If you're not obligated to tell your future partner about getting braces done, then you're not obligated to tell him or her about LL surgery. And to me, dental work changes "who you are" more than LL surgery because it's your FACE. Your FACE is YOU and it's more personal. And braces can completely change how you look. This is why I am very hesitant to mess with my face (besides braces) even though people have told me I am ugly (I had comments about my eyes, comments about my nose, comments about my lips, comments about my cheeks, comments about my chin, literally everything), but I am attached to my face and rather give myself the chance to find someone who will love my natural face as-is instead of a modified one. I am sure I will generally be treated better with facial mods though.
I had "poverty teeth" or "malnutrition teeth". I have 8 missing teeth since I was a child and that warped my palate in a lot of ways. I needed braces as a teen, which actually fked up my face because my parents had no insurance and picked just any rando to work on me. My jaws were in pain and swollen for years. I considered double jaw surgery and titanium implants but my new ortho warned against it. Then I had a corrective orthodontic treatment in my late 20's that changed my face for the better. I felt more like "me" and that my true beauty was coming through. Total spent was like 18k out of pocket. If it wasn't for ortho work, I would look completely different. No, I don't think this is something I need to sit down my future partner and "confess" I had dental work done.
You only owe people the truth when the failure to do so would cause them harm. You have your right to privacy, and it’s not a "lie" in the sense of trying to get something from others, it’s about choosing to omit certain truths based on the setting to protect yourself. Do you owe people the truth about your sex life just because they ask? Your kinks and fantasies? Do you owe people the details of your therapy sessions? Your insecurities? Your medical history? No. You don’t owe anyone .
It's easy for people to talk about integrity, "morals", and knowing everything about your partner and vice versa, but people only say that when the system is already working to their advantage and they don't have anything major that marginalizes them. It's like a rich kid who gets a job in his dad's company through nepotism alone, then he walks out to see a crippled homeless guy and go "why don't he just get a job and work hard?" Or a straight person telling a gay one "just be yourself, and if someone doesn't accept you, they're just not your people!" without acknowledging that hiding and coming out is a difference between being unemployed and starving, all the way to being potentially assaulted or killed. The straight guy isn't the one who will deal with the consequences of a gay guy "living his truth".
Also this is sad but most partners won't love you. They love the IDEA of you. They don't actually want to know your reality. There is something called "need to know", and most people don't really need to know your reality. If people can't tactfully handle your truth, then give them bull to back them off. Everyone prefers it that way anyway.