ORiGiNAL PAPERS - Dental and Medical Problems

ORiGiNAL PAPERS - Dental and Medical Problems

ORiGINAL PAPERS
Dent. Med. Probl. 2012, 49, 4, 550–555
ISSN 1644-387X
© Copyright by Wroclaw Medical University
and Polish Dental Society
Liwia Minch1, A, D, Małgorzata Zielińska2, B, C, E, F, Beata Kawala1, A
Perception of Facial Symmetry and Attractiveness
Postrzeganie symetrii i atrakcyjności twarzy
Department of Maxillofacial Orthopedics and Orthodontics, Wroclaw Medical University, Poland
Students’ Scientific Association at Department of Maxillofacial Orthopedics and Orthodontics,
Wroclaw Medical University, Poland
1
2
A – koncepcja i projekt badania; B – gromadzenie i/lub zestawianie danych; C – opracowanie statystyczne;
D – interpretacja danych; E – przygotowanie tekstu; F – zebranie piśmiennictwa
Abstract
Background. The concept of facial symmetry is very significant from the orthodontic diagnostics point of view,
and also for attractiveness assessment. A shift of the midline leads to disharmony, which negatively affects the sense
of esthetics. However, a subjective face assessment by different individuals can make a slight, seemingly indefinable
asymmetry acceptable.
Objectives. The assessment of the perception of the female face symmetry, its attractiveness by dentistry students
and by the individuals unrelated to dentistry.
Material and Methods. The test group included 101 dentistry students aged from 22–28 years (50 men and
51 women), 102 students of the University of Technology in Wrocław aged from 20–25 years (52 men and 50
women). The respondents were asked to order, according to their attractiveness, three photos of the face of every
individual: one natural and two modified, using graphic software, which were mirror images of the half right and
half left face. Additionally, the respondents assessed facial symmetry (6 photos in the scale of 1:1): of one natural
(symmetric) and asymmetrical within mandible, with a pogonion point shifted left of 2, 4, 6, 8, and 10 mm.
Results. The respondents have considered as a most attractive the symmetric face, which was the mirror image of
the half left face, less attractive was the natural face, and the least attractive was, according to them, the face that was
the mirror image of the half right side. The statistical analysis has confirmed the lack of differences in perception
of the attractiveness between both test groups (p < 0.772). Among the dentistry students approximately half of the
respondents have considered the natural face and the face with the pogonion point shifted of 2 mm as symmetrical.
The other versions were classified by most of the respondents as asymmetric. The assessment performed by the
individuals unrelated to dentistry was similar, although they have more often indicated the face with the pogonion
point shifted of 4 mm as asymmetric.
Conclusions. The facial symmetry toward the facial midline is extremely important, although it is not a unique
factor affecting the attractiveness. The perception of the asymmetry in the case of the greater deviations from the
midline (6–10 mm) was correct in the vast majority of the cases. The greater difficulty was the correct assessment
of both symmetrical, as well as slightly asymmetrical face (Dent. Med. Probl. 2012, 49, 4, 550–555).
Key words: facial asymmetry, esthetics, perception.
Streszczenie
Wprowadzenie. Pojęcie symetrii twarzy jest bardzo istotne zarówno z punktu widzenia diagnostyki ortodontycznej, jak i oceny atrakcyjności. Przesunięcie linii pośrodkowej wprowadza dysharmonię, która wpływa negatywnie
na poczucie estetyki. Subiektywna ocena twarzy przez różnych ludzi może jednak sprawić, że nieznaczna, pozornie
nieuchwytna asymetria będzie akceptowalna.
Cel pracy. Ocena postrzegania symetrii i atrakcyjności twarzy żeńskiej przez studentów stomatologii oraz osoby
niezwiązane ze stomatologią.
Materiał i metody. Badaniem objęto grupę 101 studentów stomatologii (50 mężczyzn i 51 kobiet) w wieku 22–28 lat
oraz grupę 102 osób niezwiązanych ze stomatologią (52 mężczyzn i 50 kobiet) w wieku 20–25 lat. Ankietowanych
poproszono o uszeregowanie według atrakcyjności 3 zdjęć tej samej twarzy: naturalnej oraz dwóch zmienionych
za pomocą programu graficznego, będących odbiciem lustrzanym prawej i lewej połowy twarzy. Badane osoby
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Facial Symmetry and Attractiveness
oceniały ponadto symetrię twarzy (6 zdjęć w skali 1:1): naturalnej (symetrycznej) oraz niesymetrycznych w obrębie
żuchwy z przesuniętym w lewo punktem pogonion o 2, 4, 6, 8 i 10 mm.
