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Original Research
Perception differences of altered dental esthetics by dental
professionals and laypersons
Mayuri Thomas, Rajesh Reddy, B Jayabharath Reddy
Department of Orthodontics and
Dentofacial Orthopedics,
Sri Sai College of Dental
Surgery, Vikarabad,
Andhra Pradesh, India
Received
: 16-11-09
Review completed : 06-05-10
Accepted
: 10-11-10
ABSTRACT
Background: When we smile, our smile could often become the target of close scrutiny by the
person you are smiling at. A trained eye readily detects any asymmetricity or any aspect of that
smile which may be out of balance, or disharmonious with its environment. The purpose of
this study was to determine whether any such asymmetric or symmetric dental discrepancies
were detectable by various groups of evaluators.
Aims: The aim was to determine whether asymmetric and symmetric anterior dental
discrepancies were detectable by orthodontists, general dentists, and laypersons, and to establish
threshold levels for several specific aesthetic criteria that could be used by orthodontists and
general dentists as an aid in the treatment planning.
Materials and Methods: Three images of smiles were intentionally altered with a softwareimaging program. The alterations involved the crown length, crown width, midline diastema,
and the papillary height of the maxillary anterior teeth. These altered images were then rated by
groups of general dentists, orthodontists, and laypersons using a visual analog scale. Statistical
analysis of their responses resulted in the establishment of threshold levels of attractiveness
for each group.
Results: The orthodontists were more critical than the general dentists and laypersons when
evaluating asymmetric crown length discrepancies. All three groups could identify a unilateral
crown width discrepancy of 2.0 mm. A small midline diastema was not rated as unattractive by
any group. Reduction of papillary height was generally rated as less attractive.
Conclusions: Asymmetric alterations make teeth more unattractive not only to the dental
professionals, but also to laypersons.
Key words: Aesthetics, smile, perception
The word ‘‘Esthetics’’ is derived from the Greek word
αισθητική (Transliterated: aisthitiki) meaning ‘‘perception.’’
It deals with the aspect of beauty and things beautiful.
Beauty has two dimensions: objective and subjective.
Objective (admirable) beauty is based on the consideration of
the object itself, implying that the object possesses properties
that make it unmistakably praiseworthy. Subjective
(enjoyable) beauty is a quality that is value-laden, relative
to the tastes of the person contemplating it.[1]
Address for correspondence:
Dr. Mayuri Thomas
E-mail: [email protected]
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DOI:
10.4103/0970-9290.84295
Indian Journal of Dental Research, 22(2), 2011
Facial appearance often plays a vital role in forming an
impression of others, especially during the initial stages of
acquaintance. The impression one gets of the other person
during this initial encounter is often a long lasting one and
could be either positive or negative at different times. Looks,
however, play an important role during this first impression.
While it has been the desire of most individuals to look good
and presentable, it has been their ‘‘smile’’ that often ends
up either enhancing or spoiling the looks of that person.
This has, indeed, been the quest of orthodontists the world
over to provide that ideal make over for those who are less
fortunate. The orthodontic profession has always been in
pursuit of the ideal dentition.
A century ago, the orthodontic paradigm was geared toward
achieving optimal proximal and occlusal contacts of the
teeth within the framework of a balanced profile. When
cephalometric-based diagnosis and treatment planning hit
full stride in the 1950s and 1960s, esthetics in orthodontics
was defined primarily in terms of the profile.[2] The present
emphasis, however, is toward enhancing facial esthetics and
creating a beautiful smile.
242
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Thomas, et al.
Perception differences of altered dental esthetics Several studies have evaluated esthetic perception of
different malocclusions. Even indices have been created to
measure dental esthetics based on a relatively standardized
set of variables. These indices assess treatment need, based
on occlusal health but do not focus directly on anterior
dental esthetics.[3]
It is a known fact that the orthodontist’s perception often
differs from that of other professionals and laypersons.
This fact has already been well established. However, we
find that these established parameters have been carried
out among the western population. In order for these
parameters to be acceptable for the Indian population, it
was necessary to find out whether these smile parameters
established for western population were acceptable for
the Indian population as well. Hence, this study was
aimed at evaluating the opinion of general dentists and
laypersons in addition to orthodontists. The hypothesis
of the study states that laypersons would find it a bit
more difficult to discriminate between asymmetric
levels of discrepancies compared to general dentists and
orthodontists. The purpose of this study was to evaluate
whether asymmetric and symmetric anterior dental
discrepancies were detectable by orthodontists, general
dentists, and laypersons along with the establishment of
threshold levels for several specific esthetic criteria that
could be used by orthodontists and general dentists as an
aid in treatment planning.
