark with suitable algorithms and to generate the following measurements. 1. Face center of gravity (CG) coordinates, calculated (1) on the frontal hnage using the areas of eyes (left: points SOl, LCI, IO1, MCI; right: points SOr, MCr, IOr, LCr), nose (points N, NAI, SN, NAr), and mouth (points UL, CI, LL, Cr); and (b) on the lateral hnage as center of the polygon nasion-pogonion-gonion-tragus (points N, Pg, Go, Tr). The two centers of gravity were then used as the new origin of coordinate axes, and all the points were accordingly translated. In the frontal plot, the N-CG axis (axis of symmetry) was used as a new reference y-axis, and points were accordingly rotated. Subsequently, the following angles were calculated: 2. Position of the head relative to the ground, expressed as the angle of posture (angle between the axis of symmetry N-CG and an axis perpendicular to the ground); 3. Angle of asymmetry, between the axis N-frontal pogonion (Pg) and the axis of symmetry; 4. Interpupillary angle (points PI and Pr) relative to the ground; 5. Bisacromial angle (points ACI and ACr) relative to the ground; 6. Frontal Fox plane angle relative to the axis of symmetry perpendicular; 7. Lateral Fox plane angle relative to the ground; 8. Frankfurt plane angle [between lateral tragus (Tr) and lateral soft tissue orbitale (Or)] relative to the ground; 9. Angle of the plane between Tr and lateral infraorbital foramen (IO) relative to the ground;
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L ~ C
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st,,
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UL
k~r
C ~
I
C/
N A 3N
Soft tissue n a s l o n Nasal apex Soft tissue s u b n a s a l e
UL LL P~
U p p e r lip Lower tlp So~t tissue p o g o n i o n
SOt I~Cr IOf LCr Fr NAt Cr
Right supraorbital fotamen Right eye medial canthus Right infraorbital foramen Right eye lateral canthus Right pupil Right nasal ala Right labial c o m ~ I s s u r a
501 [.el IO1 HCI PI t:Al Cl
Left Le[t Left Left Left Le[t Left
TRr Right tragus CHr Right c h e e k
supraorbital fora~ten eye lateral canthus inEraorbital toramen eye medial can[bus pupil nasal air labial c o ~ I s s u r a tragus Left cheek
loft ....
PG CO TR IO OR NA
SO~t t i s s u e pogonlon Soft t i s s u e gonion Tragus Infraorbital Eoramen orbltale Nasal ala
Soft tissue
Fig. 2. Digitized points on lateral photographs.
TRI LeEr CHl
Fig. 1. Digitized points on frontal photographs.
10. Camper's plane angle between Tr and lateral nasal ala (NA) relative to the ground. The Frankfurt plane angle was calculated both in the "standing" and in the "sitting" photographs.
Statistical calculations: planes Descriptive statistical data for all angles wcre calculated, separating positive and negative values, which correspond to planes with opposite orientation: 1. In the frontal plot, vertical posture and asymmetry axes with upward and fonvard ( + ) or downward and backward ( - ) rotations, and horizontal interpupillary, frontal Fox, and bisacromial planes going leftward-upward ( + ) or leftward-downward ( - ) ; and 2. in the lateral plot, horizontal lateral Fox, Camper's and tragus-infraorbital planes directed downwardsbackwards ( + ) or upward-backwards ( - ) .
Mean angle values were calculated, with dedicated statistics for circular variables as detailed by Batschelet t~ by using the rectangular components of each angle. The same method allowed the calculation of relevant dispersion measures (the standard angular deviations). Standard angular deviation has the same meaning as standard deviation in linear statistics. Comparisons between angles with opposite orientation and between male and female subjects were done with the Watson-Williams test, which corresponds to the Student's t test used in linear statistics." To study correlations between the various planes calculated in each subject, pairs of different angular variables were plotted on an X-Y graph, and linear regression analyses performed." The correlation coefficients in male versus female subjects were compared with the Fisher's Z transformation."
Statistical calculations: Mean face By means of bivariate analysis" performed on the x-y coordinates of the 24 points.digitized on the frontal photographs (Fig. I), the relevant 24 standard ellipses and Hotelling's 99% confidence ellipses were computed. This al-
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Table la. Mean and standard angular deviation o f angles with different orientation in male subjects (standing pictures, absolute values) Positire angles Angle
Reference a.ris
n
Posture Asymmetry
G S
26 33
Bisacromial Frontal Fox Interpupillary
G S G
35 31 30
Lateral Fox Tr-IO plane Camper
G G G
13 45 3
Mean (degrees)
I
Negative angles SAD (degrees)
Upward and forlvard 2.36 0.32 1.37 0.14 Left.up 1.64 0.18 2.90 0.37 1.59 0.23 Down-back 2.97 0.59 6.64 0.60 1.61 0.82
] n 31 24 22 26 27 44 12 54
Mean (degrees)
SAD (degrees)
Downward and bacl~3t'ard 2.70 0.27 1.52 0.36 Left.down 1.56 0.36 2.42 0.31 1.57 0.18 Up-back 6.61 0.77 2.61 0.51 9.48 0.60
~$qV test F
p
0.807 1.018
NS NS
0.014 0.943 0.083
NS NS NS
6.366 11.588 9.635
<0.025 <0.005 <0.005
Frbntal plane: upward and forward versus downward and backward rotation or lefward and upward versus leftward and downward; lateral plane: downward and backward versus upward and backward; G: ground; S: symmetry; n: number of subjects; SAD: standard angular deviation; F: Watson-Williamstest with 1; 55 df; p: probability value; NS: not significant (p > 0.05). lowed us t o plot means for males (n = 57) and females (n = 51). 9 A similar procedure was followed for fivepoints (N, Pg, G0,Tr, IO) in the lateral photographs (Fig. 2). Calculations were performed after rototranslation of each point, referring coordinates to the subject's center of gravity and axis of asymmetry (i.e., independent from head posture). Bivariate analysis was used because it provides a more integrated and statistically correct evaluation of two-dimensional structures where the horizontal and vertical coordinates depend on each other. The position of the unknown population center (the coordinates of which correspond to mean population values) is to be estimated by the sample center (mean values calculated in the sample). The confidence ellipse is a region that covers the population center with a given probability; it is a tool for statistical inference used in bivariate analysis and serves the same purpose as the confidence interval (x --- t • SE) in univariate statistics. On the other hand, the standard ellipse may be compared with the standard interval (x ___ SD) in univariate statistics: it is only a descriptive tool used to visualize the variability of individual subjects, and covers about 40% of the sample variability. In the mean male and female faces, descriptive statistical data (means and relevant measures of dispersion) of angles and distances were calculated. To make male/female comparisons two different kinds of tests were used: the WatsonWilliams' (for angles) and the Student's t test for independent samples ~4 (for linear measurements). All calculations were performed on an Olivetti M380 computer, with original programs specifically developed for this purpose.
Error of method To assess reproducibility of photographs and of head positions, 10 subjects (five males and five females) were pho-
tographed once, then a second time after a I-week interval. Moreover, 10 randomly selected sets of photographs were retraced and redisitized a week after the first set of recordings was obtained. The combined error of subject's positions, landmark location, and digitization was estimated to be about 2% of the mean values of angular and linear measurements.
RESULTS Angles" standing pictures (Tables la and Ib) Table I reports the mean values of the angles of posture, asymmetry, interpupillary, bisacromial, frontal Fox, lateral Fox, C a m p e r ' s , and tragus-infraorbital foramen plane in men (Table la) and women (Table lb). All angles were calculated on the "standing" photographs, and positive and negative values were separately considered and compared by means of the Watson-Williams test. As to the frontal tracing, mean negative and positive angles do not appear to be differently oriented (none of the tests are significant), but in both sexes there are more subjects with positive asymmetry, bisacromial, frontal Fox, and interpupillary plane angles. In the lateral tracing, males have significantly different positive and negative angles. The lateral Fox angle is directed upward and backward in 44 o f the 57 subjects (mean 6.6~ whereas in the remaining 13 men it goes downward and backward (mean 3~ The tragusinfraorbital foramen plane goes in the opposite direction, and in 45 subjects is directed downward and backward (mean 6.64~ The Camper's plane is oriented upward and backward in almost all the subjects, with a mean angle of.9.5 ~ Also in the female subjects, there are more subjects with the extended head (Tr-IO plane going downward and backward), and their angles are significantly
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Table lb. Mean and standard angular deviation of angles with different orientation in female subjects
(standing pictures, absolute values) Positive angles Reference cttis
n
Posture Asymmetry
G S
25 33
2.54 1.96
B isacromial Frontal Fox Interpupillary
G S G
28 33 34
1.55 2. i 5 1.94
Lateral Fox Tr-IO plane Camper
G G G
4 39 2
3.89 7.41 2.48
Angle
Mean (degrees)
I~V test
Negative angles
SAD (degrees)
n
Upward aridforward
I
Mean (degrees)
I
SAD (degrees)
p p
F
Downward and backward
0.35 0.35
25 18
2.37 1.01
0.22 0.31 0.25
23 18 17
I. I 0 2.32 1.84
0.83 0.82 1.56
47 12 49
8.33 3.78 9.16
Left-up
0.29 0.69
0.150 2.645
NS NS
0.17 0.49 0.47
2.446 0.104 0.070
NS NS NS
0.79 0.70 0.79
2.694 5.778 2.654
Left-down
Down-back
Up-back
NS <0.025 NS
Frontal plan~s: upward and forward versus downward and backward rotation or leftward and upward versus leftward and downward; lateral plane: downward and backward versus upward and backward; G: ground; S: symmetry; n: number of subjects; SAD: standard angular deviation; F: Watson-Williams test with 1; 49 df (for posture angle df = I; 48, being one subject = 0); p: probability value; NS: not significant
(p > 0.05). Table II. Frankfurt plane angle in male and female subjects in the tWO body positions
I
Position Standing Sitting
Males (n = 57) Mean 13.07 ~ 5.09"
WW test (2)
[
Females (n = 51)
SAD
Mean
0.70 ~ 0.80"
13.24 ~ 8.14 ~
I I
WW test (1)
SAD 0.93 ~ 0.84 ~
F
p
F
p
64.471
<0.005
16.096
<0.005
F 0.009 6.045
I
. NS
<0.025
SAD: Standard angular deviation; WW test (1): Watson-Williams test males versus females with I; 106 df; WW test (2): Watson-Williams test standing versus sitting with I; 112 (males) and I; 100 (females) df; F: variance ratio; p: probability value; NS: not significant (p > 0.05).
steeper. The lateral Fox plane is directed upward and backward in most of the female subjects (47 of 51), but the mean values in the two orientations (up/back versus down/back) do not appear to be significantly different. Similar results can be described for Camper's plane, which goes upward and backward in 49 subjects, with a mean of 9 ~ Positive and negative values pertaining to male and female subjects have been comparcd by means of the Watson-Williams test, and no differences were found.