Wyniki. Ankietowani za najatrakcyjniejszą uznali twarz symetryczną, będącą odbiciem lustrzanym lewej połowy
twarzy, za mniej atrakcyjną – twarz naturalną, najmniej atrakcyjna zaś była według nich twarz będąca odbiciem
lustrzanym prawej połowy twarzy. Analiza statystyczna potwierdziła brak różnic w postrzeganiu atrakcyjności
między badanymi grupami (p < 0,772). Oceniając symetrię względem linii pośrodkowej wśród studentów stomatologii, około połowa ankietowanych uznała twarz naturalną oraz z przesuniętym punktem pogonion o 2 mm za
symetryczną. Pozostałe wersje większość ankietowanych klasyfikowała jako niesymetryczne. Ocena dokonana przez
osoby niezwiązane ze stomatologią była podobna, chociaż częściej wskazywali oni twarz z przesuniętym punktem
pogonion o 4 mm jako symetryczną.
Wnioski. Symetria twarzy względem linii pośrodkowej jest niezmiernie ważnym, choć nie jedynym czynnikiem
wpływającym na atrakcyjność. Postrzeganie asymetrii w przypadku większych odchyleń od linii pośrodkowej (6–10
mm) było w przeważającej liczbie przypadków prawidłowe. Większą trudność stanowiła prawidłowa ocena twarzy
zarówno symetrycznej, jak i w niewielkim stopniu niesymetrycznej (Dent. Med. Probl. 2012, 49, 4, 550–555).
Słowa kluczowe: asymetria twarzy, estetyka, postrzeganie.
Facial symmetry is not only essential from the
point of view of the preservation of normal masticatory system function, but also esthetics. The
canon of the human face beauty has been formed
in ancient times, which may be seen in the preserved works of the Egyptians. An example of this
is a sculpture from the fourteenth century BC depicting Queen Nefertiti, whose face reflects perfect
harmony and symmetry, which even today is considered to be beautiful. Though in nature such extremely idealized beauty does not occur, it is true
that symmetrical faces are considered more attractive [1]. This is related to the fact that perfect symmetry is subconsciously identified with the lack
of serious illnesses or genetic mutations, and thus
is a synonym for overall health [2]. Faces considered symmetrical may have an asymmetry within the bone structures, which suggests a potential
soft tissue adaptation to offset the small deviations
from generally accepted standard [3]. On the other hand, asymmetry can be limited only to softtissue structures [2] and occur by normal occlusion [4]. Those facts suggest a question concerning which level symmetry has an influence on the
esthetics.
The ancients Greeks were the first to have noticed the “natural asymmetry” in the form of differences in the size of the right and left side of the
face. Since that time, the canon of beauty has been
repeatedly changed; however, the deviation from
the midline, considered currently as the standard,
still constitutes the individuality and uniqueness
of the face [1]. A direct confirmation of the natural asymmetry of the face is also based on manipulating the en face photos using graphic programs. They enable us to create new, ideally symmetrical faces by replacing the right face part by
the mirror image of its left half, and vice versa. In
this way we can obtain three different pictures of
originally one individual, which, though similar,
are not identical [2]. It should be noted, however,
that a slight asymmetry is often poorly observable
by the outsiders. Thus, it is difficult to determine
the border between still acceptable asymmetry
and a significantly observable disharmony [2, 5]
the more so, since the perception of the human
face beauty has a multifactor (both genetic, as also
environmental) base [1].
Accordingly to the above assumptions, the aspects related to the esthetics and symmetry of the
face should be evaluated among different groups,
especially among young people, who constitute
a significant part of patients treated orthodontically. Therefore, the aim of the following study was
to assess the perception of the female face symmetry and attractiveness by dentistry students and by
individuals unrelated to dentistry in order to show
possible differences between both groups.
Material and Methods
The test group consisted of 101 dentistry students (50 men and 51 women) aged from 22 to
28 years (mean age: 23.02) and 102 students of the Wroclaw University of Technology (52 men and 50 women) in age from 20 to 25 years (mean age: 21.62).
The en face photos of the female face with
a preserved median line and facial symmetry (taken according to the Simon’s standard, with an
Olympus Digital SLR Camera E-500 camera) were
scaled and subjected to graphic processing using
Adobe® Photoshop® CS5 12.0 × 32. Then, the photos were printed in color in the scale of 1:1.
The respondents were asked to order, according
to their attractiveness, three photos of the same face:
one natural and two modified, made of half of the
face completed by its mirror image (Figs. 1A–C).
