Since then, several smile variables have been researched as follows: Smile arc; buccal corridor; amount of gingival exposure at smiling; presence of gingival and incisal asymmetry; presence of anterosuperior diastema; presence of midline shift and changes in axial proclination; maxillary incisors ratio, size and symmetry; among others. https://www.odontologiavirtual.com/2014/11/orthodontics-10-commandments-of-smile.html