Frankfurt plane (Table II) The Frankfurt plane angle was calculated for both the "standing" and the "sitting" photographs. The angle measured in the standing position appears to be some degrees upward and fo~vard relative to the horizontal, both in the male subjects (13.07 ~) and in the female subjects (13.24~ corresponding to a more extended position of the head. The Frankfurt plane is closer to the horizontal plane in the sitting photographs, but is still directed upward and forward. The two positions are significantly different (p < 0.005).
There is also a gender difference in the angles measured in the sitting position. The Frankfurt plane is about 8 ~ in the female subjects, but only 5 ~ in male subjects. It is apparent that in male subjects, on average, head position relative to the ground is more affected by changes in body position.
Angles: correlations (Table III) In the standing photographs, the relationship between angles measured in the lateral plane (tragus-infraorbital foremen plane versus lateral Fox, and lateral Fox versus Camper's plane) was studied by means of linear regression analyses, which yielded significant correlations in both samples. The correlation coefficients were compared by using Fisher's Z transformation, and no gender differences were found. These relationships are independent from head post u r e . Correlations between the different angles were investigated also on the frontal plane pictures taken in the standing position, both independently from head posture (frontal Fox versus asymmetry angle) and relative to it (posture angle versus the other angles).
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Table III. Linear regression analysis in male (n = 57) and female (n = 51) subjects (standing pictures) Variables
Males
Y
X
r
p
Tr-IO Lateral Fox Posture Posture Posture Posture Frontal Fox
Lateral Fox Camper lnterpupillary Bisacromial Frontal Fox Asymmetry Asymmetry .
0.629 0.758 0.584 0.056 0.807 0.741 0.661
<0.001 <0.001 <0.001 0.675 <0.001 <0.001 <0.001
I
Females a
I
0.542 0.945 0.758 0.082 -0.742 - 1.484 1.440
b
r
7.101 3.791 -0.337 -0.425 -0.042 0.089 0.006
0.725 0.782 0.688 0.089 0.640 0.682 0.703
I
p
<0.001 <0.001 <0.001 0.532 <0.001 <0.001 <0.1301
I
a
0.778 0.822 0.944 1.550 -0.657 - 1.364 1.370
Comparison
I
b
10.527 -0.703 -0.516 0.029 0.462 0.853 -0.198
z
p'
0.900 0.298 0.886 0.015 1.815 0.604 0.397
NS NS NS NS NS NS NS
Y = a * X + b; r: coefficient of correlation; p': significance of the slope (difference from slope = 0); z.: comparison between correlation coefficients; p': significance of the difference between correlation coefficients; NS: not significant (p > 0.05).
The frontal Fox plane and asymmetry angles gave highly significant linear correlations in both sexes, as I well as three of the regression analyses between the angle of posture and the other four angles (asymmetry, interpupillary, and frontal Fox). On the contrary, no correlation was found between posture and bisacromial angles. Comparison of the correlations coefficients in the frontal plane yielded no significant gender differences. Mean face: frontal photographs
Fig. 3 shows the computer plot (tracing) of the mean face in male and female subjects in the standing position. For each point the relevant 99% confidence ellipse (inner) and the standard ellipse (outer) are drawn. Ellipses were computed by means of bivariate analysis on the x-y coordinates of the digitized points. The black central point is the center of gravity (CG, origin of coordinate axes) and the Cartesian Y-axis corresponds to the axis of symmetry. Table IV reports the mean values of distances and angles calculated for two plots, and which have been compared by means of the WatsonWilliams test (angles) and of the Student's t test (distances). Most of the vertical measurements are significantly higher in the male than in the female subjects. Among these there is total facial length (nasion-pogonion), nasal length, cheek length, and the distances nose to mouth, and mouth to pogonion. In the horizontal measurements, interpupillary distance, facial width measured both in the middle third (between tragi) and in the lower third (between cheeks) are higher in the male than in the female subjects. Also, nose and mouth are wider in the male stibjects. The angle between cheeks and pogonion is wider in the female than in the male subjects. Mean face: lateral photographs
The computer plot of the mean face in the lateral plane, standing position, is shown in Fig. 4. As for the
-
frontal plane plot, the center of gravity and the coordinate axes, 99% confidence ellipses (inner) and standard ellipses (outer) of the points are plotted. The mean inclinations of the Frankfurt (Tr-Or) and Camper's (TrNA) planes, as calculated on the standing photographs, are also reported on both plots. The shape of the two polygons is similar, but the male quadrangle is larger (wider and higher) than the female one. As a matter of fact, all measured angles have similar values, except the tragus-nasion-pogonion angle; male distances are always larger than the corresponding female ones (Table V). DISCUSSION
The described photographic protocol allowed assessment of the dimensions and relationships of several interrelated structures, and a mathematical description of the frontal and lateral facial structure in a group of healthy young adults in a narrow age range. Moreover, it made possible an evaluation of the posture of head in reference to the ground. Natural head position results were reproducible in our sample, and consistent with previous reports performed on several ethnic groups, by using both cephalometric methods 4'7s'16~7 and photographic techniques. ~8 In comparison to literature references, our sample is composed of full-grown subjects, and no further growth changes are to be expected. ~9-2~ As regards angles in the frontal plane, there are no differences in male versus female subjects for any of the measured variables (posture, asymmetry, interpupillary, bisacromial, frontal Fox). The asymmetry angle indicates chin position (pogonion) relative to the axis of symmetry, and therefore it is independent from the position of head relative to the ground. In both sexes more subjects have the chin rotated to the left than to the right, as can be seen in Table I, where positive asymmetry angles (upward and
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I
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333
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............. i ................
CH, ~
CHI
PG ...... F,aRkfurs pll~ ............ Camper p l a n 4 ....... CO-Old,hateaAes
(~
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.
MCI
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9
) LCI
Ir
TPa
TR
9 UL. CHr
Ca
r
CM1
GO v
P~
I
I
Fig. 3. Male (n = 57) and female (n = 51) mean faces obtained by means of bivariate analysis, frontal plot. Center of gravity, axis of symmetry, standard ellipses (outer), and 99% confidence ellipses (inner) of the correspondent 24 points digitized on the frontal photographs.
forward rotation) are found in 33 of the 57 male subjects, and in 33 of the 51 female subjects (about 60% of subjects). The bisacromial plane is higher on the left side in about 60% of subjects, whereas 54% of the male and 65% of the female subjects have frontal Fox planes directed leftward and upward. Most angles are highly correlated to one another, with no diffeiences between sexes (Table III). The frontal Fox angle and asymmetry angle are inversely correlated to posture angle (negative slopes): head position relative to the ground compensates both for occlusal
.~.. . . . .
Fwlnkfurt pllne
...........
Clmper
plane
co-o,alnlta 9
Fig. 4. Male (n = 57) and female (n = 51) mean faces obtained by means of bivariate analysis, lateral plot in standing position. Center of gravity, coordinate axes, standard ellipses (outer), and'99% confidence ellipses (inner) of the correspondent five points digitized on the lateral photographs. Interrupted fine: mean inclination of the Frankfurt plane (tragus-orbitale); dotted line: mean inclination of the Camper's plane (tragus-nasal ala).
