Principles of the Perfect Smile
Size of Central Incisors:
The width to height ratio should be 75-80%. This means the front teeth should look like a rectangle, not a square, and should appear taller than they are wide.
The “Golden Proportion” refers to mathematical dimensions that are perceived as esthetically pleasing by the human eye. This principle was discovered by the ancient Greeks and is applicable to the ratio of the widths of the front teeth.
The edge of the central incisor and canine are typically at the same horizontal level, while the lateral incisor is usually slightly shorter.
The midline between the two front teeth should be centered in the face and perpendicular to the plane between the eyes.
It is typically evaluated using the base of the nose as a reference point.
The front teeth should have an inclination or tilt slightly toward the midline. The inclination increases gradually from the central incisor back to the first bicuspid, and if these lines were extended downward, they would eventually converge.
Color and Alignment:
Teeth should be a uniform white color in comparison to one another, but may be slightly darker near the gum line. Teeth should be “straight” and aligned with no crowding or gaps.
Smile at Rest:
In middle aged adults, ~2-4 mm of the teeth are visible when the lips are in a resting position. This amount decreases as we age, causing the “window of the mouth” to gradually shift to show more of the lower teeth.
In a natural smile, a line formed by the edges of the front teeth should follow the contour of the lower lip. If there is space between the lip and teeth, it should be the same back to the canines or first bicuspids.
The space created between the corners of adjacent teeth should increase going back away from the midline. Teeth with straight edges create small embrasures and teeth with rounded corners create larger embrasures.
Gum Line Symmetry:
The position of the gum line should be symmetrical when comparing each specific tooth on the left and right sides.
Gum Line Heights:
The gum line over the lateral incisor should be ~1-2 mm below a straight line drawn from the gum line of the central incisor to the canine.
In a full smile, only ~1-3 mm of gums should be visible between the teeth and upper lip. Healthy gums are light pink in color and tightly adapted around the teeth.