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Photographic and videographic assessment ofthe smile: Objective and subjective evaluations

of posed and spontaneous smiles

Joan F. Walder,a Katherine Freeman,b Mitchell J. Lipp,c Olivier F. Nicolay,c and George J. Cisnerosd

Northampton, Mass, Delray Beach, Fla, and New York, NY

Introduction:Esthetic considerations play an increasingly important role in patient care, and clinicians need a

methodology that includes imaging techniques to capture the dynamic nature of the smile. Photographs of the

posed smile are routinely used to guide diagnosis and treatment, but there is no standardized and validated

method for recording the dynamic smile. The purposes of this study were to (1) determine whether a posed smile

is reproducible, (2) compare visual and verbal cues in eliciting a smile, and (3) compare the diagnostic value of

videography and photography in evaluating a patient's smile. Methods:The smiles of 22 subjects were simul-taneously photographed and videotaped on 2 separate occasions. For objective comparisons, measurements of

the smile were obtained from 8 3 10 color still photographs and selected digitized video images. A panel con-

sisting of a layperson, an oral surgeon, an orthodontist, and a prosthodontist subjectively assessed the repro-

ducibility of the smile, posed vs spontaneous smiles, and the diagnostic value of video vs still images.

Results: Objective measurements showed that the posed smile can be reliably reproduced, whether captured

by videography or still photography. However, subjectively, the panel members detected differences between

the posed smiles taken on different days 80% of the time. The clinician panel members expressed a strong pref-

erence for videography over photography and for the spontaneous over the posed smiles.Conclusions:This

study emphasizes the need to continue to investigate and standardize the methods of eliciting and recording a

smile of diagnostic quality. (Am J Orthod Dentofacial Orthop 2013;144:793-801)

As part of a facial esthetic evaluation, the clinicianstudies lip function and posture. During this

evaluation, the patient is often asked to smile,and a split-second image of that dynamic action iscaptured on a still photograph. This photograph, usedas part of the diagnostic process to determine a course

of treatment, remains as a permanent record in thepatients chart. If we want to depend on a still photo-graph to reect the esthetics of a patients smile, it isnecessary to capture a true representation of that smile.

For instance, if the photo was taken a few seconds earlier

or later, would it show the same smile? If a differentdirective was used to elicit a smile, would it trigger thesame response? Would videography rather than photog-raphy provide a more effective diagnostic impression?

Previous studies have qualitativelyand quantitatively

addressed the movement of a smile.1-5 Studies in the

psychology literature have found that people are betterable to detect posed emotionfrom motion photographythan from still photography.6,7 Nonetheless, the dentalliterature is surprisingly lacking in its discussion of thedynamic nature of the smile as it relates to the methodsused to elicit, record, and reproduce it and how it

re

ects our patients' esthetics.The aims of this study were to investigate the poten-tial variability in current methods of evoking a smile foranalysis and to evaluate the relative diagnostic value of

videography vs photography in capturing a dynamicevent. It is necessary to be critical of the tools used to

determine a treatment plan and to make great effortsto standardize them.

MATERIAL AND METHODS

Twenty-two subjects volunteered to participate inthe principal portion of this study. They were students,

aPrivate practice, Northampton, Mass.bPresident and founder, Extrapolate, LLC, Delray Beach, Fla.cClinical associate professor, Department of Orthodontics, College of Dentistry,

New York University, New York.dProfessor, Department of Orthodontics, College of Dentistry, New York Univer-

sity, New York.

All authors have completed and submitted the ICMJE Form for Disclosure of Po-

tential Conicts of Interest, and none were reported.

Address correspondence to: George J. Cisneros, Department of Orthodontics,

College of Dentistry, New York University, 345 E 24th St, New York, NY

10010; e-mail,[email protected].

Submitted, April 2013; revised and accepted, July 2013.

0889-5406/$36.00

Copyright 2013 by the American Association of Orthodontists.

http://dx.doi.org/10.1016/j.ajodo.2013.07.012

793

ORIGINAL ARTICLE
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faculty, and staff from Manhattan College, Bronx, New

York. The only exclusionary criteria were visible develop-mental or traumatic abnormalities of the face or facialmusculature, and missing anterior teeth.

The subjects were simultaneously photographed andvideotaped on 2 days. All participants signed informedconsents but were not told that we were looking for

possible reproducibility of the smile or any other infor-mation that would bias their responses.