surface inclination and for the intrinsic facial asymmetry (position of pogonion). As a result, the occlusal plane is about parallel to the ground, and the chin approximates the median plane. The interpupillary plane relative to the ground is more or less horizontal in both sexes (I ~ to 2~ This plane is well correlated to the posture angle (Table 111). The slight asymmetry measured by the asymmetry angle
es
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American Journal of Orthodontics and Dent*facial Orthopedics April 1993
Table IV. Mean face, frontal plot from 57 males and 51 females Males Measure
Females
MeanlSD
Comparison
Mean
SD
,
i
i
Nasion-pog~onion Nasion-CG Subnasale-upper lip L o w e r lippogonion
N-Pg N-CG SN-UL
I i i .28 34.05 11.90
6.68 3.17 2.44
101.44 3 I. 23 10.08
5.36 3.07 1.96
8.30 4,64 4.20
----
<0.00 l <0.(301 <0.00 I
LL-Pg
25.96
3.57
22.02
2.98
6,12
--
<0.001
lnterpupillary distance Facial width Tragi Cheeks Pogonion angle
Pr-PI
63.61
3.16
60.13
2.56
5.87
--
<0.001
TRr-TRI C}tr-Ctl ! Cttr-PG-CHI
142.96 123.77 120.70 ~
5.25 5.15 0.80 ~
135.51 116.11 123.83 ~
5.03 6.41 0.78 ~
7.43 6.81 --
--8.01
<0.001 <0.001 <0.01
TRr-CHr TRr-CHr-Pg
44.55 132.06 ~
8.24 0.62*
40.66 131.80 ~
6.80 0.61 ~
2.63 --
-0.09
<0.01 NS
TR l-ell I TRI-CItI-Pg
44.46 132.28"
7.35 0.61"
40.35 131.93 ~
6.32 0.67 ~
3.07 --
-0.14
<0.005 NS
Nose 9 Length : Width U p p e r angle L o w e r angle Right angle Left angle
N-SN NAr-NA 1 NAr-N-NAI NAr-SN-NAI N-NA-SN N-NAI-SN
55.66 36.22 43.23* 123.61" 96.46* 96.67"
4110 2.28 0.53 ~ 1.34" 0.81 ~ 0.81 ~
51.76 33.13 42.26 ~ 124.41 ~ 96.24 ~ 97.07 ~
3.65 2, I ! 0.54 ~ 1.33 ~ 0.86* 0,85"
5.15 7.22 -----
--1.59 0.18 0.03 0.12
<0.001 <0.001 NS NS NS NS
Right eye Length Width Upper angle L o w e r angle Lateral angle Medial angle
SOr-IOr LCr-MCr LCr-SOr-MCr LCr-IOr-MCr SOr-LCr-lOr SOr-MCr-lOr
34.25 24.85 78.20* 58.94 ~ 80.93 ~ 133.35 ~
3.85 1.65 0.97 ~ 1.00 ~ 0.91 ~ 1.96"
34.68 24.52 75.89 ~ 60.56 ~ 81.59 ~ 131.44 o
3.20 1,42 i. 19 ~ !, 12~ 0.85 ~ 2,06~
0.62 1.20 ---9 --
--2.37 i. 19 0.30 0.45
NS NS NS NS NS NS
Left eye Length Width U p p e r angle L o w e r angle Lateral angle Medial angle
SO1-10! LC 1- M C I LCI-SOI-MCI LC I -IO I - M C 1 SOI-LCI-IOI SOI-MCI-IOI
35.17 24.84 79.60* 57.97 ~ 82.01 ~ 125.73 ~
3.93 1.75 0.97 ~ !. 02" 0.93 ~ 1.93 ~
35.22 24.36 75.83 ~ 59.32~ 81,41" 131,85 ~
3.49 1.75 1.28 ~ I. 16~ 0.80 ~ 1.82 ~
0.07 1.41 -----
--5.44 0.78 0.23 5.30
NS NS <0.025 NS NS <0.025
Mouth Length Width U p p e r angle L o w e r angle Right angle Left angle
UL-LL Cr-C I Cr-UL-C 1 Cr-LL-CL UL-Cr-LL UL-CI-LL
17.86 50.40 144.53 ~ 138.00 ~ 37.67 ~ 39.76 ~
3.78 3.16 i .76 ~ 1.50" 1.07 ~ 1.08 ~
17,66 47,38 140.79 ~ ! 37,43 ~ 39.97 ~ 41,76"
2.43 3.78 1.44 ~ 1.44 ~ 0.94 ~ 0.94 ~
0.32 4.48 -----
--2,67 0.07 2.60 1.90
NS <0.001 NS NS NS NS
Right cheek : Length I: A n g l e Left c h e e k Length i Angle
Unit: Millimeter (distances), degrees (angles). CG: Center o f gravity; SD: standard deviation (distances), standard a n g u l a r deviation (angles); t: S t u d e n t ' s t test for independent samples with 106 d f (distances); F: Watson-Williams test with I; 106 d f (angles); p: probability value; NS: not significant ( p > 0 . 0 5 ) .
does not affect the upper part of the face. Since only__ young, healthy adults were included in our sample, the bisacromial angle and the posture angle have not been found to be correlated with one another: in normal subjects, the position of head relative to the ground does
not seem to influence the inclination of shoulders and vice versa. On the contrary, in many musculoskeletal disorders of the craniocervical region, these two variables are often correlated to each other. The position of pogonion indicated by the asym-
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Ferrario el al.
335
Table V. Mean face, lateral plot from 57 males and 51 females
-
I Measure
I
Males Mean
l
Comparison
Females SD
Mean[
N-Pg Pg-Go
109.21 75.50
6.10 7.24
102.97 71.53
5.73 5.76
5.41 3. I 0
---
<0.1301 <0.005
Go-Tr Tr-N Pg-Go-Tr Go-Tr-N
57.77 90.85 118.86" 98.08*
6.51 5.63 i .21" 0.88 ~
50.47 85.66 120.15 ~ 99.66 ~
5.52 4.96 1.25" 0.95*
6.19 5.01 ---
--0.55 1.50
<0.001 <0.001 NS NS
Tr-N-Pg N-Pg-Go
69.21" 73.84 ~
0.54 ~ 0.70 ~
67.53 ~ 72.64 ~
0.54 ~ 0.77 ~
---
4.70 0.90
<0.05 NS
Tr-IO IO-Tr-N
73.10 18.25 ~
4.64 0.42 ~
70.58 19.28 ~
4.07 0.38 ~
2.96 --
-3.20
<0.005 NS
IO-Tr-Go
79.27 ~
0.81 ~
80.21 *
0.90 ~
--
0.13
NS
Unit: Millimeters (distances), degrees (angles). SD: Standard deviation (distances), standard angular deviation (angles); t: Student's t test for independent samples with 106 d f (distances); F: Watson-Williams test with I; 106 df (angles); p: probability value; NS: not significant ( p > 0.05).
metry angle shows concordance with that obtained through bivariate analysis (Fig. 3, the center of the pogonion ellipse stays in the left side of face). The most surprising result regarding lateral plane angles is the position of the Frankfurt plane relative to the ground in standing subjects (Table II). The inclination of this plane is substantially different from the horizontal, measuring 13.07 ~ in the male subjects, and 13.24 ~ in the female subjects. In the seated subjects, the slope is less (5.09 ~ in the male subjects, and 8.14 ~ in the female subjects), and only 15% of the subjects have a Frankfurt plane close to the horizontal (0 ~ • 1~ in the sitting position. The slopes are significantly different in the two positions. This indicates a more extended position of the head in the standing "natural" or self-balanced position than in the standard sitting position commonly used for radiographic films. Our subjects' young age might be a factor in this significant extension of the head. ~7 As a matter of fact, data reported in the literature are often in conflict as far as reference planes are concerned. 4"7"22For example, the sella-nasion plane relative to the vertical plane ranges from 81.2 ~to 92.6 ~ in groups of comparable age, depending on body position (standing/sitting) and visual target (mirror, distance or selfbalance). ~.22 This result indicates a need for a careful reevaluation of standard cephalometric protocols, reference planes, and relevant criteria of normality. 4 The lateral Fox plane angle, which indicates the position of the transverse occlusal plane, goes in the opposite direction of the tragus-infraorbital foramen plane angle. The two angles are strictly correlated with one another in both sexes. Also, the correlation between Camper's plane and lateral Fox plane is highly significant, as already reported by many authors (Table III).
The two planes are about parallel, and their orientation changes occur in a similar pattern. ~2 The vertical position of nasion relative to the center of gravity showed very little variability in our sample, so that in the mean frontal plot (Fig. 3) it might be represented by a point. This constant location relative to the center of gravity justifies the use of nasion as a reference point, as already suggested in some reports, a In plotting the "eyes," the infraorbital point (IO) showed a smaller variability and was more easily found than the soft tissue orbitale (Or), which is probably linked to the position and amount of soft tissue. Therefore, IO was taken as the better inferior landmark for the eye area. The horizontal dimensions in our sample are more constant than the vertical dimensions (lower coefficients of variation). Among them, the interpupillary and the tragus-to-tragus distances are identical to measurement of Latta et al. 2J recorded on white adults aged 29 to 87 years. The male subjects are larger than the female subjects in both plots; as a matter of fact, all dimensions in the lateral plot are significantly greater, as are most vertical and horizontal measurements in the frontal plot. Nasion-pogonion distance has been measured in both tracings, and the two values agree (Tables IV and V). In the lateral plot, the quadrangle nasion-pogoniongonion-tragus has the same shape in both sexes, with similar angles (only the Tr-N-Pg is different, Table V), but with larger dimensions in the male subjects. In frontal vertical measurements (Table IV), the upper third of face is equal in the two sexes (structures between nose and eyes); differences, however, become greater in the middle and lower thirds of the face. As a matter of fact, the percentage difference in male versus female subjects is constant throughout the entire
336
American Journal of Orthodontics and Dentofacial Orthopedics April 1993
Ferrario et al.
face (nasion-pogonion) and in the upper part of the face, whereas it grows in the lower structures (from subnasale to pogonion) taken separately. The nasion-pogonion distance (whole face) in the male subjects is 8.8% greater than in the female subjects, the nasion-center of gravity distance is 8.3%, and the nasal length is 7%. In the male subjects the subnasale to pogonion distance is 10.7% greater than in the female subjects, accounting for most of the larger vertical measurements in the male subjects. In the study by Genecov et al. 19 the lower face was also responsible for the majority of the greater facial height in the male subjects. In a transverse direction, tlae male subjects are larger than the female subjects, with similar differences at all vertical levels: about 5.5% for both the interpupillary and the tragus-to-tragus distances, 6.6% for the cheekto-cheek distance (Table IV). These gender differences are similar to literature references. 23 The male subjects have a wider and longer face (nose, mouth, and chin) than the female subjects, and a difference in shape: a masculine face is more rectangular, and a feminine face is more squared (pogonion angle, Table IV). Our findings of a certain degree of asymmetry in the human face agree with most of the published studies, although the soft tissues in our results exhibit a lesser degree of asymmetry than the skeletal structures as reported by several authors. 6"9'z4As a matter of fact, these studies in some ways contrast one another: although Vig and Hewitt 6 found, that the cranial base and maxillary regions were significantly larger on the left side, Shah and Joshi 9 stated that the total facial structure was larger on the right side. Woo, 24 working on skulls, found that the right frontal and parietal bones were larger than the left, but that the left malar bone was predominant. It is difficult to compare these studies, since the methods, the measurements, and the sample characteristics (age, se x , race) are very different. Our photographic analysis, performed on a homogeneous sample (race and age), confirnls that the lower third of face (maxillary and mandibular regions) has a greater degree of asymmetry than other facial regions, and that the soft tissues only partially mask the underlying skeletal asymmetry. A certain compensation is gained by the "natural" posture, meaning the self-balanced position of the head relative to the ground. This finding on the frontal plane has the same functional meaning of the correlations already discovered on lateral radiographs, 7s'~ where head position relative to the cervical column was found to be in connection.with dentoalveolar structure, vertical jaw relationships, and enlarged tonsils.