MATERIALS AND METHODS
This study was conducted at the Department of Orthodontics
and Dentofacial Orthopaedics, Sri Sai College of Dental
Surgery, Vikarabad.
Materials
The following materials were used in the study.
• Digital camera [Nikon D80 Digital camera [effective
pixels 10.2 mega pixels DX format Image sensor
RGB CCD, 23.6×15.8 mm; total pixels 10.75 million
(1.5× FOV crop)]: It is used to take the digital Photographs
of the samples.
• Laptop Dell Inspiron 1420 [Processor 2.0 GHz Intel Core
2 Duo T7300, Memory 2 GB, 667 MHz DDR2, Hard Drive
160 GB 5400 r/min, Chipset Intel 965, Graphics Nvidia
GeForce 8400M GS, Operating System Windows Vista
Premium, Display 14.1 in. (1440×900)]: The captured
digital Photographs were transferred from the camera
to the laptop.
• Adobe Photoshop, version 7 [Adobe Systems Inc.,
San Jose, CA, USA]: This software is used to alter the
Photographs.
Method used for obtaining images
Digital Photographs showing the smile of the subjects
(students of the college) were taken by a single operator,
243
while the subjects were in a relaxed position. The
Photographs were taken at a fixed distance of 60 cm from
the object. Part of the face that was captured was restricted
to that of the chin below and the ala of the nose above to
decrease the compounding parameters. However, there was
no zooming done. The camera was tripod mounted while
all the Photographs were taken in true day light.
The nose and chin were eliminated from the images to
reduce the number of confounding variables.
Inclusion criteria
Inclusion criteria are as follows.
• Subjects having normal class I occlusion as specified by
Andrews in his six keys,[4] which include normal class
I molar relationship, absence of tooth rotations, tight
interdental contacts, and level curve of Spee.
• Subjects not having undergone any kind of orthodontic
treatment previously.
The images were altered for the following four esthetic
parameters based on Kokich’s approach:
• Crown length
• Crown width
• Midline diastema
• Height of papilla.[5]
These altered images were then rated using a visual analog
scale by three groups of individuals (100 individuals per
group with a male:female ratio of 57:43 in the laypersons
group, 65:35 in the general dentists group and 73:27 in the
orthodontists group) by means of a slide show shown in
the afternoon after a brief introduction about esthetics.
Informed written consent was taken from the subjects and
the approval from the ethics committee was sought prior
to the study.
• Laypersons (average age 20−40 years with a basic
education level of +2).
• General dentists (average age 30−40 years).
• Orthodontists (average age 30−40 years and having a
minimum clinical experience of 3 years).
To test the hypothesis, the three above groups rated each
of the four esthetic parameters mentioned earlier, where
each esthetic parameter consisted of five variants that
were morphed using the Adobe Photoshop. Each smile was
intentionally altered for all those parameters, which were
most common in anterior esthetic discrepancies that were
also based on their frequency and clinical significance to
smile.
The crown length of the maxillary central incisor was
altered. The crown was shortened in 0.5 mm increments by
adjusting the level of gingival margin. The reference points
for these measurements were the most superior points on
the labial gingival margin of the adjacent lateral and central
Indian Journal of Dental Research, 22(2), 2011
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Thomas, et al.
Perception differences of altered dental esthetics incisors. The incisal edges were maintained at the same
level to simulate super eruption of the central incisor and
concomitant incisal wear of that particular incisor selected[5]
[Figures 1a-e].
The alteration of crown width was done to a lateral incisor,
as it is the most common tooth, which is affected by the
size of tooth. The width of lateral incisor was reduced in
increments of 1 mm, while maintaining the gingival margin
at the same level. The relative measurements were made at
the widest part of the crown between interproximal contact
points [Figures 2a-e].
A midline diastema, which is the spacing between two upper
central incisors, was created incrementally between the
central incisors. The spacing was widened progressively in
0.5 mm increments. The measurements were made at the
interproximal contact points between the central incisor
crowns [Figures 3a-e].