The position of each subject's head was standardizedby a head holder designed specically for this study. The

holder positioned the head with a 3-point contact inboth the vertical and horizontal dimensions: 2 ear rods

were placed in the external auditory meati and a pad onthe forehead. A series of black rectangular markers, 1inchlongand 1 inchapart,were placedon the head holderand captured in the photographs to correct for any alter-

ation in magnication from image to image. The headholder was fastened to a stand, which held it in a constantposition vertically and horizontally.The height of thechair

was adjusted to accommodate for the subjects' variationsin height. Measurementsof the horizontal and verticalpo-

sitions of the forehead pad were taken with a millimeterruler at the rst session, and the head holder was resetto these same measurements for each subsequent session.

Two cameras were arranged so that each subject

could be photographed and videotaped simultaneously.For the 2 cameras to be used simultaneously, thuscapturing the same smile, it was necessary to set up isos-

celes triangles between the subject and each cameramounted on tripods (Fig 1). The centers of the 2 cameralenses were placed 4 ft 7 in from the anterior portion of

the head holder and 2.25 in from the center (a lineextended from the midsagittal plane of the subjectsetup). This made an angle of 2.34 from the midsagittal

plane of the subject to the center of each camera lens,creating a negligible distortion as determined by an

optical error analysis.For the still photography, at each session, 2 photo-

graphs of the subject were taken. The rst photographwas prompted by a verbal directive and the second by a

visual directive. The verbal directive was give me anice, big smile, one that shows your teeth. A poster

board with color photographs of 6 people smiling broadlywas used for the visual directive, and the subjects weretold to smile like the people in the photographs.The

verbal directive was uniformly given rst to prevent the

subjects from relying on the memory of the visual imagewhen presented with the verbal command.

The frontal photographs were taken by the same oper-ator (J.F.W.) using a Pentax K-1000 camera (Asahi Optical,

Tokyo, Japan) with a 90-mm F/2.8 macro lens (Sigma,Tokyo, Japan) mounted on a tripod, 35-mm Kodachrome

ISO 64 slide lm (Eastman Kodak, Rochester, NY), and astandardized camera-to-source distance of 4 ft 7 in. All88 slides, which resulted fromthe 22 subjects being photo-graphed 2 times at the 2 separate sessions each, were then

converted into 83

10 color copies via a Kodak 1550 Plusprinter (Eastman Kodak) for analytical purposes. The stillimages shown to the panel were cropped to include onlya standardized border beyond the vermilion of the lips.

For the videography, a Panasonic Palmcorder VHS-

C video camera (Matsushita Electric Corporation ofAmerica, Osaka, Japan) mounted on a tripod was manu-ally focused to show a close-up, full-face view of eachsubject. VHS-C lm was used. The object-to-source dis-tance was also 4 ft 7 in. The video camera was turned on

before the verbal directive and remained on throughout

the entire session.Randomly, 1 image from the video footage (either the

verbal or the visual smile from either day 1 or 2) wasselected for each subject to use for comparison with

the still images. The apex or height of each of the 22randomly selected smiles was determined by agreement

of 2 evaluators (J.F.W. and G.J.C.). In the case of adisagreement, a third evaluator was used. The apex ofa smile was dened as the frame in which the smile

was the largest. To measure the video images, the apices

of the smiles were converted into 35-mm slides and theninto 83 10 color copies, using the Kodak 1550 Plus. The

Media Suite Pro video-editing program (Avid Technol-ogy, Tewksbury, Mass) was used to create a videotape

of each subjects smile to be viewed by the panel.In 13 of the 22 subjects, the video camera was able to

capture an unsolicited spontaneous smile. The smileswere deemed spontaneous by 2 evaluators viewing theunedited video footage using the following criteria:(1) there was no cue by the photographer to smile before

the smile and (2) the subject appeared relaxed and wasconversing with the photographer. Two examiners,

with a third examiner consulted when there was a differ-ence of opinion between the 2 original evaluators, alsoselected the apices of these spontaneous smiles. Theapices of these smiles were then converted into 8 3 10

color copies with the Kodak 1550 Plus.For an objective assessment and comparison of the

still and video-derived images described above, mea-surements were taken twice by the same operator(J.F.W.) with a vernier caliper to the nearest 0.1 mm,then averaged (Fig 2).