CONCLUSIONS
1. This work reports the determination of mean values of several linear and angular facial measurements made on a group of healthy young adults in a narrow age range, as well as their ranges of variability. 2. It is believed these data could provide a useful resource for a wide range of basic and clinical applications, fo r example, in orthognathic, maxillofacial, and plastic surgery, where computerized systems often furnish "previews" of the final result. Computerized graphic reconstructions could be based on these measurements, which enabie the plotting of harmonic and wellbalanced facial patterns (Figs. 3 and 4). 3. The described photographic protocol could be used in dentistry whenever standardized views are to be taken, especially if a quantitative evaluation of craniofacial soft tissues is needed. The protocol also allows the assessment of the posture of head relative to the ground both in frontal and transverse planes. 4. The Frankfurt plane inclination of our subjects relative to the ground showed some variations dependent on body position and on gender, thus suggesting the need for a careful reevaluation of standard cephalometric and photographic protocols involving sitting versus standing position, and visual target (mirror, distance, or selfbalance). We are greatly indebted to Miss Roberta Siega for her technical support and help preparing this manuscript. REFERENCES
I. Ricketts RM. Perspectives in the clinical application of cephalometrics. Angle Orthod 1981;51:115-50. 2. Cox NH, Van der Linden FPGM. Facial harmony. A.',tJ ORTIIOD 1971;60:175-83. 3. Bittner C, Pancherz H. Morfologia faeciale e maloeclusioni. AM J ORTIIOD DE.N'TOFAC ORTIIOP 1990;97:308-15 (Italian
4.
5. 6. 7. 8. 9. 10.
edition). Michaels LYF, Toume LPM. Nasion true vertical: a proposcd method for testing the clinical validity of cephalometric measurements applied to a new cephalometric reference line. Int J Adult Orthod Orth~nath Surg 1990;5:43-52. Y~osawa F. Predicting soft tissue profile changes concurrent with orthodontic treatment. Angle Orthod 1990;60:199-206. Vig PS, ttewitt AB. Asymmetryof the human facial skeleton. Angle Orthod 1975;45:125-9. Solow B, TallgrenA. Head posture and craniofacialmorphol~y. Am J Phys Anthropol 1976;44:417-36. Solow B, Tallgren A. Dentoalveolar morphol~y in relation to craniocervical posture. Angle Orthod 1977;47:157-64. Shah SM, Joshi MR. An assessment of asymmetryin the normal craniofacial complex. Angle Orthod 1978;48:141-8. Claman L. Patton D, Rashid R. Standardized portrait photog-
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i 1.
12. 13. 14. 15. 16.
17.
18. 19.
raphy for dental patients. A.',t J OR'ntOD DEN'rOFACORTItOP 1990;98:197-205. Ferrario VF, Sforza C, Miani A Jr, Daddona A, Serrao G. Valutazioni della asimmetria faciale. I: i tessuti molli. Bologna: Atti XLIV Convegno-Naziousle Societ6 Italiana di Austomie. 1990. Schreinemakers J. Le basi razionali della protesi totale. Padova: Piccin, 1986. Batschelet E. Circular statistics in biol~y. London: Academic Press, 1981. Snedecor GW, Cochran WG. Statistical methods. Ames, Iowa: Iowa State University Press, 1972. Spiegel MR. Statistica. Milano: Eras libri, 1976. Siersbaek-Nielsen S, Solow B. Intra- and interexaminer variability in head posture recorded by dental auxiliaries. AM J OR"ntOD 1982;82:50-7. Cooke hiS. Five-year reproducibility of natural head posture: a longitudinal study. AM J ORTIIOD DENTOFACORTttOP 1990; 97:489-94. ChiuCSW, ClarkRKF. Reproducibilityofnatural head position. J Dent 1991;19:!30-1. Genccov ~IS,Sinclair Phi, Dechow PC. Development of the nose and soft tissue profile. Angle Orthod 1990;60:191-8.
337
20. Nanda RS, Meng H, Kapila S, Goorhuis J. Growth changes in the soft tissue facial profile. Angle Orthod 1990;60:177-90. 21. Singh NR. Changes in the soft tissue chin after orthodontic treatment. A.~i J ORTItODDENTOFACORTItOP 1990;98:41-6. 22. Showfety KJ, Vig PS, Matteson S, Phillips C. Associations between the postural orientation of sella-nasion and skeletodental morphol~y. Angle Orthod 1987;57:99-112. 23. Latta GH, Weaver JR, Conkin JE. The relationship between the width of the mouth, interalar width, bizygomatic width, and interpupillary distance in edentulous patients. J Prosthet Dent i 991 ;65:250-4. 24. Woo TL. On the asymmetry of the human skull. Biometrika 1931 ;22:324-52. 25. Behlfelt K, Linder-Aronson S, Neander P. Posture of the head, the hyoid bone, and the tongue in children with and without enlarged tonsils. Eur J Orthod 1990;12:458-67. Reprint requests to: Prof. Virgilio F. Ferrario Istituto di Anatomia Umana Normale via Mangiagalli 31 1-20133 Milano Italy
BOUND VOLUMES AVAILABLE TO SUBSCRIBERS B o u n d v o l u m e s o f the AMERICAN JOURNAL OF ORTIIODONTICS AND DENTOFACIAL ORTHOPEDICS are available to subscribers (only) for the 1993 issues from the Publisher, at a cost o f $ 5 8 . 5 0 ($73.69 Canada and $69.50 international) for Vol. 103 (January-June) and Vol. 104 ( J u l y - D e c e m b e r ) . Shipping charges are included. Each b o u n d v o l u m e contains a subject and author index and all advertising is r e m o v e d . C o p i e s are shipped within 60 days after publication o f the last issue in the v o l u m e . T h e binding is durable b u c k r a m with the journal n a m e , v o l u m e number, and y e a r stamped in gold on the spine. P a w n e n t mltSt a c c o m p a n y all orders. Contact M o s b y , Subscription S e r v i c e s , 11830 Westline Industrial Dr., St. Louis, M O 63146-3318, U S A ; telephone (314)453-4351 or (800)325-4177. S u b s c r i p t i o n s m u s t b e in f o r c e to q u a l i f y . B o u n d v o l u m e s a r e n o t a v a i l a b l e in p l a c e o f a r e g u l a r J o u r n a l s u b s c r i p t i o n .
Milano, hal)' Frontal and lateral oriented profile photographs of 108 healthy young adults (57 men and 51 women) were taken, and a standardized protocol was used to quantitatively describe the depicted craniofacial soft tissue structure, the relationships among facial structures, and head posture relative to the ground. Pictures were taken in two body positions, standing and sitting. The male faces were, on average, wider and longer than the female faces, in both frontal and lateral views, with greater differences in the mouth and chin regions. Both sexes were generally symmetrical. Persons who were asymmetric compensated for their appearance by changing head posture relative to the ground, so that in the frontal plane, the interpupillary axis and the occlusal plane were parallel to the ground. Measurements can be employed in computer graphic reconstructions used in orthognathic, maxillofacial, and plastic surgery. In the standing position, the Frankfurt plane was directed upward and forward, with a mean angle of 130 relative to the ground. In seated subjects, it was more nearly horizontal (5 ~ in the men, 8 ~ in the women). This result confirms the need for a careful reevaluation of standard cephalometric and photographic protocols. (AMJ ORTHOD DENTOFAC ORTHOP 1993;103:327-37.)
T h e evaluation of cranofacial morphology is an indispensable tool in clinical practice and in research, and can be achieved with different approaches. Radiographic cephalometrics and photographic systems are the most suitable and therefore the most commonly used. Not only can they provide points and landmarks for measurements, but they can also offer an analytical and complete evaluation of the unique craniofacial aspect of the person who is being investigated. Cephalometrics plays a major role in most of the studies dealing with growth changes; it is indispensable in clinical practice, where it is employed to aid in treatment planning, in careful monitoring of therapeutic procedures and in the final evaluation of results, t Photographic analyses are inexpensive, do not expose the patient to potentially harmful radiation, and could provide better evaluation of the harmonic relationships among external craniofacial structures, including the contribution of muscles and adipose tissue. 2 However, the lack of morphologic balance among different skeletal components can often be masked by compensatory soft tissue contributions? 5
From the Laboratorio di Anatomia Funzionale dell'Apparato Stomat~natico, Istituto di Anatomia Umana Normale, Facolt.~ di Medicina e Chirurgia, UniversitY, degli Studi, Milano, Italy. 'Professor of Human Anatomy. bAssociate Professor of Human Anatomy. Copyright 9 1993 by the American Association of Orthtxlontists. 0889-5406193151.00 + 0.10 811134030
Moreover, photography can be readily used to assess the posture of the head and the face and to compare these with the relationships existing among different craniofacial structures. To date, such mensurational assessments have been accomplished mostly with radiographic analyses. 69 Until recently, photographic analyses have been almost disregarded by researchers and dentists as "unmeasurable" tools. Photographs are widely used for documentation in the dental profession, but they are usually analyzed from a qualitative point of view only. t~ Quantitative evaluation is seldom performed, probably because of the lack of carefully standardized techniques, both in taking the pictures and in their evaluation. Once such techniques have been standardized, photographic analysis might usefully supplement conventional x-ray analysis. I' The purpose of this study is to derive some objective measurements of craniofacial soft and hard tissues from a group of healthy young adults by using a standardized photographic technique of the craniofacial complex. Measurements could then be used as a database for the determination of useful reference values and their ranges of normality, if this technique is valid. MATERIALS AND METHODS --Sample Fifty-one female and 57 rnale subjects ages 20 to 27 years (mean 22 ycars) were selccted from a group of 160 healthy northern Italian (white) dental students. 327
328
Ferrario et al.
