Although brace require some adaptation, for sure, they will not affect your singing voice. After correcting your teeth, your voice will get even better. Singing is usually affected by the vocal cords, so if the vocal cords are healthy, then you shouldn't have to worry.
Do teeth affect your voice?
It is well known that alterations to the oral cavity caused by dental prostheses may affect speech articulation, although influences on the voice are not assumed. In addition to the vocal fundamental frequency, vibrations of the vocal chords generate overtones.
Will braces affect your voice?
Braces do not affect your vocal cords. They simply correct issues with your teeth, giving you a beautiful smile. You'll need that smile to pose for pictures with your fans after every performance.