A panel of 4 people was selected to provide subjec-tive assessments of the smiles. The panel included aprosthodontist (rater 1), an orthodontist (rater 2), alayperson (rater 3), and an oral surgeon (rater 4).

The panel portion of this study was divided into 4parts. Part 1 addressed the issue of reproducibility of

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the smiles using still photography. Part 2 compared thediagnostic value of the 2 media: videography and stillphotography. With video technology, parts 3 and 4 pro-

vided comparisons of spontaneous and posed smiles. All

4 panel members were shown parts 1, 3, and 4, whereaspart 2 was shown to the professional members of thepanel only because it required a comparison of the diag-nostic value of video vs still images.

The following is a description of the 4 parts shown tothe panel.

1. Still photographsday1 vsday 2. Byrandom selection,

either the verbal or the visual set of still photographswas selected for each subject to be shown to thepanel. The randomly selected smile photos werecropped to display only a standardized border just

beyond the vermilion border of the lips so as not todistractthe panel with other facial featuresand extra-neous details such as hairstyle and makeup.

Each panel member independently was asked todetermine whether he or she thought that the 2smiles were the same. Twenty-six sets of smiles

were projected next to each other on a screen. Toascertain the validity of each panel members re-

sponses, 4 of the 26 sets of photographs reviewedwere actually duplicates, with the same pictures

shown side by side.2. Still photography vs videography. The 22 randomly

selected smiles were then shown to the 3 profes-sional members of the panel in both the video andstill formats. This provided a subjective comparisonof the clinical value of the still and video smiles. The

panel members were asked to ll out a form thatasked 2 questions: (1) which is more useful diagnos-tically, the still photo, the video footage, or no pref-erence? and (2) do you have any comments

regarding preference?3. Posed vs spontaneous smiles (uncropped). The 4 pan-

elists were shown the series of full-faced posed smilesalong with their spontaneous counterpart, both ob-tained from the video footage. They were asked toselect the most diagnostically useful image.Diagnos-

tically usefulwas dened as the smile that appearedto be the most natural, the one that seemed to bestrepresentthe subjects unsolicited smile. Thelayperson

was told to select the smilethatappeared mostnatural.4. Posed vs spontaneous smiles (cropped). The 4 pan-

elists were also shown the series of spontaneous

Fig 1. Scaled diagram of equipment conguration: subject/headholder at the apex and 2 cameras at

each base of the isosceles triangles. A 2.34 angle was created from the midsagittal plane of the sub-

ject to the center of each camera lens for negligible distortion of images.

Fig 2. Objective measurements of still and video-derived

images: A, commissure to commissure; B, vermilion

border to vermilion border*; C, inferior border of the upper

lip to superior border of the lower lip*; D, maxillary incisal

edge to the inferior border of the upper lip*; E, maxillary

incisal edge to the vermilion border of the upper lip*; F,

maxillary incisal edge to the interpupillary line*; G, inter-

canthal distance. Also measured was the 1-in marker on

the head holder to determine the change in magnication.

*Measured at midpoint of commissure to commissure

distance.

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smiles along with their posed counterparts, withboth images cropped to display only a standardized

border beyond the vermilion of the lips. The panelmembers were asked to select the most diagnosti-cally useful image. Once again, diagnostically use-ful was dened as the smile that appeared to be

the most natural, the one that seemed to bestrepresent the subjects unsolicited smile. Thelayperson was told to select the smile that appearedmost natural.

The raw data were standardized to account for

magnication differences between the imagesmeasured. For the data sets comparing still imagesonly, the measured length of the 1-in marker(25.4 mm) in the image was used to adjust for changesin magnication. The formula used in these cases is

shown in Equation 1.We were unable to use the 1-in marker as a standard

measure for the video-derived images because the repro-duced quality tended to blur the marker edges. Instead,the intercanthal distance was used for each subject

because the data sets compared in this section were all

taken at the same time, and thus there was no concernfor change in head position or camera angulation. Theformula used to standardize the data set that comparedthe video-derived images with the still images is shown

in Equation 2.The formula used to standardize the data set that

compared the apices of the video-derived spontaneoussmiles and the video-derived posed smiles is shown in

Equation 3.

