Comparing the use of static versus dynamic images to evaluate a smile

Most studies that refer to smile analysis are based on static images. A more comprehensive evaluation can be made with dynamic video images that can be stopped at the most appropriate frame to ensure the best static images for analysis. Purpose: The purpose of this clinical study was to evaluate the posed and dynamic smiles of both sexes, considering the type of smile, prevalence of gingival display, dental display at rest, dentogingival display at posed and spontaneous smile, and lip mobility, through digital image acquisition (photographs and video clips) manipulated by using a software program. Material and methods: Three photographs and 1 video clip were made for each of the 380 voluntary participants aged between 18 and 32 years by using an iPhone 6 iSight 8 MP camera, Moment lens, and artificial 5500 Kelvin light (IceLight). Digital files were evaluated by using a software program (Keynote), determining each point to be evaluated with posed and spontaneous smiles. Results: With static images, 90% of women and 74% of men had gingival display, with only 35% of women and 21% of men having continuous gingival display. With dynamic analysis, these values increased to 100% of women and 95% of men having gingival display and 62% of men and 81% of women having a continuous gingival display (P<.05). The difference between dentogingival display during posed and spontaneous smiles was clear, with 68% of the participants having 2.25 mm more gingival display. Women tend to show slightly more dental display at rest, posed and spontaneous dentogingival display, as well as lip mobility, than men. Conclusions: The type of smile changes significantly when posed and spontaneous smiles are compared. Women generally show more gingiva and teeth in all the parameters evaluated than men. Dental treatments should be individually planned according to each patient's smile characteristics.