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ORIGINAL ARTICLE

Linear photogrammetric analysis of the softtissue facial profile

Paula Fernandez-Riveiro, DDS, PhD,a David Suarez-Quintanilla, DDS, PhD,b

Ernesto Smyth-Chamosa, DDS, PhD,c and Mercedes Suarez-Cunqueiro, DDS, PhDd

Santiago, Spain

This study digitally analyzes the soft tissue facial profile of a European white population of young adults by

means of linear measurements made on standardized photographic records taken in natural head position.

The application of the Student ttest showed sexual dimorphism in most parameters of the labial, nasal, and

chin areas. In general, males had greater heights and lengths as well as greater prominences of these 3 areas.

They also had greater nasal and facial depths at the level of the tragus point. (Am J Orthod Dentofacial

Orthop 2002;122:59-66)

The analysis of the soft tissue profile of the face

was a concern for the pioneers of orthodontics

such as Angle and Case at the end of the 19th

century and the beginning of the 20th. Angle took the

sculpture of Apollo Belvedere as his canon of corporal

and facial beauty. However, its straight, almost con-

cave, profile would be difficult to attain orthodontically

with Angles nonextraction theory; he claimed that the

correct occlusion of all teeth in both jaws was necessary

to reach an optimum facial appearance.

Case, a contemporary of Angle, did not try to

follow a single canon representing the ideal of beauty

and thus the treatment objective. He tried to individu-

alize the facial esthetic goal of treatment. He looked for

the best facial appearance of each person, according to

his or her own morphological features and tried to

integrate the occlusal and facial objectives into the

orthodontic treatment plan.

After the standardization of the radiographic tech-

nique in 1931 by Broadbent and Hofrath, the impor-

tance of soft tissue facial analysis was downplayed, and

dentoskeletal relationships became the deciding factor

in diagnosis and treatment planning.

However, some authors such as Downs1 began to

incorporate measurements of the soft tissue facialprofile into their cephalometric analyses, introducing

filters that allowed the visualization of soft tissues. The

objective was to obtain information about the relation-

ship between the soft tissue facial profile and the

underlying dentoskeletal profile, as they realized that

possible anomalies in the hard tissues could be masked

or exaggerated by the soft tissues. In other words, soft

tissues did not always follow the underlying dentoskel-

etal profile.

In a longitudinal growth study, Subtelny2 used

linear measurements of the soft tissue facial profile,

such as nasal length (measured perpendicular to the

palatine plane), length of the upper lip, thickness of the

upper lip at A-point, and the chin at pogonion (Pg).

Steiner3 described the S-line (S-Pg) as tangent to the

upper and lower lips.

Ricketts4 established what he called the law of the

labial relationship according to the esthetic E-plane

(nasal tip-pogonion). The upper and lower lips should

be slightly behind the E-line, with the lower lip closer

to it (2 mm).

Burstone5,6 carried out an exhaustive esthetic anal-

ysis of the facial profile. Within the linear parameters,

he defined the position of the upper (Ls) and lower (Li)

lips regarding the Sn-Pg line, the nasal length (mea-

sured perpendicular to the palatine plane), the length of

the upper (Sn-Sto) and lower (Sto-Me) lips, and theinterlabial gap (Stos-Stoi).

In the 1980s, Ricketts7,8 used the golden divider in

his morphologic dentofacial analysis; ie, he established

divine or golden proportions ( 1.618) among thedifferent parts of the face (width of the nose/width of

the mouth, length of the upper lip/nasal length, facial

height).

Holdaway9 defined the H-line (Ls-Pg) with which

he evaluated the subnasal position (Sn-H), and the

positions of the superior labial sulcus (Sls-H), the

inferior labial sulcus (Sli-H), and the inferior lip (Li-H).

From the University of Santiago de Compostela, Santiago, Spain.aResearch associate, Department of Orthodontics.bProfessor and Chairman, Department of Orthodontics.cProfessor, Department of Oral Health.dAssistant professor, Department of Oral Health.

Reprint requests to: Paula Fernandez-Riveiro, DDS, PhD, Lopez Mora 86, 1

36211 Vigo, Spain; e-mail, [email protected].

Submitted, August 2001; revised and accepted, December 2001.

Copyright 2002 by the American Association of Orthodontists.

0889-5406/2002/$35.00 0 8/1/125236

doi:10.1067/mod.2002.125236

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He also defined the nasal prominence and the thickness

of the upper lip at the level of A-point and the chin at

Pg.

