Orthodontists' and laypeople's perception of smile height aesthetics in relation to varying degrees of transverse cant of anterior teeth.

Aims: To determine the effect of varying the transverse cant of the anterior teeth on orthodontists' and laypeople's perceptions of smile aesthetics, and the influence that smile height has on this perception.

Materials and methods: A 20-year-old Chinese female with an aesthetic smile and normal occlusion was chosen and agreed to participate. Digital pictures of her posed smile were taken and manipulated to create three smile height variations: low, medium, or high. Each variation was further manipulated to create varying degrees of transverse anterior tooth cant. Fifty-six laypeople and 40 orthodontists participated as raters of the dental and facial impact of the altered smile images.

Results: The orthodontists more commonly and precisely identified the transverse cants of the anterior teeth and the detracting influence on smile aesthetics compared with laypersons. The orthodontists accepted a lesser range of anterior transverse cant. Increased smile heights enhanced the capability of all raters to detect a transverse cant and reduced the acceptable cant range. In addition, an increased smile height worsened the detracting effects of the transverse anterior cant in all raters' perceptions of smile aesthetics. An increased display of teeth and angulation of an anterior cant increased the ability of raters in both groups to detect differences.

Conclusion: Transverse cants of anterior teeth can affect orthodontists' and laypeople's perceptions of smile aesthetics. Smile height and incisor display were significant factors that affected the orthodontist's and layperson's perceptions of smile aesthetics, and suggested that a description of the detracting effect of an anterior transverse cant should also consider smile height.

Clinical relevance: A transverse occlusal cant is an important aesthetic factor used by clinicians during orthodontic diagnosis and review. It is important to appreciate that there is a difference in perception between orthodontic professionals and patients (laypeople). The extent of this perceptual difference and influencing factors could help the clinician set more appropriate treatment goals.