Without seeing a photo or a X-ray it is difficult to diagnose. Once you have an examination and X-rays taken, your dentist can advise you further. If it is just some white spots I recommend whitening first and then restoring with bonding. The best results will be from a high potency in-office whitening system (I.e. Zoom!). Once the shade has settled (after 24-48 hours) you can have bonding done to match the new, lighter shade. If it is a larger white spot, you be better served with veneers. Either way, veneers or composite bonding do not whiten. So you want to whiten your teeth first and then have the dentist match that shade with the restoration.
