The social thing, mainly. As a child I was an outsider of some sort. I remember what some kids in braces had to endure, having seen that from the sideline.
I'm not, I never was, someone with loads of selfesteem, and eveyone around me, nowadays, tends to enjoy a rather sharp whit. As do I, most of the time, but I'm not entirely sure how I will cope with those whitty remarks I'm going to get.
In addition I wonder how it feels like when the brackets are in. I do not fear a bit of pain, since the reason for my treatment are haedaches almost every day. I presume I can handle any pain the braces may inflict. But it is a big change, for examplte in how my mouth will feel like and how my reflection looks back at me when I'm shaving, and that makes me nervous.