The following criteria were required for the selection: I. Bilateral Angle Class I first permanent molar relationship 2. Absence of moderate or severe clinical mandibular disorders (no TMJ sounds, no tenderness to palpation of the TMJ or the masticatory muscles, no painful limitations of mandibular movements) 3. Absence of moderate or severe musculoskeletal disorders of the craniocervical region 4. No current orthodontic treatment 5. Absence of anterior or lateral crossbite Subjects entering this study were already selected for a wider protocol, aimed at the definition of some electromyographie and kinesiographic criteria of normal function. All subjects were photographed, using a precise standardized technique for frontal and lateral views of the face. The following 16 points were located by careful inspection (i) a~ad/or palpation (p) and traced on the face of each subject, with a black eye pencil: Median points (on the midsagittal plane): soft tissue nasion (the innermost point between the forehead and nose) (i/p); nasal apex (i); soft tissue subnasale (i); upper lip (at the boundary between skin and vermilion border) (i); lower lip (i); and soft tissue pogonion (the most prominent point on the chin) (i). Lateral (left and right) points: supraorbital foramen (p); infraorbital foramen (p); soft tissue orbitale (infraorbital margin) (p); tragus (i): soft tissue gonion (i/p). The right and left acromial prominences were palpated and indicated with adhesive red marks. All points were located and traced by the same operator.
Photographic technique Five pictures were taken for each subject: two frontal and three right side as follows: Frontal standing, in rest position Frontal standing, clenching a Fox plane between teeth u Lateral standing, in rest position Lateral standing, clenching a Fox plane Lateral sitting, in rest position In all photographs taken in the standing position, subjects stood 2.55 meters from the camera, which was mounted on a tripod, leveled, with the optical axis of the lens horizontal and the film plane vertical. The subjects stood with bare feet, looking straight into a mirror mounted at eye level on the wall, so that they could see the reflected image of their eyes. They were then asked to assume and maintain a "natural and normal" erect posture of head and shoulders, with both arms hanging free beside the trunk. Thi~ should correspond to Broca's "natural head position. ''~~ Two mirrors were used: one frontal and one lateral. In the frontal views, the mirror was replaced by the camera. In the sitting right-side photograph, the subject was seated with the head unsupported and looking into the..mi~or mounted at eye level. On each photograph, a reference line was drawn between two markers placed 10 cm apart. The line was placed parallel
American Journal of Orthodontics and Dentofacial Orthopedics April 1993
to the ground with a small spirit level. This allowed careful control of magnification and of position of the subject relative to reference planes. All the photographs were taken with the same camera, Praktica MTL 5B, lens Pentacon Auto 2.8/135 M e , using llford HPS 135 (ISO 400/27 ~ films. They were developed and printed by the same operator, employing consistent and rigorously controlled procedures. Final magnification was • 0.62.
Digitized points and measurements A set of standardized points was then traced on all the prints by the same operator as shown in Figs. 1 (frontal photographs, 24 points) and 2 (lateral photographs, seven points). In the frontal photographs, the left and right acromial prominences (ACI and ACr) were also traced. The Fox plane was used on both lateral and frontal photographs to register the position of the occlusal plane relative to other facial structures and reference planes. The lateral and frontal points were digitized by means of a semiautomatic image analyzer (MM 1201, Summagraphics Co., Fairfield, Conn.) interfaced with an AT computer (Olivetti M380, Olivetti, Ivrea, Italy). By using a pa'ogram developed for this purpose, the x-y coordinates of these points were used to reconstruct each facial feature or landmark with suitable algorithms and to generate the following measurements. 1. Face center of gravity (CG) coordinates, calculated (1) on the frontal hnage using the areas of eyes (left: points SOl, LCI, IO1, MCI; right: points SOr, MCr, IOr, LCr), nose (points N, NAI, SN, NAr), and mouth (points UL, CI, LL, Cr); and (b) on the lateral hnage as center of the polygon nasion-pogonion-gonion-tragus (points N, Pg, Go, Tr). The two centers of gravity were then used as the new origin of coordinate axes, and all the points were accordingly translated. In the frontal plot, the N-CG axis (axis of symmetry) was used as a new reference y-axis, and points were accordingly rotated. Subsequently, the following angles were calculated: 2. Position of the head relative to the ground, expressed as the angle of posture (angle between the axis of symmetry N-CG and an axis perpendicular to the ground); 3. Angle of asymmetry, between the axis N-frontal pogonion (Pg) and the axis of symmetry; 4. Interpupillary angle (points PI and Pr) relative to the ground; 5. Bisacromial angle (points ACI and ACr) relative to the ground; 6. Frontal Fox plane angle relative to the axis of symmetry perpendicular; 7. Lateral Fox plane angle relative to the ground; 8. Frankfurt plane angle [between lateral tragus (Tr) and lateral soft tissue orbitale (Or)] relative to the ground; 9. Angle of the plane between Tr and lateral infraorbital foramen (IO) relative to the ground;
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American Journal of Orthodontics and Dentofacial Orthopedics Volume 1 0 3 , A'o. 4
L ~ C
'
,o,
~
st,,
:
,o,
329
UL
k~r
C ~
I
C/
N A 3N
Soft tissue n a s l o n Nasal apex Soft tissue s u b n a s a l e
UL LL P~
U p p e r lip Lower tlp So~t tissue p o g o n i o n
SOt I~Cr IOf LCr Fr NAt Cr
Right supraorbital fotamen Right eye medial canthus Right infraorbital foramen Right eye lateral canthus Right pupil Right nasal ala Right labial c o m ~ I s s u r a
501 [.el IO1 HCI PI t:Al Cl
Left Le[t Left Left Left Le[t Left
TRr Right tragus CHr Right c h e e k
supraorbital fora~ten eye lateral canthus inEraorbital toramen eye medial can[bus pupil nasal air labial c o ~ I s s u r a tragus Left cheek
loft ....
PG CO TR IO OR NA
SO~t t i s s u e pogonlon Soft t i s s u e gonion Tragus Infraorbital Eoramen orbltale Nasal ala
Soft tissue
Fig. 2. Digitized points on lateral photographs.
TRI LeEr CHl
Fig. 1. Digitized points on frontal photographs.
10. Camper's plane angle between Tr and lateral nasal ala (NA) relative to the ground. The Frankfurt plane angle was calculated both in the "standing" and in the "sitting" photographs.
Statistical calculations: planes Descriptive statistical data for all angles wcre calculated, separating positive and negative values, which correspond to planes with opposite orientation: 1. In the frontal plot, vertical posture and asymmetry axes with upward and fonvard ( + ) or downward and backward ( - ) rotations, and horizontal interpupillary, frontal Fox, and bisacromial planes going leftward-upward ( + ) or leftward-downward ( - ) ; and 2. in the lateral plot, horizontal lateral Fox, Camper's and tragus-infraorbital planes directed downwardsbackwards ( + ) or upward-backwards ( - ) .
Mean angle values were calculated, with dedicated statistics for circular variables as detailed by Batschelet t~ by using the rectangular components of each angle. The same method allowed the calculation of relevant dispersion measures (the standard angular deviations). Standard angular deviation has the same meaning as standard deviation in linear statistics. Comparisons between angles with opposite orientation and between male and female subjects were done with the Watson-Williams test, which corresponds to the Student's t test used in linear statistics." To study correlations between the various planes calculated in each subject, pairs of different angular variables were plotted on an X-Y graph, and linear regression analyses performed." The correlation coefficients in male versus female subjects were compared with the Fisher's Z transformation."
Statistical calculations: Mean face By means of bivariate analysis" performed on the x-y coordinates of the 24 points.digitized on the frontal photographs (Fig. I), the relevant 24 standard ellipses and Hotelling's 99% confidence ellipses were computed. This al-
330 Ferrario el al.
American Journal of Orthodontics and Dentofacial Orthopedics April 1993
Table la. Mean and standard angular deviation o f angles with different orientation in male subjects (standing pictures, absolute values) Positire angles Angle
Reference a.ris
n
Posture Asymmetry
G S
26 33
Bisacromial Frontal Fox Interpupillary
G S G
35 31 30
Lateral Fox Tr-IO plane Camper
G G G
13 45 3
Mean (degrees)
I
Negative angles SAD (degrees)
Upward and forlvard 2.36 0.32 1.37 0.14 Left.up 1.64 0.18 2.90 0.37 1.59 0.23 Down-back 2.97 0.59 6.64 0.60 1.61 0.82
] n 31 24 22 26 27 44 12 54
Mean (degrees)
SAD (degrees)
Downward and bacl~3t'ard 2.70 0.27 1.52 0.36 Left.down 1.56 0.36 2.42 0.31 1.57 0.18 Up-back 6.61 0.77 2.61 0.51 9.48 0.60
~$qV test F
p
0.807 1.018
NS NS
0.014 0.943 0.083
NS NS NS
6.366 11.588 9.635
<0.025 <0.005 <0.005
Frbntal plane: upward and forward versus downward and backward rotation or lefward and upward versus leftward and downward; lateral plane: downward and backward versus upward and backward; G: ground; S: symmetry; n: number of subjects; SAD: standard angular deviation; F: Watson-Williamstest with 1; 55 df; p: probability value; NS: not significant (p > 0.05). lowed us t o plot means for males (n = 57) and females (n = 51). 9 A similar procedure was followed for fivepoints (N, Pg, G0,Tr, IO) in the lateral photographs (Fig. 2). Calculations were performed after rototranslation of each point, referring coordinates to the subject's center of gravity and axis of asymmetry (i.e., independent from head posture). Bivariate analysis was used because it provides a more integrated and statistically correct evaluation of two-dimensional structures where the horizontal and vertical coordinates depend on each other. The position of the unknown population center (the coordinates of which correspond to mean population values) is to be estimated by the sample center (mean values calculated in the sample). The confidence ellipse is a region that covers the population center with a given probability; it is a tool for statistical inference used in bivariate analysis and serves the same purpose as the confidence interval (x --- t • SE) in univariate statistics. On the other hand, the standard ellipse may be compared with the standard interval (x ___ SD) in univariate statistics: it is only a descriptive tool used to visualize the variability of individual subjects, and covers about 40% of the sample variability. In the mean male and female faces, descriptive statistical data (means and relevant measures of dispersion) of angles and distances were calculated. To make male/female comparisons two different kinds of tests were used: the WatsonWilliams' (for angles) and the Student's t test for independent samples ~4 (for linear measurements). All calculations were performed on an Olivetti M380 computer, with original programs specifically developed for this purpose.
