I used to wear braces (on my teeth) a long time ago before I was religious. Now I have a retainer which is worn in order to prevent the teeth from moving back to their original position. I do not know whether or not the braces were for a legitimate reason or for cosmetic purposes. The doctors told me that I had an overbite, but I still don't know whether or not the braces were necessary. I'm in a non-Muslim country so I suspect that the orthodontist is a kaafir. I haven't asked him whether or not the braces were necessary because I feel that he would simply tell me that I "needed" them. Now it has been a long time since I wore the retainer, but I want to start wearing it again just in case it was needed because I fear for my bite that it would cause problems in the future and I don't want to get braces again. My question: can I wear the retainer without asking my doctor about my original condition or must I ask him whether or not it was cosmetic. I don't want to go to his office again after so long because I feel like I won't trust his response (that he will just tell me that I needed the braces and won't tell me if they were purely cosmetic) and there are female nurses and employees.

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

Undergoing orthodontic treatment is permissible if it is intended to correct a defect or ward off harm like pain and the like. As for undergoing orthodontic treatment merely for cosmetic purposes and enhancement of one’s beauty, it is impermissible. You have to be certain or most likely believe that you need this orthodontic treatment and that it falls into the category of what is permitted by the Sharee‘ah. This is achieved by asking the orthodontist and acting upon his advice. Many scholars held that it is permissible to act upon the medical advice of a non-Muslim doctor if he is trustworthy. However, it is better if you can consult a trusted Muslim orthodontist. Otherwise, you may act upon the advice of the non-Muslim orthodontist if he is trustworthy, and you are not obliged to ask the same orthodontist who installed your previous braces. Rather, you should ask the orthodontist who will install the new braces because what happened in the past is over. As long as the orthodontist informed you that you needed to wear the braces, then there is nothing wrong in acting upon his advice, particularly if you cannot find a Muslim orthodontist.

Allah Knows best.