Hello,Invisalign aligners can be used effectively in most cases to whiten your teeth with whitening gel, but there can be some issues.If you have any of the resin attachments on your teeth, I would not recommend trying to whiten during treatment. If you did, those areas of the tooth that are covered in resin would not whiten, and your teeth would look spotty after removal of the attachments. Also, during Invisalign treatment, teeth tend to gather stain over time due to constantly wearing the aligners. Even if you did whiten during your treatment, you would probably feel the need to whiten again when you are finished. My usual recommendation is to whiten with your Invisalign retainers after treatment is completed.