Error of method To assess reproducibility of photographs and of head positions, 10 subjects (five males and five females) were pho-
tographed once, then a second time after a I-week interval. Moreover, 10 randomly selected sets of photographs were retraced and redisitized a week after the first set of recordings was obtained. The combined error of subject's positions, landmark location, and digitization was estimated to be about 2% of the mean values of angular and linear measurements.
RESULTS Angles" standing pictures (Tables la and Ib) Table I reports the mean values of the angles of posture, asymmetry, interpupillary, bisacromial, frontal Fox, lateral Fox, C a m p e r ' s , and tragus-infraorbital foramen plane in men (Table la) and women (Table lb). All angles were calculated on the "standing" photographs, and positive and negative values were separately considered and compared by means of the Watson-Williams test. As to the frontal tracing, mean negative and positive angles do not appear to be differently oriented (none of the tests are significant), but in both sexes there are more subjects with positive asymmetry, bisacromial, frontal Fox, and interpupillary plane angles. In the lateral tracing, males have significantly different positive and negative angles. The lateral Fox angle is directed upward and backward in 44 o f the 57 subjects (mean 6.6~ whereas in the remaining 13 men it goes downward and backward (mean 3~ The tragusinfraorbital foramen plane goes in the opposite direction, and in 45 subjects is directed downward and backward (mean 6.64~ The Camper's plane is oriented upward and backward in almost all the subjects, with a mean angle of.9.5 ~ Also in the female subjects, there are more subjects with the extended head (Tr-IO plane going downward and backward), and their angles are significantly
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Table lb. Mean and standard angular deviation of angles with different orientation in female subjects
(standing pictures, absolute values) Positive angles Reference cttis
n
Posture Asymmetry
G S
25 33
2.54 1.96
B isacromial Frontal Fox Interpupillary
G S G
28 33 34
1.55 2. i 5 1.94
Lateral Fox Tr-IO plane Camper
G G G
4 39 2
3.89 7.41 2.48
Angle
Mean (degrees)
I~V test
Negative angles
SAD (degrees)
n
Upward aridforward
I
Mean (degrees)
I
SAD (degrees)
p p
F
Downward and backward
0.35 0.35
25 18
2.37 1.01
0.22 0.31 0.25
23 18 17
I. I 0 2.32 1.84
0.83 0.82 1.56
47 12 49
8.33 3.78 9.16
Left-up
0.29 0.69
0.150 2.645
NS NS
0.17 0.49 0.47
2.446 0.104 0.070
NS NS NS
0.79 0.70 0.79
2.694 5.778 2.654
Left-down
Down-back
Up-back
NS <0.025 NS
Frontal plan~s: upward and forward versus downward and backward rotation or leftward and upward versus leftward and downward; lateral plane: downward and backward versus upward and backward; G: ground; S: symmetry; n: number of subjects; SAD: standard angular deviation; F: Watson-Williams test with 1; 49 df (for posture angle df = I; 48, being one subject = 0); p: probability value; NS: not significant
(p > 0.05). Table II. Frankfurt plane angle in male and female subjects in the tWO body positions
I
Position Standing Sitting
Males (n = 57) Mean 13.07 ~ 5.09"
WW test (2)
[
Females (n = 51)
SAD
Mean
0.70 ~ 0.80"
13.24 ~ 8.14 ~
I I
WW test (1)
SAD 0.93 ~ 0.84 ~
F
p
F
p
64.471
<0.005
16.096
<0.005
F 0.009 6.045
I
. NS
<0.025
SAD: Standard angular deviation; WW test (1): Watson-Williams test males versus females with I; 106 df; WW test (2): Watson-Williams test standing versus sitting with I; 112 (males) and I; 100 (females) df; F: variance ratio; p: probability value; NS: not significant (p > 0.05).
steeper. The lateral Fox plane is directed upward and backward in most of the female subjects (47 of 51), but the mean values in the two orientations (up/back versus down/back) do not appear to be significantly different. Similar results can be described for Camper's plane, which goes upward and backward in 49 subjects, with a mean of 9 ~ Positive and negative values pertaining to male and female subjects have been comparcd by means of the Watson-Williams test, and no differences were found.
Frankfurt plane (Table II) The Frankfurt plane angle was calculated for both the "standing" and the "sitting" photographs. The angle measured in the standing position appears to be some degrees upward and fo~vard relative to the horizontal, both in the male subjects (13.07 ~) and in the female subjects (13.24~ corresponding to a more extended position of the head. The Frankfurt plane is closer to the horizontal plane in the sitting photographs, but is still directed upward and forward. The two positions are significantly different (p < 0.005).
There is also a gender difference in the angles measured in the sitting position. The Frankfurt plane is about 8 ~ in the female subjects, but only 5 ~ in male subjects. It is apparent that in male subjects, on average, head position relative to the ground is more affected by changes in body position.
Angles: correlations (Table III) In the standing photographs, the relationship between angles measured in the lateral plane (tragus-infraorbital foremen plane versus lateral Fox, and lateral Fox versus Camper's plane) was studied by means of linear regression analyses, which yielded significant correlations in both samples. The correlation coefficients were compared by using Fisher's Z transformation, and no gender differences were found. These relationships are independent from head post u r e . Correlations between the different angles were investigated also on the frontal plane pictures taken in the standing position, both independently from head posture (frontal Fox versus asymmetry angle) and relative to it (posture angle versus the other angles).
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American Journal of Orthodontics and Dentofacial Orthopedics April 1993
Table III. Linear regression analysis in male (n = 57) and female (n = 51) subjects (standing pictures) Variables
Males
Y
X
r
p
Tr-IO Lateral Fox Posture Posture Posture Posture Frontal Fox
Lateral Fox Camper lnterpupillary Bisacromial Frontal Fox Asymmetry Asymmetry .
0.629 0.758 0.584 0.056 0.807 0.741 0.661
<0.001 <0.001 <0.001 0.675 <0.001 <0.001 <0.001
I
Females a
I
0.542 0.945 0.758 0.082 -0.742 - 1.484 1.440
b
r
7.101 3.791 -0.337 -0.425 -0.042 0.089 0.006
0.725 0.782 0.688 0.089 0.640 0.682 0.703
I
p
<0.001 <0.001 <0.001 0.532 <0.001 <0.001 <0.1301
I
a
0.778 0.822 0.944 1.550 -0.657 - 1.364 1.370
Comparison
I
b
10.527 -0.703 -0.516 0.029 0.462 0.853 -0.198
z
p'
0.900 0.298 0.886 0.015 1.815 0.604 0.397
NS NS NS NS NS NS NS
Y = a * X + b; r: coefficient of correlation; p': significance of the slope (difference from slope = 0); z.: comparison between correlation coefficients; p': significance of the difference between correlation coefficients; NS: not significant (p > 0.05).
The frontal Fox plane and asymmetry angles gave highly significant linear correlations in both sexes, as I well as three of the regression analyses between the angle of posture and the other four angles (asymmetry, interpupillary, and frontal Fox). On the contrary, no correlation was found between posture and bisacromial angles. Comparison of the correlations coefficients in the frontal plane yielded no significant gender differences. Mean face: frontal photographs
Fig. 3 shows the computer plot (tracing) of the mean face in male and female subjects in the standing position. For each point the relevant 99% confidence ellipse (inner) and the standard ellipse (outer) are drawn. Ellipses were computed by means of bivariate analysis on the x-y coordinates of the digitized points. The black central point is the center of gravity (CG, origin of coordinate axes) and the Cartesian Y-axis corresponds to the axis of symmetry. Table IV reports the mean values of distances and angles calculated for two plots, and which have been compared by means of the WatsonWilliams test (angles) and of the Student's t test (distances). Most of the vertical measurements are significantly higher in the male than in the female subjects. Among these there is total facial length (nasion-pogonion), nasal length, cheek length, and the distances nose to mouth, and mouth to pogonion. In the horizontal measurements, interpupillary distance, facial width measured both in the middle third (between tragi) and in the lower third (between cheeks) are higher in the male than in the female subjects. Also, nose and mouth are wider in the male stibjects. The angle between cheeks and pogonion is wider in the female than in the male subjects. Mean face: lateral photographs
The computer plot of the mean face in the lateral plane, standing position, is shown in Fig. 4. As for the
-
frontal plane plot, the center of gravity and the coordinate axes, 99% confidence ellipses (inner) and standard ellipses (outer) of the points are plotted. The mean inclinations of the Frankfurt (Tr-Or) and Camper's (TrNA) planes, as calculated on the standing photographs, are also reported on both plots. The shape of the two polygons is similar, but the male quadrangle is larger (wider and higher) than the female one. As a matter of fact, all measured angles have similar values, except the tragus-nasion-pogonion angle; male distances are always larger than the corresponding female ones (Table V). DISCUSSION
The described photographic protocol allowed assessment of the dimensions and relationships of several interrelated structures, and a mathematical description of the frontal and lateral facial structure in a group of healthy young adults in a narrow age range. Moreover, it made possible an evaluation of the posture of head in reference to the ground. Natural head position results were reproducible in our sample, and consistent with previous reports performed on several ethnic groups, by using both cephalometric methods 4'7s'16~7 and photographic techniques. ~8 In comparison to literature references, our sample is composed of full-grown subjects, and no further growth changes are to be expected. ~9-2~ As regards angles in the frontal plane, there are no differences in male versus female subjects for any of the measured variables (posture, asymmetry, interpupillary, bisacromial, frontal Fox). The asymmetry angle indicates chin position (pogonion) relative to the axis of symmetry, and therefore it is independent from the position of head relative to the ground. In both sexes more subjects have the chin rotated to the left than to the right, as can be seen in Table I, where positive asymmetry angles (upward and
Ferrario et al.