Papillary height was altered symmetrically between the
maxillary anterior teeth by progressively lengthening the
interproximal contact points in 0.5 mm increments in a
a
b
c
gingival direction between all maxillary anterior teeth.
The natural tooth shape and papillary form was maintained
[Figures 4a-e].
All the 20 altered smile photographs (five variants each
of the four esthetic parameters) were grouped randomly
but in such a way that different variables were presented
on each page of the questionnaire so that intra and inter
parameter variations were minimized. Copies of the original
questionnaire were distributed among all the three groups.
A visual analog scale (VAS) graded from 1 to 10 was used for
the ratings and was presented below the questionnaire. The
scale progressed one end to the other from ‘‘very pleasing’’ to
‘‘unpleasing.’’ Each rater was asked to mark a point along the
scale according to his or her perception of dental esthetics.
Statistical methods
The VAS scores rated by all the groups were analyzed to find
out the mean and standard deviation of all twenty altered
smile Photographs. These were used for the statistical
comparison using the one-way analysis of variance
(ANOVA) test for comparison between all groups; post hoc
d
e
Figure 1 (a-e): The crown length of the maxillary central incisor shortened in increments of 0.5mm
a
b
c
d
e
Figure 2 (a-e): The crown width of the maxillary lateral incisor reduced in increments of 1mm
a
b
c
d
e
Figure 3 (a-e): The midline diastema widened progressively in 0.5mm increments between the maxillary central incisor crowns
a
b
c
d
e
Figure 4 (a-e): Symmetric alteration of the papillary height by progressively lengthening the interproximal contact points in 0.5 mm increments
in a gingival direction between all maxillary anterior teeth
Indian Journal of Dental Research, 22(2), 2011
244
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Thomas, et al.
Perception differences of altered dental esthetics test for multiple comparisons between all the groups was
also employed.
RESULTS
The statistical tests used were ANOVA and post hoc tests,
initially the mean was found of each group and an ANOVA
test performed to compare all parameters between the
groups, and later Mann−Whitney test (post hoc) was used
to compare the parameters within each group.
An ANOVA test was conducted in each group to assess
how the groups rated each level of deviation. Significant
overall tests were followed with a series of post hoc multiple
comparisons to test hypotheses. Multiple comparisons
between each level of variation were used to determine
the level of deviation at which each group discriminated
between esthetic and less esthetic dental features.
The assessment for all the four parameters has shown a
significant difference in perception by all three groups.
The multiple comparison tests showed the difference in
Table 1: The mean and S.D. for all the four parameters
Groups
N
Mean
Crown length
Crown width
Midline diastema
Papillary height symmetry
1
2
3
Total
1
2
3
Total
1
2
3
Total
1
2
3
Total
Lower
bound
100
100
60
260
100
100
60
260
100
100
60
260
100
100
60
260
Upper
bound
6.55
4.87
5.52
5.66
6.468
5.313
4.518
5.569
4.21
4.07
3.94
4.09
5.762
4.939
4.902
5.244
perception within the groups. Table 1 describes the mean
and standard deviation for all the four parameters. Table 2
shows ANOVA test of all four parameters between groups,
and Table 3 denotes post hoc test of all four parameters
between and within the groups.
Crown length
• The general dentists showed a lesser threshold level for
the unattractiveness of crown length, than did the other
groups (mean of 4.8 and S.D. of 1.4) [Table 1].
• The orthodontists were more critical in identifying the
discrepancy under this esthetic parameter (mean of 4.5
with S.D. of 1.1) than the other groups [Table 1].
• The ANOVA test showed that all the three groups
rated this parameter as unattractive (significant value
of 0.41) [Table 2] compared to the other three esthetic
parameters.
• The discrepancy of this parameter was more easily
recognized by orthodontists than the other groups (mean
difference of 0.037) [Table 3].
• However, the multiple comparison tests showed no
significant value between the groups [Table 3].
S.D.
Lower
bound
1.829
1.447
1.294
1.734
1.6880
1.1251
1.1595
1.5710
1.554
1.101
0.998
1.273
1.5481
1.1616
.9802
1.3466
S. E.
Upper
bound
0.183
0.144
0.166
0.107
0.1688
0.1120
0.1485
0.0971
0.155
0.110
0.128
0.079
0.1548
0.1156
0.1255
0.0832
95% confidence interval for mean
Lower
Upper
bound
bound
6.18
6.91
4.58
5.15
5.19
5.86
5.45
5.87
6.133
6.803
5.091
5.535
4.221
4.815
5.378
5.760
3.91
4.52
3.85
4.28
3.69
4.20
3.94
4.25
5.455
6.069
4.709
5.168
4.651
5.153
5.080
5.408
Min.
