Comparison between Still Photography and Videography for Smile Analysis

Introduction

The smile plays an important part in orthodontic diagnosis and treatment planning. This has been recognized since the beginning of our specialty, and in the current esthetically oriented society, it seems to play a central part in self-perception and social image.^[1]

Conventionally, photography is used for an orthodontic record, but new videographic and computer technologies have enabled other diagnostic assessments. As part of a facial esthetics evaluation, a clinician studies lip function and posture. During this evaluation, a patient is often asked to smile and a split-second image of that dynamic action is captured on a still photograph. This photograph, used as part of the diagnostic process to determine a course of treatment, remains as a permanent record in the patient’s chart. If we want to depend on a still photograph to reflect the esthetics of patient’s smile, it is necessary to capture a true representation of that smile. For instance, if the photograph was taken a few seconds earlier or later, would it show the same smile? If a different directive was used to elicit a smile, would it trigger the same response? Would videography rather than photography provide a more effective diagnostic impression? Studies in the psychology literature have found that people are better able to detect posed emotion from motion photography than from still photography.^[2-8]

Analysis of orofacial esthetics during spontaneous smiling and speaking is now feasible because the optimal record can be selected from a video registration. The use of digital videography to capture an authentic, spontaneous smile combined with digital measurements has been tested lately, and it appeared to be reliable, reproducible, and valid for use in clinical practice.

Materials and Methods

This study was conducted and reported in line with the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA).

Results

The database search showed 91 articles listed in PubMed. Twelve articles were selected after duplicate removal. Using the PRISMA flow diagram, an overview of the article selection process is illustrated in the flowchart.

A standard pilot form in Excel Sheet was initially used, and then, all those headings which were not applicable for our review were removed. Data extraction was done for one article initially and this form was reviewed by an expert and finalized. This was followed by data extraction for all the articles.

A summary of the main findings and the data regarding participants, intervention, comparisons, outcomes study design (PICOS) in this systematic review is presented in Table 3.

Description of various studies

As previously mentioned, there are twelve studies which were conducted mainly in the United States, United Kingdom, Netherland, Germany, Iran, and China and were published between 2002 and 2013. Their main objectives were to compare and evaluate smile esthetics using videography and photography. The age of the participants ranged from 12 to 55 years. Some studies showed significant differences among the spontaneous smile and posed smile using videography and photography. Some studies concluded that digital video clips offer a tremendous amount of information for analyzing the dynamic character of the smile, but a standard digital photograph allows for immediate viewing and is a valid tool for analysis of the post-treatment smile and some found the need to continue to investigate and standardize the methods of eliciting and recording a smile of diagnostic quality. The fast onset and fading out of a spontaneous smile makes it impossible to capture the right moment with a static photograph. Therefore, it is proposed to switch from static to dynamic video recording of the smile for diagnostic purposes.

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Figure 1

Flow diagram of the article-selection process

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Discussion

This systematic review assessed the existing evidence on the esthetics of smile and the relationship between smiles captured by clinical photography and smile images obtained from digital video clips. Because esthetic concerns have become more critical in orthodontic diagnosis and treatment planning, a fundamental question arises: Are standard static records obtained routinely by orthodontists capable of capturing the smile accurately?

The literature has addressed many aspects of the smile, but only a few studies have been touched on the aspect of the reproducibility of the smile by videography and photography together.

Walder et al.^[9] analyzed smiles of 22 individuals simultaneously by videography and photography on two separate occasions. Objective measurements showed that the posed smile prompted with a visual or a verbal clue, or taken on day 1 or 2 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.

Schabel et al.^[10] used the Smile Mesh program in their study to quantify and compare 14 characteristics of smiles captured by clinical photography and digital videography. A significant difference was found between 7 of the 14 mean Smile Mesh measurements. These were maximum incisor exposure, upper lip drape, buccal corridor right, left, buccal corridor ratio, upper lip height, and lower lip height. Other than lower lip to maxillary incisor, all showed moderate to strong relation with each other (P values 0.47–0.82; P < 0.001). In other studies, Schabel et al.^[11,12] evaluated the reliability of and the relationship between the Q-sort and visual analog scale methods used to measure esthetic preferences. Kappa agreement and the McNemar test were used to evaluate the level of agreement between orthodontists and parents for “attractive” and “unattractive” images of smiles captured with clinical photography. A statistically significant result (P < 0.05) of the McNemar test indicated that the raters disagreed on the percentage of “attractive” images.

Sarver and Ackerman^[13] and Ackerman and Ackerman^[14] described the evolution of smile analysis and reviewed the dynamic records needed. They concluded that visualization and quantification of the dynamics of the smile is a two-stage process. The first crucial step is the clinical examination and second is record taking.

Van Der Geld et al.^[15] used records of spontaneous smiling next to posed smiling; diagnostics can be improved so that they approach the daily perceptions of patients by their social analysis. They found that for four-grade scale estimation, kappa values were slightly lower. Posterior-tooth kappa values for spontaneous smiling varied between moderate and substantial. Significant correlation for rating errors of smile line height of spontaneous smiling (Central incisor: r = 0.20, P = 0.026; second premolar: r = −0.26, P = 0.007).

Oshagh et al.^[16] addressed one of the numerous factors determining smile esthetics and showed that, generally, dental students, art students, and laypeople do not prefer smiles with minimal and excessive buccal corridors for both male and female individuals. They concluded that regarding the male individuals, art students rated 10% buccal corridor as most attractive and 28% least attractive, but dental students rated 15% buccal corridor the best and 28% buccal corridor the least attractive. Art and dental students rated 22% buccal corridor the best and 2% buccal corridor the least attractive in female individuals. Laypeople rated 10% buccal corridor the best in male and 15% in female individuals. They rated 28% buccal corridor the least attractive in both genders. The data provided no significant differences (P > 0.05) between the male and female judges or between male and female individuals for each of the images using Mann–Whitney test.

Batwa et al.^[17] measured the occlusal plane angle to the true horizontal rather than to the sella-nasion line. The occlusal plane range that was investigated in this study was 0–20° to the true horizontal. 10° rated as most attractive by patients and 15° smile as most attractive by dentist.

Van Der Geld et al.,^[18] Liang et al.,^[19] and Hu et al.^[20] used the videographic method to capture spontaneous smiling and posed smiling images reproducibly. The spontaneous smile is a more relevant emotion than a photographic posed smile and approaches the way patients are perceived by their social environment. For most patients, the outcome of orthodontic therapy is directly related to visible improved dentofacial attractiveness and not so much to the more invisible occlusal relationships according to scientific standards. The central question in these studies was whether the use of posed smile rather than spontaneous smile is sufficient as a diagnostic record for facial esthetics and, more specifically, lip-tooth relationships. They concluded that the fast onset and fading out of a spontaneous smile makes it impossible to capture the right moment with a static photograph. Therefore, it is proposed to switch from static to dynamic video-recording of the smile for diagnostic purposes. Experiences of plastic surgeons, oral and maxillofacial surgeons, and orthodontists show that (digital) video registration in clinical practice is feasible.

Conclusions

Digital video clips offer a tremendous amount of information for analyzing the dynamic character of the smile, but a standard digital photograph allows for immediate viewing and is a valid tool for analysis of the post-treatment smile.

Posed smiles can be reliably reproduced as measured objectively, but, subjectively, differences were noted. Spontaneous smiles are preferred to posed smiles by professional diagnosticians.

Video images are preferred to still images by professional diagnosticians. Videography provides diagnostic information that cannot be obtained with still photography alone.