Wa`alaykum as-salam wa rahmatullahi wa barakatuh.

If it is simply a cosmetic procedure, it is not allowed or desirable. If, however, it is a corrective procedure intended to correct a deformity, then it is allowed.

Having said this, however, I must caution you against resorting to this procedure simply for cosmetic purposes; for to do so for mere cosmetic reasons is considered akin to mutilation of the creation of Allah.

If, on the other hand, it is considered a deformity and your teeth alignment causes you emotional and psychological harm as it invites jeers and laughs, then that is considered a genuine reason for undertaking corrective surgery.

The Prophet, peace be upon him, is reported to have told ‘A’ishah, “You are allowed to remove what is objectionable and causing harm!” One of the accepted principles of jurisprudence states, “harm/injury shall be averted”.

There are also precedents from the Prophet, peace be upon him, in the sources that he allowed his companions to resort to corrective procedures in case of broken teeth and nose.