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Background: The human face is a living mirror held out to the world. Natural, marked, painted or adorned, it haspower to attract, charm, captivate or brighten. Therefore the subject of the smile and facial animation, as theyrelate to communication and expression of emotion, should be of great interest to orthodontists so the aims of thisstudy were to determine the difference of outer commissure width, inter-labial gap, smile index, modified smile index,visible maxillary interdental width, buccal corridor percentage and maximum incisor show among different smilestyles (Monalisa, Cuspid and complex) during emotion, posed smile and speech. And to determine the differences ofthe same variables for each smile style among emotional smile, posed smile and speech.Materials and methods: The sample consisted of 77 Iraqi adult subjects (18-30) years with skeletal class I occlusion,classified into three categories according to a certain neuromuscular mechanism of smile called smile style, the firstgroup consisted of 34 (24 male, 10 female) subjects with Monalisa smile style, the second consisted of 34 (22 male, 12female) subjects with Cuspid smile style, the last 9 subjects (5 male, 4 female) were the third group with Complexsmile style. Each subject was recorded using digital videographic camera while watching a comical movie to elicitemotional smile, then they asked to say “Chelsea eats cheesecake” to record them during speech. The videographswere imported to the PMB-picture motion browser to capture emotional smile, posed smile and speech frames. Fourlinear measurements were measured for each frame using AutoCAD program 2011.Results: The results of this study showed that all the variables changed significantly when the subject change fromspeech to emotional smile frame in all smile styles. And these changes revealed almost the same behavior when thesubject changed from speech to pose or to emotional smile frames.Conclusion: The result of this study revealed that emotional smile is largely different from posed smile in differentaspects which has an effect on decisions related to orthodontic diagnosis and treatment plan

smile style --- emotional smile --- posed smile --- digital videography