Lower
bound
1
2
3
1
1.0
1.6
2.0
1.0
1
2
1
1
1.8
2.6
2.4
1.8
Max.
Upper
bound
10
10
9
10
9.8
8.0
6.8
9.8
8
8
6
8
9.2
8.6
6.8
9.2
Table 2: ANOVA test of all four parameters between groups
Esthetic parameter
Crown length
Crown width
Midline diastema
Papillary height uniformity
Groups
Between groups
Within groups
Total
Between groups
Within groups
Total
Between groups
Within groups
Total
Between groups
Within groups
Total
Sum of squares
143.397
641.050
784.447
154.822
489.361
644.183
2.879
419.893
422.773
43.402
429.845
473.246
d.f.
2
259
261
2
259
261
2
259
261
2
259
261
Mean square
71.698
2.475
F
28.968
Sig.
0.000
77.411
1.889
40.971
0.000
1.440
1.621
0.888
0.413
21.701
1.660
13.076
0.000
d.f. - degree of freedom, F - the measurement of distance between individual distributions, ANOVA - Analysis of variance
245
Indian Journal of Dental Research, 22(2), 2011
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Thomas, et al.
Perception differences of altered dental esthetics Table 3: Post hoc test of all four parameters between and within groups Post hoc tests
Multiple comparisons test
L.S.D.
Dependent variable
Crown length
Group
Group
1
2
3
1
3
2
3
1
3
2
3
1
3
2
3
1
3
2
Crown width
1
2
Midline diastema
1
2
Papillary height symmetry
1
2
Mean
difference
1.681
1.021
1.681
0.659
1.1551
1.9500
1.1551
0.7948
0.147
0.270
0.147
0.123
0.8234
0.8604
0.8234
0.0370(*)
Std. error
Sig.
0.222
0.256
0.222
0.255
0.1939
0.2233
0.1939
0.2229
0.180
0.207
0.180
0.206
0.1817
0.2093
0.1817
0.2089
0.000
0.000
0.000
0.010
0.000
0.000
0.000
0.000
0.415
0.193
0.415
0.552
0.000
0.000
0.000
0.860
95% confidence interval
1.24
0.52
–2.12
–1.16
.773
1.510
–1.537
0.356
–0.21
–0.14
–0.50
–0.28
0.466
0.448
–1.181
–0.374
2.12
1.52
–1.24
–0.16
1.537
2.390
–0.773
1.234
0.50
0.68
0.21
0.53
1.181
1.272
–0.466
0.448
* The mean difference is significant at the 0.05 level
Crown width
• The orthodontists were more critical in identifying the
discrepancy in this esthetic parameter (mean of 4.5 with
S.D. of 1.1) than the other groups [Table 1].
• The multiple comparison tests showed no significant
value between all the three groups [Table 3].
Midline diastema
• In this parameter, orthodontists identified the discrepancy
to be unattractive (mean of 3.9 with S.D. of 0.9)
[Table 1].
• The ANOVA test revealed that all the three groups
rated this parameter as unattractive (significant value
of 0.41) [Table 2] compared to the other four esthetic
parameters.
• There was no significant difference in relation to midline
diastema between the groups as shown by the multiple
comparison tests [Table 3]
Papillary height symmetry
• The discrepancy of this parameter was more recognized
by orthodontists than the other groups (mean difference
of 0.037) [Table 3].
• There was no significant difference in the perception
compared to other parameters [Table 2].
DISCUSSION
It is a well-known fact that the perception of orthodontists
often differs from that of the perception of other professionals
and laypersons, and that the esthetic perception could
differ for different ethnic groups as well. Though many
researchers, including Bjorn Zachrisson, Sheldon Peck,
and Vincent Kokich have proposed various parameters
for esthetic smiles. [1,5,6] While most of these studies
were carried out in the western population, there have
Indian Journal of Dental Research, 22(2), 2011
been very few studies including the study done by
Krishnan et al.[7] carried out in the Indian environment.
