The influence of nasal deviation on the perception of maxillary dental centreline and smile aesthetics

To assess the impact of nasal deviation on the perception of the maxillary dental centreline position as judged by orthodontists, dentists and laypersons.

Cross-sectional study.

Barts and the London School of Medicine and Dentistry, Queen Mary University of London, UK.

Three groups of raters comprising 30 orthodontists, 30 dentists and 30 laypersons.

A frontal photograph of a smiling white woman was captured and digitally manipulated with varying degrees of nasal deviation and dental centreline (DC) position in increments of 1.5 mm and 3 mm to the right and left. Three rater groups assessed the attractiveness of images using a visual analogue scale (VAS). Multiple regression analysis was undertaken, and images were compared using the Tukey HSD method.

Using a mixed linear model, the intraclass correlation coefficient (ICC) was estimated in the range of 69%-86%, indicating good inter-rater reliability. The interaction between image rating and nasal position (P < 0.001), DC position (P < 0.001) and the relationship between nose and DC position (P < 0.001) were found to be statistically significant with symmetrical upper midline and nasal tip position, both considered to be most aesthetically pleasing. Image rating was not influenced by rater group type (P = 0.995), age (P = 0.983) or sex (P = 0.476).

There was a preference for a central and coincident nose and maxillary DC position uniformly across the rater groups. Deviations of the nose, DC and their interactions negatively impacted on perceived smile aesthetics with increasing extent and opposing direction of deviations rated progressively more unaesthetic. No differences were observed between orthodontists, general dental practitioners and lay people with respect to perceived impact on smile aesthetics.