What is the ruling on undergoing cosmetic surgery to reposition the upper jaw if its appearance is repulsive?

Plastic surgery is divided into two categories: necessary or essential, which is permissible for removing defects resulting from illness, accident, burns, or congenital defects. The second category is cosmetic (tahseeni), which is not permissible and aims at improving appearance, such as reducing the size of the nose or breasts, or performing a facelift.