Statistical analysis

A power analysis was performed to determine thenumber of subjects required for this investigation. Themaximum change in the width of a smile (commissureto commissure) considered by the principal investigator

of this study (J.F.W.) to be diagnostically acceptablewas measured on 4 subjects. At 2 times, each subject

was asked to begin at his or her broadest smile andthen to slowly reduce the smile until the examinerthought that the smile no longer had diagnostic quality.The change in width was found to average 4 mm. Thefull range of the smile was also measured; it averaged13 mm. Using these estimates, we calculated that 22subjects (11 men, 11 women) were required for the com-

parison between the different smiles obtained in thisstudy, for a type I error of .05 and a 2-tailed test with80% power.

All analyses performed on the objective measure-

ments were done using the standardized data. The dif-

ferences between days 1 and 2 were tested forsignicance using either a paired ttest or the Wilcoxonsigned rank test, depending on whether the assumptionsof normality were met for thettest. The same approach

was used to assess the signicance of the following: (1)

the differences between the still and video images, (2)the differences between the verbal and visual cues inthe still photographs, and (3) the differences betweenthe spontaneous and posed smiles taken from the video.Tests of signicance were 2-tailed, with a type I error of.05. An intraclass correlation coefcient (ICC) for the

repeated measurements was computed to determine

reliability.

RESULTS

A total of 22 subjects (11 women, 11 men) partici-

pated in this study. They were between the ages of 20and 49, with average ages of 24.7 years for the menand 27.2 years for the women.

The average length of each subjects videotaped ses-sion was about 57 seconds, with a range of 35 to 90 sec-onds. The videotape segments averaged 49 seconds for

the women (range, 35-65 seconds) and 65 seconds forthe men (range, 45 -90 seconds).

variable measuredmm

length of marker in still imagemm3 25:4 mm 1-inch marker (Equation 1)

variable measuredmm

intercanthal distancemm3 intercanthal distance as measured in still imagesmm (Equation 2)

variable measuredmm

intercanthal distancemm3 intercanthal distance as measured in spontaneous images mm (Equation 3)

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We considered the reproducibility of the posed smile.The results of the objective data are given in Table I; forthe most part, no statistically signicant differences

were found between the smile measurements taken onday 1 and day 2. The exception was the difference in

commissure to commissure distance between the visu-ally commanded smile on day 1 and the visually com-manded smile on day 2. The mean difference in thisinstance was 1.51 mm, with a standard deviation of2.93 mm and a range of 10.57 mm.

No statistically signicant differences were found

when the verbally directed smiles of day 1 were

compared with the visually directed smiles of day 1(Table II). The only statistically signicant difference inmeasurement was found between the intercanthal dis-tances recorded on the verbally directed smiles on day2 and the visually commanded smiles on day 2. The

mean difference was 0.30 mm with a standard deviationof 0.49 mm and a range of 1.73 mm.

For the results of subjective data, the ICC for agree-ment among the raters in comparing the still images

taken on day 1 with the still images on day 2 was0.52842; that was moderate agreement. The ICC forthis same group without the duplicates (identical slides)

was 0.28763; this was considered fairagreement. Therelative frequencies of the same subject's smiles on days1 and 2 classied as the same or different for the panelmembers were tabulated to assess the reproducibility of

the smiles within raters. The 2 smiles were determined tobe different 95% of the time by rater 1, 73% of the timeby rater 2, 64% of the time by rater 3, and 95% of thetime by rater 4. Overall, the panel determined the smilesto be different in 83% of the cases. In addition, when the

laypersons responses were omitted from the distribu-tion, 88% of the smiles were determined to be different.

Raters 1, 2, and 3 were able to identify all 4 duplicates,

and rater 4 recognized 3 of the 4 duplicates.We also compared the videography with the still

photography. For the results of the objective data,when comparing the still photographs with the videog-raphy, 3 measurements had statistically signicant dif-ferences: (1) the commissure to commissure distance,(2) the maxillary incisal edge to the vermilion border of

the upper lip distance, and (3) the maxillary incisaledge to the interpupillary line distance (Table III). Theaverage magnitude of the difference in the commissureto commissure distance was 1.19 mm; the video distance

was smaller, with a standard deviation of 1.28 mm and a

Table I. Objective comparisons of smiles elicited on day 1 vs day 2 (n 5 22)

Objective measurement (mm)

Verbal Visual

Mean difference* Range* Signicance Mean difference* Range* Signicance

Commissure to commissure 0.9 8.9 NS 1.5 10.6 SVermilion upper lip to vermilion lower lip 0.4 9.0 NS 0.2 10.8 NS

Superior lower lip to inferior upper lip 0.5 9.1 NS 0.3 9.1 NS

Upper incisal edge to inferior upper lip 0.4 5.1 NS 0.1 4.2 NS

Upper incisal edge to vermilion upper lip 0.5 4.3 NS 0.3 5.6 NS

Upper incisal edge to interpupillary line 0.6 6.4 NS 0.1 5.8 NS

Intercanthal distance 0.1 3.8 NS 0.2 3.2 NS

NS, No statistically signicant difference;S, statistically signicant difference at the alpha\0.05 level.

