This is a great point to raise. OP, please make sure that both the plastic you used, and the chemicals released as saliva gradually breaks down the plastic, are not going to be harmful. You wouldn't want long-term exposure of your gums to harmful agents. But that's probably the only concern.
Regardless: great job. I'm very impressed by this project -- I love seeing applications of 3d printing. Especially one like this turns an expensive (and slow!) medical procedure into something that can be done easily at home, or cheaply in the office of a trained professional.
So do we over at Additively (your post made me signup after just reading HN for a while). We publish showcases such as the commercial application of the posted aligners on our site - more curated showcases will be published soon.
Regardless: great job. I'm very impressed by this project -- I love seeing applications of 3d printing. Especially one like this turns an expensive (and slow!) medical procedure into something that can be done easily at home, or cheaply in the office of a trained professional.