There are three basic cosmetic dentistry smile design styles, and within each division there are variations on the theme.
The Attractive Smile
The attractive smile has variation in the lengths of the teeth. Since the central incisors tend to be longer than the other front teeth when they first come in and then wear down over time to an even length, we associate longer, more prominent central incisors with youth and "attractiveness."
Therefore, in the "attractive" smile design, the central incisors are significantly longer than the lateral incisors. The attractive smile conveys youth and boldness, or it can also convey warmth. The attractive smile design also draws the eye to the center of the face, emphasizing the nose and chin. It is good for people with prominent, attractive lips.
The Sophisticated Smile
Teeth in the sophisticated smile make a straight horizontal line. A sophisticated smile conveys maturity and intelligence. It tends to emphasize the width of the lower face. When teeth first erupt, the lengths tend to be more uneven. As we age, they wear to even lengths. Therefore, we associate teeth of even lengths with maturity, wisdom, and "sophistication."
The Sporty Smile
A sporty smile is between sophisticated and attractive. The central incisors are a little longer than the laterals. A sporty smile design conveys casualness and informality, and can also convey warmth. It's not quite as serious as the sophisticated smile nor as young as the attractive smile.
Factors that influence the smile design are:
Your facial shape. For example, a long face may need to accentuate width to appear more oval. Someone with attractive features in the center of the face may need bold central incisors to draw attention to that center.
Your image aspirations. How do you want to appear to others? A sophisticated smile gives the appearance of more intelligence, maturity and judgment. A sexy smile gives the appearance of more warmth, energy and boldness.
Your age, or how old you want to appear. Longer central incisors make you appear younger. Also, whiter teeth make you appear younger. Conversely, a flatter smile or a more subdued color to the teeth make you appear more mature.