*Standardized data.

Table II. Objective comparisons of verbally vs visually prompted smiles (n 5 22)

Objective measurement (mm)

Day 1 Day 2

Mean difference* Range* Signicance Mean difference* Range* Signicance

Commissure to commissure 0.5 11.6 NS 1.0 14.2 NS

Vermilion upper lip to vermilion lower lip 1.0 3.2 NS 0.4 13.6 NS

Superior lower lip to inferior upper lip 1.2 13.4 NS 0.4 11.8 NS

Upper incisal edge to inferior upper lip 0.4 6.2 NS 0.4 7.6 NS

Upper incisal edge to vermilion upper lip 0.1 6.3 NS 0.3 7.7 NS

Upper incisal edge to interpupillary line 0.1 1.8 NS 0.2 3.6 NS

Intercanthal distance 0.1 1.8 NS 0.3 1.7 S

NS, No statistically signicant difference;S, statistically signicant difference at the alpha\0.05 level.

*Standardized data.

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range of 4.76 mm. The mean difference in the maxillaryincisal edge to the vermilion border of the upper lip was0.50 mm; the video distance was smaller again, with astandard deviation of 0.66 mm and a range of 2.24

mm. The mean difference in the interpupillary line tothe maxillary incisal edge was 1.47 mm (video smaller),

with a standard deviation of 0.78 mm and a range of2.64 mm.

In the results of the subjective data, the agreement

among raters for the comparison of the video footage

with the still images was not statistically signicant. Us-ing a frequency distribution, overall, the panel preferredthe video 68% of the time, the still images 23% of thetime, and had no preference 9% of the time (Fig 3).The preferences were 63%, 63%, and 77% for the video

by raters 1, 2, and 4, respectively (rater 3, the layperson,was excluded from this portion of the panel).

We compared the spontaneous and posed smiles.The objective data showed no statistically signicant

differences in the measurements of the spontaneousand posed smiles from the video footage (Table IV).

However, this study was not designed with sufcient

power to address this issue. The number of subjects(13) in this section was insufcient, and thus inferencesdrawn from this might be limited.

The results of the subjective data showed that agree-ment among raters with regard to the comparison of thespontaneous smiles with the posed smiles was statisti-

cally signicant for the cropped images (ICC, 0.17149:slight agreement) and not statistically signicant for

the uncropped images.A frequency distribution showed the following

(Fig 4). The spontaneous smile was preferred 85% ofthe time by rater 1 (prosthodontist), 77% of the time

by rater 2 (orthodontist), 62% of the time by rater 3(layperson), and 77% of the time by rater 4 (oral sur-geon). Overall, the panel preferred the spontaneous tothe posed smile 75% of the time. When the layperson s

responses were omitted from the distribution, the spon-taneous smile was selected 79% of the time. When theimages were cropped, the panels preference for thespontaneous smiles declined to 67%.

Fig 3. The professional panel preferred the video to still

images 68% of the time. The individual preferences

were as follows: 63%, 63%, and 77% preference for the

video by raters 1 (prosthodontist), 2 (orthodontist), and

4 (oral surgeon), respectively.

Table III. Objective comparison of smiles captured byvideography vs still photography (n 5 22)

Objective measurement (mm)Mean

difference* Range* Signicance

Commissure to commissure 1.2 4.8 S

Vermilion upper lip to vermilion

lower lip

0.2 6.6 NS

Superior lower lip to inferior

upper lip

0.0 2.7 NS

Upper incisal edge to inferior

upper lip

0.1 1.8 NS

Upper incisal edge to vermilion

upper lip

0.5 2.2 S

Upper incisal edge to

interpupillary line

1.5 2.6 S

S, Statistically signicant difference at the alpha\0.05 level;NS, no

statistically signicant difference.

*Standardized data.

