Even if treatment with braces has lasted a very long time, there is no visible difference in the colour of the tooth under the base of the brace once it has been removed. You won’t see squares on your teeth. If the patient’s hygiene has been poor, white spots form on the surface of the enamel around the brace, but not underneath it. This enamel is compromised – its structure has been damaged by the bacteria in plaque over a long period – and it needs treatment with a remineralising toothpaste or, if the process is very advanced, with bonding or veneers.
This answer is for general information. Your own case needs an examination by an orthodontist.