Highly recommend a water flosser:
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This does NOT replace flossing entirely. But it really helps cleans out braces in hard to reach areas with build up.
You can also use floss picks: (this is just a photo for reference, not a specific recommendation; there are a huge variety of floss picks)
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As uncomfortable and painful as it is, be
very diligent with your flossing. Your gums will thank you after the braces are taken off. Flossing will prevent inflammation, gingivitis, as well as receding gums, because no one want their teeth to fall out when in their 40s/50s. Gum help hold your teeth in place (besides the roots of your teeth), so it's important to keep them healthy and happy.
If any of the parts are cutting into your mouth, if they are severe, tell your dentist; he/she may be able to make some adjustments. You can also ask your dentist or go to your local CVS/walgreens and buy wax. The wax can be put on rough surfaces to prevent cuts. However, they do need to be removed when brush your teeth.
As for the discomfort and pain, unfortunately it's like a right of passage. It's something everyone has to deal with when they get braces. Once you're about a week in, it should feel a lot better.
Note: I have not had braces for over 15 years, so I am not the most up-to-date; but these are just my initial thoughts from my experiences (I had braces twice).
Good luck!