In America, teeth are not just tools for tearing and grinding food, but a commentary on character. We equate dental hygiene with good character. People with yellow teeth or bad breath are suspect. People who take care of their teeth are people we trust to take care of us. Many cultures have considered the eyes to be a reflection on the soul, but in the United States we also see the teeth as a sign of a person's essential spirit.
Braces enhance a person's smile.
But it says little or nothing about the inner life of friendship. Friends must enjoy one another's company. They must be useful to one another. And they must share a common commitment to the good. Friends help friends to be better persons, and they help maintain nurturing communities for each other.