In 1991, Bass10 introduced the position of the upper

incisor as a key for orthodontic treatment. He took therecords in natural head position (NHP), using the true

horizontal (TH) as a reference line. He defined the ideal

position of the upper incisor, Pg, and the upper lip using

a perpendicular line to the TH. He also established the

exhibition of 2 to 3 mm of the upper incisor below the

interlabial gap.

In Canuts 1996 esthetic analysis,11 he studied the

interrelationship of nasal, labial, and chin prominences

with regard to the Sn-Sm line (facial esthetic triad) and

the depth of the nasolabial sulcus that he called the

nasolabial esthetic sigma and measured between 2

perpendicular lines to the Frankfort plane through Snand Ls.

Parallel to the development of radiographic cepha-

lometrics, the linear analysis of the soft tissue facial

profile on photographic records was developed. In

1981, Farkas,12 using a sample of young people (6-18

years old) of both sexes, standardized the photographic

technique and the taking of records in NHP. Included in

his linear measurements were nasal length (N-Sn),

height of the middle and inferior third of the face

(Sn-Me), and length of the upper lip (Sn-Sto). In 1985,

he observed that the measurements in his studies on

young white subjects were different from the Neoclas-

sical canons13 of facial esthetics used as the norm for

orthodontic facial esthetic objectives.

The surgeons Powell and Humphreys14 defined

their esthetic triangle between the planes N-G/nasal

dorsum/G-Pg/E-plane/cervical plane C-Me. In their

analysis, they also defined the position of the lips, the

exposure of the incisor edge at rest (2 mm with an

interlabial gap of 3 mm), and the incisor exposure at

broadest smile (two thirds of the clinical crown)

Epker15 took his records in NHP, using the true

vertical (TV) as the reference line on which he defined

proportional measures as the following: the upper lip

(Sn-Sto) is 30% of the inferior third of the face(Sn-Gn), the inferior lip (Sto-Sm) is 28% of the inferior

third of the face, the height of the chin is 42% of the

inferior third, the nasal depth (Sn-Prn) is 40% of the

nasal length (N-Sn).

Arnett and Bergman16 described an analysis of the

soft tissue facial profile on photographic records in

NHP. Their analyses of the symmetry, both vertical and

horizontal, the contour of the smile line, the facial

middle lines, and the facial contour were important. In

their linear measurements, they analyzed the position of

the upper and lower lips in relation to the Sn-Pg line

(previously used by Burstone), the length of the upper

(Sn-Ls) and lower (Li-Me) lips, the upper incisor

exposure at rest (1-5 mm), and the interlabial gap. The

authors defended the equality in the facial thirds Tri-

G/G-Sn/Sn-Me (55-65 mm).On the other hand, all the factors that influence the

normality criteria when making a facial analysis should

be taken into account, including age, sex, and race.17,18

It has been proven that most facial changes occur

before age 18, although growth and reshaping continue

throughout life. Through the years, the profile becomes

more concave, the nose and the chin grow, the lips

become more retrusive, and the nasolabial angle in-

creases.11,17,19-21 These changes are significantly

greater in males than in females.22 In general, the

existence of sexual dimorphism in the facial features

and their remodelling throughout life has been proved.According to this, males experience a greater change, in

both hard and soft tissues.21,23

In this study, we tried to determine the linear

measurements that define the average soft tissue profile

of a young adult white sample. We used a standardized

photogrammetric analysis of the profile in NHP.

MATERIAL AND METHODS

Our subjects were students from the Faculty of

Medicine and Dentistry of the University of Santiago

de Compostela, Santiago, Spain. A sample of 212

people, 50 males and 162 females (23.6% male, 76.4%

female) between 18 and 20 years old, was randomly

selected. All of them were white Galician, which we

defined as having 4 grandparents of Galician origin.

The photographic setup (Fig 1) consisted of a tripod

that held a 35-mm camera with a 100-mm macro lens

and a primary flash. The 100-mm macro lens was

chosen to avoid facial deformations. The stability of the

elements and the easy adjustment of the tripod height

allowed us to keep the optic axis of the lens horizontal

during the recording. Levelling devices at the base of

the tripod and on the camera controlled its correct

horizontal position. The primary flash was attached to

the tripod by a lateral arm, at a distance of 27 cm fromthe optic axis to avoid the red-eye effect on the

records. A secondary flash was placed behind the

subject to light the background and eliminate undesir-

able shadows from the contours of the facial profile.