Hence, it was necessary to find out if the parameters
established for the western population were also acceptable
for the Indian population. Hence, there was a need felt,
to evaluate how the orthodontists, general dentists, and
laypersons judged these parameters in the Indian context.
This study has shown significant differences for several
esthetic parameters. Very few studies have established
threshold levels of noticeability of various esthetic
parameters by orthodontists, general dentists and the
laypersons.[3,5,8]
Contrary to the present study, orthodontists during previous
studies[1,3,5,9,10] found the discrepancy in crown length to be
more unattractive.
According to orthodontic perspective, the normal width of
a lateral incisor is important for achieving a better esthetic
result while restoring a peg shaped lateral incisor or the
decreased width of the tooth, however in the present study it
was found that the crown width changes were not significant
in all three groups and this finding matches with the result
of Bhukary et al.[11] and others.[3,5,12]
In the present study, however, the orthodontists identified
the midline discrepancy to be more unattractive which again
is in accordance to the studies that have been done on esthetic
discrepancies.[1,3,13-15] This study also shows that the correction
of midline diastema is an important aspect recognized both
by the orthodontist and the layperson as well.
Also in this study the discrepancy of papillary height
symmetry was spotted more by orthodontists than the
other groups as was shown in earlier studies.[1,3,5,16] The
246
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Thomas, et al.
Perception differences of altered dental esthetics level of papilla should be maintained to prevent either the
black triangle appearance or the increased length of clinical
crown. Therefore, maintaining the papillary height is an
important factor from the orthodontic perspective.
As the orthodontists recognize specific dental esthetic
parameters more readily than the layperson or even the
general dentist except when it comes to the crown length,
both the general dentists and the laypersons seemed to
have a similar level of threshold for assessing the midline
diastema. Even though both orthodontists and general
dentists were able to detect discrepancies at the same level
for papillary height, the orthodontists, however, were able
to identify crown width, midline diastema, papillary height
at a smaller level of deviation than both the general dentists
and the layperson.
The level of detection of various anterior esthetic parameters
differed according to the parameter and the responding
group. The findings revealed that all the three groups found
midline diastema to be more unattractive. General dentists
rated variation in crown length to be more unattractive than
the other two groups where as orthodontists found crown
width, and papillary height as being more unattractive.
Even though the ratings of different judges varied, there
was an understanding ability of identifying the positive
and negative attributes of an acceptable smile according
to each group. Orthodontist’s perception differed slightly
for acceptance with respect to crown width and papillary
height. General dentists differed with respect to crown
length. However, there was a similarity between the
perceptions in remaining parameters. When we see in an
overall sense of perception, esthetic judgments did not vary
in the Indian context.
Results of this study showed that the perception of
orthodontists varied from the perception of other
professionals. The overall acceptance of smile parameters
showed that an acceptable smile should have no asymmetry
of crown length, crown width and papillary height
with absence or minimal of midline diastema. Clinical
implications of the findings from this study can have
significant influence on diagnosis and treatment planning
in the orthodontic treatment.
The main limitations of the study were consideration
of anterior dental esthetics alone and the probability of
individual variations changing the results.
SUMMARY AND CONCLUSION
The conclusions from this study are:
• Asymmetric alterations make teeth more unattractive
not only to dental professionals but also to laypersons.
• Symmetric alterations might appear unattractive to
dental professionals, but the laypersons group often did
not recognize some symmetric alterations.
• Orthodontists were able to identify crown width,
247
midline diastema and papillary height at a smaller
level of deviation than general dentists and the
laypersons. Hence, these parameters should be taken
into consideration during orthodontic treatment plan.
• Among all the four esthetic parameters, midline diastema
was more unattractive for all the groups. So, correction of
this parameter by the dental professional is of paramount
importance for a better esthetic result.
Since this study gives an insight into the perception
of esthetics by orthodontists, general dentists and the
laypersons, a detailed clinical examination of smile
parameters should be stressed upon in the orthodontic
protocol before planning any kind of an orthodontic
treatment, to give the best possible smile for the patients.
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How to cite this article: Thomas M, Reddy R, Reddy BJ. Perception
differences of altered dental esthetics by dental professionals and laypersons.
Indian J Dent Res 2011;22:242-7.
Source of Support: Nil, Conflict of Interest: None declared.
Indian Journal of Dental Research, 22(2), 2011