Secondly, both test groups assessed the facial
symmetry (6 photos): of one natural and five asym-
552
a
L. Minch, M. Zielińska, B. Kawala
b
c
Fig. 1. Photographs of the same face: one natural (b) and 2 modified, made of half of the face completed by its mirror
image: right (a) and left (c)
Ryc. 1. Zdjęcia tej samej twarzy: naturalnej (b) i 2 zmienionych, będących połową twarzy uzupełnioną jej lustrzanym
odbiciem: prawym (a) i lewym (c)
metrical faces with a pogonion point shifted left by 2,
4, 6, 8, and 10 mm respectively (Figs. 2A–F) and the
asymmetry grade (minimal or significant) was evaluated. Additionally, both test groups were asked to
pay no attention to elements such as earrings, ears
or hairline and used no tools that could be helpful in
assessing the deviations from the median line. The
pictures were shown individually, without comparing them with each other and in random order.
The results were subjected to the statistical analysis in STATISTICA 10.0 software, using Pearson’s
chi-squared test (statistical significance = 0.05).
Results
The attractiveness assessment of the face has
shown that the face with the mirror image of its
left part was considered the most attractive by
77 dentistry students and by 71 students of the
University of Technology. The natural face has been
considered second most attractive (respectively 19
and 23 students). The smallest number of respondents considered the face with the mirror image
of its right part as the most attractive (respectively
5 and 8 students). The statistical analysis has confirmed a lack of differences in perception of the attractiveness between both test groups (p < 0.772).
The results of the facial symmetry assessment
are shown in Table 1. It is worth noting that the
natural face assessment by the two groups was similar. They have also similarly perceived the asymmetry in the case of deviations from the pogonion point, ranging from 6 to 10 mm, where most
of them assessed these faces as asymmetrical. The
statistical analysis has confirmed that the differences between the results of both groups in these
ranges were not statistically significant (p > 0.05).
Whereas the results of perception of the deviations from the median line in case of shifting the
pogonion point by 2 and 4 mm were statistically
significant (p < 0.005) – the tested groups have attained different results in this range.
Discussion
Esthetics and symmetry of the face are currently sufficiently important issues and, from the
point of view of the orthodontic patients, are one
of the overarching goals of the treatment [6]. Although there are differences in the perception of
the midline by orthodontists and dentists, and
people, who are not related to the dentistry [5], the
symmetrical face is considered by the general public as the most attractive. The incidence of facial
asymmetry, according to studies of various foreign
authors ranges from 34% [7] to even 69.2% [8], and
is observed also in individuals considered attractive. Most often it involves the shift of the midline
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Facial Symmetry and Attractiveness
a
b
c
d
e
f
Fig. 2. Photographs of one natural (a) and 5 asymmetrical faces with a pogonion point shifted left by 2 (b), 4 (c), 6 (d),
8 (e), and 10 mm (f)
Ryc. 2. Zdjęcia twarzy naturalnej (a) i 5 asymetrycznych twarzy z punktem pogonion przesuniętym o 2 (b), 4 (c), 6 (d),
8 (e), and 10 mm (f)
within the lower face section [7, 9–11]. Some of the
researchers have proven that in the population the
shift to the right side is seen more often [10], and
some of them have proven that it is the shift to
the left side [8, 9, 11–13]. Depending on the deviation degree, the asymmetry concerning mandible
location can be not only an esthetic problem, but
also have its implications in the stomatognathic
system function. [3, 14]. The symmetry disorders
within the facial portion of the skull can correlate,
although they must not do so with the occlusion
defects. They are diagnosed predominantly in patients with the transverse defects and also with the
anteroposterior defects, where they most often occur along with the 2nd or 3rd, less frequently with
the 1st Angle class. The etiology of these changes
is various and can be associated with the congenital, developmental or acquired during individu-
554
L. Minch, M. Zielińska, B. Kawala
Table 1. Results of the facial symmetry assessment
Tabela 1. Wyniki oceny symetrii twarzy
Natural face
(Twarz
naturalna)
Shift of 2 mm
(Przesunięcie
o 2 mm)
Shift of 4 mm
(Przesunięcie
o 4 mm)
Shift of 6 mm
(Przesunięcie
o 6 mm)
Shift of 8 mm
(Przesunięcie
o 8 mm)
Shift of 10 mm
(Przesunięcie
o 10 mm)
S
AS
S
AS
S
AS
S
AS
S
AS
S
AS
Dentistry students
(Studenci stomatologii)
minimally
significantly
%
50
50
40
60
15
85
9
91
7
93
8
92
Wrocław University
of Technology students
(Studenci Politechniki
Wrocławskiej)
minimally
significantly
%
45
Statistical analysis
(Analiza statystyczna)
p = 0.625
84
16
55
84
16
77
23
58
42
81
19
p < 0.005
65
23
35
65
89
11
p < 0.005
42
58
8
92
67
33
p = 0.982
45
55
12
88
60
40
p = 0.347
18
82
14
86
47
53
p = 0.269
S – symmetrical, AS – asymmetrical.