The primary and secondary flashes were synchronized.

The camera was used in its manual position, the

shutter speed was 1/125 second, and the opening of the

diaphragm was f/11. The film was Agfachrome 100

ISO developed with the E-6 process in the same

laboratory to ensure that the processing was identical

throughout the study.

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Each subject stood on a line on thefloor, framed by

a vertical scale divided in 5-cm segments. From the

scale hung a plumbline held by a thick black thread that

indicated the TV. The scale allowed measurements at

life size (1:1). On the opposite side of the scale and

outside the frame was a vertical mirror, approximately

110 cm from the subject.The records were taken in NHP. Each subject was

shown where to stand and asked to relax, and then told

to walk a few steps, stand at rest facing the camera, and

look into his or her own eyes in the mirror. The lips were

also relaxed, adopting their normal position during the

day. Glasses were removed, and the patients forehead,

neck, and ears were clearly visible during the recording.

The photographic records, 35-mm slide format,

were digitized and analyzed with the Nemoceph 2.0

(Nemotec Dental Systems, Madrid, Spain) software

program for Windows. The program was previously

customized with the landmarks defined in the analysisof this work. The landmarks were located on a digitized

image to obtain all the measurements by the computer.

The following landmarks are shown in Figure 2:

Trichion (Tri), the sagittal midpoint of the forehead

that borders the hairline

Glabella (G), the most anterior point of the middle

line of the forehead

Nasion (N), the point in the middle line located at the

nasal root

Pronasal (Prn), the most prominent point of the tip of

the nose

Columella (Cm), the most inferior and anterior point

of the nose

Subnasal (Sn), the point where the upper lip joins the

columella

Labial superior (Ls), the point that indicates the

mucocutaneous limit of the upper lip

Stomion superior (Sts), the most inferior point of the

upper lip Stomion inferior (Sti), the most superior point of the

lower lip

Labial inferior (Li), the point that indicates the

mucocutaneous limit of the lower lip

Supramental (Sm), the deepest point of the inferior

sublabial concavity

Pogonion (Pg), the most anterior point of the chin

Menton (Me), the most inferior point of the inferior

edge of the chin

Tragus (Trg), the most posterior point of the auricu-

lar tragus

Alar (Al), the most lateral point of the alar contour ofthe nose

Superior point of the TV (sTV)

Inferior point of the TV (iTV)

Ort, the point joining the TV and the TH

The following reference lines are also shown in

Figure 2:

TV, sTV-iTV

TV in N (N-Ort), parallel to TV through N

TH, Trg-Ort, perpendicular to TV through Trg

Canut line (Juanita Line),22 Sn-Sm

Fig 1. Photographic setup.

Fig 2. Landmarks and reference lines used in this

analysis.


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The following vertical linear measurements (paral-

lel to TV) are shown in Figure 3:

Superior facial third, Tri-G

Middle facial third, G-Sn

Inferior facial third, Sn-Me

Nasal length, N-Sn

Length of upper lip, Sn-Sts

Interlabial gap, Sts-Sti

Length of lower lip, Sti-Sm

Vermilion of upper lip, Ls-Sts

Vermilion of lower lip, Li-Sti

Height of chin, Sm-Me

Height of nasal tip, Sn-Prn

The following linear horizontal measurements (par-

allel to TH) are shown in Figure 4:

Facial depth, Trg-Sn

Nasal depth, Al-Prn

Nasal prominence, Prn to N-Ort line

Subnasal depth, Sn to N-Ort line Mentolabial depth, Sm to N-Ort line

Prominence of upper lip, Ls to N-Ort line

Prominence of lower lip, Li to N-Ort line

Prominence of chin, Pg to N-Ort line

The following Canuts linear measurements (per-

pendicular to Sn-Sm line) are shown in Figure 5:

Canuts nasal prominence, Prn to Sn-Sm Canuts prominence of upper lip, Ls to Sn-Sm

Canuts prominence of lower lip, Li to Sn-Sm

Canuts prominence of pogonion, Pg to Sn-Sm

STATISTICAL ANALYSIS

A descriptive statistics analysis of the linear mea-

surements was carried out, with the results presented in

Table I. Sexual dimorphism was evaluated by the

Student t test (Table II). The reliability of the method

was analyzed by using Dalhbergs formula, ME (x1-x2)

2/2n, to determine the difference between 2

measurementes made at least a month apart. For this

purpose, 54 randomly selected records were retraced

and redigitized (Table III).