Table IV. Objective comparison of posed vs sponta-neous smiles (n 5 13)

Objective measurement (mm)Mean

difference* Range* Signicance

Commissure to commissure 0.1 22.6 y

Vermilion upper lip to vermilion

lower lip

0.7 8.2 y

Superior lower lip to inferior

upper lip

0.1 6.5 y

Upper incisal edge to inferior

upper lip

0.4 4.1 y

Upper incisal edge to vermilion

upper lip

0.1 5.2 y

Upper incisal edge to

interpupillary line

1.4 24.2 y

*Standardized data;ysample size (n) was insufcient to reach signif-

icance.

Fig 4. The spontaneous smile was preferred 75% of the

time overall. When limited to the professional panel mem-

bers, this preference increased to 79%. The individual

preferences were as follows: 85%, 77%, 62%, and 77%preference for spontaneous smiles by raters 1, 2, 3, and

4, respectively.

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DISCUSSION

In this study, we found that whether recorded with a

video or a still camera, prompted with a visual or a verbalcue, or taken on day 1 or 2, the posed smile could be reli-

ably reproduced. Greater reproducibility was obtainedwith objective measures; however, as noted by the panelmembers, the eye of the diagnostician might be morecritical than objective measures.

The literature has addressed many aspects of thesmile, but only a few studies have even touched onthe aspect of the reproducibility of the smile.1,2 Pecket al3 coached their subjects before taking smile recordsand found that they were easily able to attain a repro-ducible maximum smile.However, prior methods usedto determine smile reproducibility have been ambig-

uous or determined by visual inspection alone, and

were not a speci

c aim of the studies. The psycholog-ical literature has often attributed specic characteris-tics to the posed smile.8-11 By imparting specicattributes to the posed smile, this implies that theposed smile is consistent.

Johnson and Smith12 suggested that their smilemeasurements could not be considered precise

because they did not use a device to limit head posi-tion or correct for magnication changes. After re-

viewing the literature, we decided to use a headholder to apply stringent control over the changes inmeasurements that can occur with head positionchanges. However, for clinical purposes, the use of ahead holder while taking diagnostic photographs or

video of a patient might hinder the patients ability

to smile naturally by restricting his or her ability torespond normally. The reproducibility of natural headposition has been shown to be within a clinicallyacceptable range of 2.13 Perhaps accurate informa-tion could be obtained from facial photography or

videography if the patients were allowed to hold theirhead in a more natural manner. Further investigation

comparing facial images taken in natural head posi-tion with facial images taken when the subject isplaced in a head holder would address this issue

more denitively.Analysis of the smiles by the panel members showed

that there might be subtleties about a smile that cannot

be measured objectively. More than 80% of the time, thepanel could distinguish between the smiles taken ondifferent days. When the data were limited to the profes-sional panel members, the ability to discriminate be-

tween the 2 smiles increased, suggesting that thepractitioners eye might be more discriminating thanobjective measures for diagnosis and treatmentplanning.

To truly analyze an action, it seems logical that onewould require a tool to capture the dynamic nature ofthat action. Nonetheless, the prevailing clinical ques-tion in this study was whether the practice of ortho-

dontics requires a technique that can record theentire dynamic range of the smile, or whether it is suf-cient to rely on the standard still photographs fordiagnostic information. Are diagnostic photographsproviding sufcient information about the smile or

would videography be a better diagnostic tool? Forthose interested in information regarding the heightof the smile alone, a still photograph might be suf-cient, assuming that the photographer has capturedthe apex of the smile. However, we found video to

be the method of choice by the clinicians. The panel

members comments supporting the preference forvideo were the following: (1) the whole range of thesmile was visible, (2) it provided a record of musclefunction and strain, (3) it showed whether the smile

was guarded or not, (4) it revealed swallowing pat-terns, (5) it demonstrated lip posture and compe-

tence, and (6) it provided 2 viewsthe patient atrest and the patient smiling.

Previous studies have found that still images of a dy-namic action are more difcult for the viewer to correctly

analyze. A xed representation of a facial expression canremove many of the cues for interpretation of thatexpression.14 As the panel members suggested, theypreferred to see the entire range of the smile because it

gave them signicantly more information thandid thestill images. Certainly, as Bruner and Tagiuri15 main-

tained, a millisecond of exposure surely cannot representclinical observations.