S – symetryczna, AS – niesymetryczna.
al development defects (e.g. temporo-mandibular
joint disorders, traumas) [15].
In the present study of facial symmetry assessment it is worth noting that both test groups similarly assessed the natural face, with a preserved median line and symmetry; however, approximately
half of the respondents considered it to be asymmetrical. Interestingly, the face with the pogonion
point shifted of 2 mm was considered symmetrical
more often in a group of University of Technology
students than the natural face. Not without significance seems to be the influence of the suggestions
of respondents that among the images shown was
also one with the symmetrical face. Additionally,
the photographs were presented in random order,
which could enhance the suggestion effect. Despite these nuances, faces with the pogonion point
shifted of 6 mm and more were assessed correctly
by most of the respondents as asymmetrical. Thus,
the value of 6 mm can be regarded as boundary
in the present studies for the undeniable perception by outsiders of the asymmetry within the lower third part of the face.
The most difficult factor in both test groups was
to assess the face with asymmetry in the range of
2 and 4 mm. Although the dentistry students have
obtained in these cases better results than individuals not related to dentistry (which was statistically
significant), this assessment was however not unambiguous, especially concerning the natural face assessment. Therefore, it can be assumed that asymmetry within the limit of 4 mm is not unequivocally visible. The more so, when one considers factors which
under normal conditions distract us from such facial details, as e.g. hairstyle, make-up, head covers,
glasses etc. Similar results have been obtained studying the perception of the dental midline. For the acceptable, still unobservable by the outsiders, asymmetry was considered deviations ranging from approximately 2 mm [5, 16–18] to even 4 mm [19].
The value of the accepted asymmetry can turn
out to be very significant in making a decision
about the treatment type. A special case is the lack
of symmetry in the bone bases coexisting with the
occlusion defect, where surgical intervention is considered [2]. However, when making decisions about
the surgery together with the patient, we should
take into account not only the end result, but also
the possible complications, postoperative rehabilitation, prolonged treatment and the increase in the
cost. If the deviations from the midline are in the
range up to 4 mm, which has been shown to be unobservable to the outsiders, the decision about less
radical treatment is acceptable.
In the common opinion, an attractive face is
symmetrical and there are reports confirming such
relationship [20, 21]. On the other hand, scientific
studies refuting this assumption can also be found.
The studies of Zaidel et al. [22] show that ideal symmetry is not the only component of beauty, because
the natural faces compared to the perfectly symmetrical faces can be equally attractive [22, 23], or
even slightly more attractive [24]. The results of this
study partially confirm both of these theses. First
of all, one of the most striking results was the difference in the assessment of the symmetrical faces,
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Facial Symmetry and Attractiveness
where the one with the mirror image of its left half
was for a greater number of subjects considered to
be attractive, than the one with the mirror image
of its right half. Most likely, such a perception of
beauty was affected by other factors, such as facial
proportions in transversal dimension, distance between eyes and nose width. Since there is no indisputable advantage of symmetry in shaping the concept of facial attractiveness, this issue is worth analyzing further in order to study the other elements
affecting the perception of esthetics.
The authors concluded that facial symmetry
toward the midline was extremely important, although not a unique factor affecting the perception of attractiveness. Facial asymmetry, in the case
of greater deviations from the midline, with the
pogonion point shifted of 6 to 10 mm, was distinctly
visible by outsiders. The greatest difficulty was the
correct assessment of both symmetrical, as well as
slightly asymmetrical (2–4 mm), faces. In the latter
case, dentistry students attained only slightly better
results than the students unrelated to dentistry.
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Address for correspondence:
Liwia Minch
Department of Maxillofacial Orthopedics and Orthodontics
Wroclaw Medical University
Krakowska 26
50-425 Wrocław
Poland
Tel.: +48 609 179 289
E-mail: [email protected]
Received: 16.07.2012
Revised: 28.09.2012
Accepted: 24.10.2012
Praca wpłynęła do Redakcji: 16.07.2012 r.
Po recenzji: 28.09.2012 r.
Zaakceptowano do druku: 24.10.2012 r.