Can I use Crest whitening strips if I have a permanent retainer?

Hello,

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The strips will whiten only the portion of the tooth that it comes in contact with. If it is a fixed retainer, then you can use it on the front surface, but do not let the chemical touch your inner surfaces of teeth. I will prefer not using it in such a case, as there will be a difference of color in your outer (front) and back (inner) surfaces of teeth. If it is removable, you can. Make sure you remove all the excess material from the mouth and teeth before putting the retainer back on. If your teeth are sensitive, then it might ache a little while placing back the retainers. I would recommend you not to whiten teeth regularly as it can weaken your teeth and cause sensitivity in the long run. You can also ask your dentist regarding tray and gel method, for at-home whitening methods. I hope this helps. Take care.