The Eye-Tracking Study of the Impact of the Gingival Margin Height of Maxillary Lateral Incisors

The objective of this study was to verify differences in eye-tracking metrics and subjective smile esthetic ratings between general practitioners, orthodontists, and laypersons in cases of maxillary lateral incisor gingival margin deviations. Unilateral apical and incisal gingival margin deviations of 1, 2, and 3 mm were digitally produced in pictures of a man and a woman smiling. Specific areas of interest (AOIs) were created in each picture. Eye-tracking metric data included the time to first fixation (TFF) and number of fixations (NF). A specific sensor and software were used to acquire information on the eye movements. Data on the smile esthetic ratings were obtained using a visual analog scale (VAS). Analysis of variance and Pearson correlation were applied. The TFF on the AOIs in the mouth was shorter for general practitioners and orthodontists, signifying that general practitioners and orthodontists rapidly perceived the features in these areas, while for laypersons, the TFF was shorter for the AOIs of the eyes (P .05). The NF was greater on the AOIs in the mouth for general practitioners and orthodontists, whereas to the laypersons, the NF tended to be greater on the AOIs in the eyes. Mean VAS scores differed between observer groups (P .05). For the male picture, the 1-mm and 2-mm apical gingival margin deviations received the highest scores from the laypersons, while for both female and male pictures, the 1-mm apical deviation received the highest scores from the general practitioners and orthodontists. Higher VAS scores resulted in longer times that general practitioners and orthodontists spent looking at the gingival margin changes. General practitioners and orthodontists differ from laypersons in their perceptions of smile esthetics. Eye-tracking metrics revealed that the AOIs in the mouth aroused greater interest from the general practitioners and orthodontists, and this interest became greater as the gingival margin deviations increased to 3 mm. Laypersons fixated more on the AOIs of the eyes. The VAS scores indicated that general practitioners and orthodontists were more critical than laypersons, accepting smaller deviations in the gingival margins of the maxillary lateral incisors.