An in vitro comparison of nonvital bleaching techniques in the discolored tooth

By Freccia, W.F., Peters, D.D., Lorton, L., and Bernier, W.E

Date: 01/1982
Journal: JOE


To compare and evaluate the results of three commonly used nonvital bleach techniques: thermocatalytic, walking bleach, and combination.


  • n=39 extracted anterior teeth with intact crowns; in 5.25% NaOCl for 8 hrs
  • scaled and polished teeth with pumice
  • pre-op shade determined and teeth photographed
  • lightest, median, and darkest teeth determined, stored in saline
  • lingual accesses made, pulp extirpation, stained with hemolyzed blood
  • ranked teeth from lightest to darkest in 3 groups of 12
  • 2mm IRM placed in root canal space from CEJ.; chamber freshened with round burs
  • thermocatalytic: electric bleaching instrument set to 153 F on facial and in access, heated 35% H202 soln in chamber on cp for 2 min cycles for 12 min total, rinsed, dried, dry cp with cavit placed, repeated at 1 wk, recorded shades at 1wk and 1 mo postops
  • walking bleach: H202 and sodium perborate paste placed in chamber, cavit placed, procedure repeated at 1 wk, 1 wk and 1 mo shades postop recorded
  • combination: thermocatalytic done then placed walking bleach paste for 1 wk, repeated thermocatalytic, placed cavit and recorded shades at 1 wk and 1 mo postops


  • the three techniques are equally effective in bleaching crowns in which pulpal hemorrhage was primary cause of discoloration
  • rapidity of walking bleach technique in respect to a decrease of operator time was high significant (P< .0000)

Clinical Significance:

Walking bleach technique is fastest and produces clinically acceptable bleaching.