Yes, but like I said, it varies what exactly they cover and what the percentage is. The dental insurance you get through work might not cover braces at all or maybe only 50%, who knows. For sure you can buy insurance but usually there is a 3-6 month waiting period before it kicks in because they don't want you to go and buy the insurance, right away charge your expenses to it and then cancel it as soon as you don't need it anymore. They would lose money then.
If you already have the braces on, a good orthodontist might charge you $100 per month to do the maintenance.