Fig 3. Vertical measurements (measured parallel to TV

line). Fig 4. Horizontal measurements (measured parallel to

TH line).

Fig 5. Measurements related to Sn-Sm line.


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RESULTS AND DISCUSSION

In the study of facial heights (Tri-G, G-Sn, Sn-Me),

the similarity between the inferior facial third (Sn-Me:

males 71.4 5.7 mm and females 65.4 4.3 mm) andthe middle facial third (G-Sn: males 72.1 5 mm andfemales 68.7 4.5 mm) was observed, as Powell andHumphreys14 pointed out. Epker,15 however, found that

the inferior third was slightly larger (38%) than the

middle third (32%). In both cases, males showed more

similarity between the facial thirds and significantly

larger absolute values than did females; this coincides

with thefindings of other authors.19,24 However, in the

superior third (Tri-G: males 45.3 6 mm and females45.2 6 mm), sexual dimorphism was not found nor

were the facial thirds proportional with the other thirds.Farkas12 published sexual differences (males 58 6mm and females 51 6 mm) in which the heights were

also larger in males. Facial depth (Trg-Sn) was also

shown to be significantly larger in males (106.5 8mm) than in females (102.5 8 mm). Nanda andGhosh17 studied the facial depth in nasal tip (Trg-Prn),

observing significant sexual differences (males 122 4

mm and females 113 5 mm). On the other hand, thegreat individual variability, with high standard devia-

tions (SDs), and the difficulty of measuring the Trg and

the Tri points should be mentioned. This was reflected

in the high method error at the facial superior height

and the facial depth.

On analyzing the nose, it was observed that maleshad greater length (N-Sn: males 52.5 4 mm and

females 49.8 4 mm) and nasal prominence (Prn/Sn-

Sm: males 13.4 2.5 mm and females 12.39 1.9

mm; Prn/TV: males 25.3 3.75 mm and females

21.69 3.1 mm; al-Prn: males 30 3 mm and females

27.4 2.5 mm) than females, with statistically signif-

icant differences. The height of the nasal tip (Sn-Prn:

males 11.6 2.2 mm and females 11.1 1.7 mm) was

the only nasal measurement that did not show sexual

dimorphism. This finding coincides with those of

Nanda and Ghosh.17 With regard to the reliability of the

parameters, we can say that, in most measurements,variability was not excessive (SD 2-4 mm), as was

the case with the error, which ranged from 1 to 1.5 mm.

The labial area should be thoroughly evaluated

because the appearance of the lips and the smile can be

modified by orthodontic treatment. The length of both

lips was larger in males than females (P .01) (Sn-Sts:

males 23 2.6 mm and females 21.4 2 mm; Sti-Sm:

males 19 2.5 mm and females 17.5 2 mm). Park

and Burstone25 and Yuen and Hiranaka24 also found a

larger length of the upper lip in males (Park and

Burstone: males 22 2 mm and females 18 2 mm;

Table I. Application of Student ttest relating to sex

Variable P*Inferior limit of confidence

interval (95%)

Superior limit of

confidence interval (95%)

Tri-G .92 2.02 1.83N-Sn .000* 3.88 1.44

Prn/TV(N) .000* 4.55 2.23

Prn/Sn-Sm .002* 1.71 0.38

Sn-Prn .13 1.19 0.16

al-Prn .000* 3.48 1.80

Sn-Sts .000* 2.39 0.78

Sti-Sm .000* 2.29 0.75

Sts-Sti .04* 0.009 0.64

Ls-Sts .52 0.31 0.61

Li-Sti .36 0.27 0.73

Ls/TV(N) .000* 4.36 1.46

Ls/Sn-Sm .27 0.98 0.28

Li/TV .000* 5.07 1.47

Li/Sm-Sn .65 0.36 0.57

Sm-Me .000* 4.06 2.40Pg/TV(N) .000* 7.03 2.39

Pg/Sn-Sm .000* 2.19 1.07

G-Sn .000* 4.89 1.88

Sn-Me .000* 7.77 4.27

T-Sn .003* 6.71 1.41

Sn/TV(N) .000* 3.90 1.39

Sm/TV(N) .013* 6.77 0.79

*Statistically significant differences, P .05.


