A morphometric analysis of the posed smile.

A fundamental goal of orthodontics is to improve the smile, but no objective criteria exist to assess the lip-teeth relationship, establish objectives of treatment or measure treatment outcome. Here we propose a method to digitally measure the smile characteristics of orthodontic patients. Specifically, the 'posed smile' is measured. By definition the posed smile is voluntary and not elicited by an emotion. It can be a learned greeting or a signal of appeasement and can be sustained. The posed smile is reliably repeatable. The multimedia computer program for smile measurement we developed was based on studies of the utility of the smile photograph and the assessment of the lip-teeth characteristics of the posed smile in treated and untreated patients. On the computer screen a grid, or smile mesh, employs horizontal and vertical lines to measure eleven attributes of a smile. Not all orthodontically 'well-treated' patients with exemplary plaster casts exhibit desirable anterior tooth display while smiling. We suggest that the photographic analysis of an unstrained posed smile might be a standard orthodontic record.