My son is a 2 year old thumbsucker, also! My advice to the both of us is, don't worry! I began to get worried about it after his first birthday and when he was weaning from breastfeeding. Not because of my own thoughts, but because of off-hand comments from others!! I would have my own family members almost rudely ask me, "so when you gonna wean him from THAT?" I'm sure you can imagine the pang in my heart when I thought that the cute little comfort method he had was suddenly taboo. After endless nights of reading and researching thumbsucking, I discovered that it's normal, it's okay, and they do stop when the time is right for them. In fact, pressuring, chastising and forcing a thumbsucker to stop can actually be counterproductive. In one reading, they studied adult thumbsuckers and the only common link was that every single one of their caregivers had attempted to stop them with one harsh method or another at a young age. It's almost as if they became closet thumbsuckers and needed it later into their life.
I've decided that I will wait until he becomes school-aged or when we can appropriately have a conversation about how he can suck his thumb when he wants to at home and if he would like help stopping (some want to stop because of realization from peers) when we're in public, that we can come up with a signal or a word just for him that will help remind him (because they can start sucking sometimes without even realizing).
This may or may not work, but hopefully you can find a loving trick that works just for him. Just remember that you and your spouse and your home should be a safe and comfort spot for the kids to land. He shouldn't have to worry about his comforting method being seen as wrong or bad to you.
And as for the dental aspect of it, it remains to be seen if thumbsucking is the end-all when it comes to needing braces. Our children already have issues with spacing and crowding and we've been told that our kids, like my husband and I, will most likely need braces at some point. So again, we've decided it's no point in trying to stop the thumbsucking to avoid braces.
Thanks for reading this long-winded note. I hope whatever works, works well for you and your little one.