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mm larger than the superior one (Ls-Sts) in both

studies. The size of the vermilion causes the exposure

of more or less mucocutaneous lip. Its volume is also a

reflection of the muscular tension of that lip. The more

vermilion that is exposed, the smaller the muscular

tension of the same lip.

On analyzing the labial prominence with regard to

the Sn-Sm line, it was observed that both the upper lip

(Ls/Sn-Sm: males 4 2 mm and females 3.69 1.4mm) and the lower lip (Li/Sn-Sm: males 4 1.6 mmand females 4 1.4 mm) protruded 4 mm beyond thereference line, without noticeable sexual differences.

Regarding the TV in N, however, both the upper lip

(Ls-TV: males 8.8 5 mm and females 6 4.5 mm)

and the lower lip (Li-TV: males 5 6 mm and females1.7 5.4 mm) showed a different prominence, whichwas significantly more evident in males. In both cases,

the upper lip was more forward than the lower one. The

different prominence of the lips with regard to the

reference lines could possibly be explained by the

different NHP in males and females, but this hypothesis

needs further research.

The subnasal point with regard to the TV in N

(Sn-TV: males 8.6 4 mm and females 6 4 mm)was more prominent in males. The great variability of

the measurements obtained by using the TV should be

considered in the analysis of the results. The error

committed in the localization of the points was accept-

able (1-1.5 mm) and similar in the different parame-

ters of the labial area.

The height of the chin (Sm-Me), analyzed by Parkand Burstone,25 measured 30 to 35 mm with no sexual

differences. In this study, all measurements of the

analysis in the area of the chin showed sexual dimor-

phism characterized by greater length (Sm-Me: males

29 3 mm and females 26 2.5 mm) and greaterprominence (P .01) in males than in females (Pg-TV:males 2 8.5 mm and females 2.7 7 mm;Pg/Sn-Sm: 6.7 2 mm and females 5 1.6 mm). The

mentolabial sulcus regarding the TV was also deeper in

males than in females (Sm-TV: males 1.8 7 andfemales 1.2 7.2 mm). It was quite surprising that

the position of this point is located in both sexes behindthe TV (through N). The same is true with the promi-

nence of Pg relative to the TV in females, which was

located behind the TV line. Again, these measurements

relative to the TV showed great variability.

CONCLUSIONS

The labial, nasal, and chin areas showed sexual

dimorphism in most of the parameters we used. Males

have larger faces in general, with greater facial heights;

longer nasal, labial, and chin lengths; larger nasal,

labial, and chin prominences; and a greater nasal and

facial depth in the tragus point. In facial heights, aproportion of 1:1 between the middle and the inferior

facial thirds was observed. In the height of the vermil-

ions, sexual dimorphism was not observed. The inferior

vermilion was 1 mm larger than the superior.

A great variability and a greater sexual dimorphism

in the relative measurements to the TV were observed.

In particular, the differences were very marked in the

prominence of the lower lip and the chin with regard to

the TV.

The highest errors were found in facial superior

height and facial depth, mainly due to the difficulty in

the localization of trichion and tragus points.

REFERENCES

1. Downs WB. Analysis of the dentofacial profile. Angle Orthod

1956;26:191-212.

2. Subtelny JD. A longitudinal study of soft tissue facial structures

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skeletal structures. Am J Orthod 1959;45:481-507.

3. Steiner C. The use of cephalometrics as an aid to planning and

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4. Ricketts RM. Esthetic, environment and the law of lip relation.

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5. Burstone CJ. The integumental profile. Am J Orthod 1958;44:1-

25.

Table III. Method error according to Dalhbergs

formula

Parameter Method error (mm)

Tri-G 2.92N-Sn* 1.31

Prn/TV* 0.58

Prn/Sn-Sm* 1.23

Sn-Prn 0.90

al-Prn* 2

Sn-Sts* 0.83

Sti-Sm* 0.78

Sts-Sti* 0.6

Ls-Sts 0.8

Li-Sti 1

Ls/TV(N)* 0.58

Ls/Sn-Sm 0.47

Li/TV(N)* 0.5

Li/Sm-Sn 0.46

Sm-Me* 1.3

Pg/TV(N)* 0.84

Pg/Sn-Sm* 0.66

G-Sn* 0.95

Sn-Me* 0.77

T-Sn* 2.38

Sn/TV(N)* 0.66

Sm/TV(N)* 0.76

*Statistically significant differences.


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