Is it permissible to perform a Hollywood smile or place zirconia dental crowns on teeth that have recurrent decay and yellowness, knowing that whitening may cause sensitivity?

If the purpose of installing orthodontic braces or making a tooth-colored filling is for treatment and to cure decay or a defect in the tooth, then there is no objection to it. However, if the original purpose is to seek beauty and enhance appearance, then this is forbidden, based on Al-Nawawi's statement: "What is forbidden is that which is done for the sake of beauty. But if it is needed for treatment or a defect in the tooth, or similar, then there is no harm."

Dr. Saleh Al-Fawzan mentioned that if the intention behind placing a white filling is to increase the beauty of the teeth, without there being any apparent deformity, then it may not be permissible, especially if it leads to the removal of some tooth material by filing, as this falls under the prohibited "washr" (tooth-filing).

Regarding tooth leveling and cosmetic veneers, it is permissible if the purpose is to treat the tooth due to decay, breakage, a disfiguring discoloration, or irregular alignment of the teeth, based on the hadith: "those who widen gaps between teeth for beauty" and the narration: "except for a disease." It is forbidden if the purpose is to increase the beauty of the teeth, due to it involving the prohibited alteration of creation.