Tooth display and lip position during spontaneous ...[Acta Odontol Scand. 2008] - PubMed Result

Tooth display and lip position during spontaneous ...[Acta Odontol Scand. 2008] - PubMed Result: "Tooth display and lip position during spontaneous and posed smiling in adults.
Van Der Geld P, Oosterveld P, Berge SJ, Kuijpers-Jagtman AM.

Department of Orthodontics and Oral Biology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.

OBJECTIVE: To analyze differences in tooth display, lip-line height, and smile width between the posed smiling record, traditionally produced for orthodontic diagnosis, and the spontaneous (Duchenne) smile of joy. MATERIAL AND METHODS: The faces of 122 male participants were each filmed during spontaneous and posed smiling. Spontaneous smiles were elicited through the participants watching a comical movie. Maxillary and mandibular lip-line heights, tooth display, and smile width were measured using a digital videographic method for smile analysis. Paired sample t-tests were used to compare measurements of posed and spontaneous smiling. RESULTS: Maxillary lip-line heights during spontaneous smiling were significantly higher than during posed smiling. Compared to spontaneous smiling, tooth display in the (pre)molar area during posed smiling decreased by up to 30%, along with a significant reduction of smile width. During posed smiling, also mandibular"