Varnishes: the effect of a second coat on apical root leakage of retrofill amalgams

The root canals of 60 single-rooted human teeth were obturated with gutta-percha. Each root was then resected and randomly received one of five retrofill procedures: copal varnish before the retrofill amalgam; copal varnish before and after the retrofill amalgam; Barrier (polyamide varnish) before the retrofill amalgam; Barrier before and after the retrofill amalgam; or retrofill amalgam with no varnish. All roots were placed in methylene blue dye for 11 days, and apical dye leakage was measured. This study showed that a single coat of either varnish prior to the retrofill improves the apical seal. No statistically significant differences were observed between the use of the two varnishes or between placement of a second coat of either varnish and the use of only one coat.