Influence of gingival margin height variation on perceived aesthetics following absent maxillary lateral incisor-canine substitution.

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Maxillary lateral incisor agenesis is often managed with orthodontic space closure and canine substitution. Anatomic gingival margin heights associated with the maxillary anterior teeth are considered important for achieving aesthetic excellence with space closure, but evidence relating to the perceptions of lay people is poor. This study investigated the influence of gingival margin height variation in the maxillary anterior teeth following orthodontic space closure and canine substitution in the absence of maxillary lateral incisor teeth on perceived aesthetics judged by a lay population. Images of a case treated with space closure and bilateral canine substitution were digitally modified to create gingival margin height variation for the substituted lateral incisors and canines. Six variations were created, including one conforming to accepted norms for anatomic gingival margin heights. Lay people represented by parents of orthodontic patients ranked the images based on aesthetics, with data analysed statistically using linear models at 5%. One hundred and twenty responders were included (median age 48.0 years), 50% male and 81.7% Caucasian, with 87% able to provide specific preferences. In absolute terms, the highest-ranking [image C] had substituted lateral incisor gingival margins below the central incisors (considered normal) but substituted canine margins symmetrically below the substituted lateral incisors (considered to be too low); followed by [image D] with symmetrically level gingival margins; and [image F] with asymmetric substituted lateral incisor margins and substituted canine margins symmetrically too low. The lowest-ranked [image E] had normal substituted lateral incisor margins but asymmetric substituted canine margins. Image C was most often ranked first (29.8% of responders) and image E last (22.1%). After adjusting for potential confounding effects, image E received the worse scores. Anatomic norms for gingival margin height in absent maxillary lateral incisor-canine substitution do not correlate with the highest-ranking aesthetic choices of a lay population. Lateral incisor gingival margins symmetrically below the central incisors and substituted canine margins symmetrically below these ranked highest. Vertical asymmetry in the substituted canine position was considered the least aesthetic.