We’ve all heard the saying that it takes less effort to smile than it does to frown, so we ought to smile as often as we can. Whether that particular claim is true or not, most of us can agree that choosing to smile can quickly brighten and better nearly any day, situation, mood, or attitude.   But some people find it hard to smile—not because they’re unhappy, but unconfident. Having off-colored teeth can greatly affect a person’s self-esteem.  There are a…