Will whitening trays damage teeth after continuous use?

Most people bleach their teeth once every six months, but would bleaching teeth more than that cause damage?
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DAMAGE TO TEETH= UNLIKELY DAMAGE TO GUMS IF THE BLEACHING GEL GETS ON THE GUMS = A POSSIBILITY WILL THIS BE PERMANENT DAMAGE? = NO, JUST IRRITATED. WHAT WILL DO TO THE TEETH THEMSELVES? MAKE THEM MORE SENSITIVE TO COLD. DOING A TOUCH-UP WHITENING IS A NICE IDEA EVERY 6 MONTHS TO KEEP A SMILE LOOKING GREAT.
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