So I went to see my orthodontist today for my treatment with the braces and just realized...what the hell am I going to say when my voice REALLY drops and my appearance changes? I see her once a month and I could probably get away with not telling her for 1 more visit, maybe two tops.

Well, hopefully you can tell her the truth and being a professional medical practitioner she will be 100% OK with that.

As a Paramedic I can tell you medical people do not usually judge. They are more interested in providing their level of care. I made sure all of my providers knew so nothing they do would hurt HRT or cause problems with it. 

I didn't tell my dental hygienist doodly squat outside of responding to questions to update their file on what medications I'm on. Pretty sure between "testosterone cypionate", the effects thereof, a name change, and the effects of top surgery they knew something was up. Seemed a tad weirded out the whole visit - could swear they were less thorough than usual as a result - but they didn't say anything about it and kept it professional.