They can. ... They can... A small layer of enamel is removed with bleaching. Overdoing bleaching can produce permanent discoloration. Please see only a dentist for bleaching and refrain from the current trend of whitening in a spa or mall or beauty salon. Bleaching teeth is best managed by an experienced dentist with your dental & gum health as the main focus of their attention!
No. When used as directed they are very safe. The enamel is simply being supercleaned.
Possibly. Over the counter tooth whitening products contain low levels of the active ingredient normally used in professional tooth whitening gels: carbamide peroxide. To make teeth appear whiter, many otc products contain acid that frosts the teeth giving them a whiter appearance just like frosted glass. Unfortunately acid treated teeth will in the long run pick up more stain due to a rough surface.
No. The enamel is somewhat porous. Food and organic material get trapped in the outer layer and causes the yellowing. All whitening products work similarly. You should start with the least percentage of whitnening to start. The crest whitestipes are low percentage (5%) but cover the entire tooth surface well. If these don't work, trays can be created and more intense whtening products can be used.
Possible. Be sure to follow directions, use only as directed do not use more than directed do not use home remedy ideas along with strips.