The Influence of Anteroposterior Head Inclination on the Perceived Consonance of the Smile Arc and Lower Lip Curvature on Photographs : A Cross-Sectional Study

Article Article scientifique Article The Influence of Anteroposterior Head Inclination on the Perceived Consonance of the Smile Arc and Lower Lip Curvature on Photographs : A Cross-Sectional Study eng 2025-02-28 author Khadem Amir Reza 0009-0004-0403-4352 839279 author Togninalli Matteo author Antonarakis Gregory 0000-0001-6741-6922 133276 CUMD - Division d'orthodontie - communs (DORT) author Vento Bosch Cristina 671542 CUMD - Clinique d'orthodontie (CORT) 1658 10.3390/jcm14051658 2077-0383 https://www.mdpi.com/2077-0383/14/5/1658 Objectives : To determine the extent to which anteroposterior head inclination influences smile arc curvature assessment on frontal photographs. Materials and Methods : Sixty-three young adults participated in this study. Each had five standardized frontal-view photographs captured with posed smiles at five anteroposterior head inclinations (−20°, −10°, 0°, +10°, +20°) using a cervical range of motion device. Two curves were traced per photograph: one following the shape of the lower lip and the other the incisal edge of the maxillary anterior teeth from canine to canine (smile line). These curvatures were approximated by quadratic function and compared for concordance based on the maximum curvature of the obtained functions. A score was calculated, with 0 denoting a consonant smile (perfect concordance) and 2 a non-consonant smile. Results : Among the sixty-three participants, fifty-nine were included in the analysis after excluding those with insufficient tooth exposure in the photographs for the smile line assessment. The analysis revealed that the perceived smile line was more consonant (concordant with lower lip curvature) with a −20° head anteroposterior inclination (score: 0.146), and the least consonant with +20° anteroposterior inclination (score: 1.326), with statistically significant differences (p < 0.05). Conclusions : The smile arc curvature assessment on frontal photographs may be influenced by the anteroposterior inclination of the head on frontal photographs. However, due to the two-dimensional nature of this study, further investigations incorporating three-dimensional imaging are recommended. Smile arc Head position Smile consonance Dewey 617.6 209 Division d'orthodontie 24Q1 false 1448 Orthodontie 1065 Journal of clinical medicine 14 5 46ef95d3-8929-490d-8ee5-7830e329651d Article (Published version) Public Article_scientifique_from_crossref.pdf 3472038 application/pdf CC BY-4.0 0f4212fbb3ee05c143b39c83bf812c3f3deca456656c20feaeddc96ca1963aec openAccess Faculté de médecine / Section de médecine dentaire / Département de réhabilitation oro-faciale / Division d'orthodontie

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The Influence of Anteroposterior Head Inclination on the Perceived Consonance of the Smile Arc and Lower Lip Curvature on Photographs : A Cross-Sectional Study	Journal of clinical medicine			2025	59	149

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Khadem, Amir Reza

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