Is it possible to rebuild the enamel lost due to bleaching with tray?

Yes: If you have white spots or areas of demineralization, your dentist can rx you mi paste. This cream restores the oral mineral imbalances that cause demineralization by replacing minerals while improving saliva flow and Fluoride uptake as well as soothing sensitive surfaces. It binds readily to pellicle, plaque, soft tissue & hydroxyapatite when applied within the oral cavity.