American Journal of Orthodontics and Dentofaciat Orthopedics Volume 103, No. 4 I
I
I i
SOr
333
S~4
............. i ................
CH, ~
CHI
PG ...... F,aRkfurs pll~ ............ Camper p l a n 4 ....... CO-Old,hateaAes
(~
I I I ' so,
LCt
T~
N
I
idC.4
so,
.
MCI
" .." ."
9
) LCI
Ir
TPa
TR
9 UL. CHr
Ca
r
CM1
GO v
P~
I
I
Fig. 3. Male (n = 57) and female (n = 51) mean faces obtained by means of bivariate analysis, frontal plot. Center of gravity, axis of symmetry, standard ellipses (outer), and 99% confidence ellipses (inner) of the correspondent 24 points digitized on the frontal photographs.
forward rotation) are found in 33 of the 57 male subjects, and in 33 of the 51 female subjects (about 60% of subjects). The bisacromial plane is higher on the left side in about 60% of subjects, whereas 54% of the male and 65% of the female subjects have frontal Fox planes directed leftward and upward. Most angles are highly correlated to one another, with no diffeiences between sexes (Table III). The frontal Fox angle and asymmetry angle are inversely correlated to posture angle (negative slopes): head position relative to the ground compensates both for occlusal
.~.. . . . .
Fwlnkfurt pllne
...........
Clmper
plane
co-o,alnlta 9
Fig. 4. Male (n = 57) and female (n = 51) mean faces obtained by means of bivariate analysis, lateral plot in standing position. Center of gravity, coordinate axes, standard ellipses (outer), and'99% confidence ellipses (inner) of the correspondent five points digitized on the lateral photographs. Interrupted fine: mean inclination of the Frankfurt plane (tragus-orbitale); dotted line: mean inclination of the Camper's plane (tragus-nasal ala).
surface inclination and for the intrinsic facial asymmetry (position of pogonion). As a result, the occlusal plane is about parallel to the ground, and the chin approximates the median plane. The interpupillary plane relative to the ground is more or less horizontal in both sexes (I ~ to 2~ This plane is well correlated to the posture angle (Table 111). The slight asymmetry measured by the asymmetry angle
es
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American Journal of Orthodontics and Dent*facial Orthopedics April 1993
Table IV. Mean face, frontal plot from 57 males and 51 females Males Measure
Females
MeanlSD
Comparison
Mean
SD
,
i
i
Nasion-pog~onion Nasion-CG Subnasale-upper lip L o w e r lippogonion
N-Pg N-CG SN-UL
I i i .28 34.05 11.90
6.68 3.17 2.44
101.44 3 I. 23 10.08
5.36 3.07 1.96
8.30 4,64 4.20
----
<0.00 l <0.(301 <0.00 I
LL-Pg
25.96
3.57
22.02
2.98
6,12
--
<0.001
lnterpupillary distance Facial width Tragi Cheeks Pogonion angle
Pr-PI
63.61
3.16
60.13
2.56
5.87
--
<0.001
TRr-TRI C}tr-Ctl ! Cttr-PG-CHI
142.96 123.77 120.70 ~
5.25 5.15 0.80 ~
135.51 116.11 123.83 ~
5.03 6.41 0.78 ~
7.43 6.81 --
--8.01
<0.001 <0.001 <0.01
TRr-CHr TRr-CHr-Pg
44.55 132.06 ~
8.24 0.62*
40.66 131.80 ~
6.80 0.61 ~
2.63 --
-0.09
<0.01 NS
TR l-ell I TRI-CItI-Pg
44.46 132.28"
7.35 0.61"
40.35 131.93 ~
6.32 0.67 ~
3.07 --
-0.14
<0.005 NS
Nose 9 Length : Width U p p e r angle L o w e r angle Right angle Left angle
N-SN NAr-NA 1 NAr-N-NAI NAr-SN-NAI N-NA-SN N-NAI-SN
55.66 36.22 43.23* 123.61" 96.46* 96.67"
4110 2.28 0.53 ~ 1.34" 0.81 ~ 0.81 ~
51.76 33.13 42.26 ~ 124.41 ~ 96.24 ~ 97.07 ~
3.65 2, I ! 0.54 ~ 1.33 ~ 0.86* 0,85"
5.15 7.22 -----
--1.59 0.18 0.03 0.12
<0.001 <0.001 NS NS NS NS
Right eye Length Width Upper angle L o w e r angle Lateral angle Medial angle
SOr-IOr LCr-MCr LCr-SOr-MCr LCr-IOr-MCr SOr-LCr-lOr SOr-MCr-lOr
34.25 24.85 78.20* 58.94 ~ 80.93 ~ 133.35 ~
3.85 1.65 0.97 ~ 1.00 ~ 0.91 ~ 1.96"
34.68 24.52 75.89 ~ 60.56 ~ 81.59 ~ 131.44 o
3.20 1,42 i. 19 ~ !, 12~ 0.85 ~ 2,06~
0.62 1.20 ---9 --
--2.37 i. 19 0.30 0.45
NS NS NS NS NS NS
Left eye Length Width U p p e r angle L o w e r angle Lateral angle Medial angle
SO1-10! LC 1- M C I LCI-SOI-MCI LC I -IO I - M C 1 SOI-LCI-IOI SOI-MCI-IOI
35.17 24.84 79.60* 57.97 ~ 82.01 ~ 125.73 ~
3.93 1.75 0.97 ~ !. 02" 0.93 ~ 1.93 ~
35.22 24.36 75.83 ~ 59.32~ 81,41" 131,85 ~
3.49 1.75 1.28 ~ I. 16~ 0.80 ~ 1.82 ~
0.07 1.41 -----
--5.44 0.78 0.23 5.30
NS NS <0.025 NS NS <0.025
Mouth Length Width U p p e r angle L o w e r angle Right angle Left angle
UL-LL Cr-C I Cr-UL-C 1 Cr-LL-CL UL-Cr-LL UL-CI-LL
17.86 50.40 144.53 ~ 138.00 ~ 37.67 ~ 39.76 ~
3.78 3.16 i .76 ~ 1.50" 1.07 ~ 1.08 ~
17,66 47,38 140.79 ~ ! 37,43 ~ 39.97 ~ 41,76"
2.43 3.78 1.44 ~ 1.44 ~ 0.94 ~ 0.94 ~
0.32 4.48 -----
--2,67 0.07 2.60 1.90
NS <0.001 NS NS NS NS
Right cheek : Length I: A n g l e Left c h e e k Length i Angle
Unit: Millimeter (distances), degrees (angles). CG: Center o f gravity; SD: standard deviation (distances), standard a n g u l a r deviation (angles); t: S t u d e n t ' s t test for independent samples with 106 d f (distances); F: Watson-Williams test with I; 106 d f (angles); p: probability value; NS: not significant ( p > 0 . 0 5 ) .
does not affect the upper part of the face. Since only__ young, healthy adults were included in our sample, the bisacromial angle and the posture angle have not been found to be correlated with one another: in normal subjects, the position of head relative to the ground does
not seem to influence the inclination of shoulders and vice versa. On the contrary, in many musculoskeletal disorders of the craniocervical region, these two variables are often correlated to each other. The position of pogonion indicated by the asym-
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335
Table V. Mean face, lateral plot from 57 males and 51 females
-
I Measure
I
Males Mean
l
Comparison
Females SD
Mean[
N-Pg Pg-Go
109.21 75.50
6.10 7.24
102.97 71.53
5.73 5.76
5.41 3. I 0
---
<0.1301 <0.005
Go-Tr Tr-N Pg-Go-Tr Go-Tr-N
57.77 90.85 118.86" 98.08*
6.51 5.63 i .21" 0.88 ~
50.47 85.66 120.15 ~ 99.66 ~
5.52 4.96 1.25" 0.95*
6.19 5.01 ---
--0.55 1.50
<0.001 <0.001 NS NS
Tr-N-Pg N-Pg-Go
69.21" 73.84 ~
0.54 ~ 0.70 ~
67.53 ~ 72.64 ~
0.54 ~ 0.77 ~
---
4.70 0.90
<0.05 NS
Tr-IO IO-Tr-N
73.10 18.25 ~
4.64 0.42 ~
70.58 19.28 ~
4.07 0.38 ~
2.96 --
-3.20
<0.005 NS
IO-Tr-Go
79.27 ~
0.81 ~
80.21 *
0.90 ~
--
0.13
NS
Unit: Millimeters (distances), degrees (angles). SD: Standard deviation (distances), standard angular deviation (angles); t: Student's t test for independent samples with 106 d f (distances); F: Watson-Williams test with I; 106 df (angles); p: probability value; NS: not significant ( p > 0.05).
metry angle shows concordance with that obtained through bivariate analysis (Fig. 3, the center of the pogonion ellipse stays in the left side of face). The most surprising result regarding lateral plane angles is the position of the Frankfurt plane relative to the ground in standing subjects (Table II). The inclination of this plane is substantially different from the horizontal, measuring 13.07 ~ in the male subjects, and 13.24 ~ in the female subjects. In the seated subjects, the slope is less (5.09 ~ in the male subjects, and 8.14 ~ in the female subjects), and only 15% of the subjects have a Frankfurt plane close to the horizontal (0 ~ • 1~ in the sitting position. The slopes are significantly different in the two positions. This indicates a more extended position of the head in the standing "natural" or self-balanced position than in the standard sitting position commonly used for radiographic films. Our subjects' young age might be a factor in this significant extension of the head. ~7 As a matter of fact, data reported in the literature are often in conflict as far as reference planes are concerned. 4"7"22For example, the sella-nasion plane relative to the vertical plane ranges from 81.2 ~to 92.6 ~ in groups of comparable age, depending on body position (standing/sitting) and visual target (mirror, distance or selfbalance). ~.22 This result indicates a need for a careful reevaluation of standard cephalometric protocols, reference planes, and relevant criteria of normality. 4 The lateral Fox plane angle, which indicates the position of the transverse occlusal plane, goes in the opposite direction of the tragus-infraorbital foramen plane angle. The two angles are strictly correlated with one another in both sexes. Also, the correlation between Camper's plane and lateral Fox plane is highly significant, as already reported by many authors (Table III).
