Can bleaching trays be used to whiten dark teeth that have darkened after a root canal?

Sometimes trays can be utilized for nonvital tooth bleaching The filling in the tooth is removed and a glass ionomer sealer is placed over the guttapercha. Then using normal tooth whitening trays, the patient is instructed to place whitening gel in the part of the tray corresponding to the dark tooth.

I usually request that the patient return to my office once per week, so that I can monitor the progress and to clean out any debris that has gotten into the access hole in the tooth. After the desired result is a achieved the permanent filling is replaced.