There are office bleach & home bleach.. but both should b done under expert supervision .. because it is done with Hydrogen & carbamide peroxide .
Office bleach followed by home bleach will help to improve few shades brighter.. it will last long
Next Steps
Visit dental clinic .. dentist will make proper custom tray of your mouth & recommend proper bleaching agent with required amount & time for definite time span..
Health Tips
Dont use whitening paste or home remedies for whitening.. it will cause permanent sensitivity & loss of enamel...
Improper application of peroxide may burn oral soft tissues & loss of taste & sense