I'm roughly at the 1 year mark of my Invisalign treatment. It's ongoing, as my orthodontist is a perfectionist and decided to be greedy, which I'm fine with. Once I'm done I'll get whatever whitening treatment is available.
The total cost will be ~US$ 6,000. Does it improve my looks? Yes. Does it give the best bang for the buck for that kind of money? That's very difficult to say, that would require incredible knowledge and judgment. Aside from looking better, my teeth are also better aligned which means they're less likely to grind out into oblivion as I get older.
Teeth are definitely much more important in North America. I noticed when I got to Australia that wildly crooked and yellow teeth were very common, even among educated people. In North America, it's the norm for middle class teenagers to get braces for a few years. A friend of mine from England was also told by her dentist, prior to moving to the USA, that she should get cosmetic treatments prior to moving here, as the standards here are higher. It's just expected. Since beauty is relative, having bad teeth becomes a catastrophe. It also matters more for online dating, which is mostly about how attractive your face is in photos.
Here's a good before and after photo, she looks awful in the before-photo and passable in the after-photo:
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Here's another:
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There's speculation online that good teeth are attractive because they're an indicator of good bone health. I don't know if that's true, I think that they're a subconscious signifier of social class. Either way, it's valuable, and those of you who live in North America should definitely consider Invisalign. It's non-invasive and it works.