Cervical canal leakage after internal bleaching.

The effects that walking bleach procedures had on root canal filling leakage and the extent of dentinal penetration were studied. Forty teeth were divided into four groups: 1--GP, set sealer, no base; 2--GP, set sealer, 2-mm Cavit base; 3--GP, unset sealer, no base; and 4--GP, unset sealer, 2-mm Cavit base. All were bleached for 7 days, fresh bleach was added for another 7 days, then methylene blue dye was placed for 5 days. The extent of dye penetration apically along the root canal filling and through the dentinal tubules was evaluated. The results indicate that 2 mm of Cavit was sufficient to significantly reduce linear leakage and dentinal penetration. The Cavit should be placed to a level slightly coronal to the facial cementoenamel junction. Teeth with cemental defects demonstrated greater perpendicular dye penetration in the areas of the defects than those with intact cementum. The data from this study suggest the use of a base material over gutta-percha in clinical practice prior to internal walking bleach procedures.