Unlike past studies of facial esthetics, we attemptedto specically address the diagnostic value of obtaining

videographic records of the smile. Few studies havetouched on the smile as a dynamic action; however,for the most part, it has been in relation to dentaland gingival display at maximum smile. Their focus

was a xed point at the height of the smile.1,2,16,17

Studies in the plastic and reconstructive surgery

literature have evaluated smile dynamics and thesoft-tissue changes that occur when the face movesfrom rest to maximum smile.3-5 These studies dorecognize the value of closely evaluating the smile asa dynamic action.

The video footage seemed to provide a reliable repre-

sentation of the subjects level of comfort during thephotographic or videographic sessions. In several in-stances, the still image shown to the panel members ap-peared to depict a relaxed person giving a relaxed smile.

However, when the video footage of this same smile wasviewed, it became obvious that the person was not at all

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comfortable, and the smile was forced. Videography

might give practitioners insight into how patients feelabout their appearance or smile that can be missed ina hectic clinical examination or the still photographs

taken by auxiliary staff.The panel members were less likely to select the spon-taneous smile when the images were cropped,removing

all other cues of facial expression. Duchenne18 describedthe use of 2 facial muscles to distinguish a deliberatesmile from a spontaneous smile: The rst (zygomaticmajor) obeys the will but the second (orbicularis oculi)

is only put in play by the sweet emotions of the soul;the .fake joy, deceitful laugh, cannot provoke the

contraction of the latter muscle. In 1980, Ekmanet al10 conrmed Duchennes observations, ndingthat most people cannot voluntarily contract the outerportion of the orbicularis oculi and thus do not exhibitthis action in a deliberate smile.

A signicant aim of this study was to begin to ne-tune our methods of eliciting and capturing smiles.Two behavioral patterns recognized in this study are

worthy of discussion: (1) variations in response to theverbal and visual cues, and (2) sex differences in elicitinga posed smile. Although thesendings were not specif-

ically pinpointed in this study, they are of interest topractitioners because they might help to better elicitsmiles from patients.

The principal investigator (J.F.W.) observed that 45%of the subjects responded more easily to the verbal com-

mand, whereas only 18% seemed to smile more readilywhen shown the visual cue. The remainder had no pref-erences. The visual cue appeared to be confusing formany subjects. When the investigator provided the visual

cue, several subjects asked What do you mean?or Doyou want me to imitate the smiles? A few others neededto hear the instructions again. Studies have found indi-

vidual variations in the responses to verbal and visualcues.19 Perhaps it would be benecial to provide both

verbal and visual commands.It was harder to elicit a posed smile from the men

than from the women. Five of the 11 men (45%) had dif-

culty smiling on command, but only 1 of the 11 women(9%) had difculty responding to the command. A sub-

ject was considered to have difculty smiling on com-mand if he or she did not respond with a facialexpression that resembled a smile or did not appear torespond at all to the command as judged by the principal

investigator and another impartial observer. The averagelength of the video footage used to capture the smiles ofthe men (65 seconds; range, 45-90 seconds) was longerthan the average length of the video footage needed for

the women (49 seconds; range, 35-65 seconds). Part ofthis discrepancy might be because all sessions were

directed by and all images were photographed by awomen (J.F.W.); thus, the men might have felt more in-hibited to respond than did the women. Interestingly,although it took the men longer to smile, there was no

difference in the number of male subjects (7 of 11)compared with the female subjects (7 of 11) who showed

a spontaneous smile in the video footage. This wouldseem to imply that men might not necessarily smileless frequently than women in all situations, but theymight be less able to pretendto smile.20-22

CONCLUSIONS

This study emphasizes the need to continue to inves-

tigate and standardize the methods of eliciting andrecording a smile of diagnostic quality. The following

are our specic conclusions.

1. Posed smiles can be reliably reproduced as measuredobjectively, but, subjectively, differences were noted.

2. When the entire face is visible, practitioners candetect important differences between posed and

spontaneous smiles. However, this ability isdecreased when only the smile is shown.

3. Spontaneous smiles are preferred to posed smiles byprofessional diagnosticians.

4. Videography provides diagnostic information thatcannot be obtained with still photography alone.

5. Video images are preferred to still images by profes-sional diagnosticians.

ACKNOWLEDGMENTS

We thank Graham Walker for his guidance and assis-tance; Hugh Gilmore for his video-editing wizardry; andthe highly perceptive panel members for their enthusiasmand remarkable attention to detail.

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