The composite filling inside the crown and the old root filling were removed 2 mm below the bone level. The quality of the root filling was evaluated to be good and no retreatment was initiated. One mm thick IRM was placed on top of the root filling to prevent leakage of bleaching chemicals and products apically and cervically. Vaseline was spread over gingiva and the working field was disinfected with chlorhexidine-ethanol. The tooth was then acid etched with 37 % phosphoric acid to remove smear layer and to open dentine canals. After washing and drying the cavity was filled with sodium perborate in 3 % hydrogen peroxide.

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