Effect of facial height on the perception of mandibular asymmetry by laypeople, orthodontists and oral and maxillofacial surgeons

Purpose This study evaluated how facial height affects perceptions of mandibular asymmetry in individuals with short and long faces, as viewed by three groups of raters.Materials and methods Long-face and short-face models were selected based on the facial index. Symmetrical frontal-view photographs of the models were altered with mandibular rotations of 0–6 degrees. Seventy laypeople, 24 orthodontists, and 24 oral and maxillofacial surgeons rated the images for aesthetics using a 0–100 visual analogue scale (VAS) and assessed treatment needs. Data were analysed using ANOVA, LSD, Tukey’s HSD and Spearman correlation, with a significance set at p < 0.05.Results The treatment need threshold for the long-face model was identified at 4, 4 and 5 degrees by orthodontists, surgeons and laypeople, respectively. In contrast, for the short-face model, it was 6 degrees according to orthodontists and surgeons; laypeople did not perceive a need for treatment even at 6 degrees. All groups detected 1-degree rotations in the long-face model. Still, in the short-face model, laypeople and orthodontists noticed 1-degree rotations, while surgeons did not show significant differences for 0-, 1- and 2-degree rotations but were better at detecting higher degrees.Conclusion All raters identified a 1-degree detection threshold for mandibular rotation in the long-face model. In the short-face model, orthodontists and laypeople noted 1 degree, while surgeons noticed 3 degrees. The long-face model needed treatment for a lower degree of rotation based on all three rater groups. Specialists generally require lower degrees of asymmetry to determine treatment needs compared to laypeople.