Table I.
List of variables used in smile analysis and their definitions
| Variable | Practical definition |
|---|---|
| Philtrum height at rest | The distance between subspinale and inferior point of upper lip vermilion under philtrum column at rest |
| Commissure height at rest | The distance between the line passed from subspinale parallel to alar base to outer commissures |
| Upper lip curvature at rest | Upper lip curve from midline to outer commissures at rest |
| Interlabial gap at rest | The distance between inferior upper lip border and superior lower lip border at rest |
| Upper Incisor exposure at rest | The amount of upper incisors exposure at rest |
| Lower incisor exposure at rest | The amount of lower incisors exposure at rest |
| Philtrum height on smile | the distance between subspinale and inferior point of upper lip vermilion under philtrum column on smile |
| Commissure height on smile | The distance between the line passed from subspinale parallel to alar base to outer commissures on smile |
| Upper lip curvature on smile | Upper lip curve from midline to outer commissures on smile |
| Interlabial gap on smile | The distance between inferior upper lip border and superior lower lip border on smile |
| Upper incisor exposure on smile | The amount of upper incisors exposure on smile |
| Lower incisor exposure on smile | The amount of lower incisors exposure on smile |
| Smile index | The result of smile width divided by interlabial gap |
| Intercommissure width (smile width) | The distance between outer commissures on smile |
| Buccal corridor | The distant between the most distal point of upper right canine or first premolar to inner commissure on smile |
| Buccal corridor ratio | The result of distance between lines tangent on most distal points of upper canines or first premolars divided by smile width on smile |
| Gingival display | Amount of gingival display of upper central incisors from marginal gingiva to inferior border of upper lip on smile |
| Transverse symmetry | Smile symmetry in transverse dimension according to differential distance between outer commissures and midline in both sides |
| Vertical symmetry | Smile symmetry in vertical dimension according to the angle between line passes through outer commissures and midline |
| Transverse cant of occlusal plane | Cant of occlusal plane (line passes through peaks of upper canines) according to its angle with midline |
| Upper dental midline angulation | Angle between upper dental midline and facial midline |
| Upper dental midline deviation | Distance between upper dental midline and facial midline and its direction |
| Over jet | Distance between labial surface of upper and lower central incisors |
| Incisor inclination | Anterior-posterior inclination of longidudinal axis of upper central incisors in smile sagittal view in relation to frontal plane |
| Smile arc | The difference between distance of incisor edge of upper central incisors, and peak of upper right and left canines or first premolars to inferior border of upper lip |