The two planes are about parallel, and their orientation changes occur in a similar pattern. ~2 The vertical position of nasion relative to the center of gravity showed very little variability in our sample, so that in the mean frontal plot (Fig. 3) it might be represented by a point. This constant location relative to the center of gravity justifies the use of nasion as a reference point, as already suggested in some reports, a In plotting the "eyes," the infraorbital point (IO) showed a smaller variability and was more easily found than the soft tissue orbitale (Or), which is probably linked to the position and amount of soft tissue. Therefore, IO was taken as the better inferior landmark for the eye area. The horizontal dimensions in our sample are more constant than the vertical dimensions (lower coefficients of variation). Among them, the interpupillary and the tragus-to-tragus distances are identical to measurement of Latta et al. 2J recorded on white adults aged 29 to 87 years. The male subjects are larger than the female subjects in both plots; as a matter of fact, all dimensions in the lateral plot are significantly greater, as are most vertical and horizontal measurements in the frontal plot. Nasion-pogonion distance has been measured in both tracings, and the two values agree (Tables IV and V). In the lateral plot, the quadrangle nasion-pogoniongonion-tragus has the same shape in both sexes, with similar angles (only the Tr-N-Pg is different, Table V), but with larger dimensions in the male subjects. In frontal vertical measurements (Table IV), the upper third of face is equal in the two sexes (structures between nose and eyes); differences, however, become greater in the middle and lower thirds of the face. As a matter of fact, the percentage difference in male versus female subjects is constant throughout the entire
336
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Ferrario et al.
face (nasion-pogonion) and in the upper part of the face, whereas it grows in the lower structures (from subnasale to pogonion) taken separately. The nasion-pogonion distance (whole face) in the male subjects is 8.8% greater than in the female subjects, the nasion-center of gravity distance is 8.3%, and the nasal length is 7%. In the male subjects the subnasale to pogonion distance is 10.7% greater than in the female subjects, accounting for most of the larger vertical measurements in the male subjects. In the study by Genecov et al. 19 the lower face was also responsible for the majority of the greater facial height in the male subjects. In a transverse direction, tlae male subjects are larger than the female subjects, with similar differences at all vertical levels: about 5.5% for both the interpupillary and the tragus-to-tragus distances, 6.6% for the cheekto-cheek distance (Table IV). These gender differences are similar to literature references. 23 The male subjects have a wider and longer face (nose, mouth, and chin) than the female subjects, and a difference in shape: a masculine face is more rectangular, and a feminine face is more squared (pogonion angle, Table IV). Our findings of a certain degree of asymmetry in the human face agree with most of the published studies, although the soft tissues in our results exhibit a lesser degree of asymmetry than the skeletal structures as reported by several authors. 6"9'z4As a matter of fact, these studies in some ways contrast one another: although Vig and Hewitt 6 found, that the cranial base and maxillary regions were significantly larger on the left side, Shah and Joshi 9 stated that the total facial structure was larger on the right side. Woo, 24 working on skulls, found that the right frontal and parietal bones were larger than the left, but that the left malar bone was predominant. It is difficult to compare these studies, since the methods, the measurements, and the sample characteristics (age, se x , race) are very different. Our photographic analysis, performed on a homogeneous sample (race and age), confirnls that the lower third of face (maxillary and mandibular regions) has a greater degree of asymmetry than other facial regions, and that the soft tissues only partially mask the underlying skeletal asymmetry. A certain compensation is gained by the "natural" posture, meaning the self-balanced position of the head relative to the ground. This finding on the frontal plane has the same functional meaning of the correlations already discovered on lateral radiographs, 7s'~ where head position relative to the cervical column was found to be in connection.with dentoalveolar structure, vertical jaw relationships, and enlarged tonsils.
CONCLUSIONS
1. This work reports the determination of mean values of several linear and angular facial measurements made on a group of healthy young adults in a narrow age range, as well as their ranges of variability. 2. It is believed these data could provide a useful resource for a wide range of basic and clinical applications, fo r example, in orthognathic, maxillofacial, and plastic surgery, where computerized systems often furnish "previews" of the final result. Computerized graphic reconstructions could be based on these measurements, which enabie the plotting of harmonic and wellbalanced facial patterns (Figs. 3 and 4). 3. The described photographic protocol could be used in dentistry whenever standardized views are to be taken, especially if a quantitative evaluation of craniofacial soft tissues is needed. The protocol also allows the assessment of the posture of head relative to the ground both in frontal and transverse planes. 4. The Frankfurt plane inclination of our subjects relative to the ground showed some variations dependent on body position and on gender, thus suggesting the need for a careful reevaluation of standard cephalometric and photographic protocols involving sitting versus standing position, and visual target (mirror, distance, or selfbalance). We are greatly indebted to Miss Roberta Siega for her technical support and help preparing this manuscript. REFERENCES
I. Ricketts RM. Perspectives in the clinical application of cephalometrics. Angle Orthod 1981;51:115-50. 2. Cox NH, Van der Linden FPGM. Facial harmony. A.',tJ ORTIIOD 1971;60:175-83. 3. Bittner C, Pancherz H. Morfologia faeciale e maloeclusioni. AM J ORTIIOD DE.N'TOFAC ORTIIOP 1990;97:308-15 (Italian
4.
5. 6. 7. 8. 9. 10.
edition). Michaels LYF, Toume LPM. Nasion true vertical: a proposcd method for testing the clinical validity of cephalometric measurements applied to a new cephalometric reference line. Int J Adult Orthod Orth~nath Surg 1990;5:43-52. Y~osawa F. Predicting soft tissue profile changes concurrent with orthodontic treatment. Angle Orthod 1990;60:199-206. Vig PS, ttewitt AB. Asymmetryof the human facial skeleton. Angle Orthod 1975;45:125-9. Solow B, TallgrenA. Head posture and craniofacialmorphol~y. Am J Phys Anthropol 1976;44:417-36. Solow B, Tallgren A. Dentoalveolar morphol~y in relation to craniocervical posture. Angle Orthod 1977;47:157-64. Shah SM, Joshi MR. An assessment of asymmetryin the normal craniofacial complex. Angle Orthod 1978;48:141-8. Claman L. Patton D, Rashid R. Standardized portrait photog-
Ferrario et al.
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i 1.
12. 13. 14. 15. 16.
17.
18. 19.
raphy for dental patients. A.',t J OR'ntOD DEN'rOFACORTItOP 1990;98:197-205. Ferrario VF, Sforza C, Miani A Jr, Daddona A, Serrao G. Valutazioni della asimmetria faciale. I: i tessuti molli. Bologna: Atti XLIV Convegno-Naziousle Societ6 Italiana di Austomie. 1990. Schreinemakers J. Le basi razionali della protesi totale. Padova: Piccin, 1986. Batschelet E. Circular statistics in biol~y. London: Academic Press, 1981. Snedecor GW, Cochran WG. Statistical methods. Ames, Iowa: Iowa State University Press, 1972. Spiegel MR. Statistica. Milano: Eras libri, 1976. Siersbaek-Nielsen S, Solow B. Intra- and interexaminer variability in head posture recorded by dental auxiliaries. AM J OR"ntOD 1982;82:50-7. Cooke hiS. Five-year reproducibility of natural head posture: a longitudinal study. AM J ORTIIOD DENTOFACORTttOP 1990; 97:489-94. ChiuCSW, ClarkRKF. Reproducibilityofnatural head position. J Dent 1991;19:!30-1. Genccov ~IS,Sinclair Phi, Dechow PC. Development of the nose and soft tissue profile. Angle Orthod 1990;60:191-8.
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20. Nanda RS, Meng H, Kapila S, Goorhuis J. Growth changes in the soft tissue facial profile. Angle Orthod 1990;60:177-90. 21. Singh NR. Changes in the soft tissue chin after orthodontic treatment. A.~i J ORTItODDENTOFACORTItOP 1990;98:41-6. 22. Showfety KJ, Vig PS, Matteson S, Phillips C. Associations between the postural orientation of sella-nasion and skeletodental morphol~y. Angle Orthod 1987;57:99-112. 23. Latta GH, Weaver JR, Conkin JE. The relationship between the width of the mouth, interalar width, bizygomatic width, and interpupillary distance in edentulous patients. J Prosthet Dent i 991 ;65:250-4. 24. Woo TL. On the asymmetry of the human skull. Biometrika 1931 ;22:324-52. 25. Behlfelt K, Linder-Aronson S, Neander P. Posture of the head, the hyoid bone, and the tongue in children with and without enlarged tonsils. Eur J Orthod 1990;12:458-67. Reprint requests to: Prof. Virgilio F. Ferrario Istituto di Anatomia Umana Normale via Mangiagalli 31 1-20133 Milano Italy
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