What's the best way to whiten persistent yellow canines and premolars? (Photo)

You can first try using your Invisalign aligners to put whitening gel onto those teeth only until they blend in with your other teeth.  Generally, the cuspids are naturally the darkest of your front teeth.  Your dentist can get whitening gel with up to 30% concentration of the active ingredient.  If this does not work for you, consult with a dentist that uses the Kor Whitening Gel.  This is the process and gel that will get your teeth the whitest. 

One thing to be verified is that any bonding resin from invisalign attachments was thoroughly polished away on these teeth. If left on the tooth it will seal the enamel and not allow whitening agents to be effective. Be aware that incisors are much thinner and do respond to bleaching agents more quickly. Also if you are using strips that they are less effective overall and professional whitening systems should give you better results. Good Luck

Veneers is the only effective way to go, because the canines are always more yellow, so you can try all systems, but at the end you will go back to the same color, bondings just help some time, and later on, they will turn yellow , veneers is your option.