Effect of access design on intracoronal bleaching of endodontically treated teeth: An ex vivo study

To determine the effect of access design on intracoronal bleaching with 35% carbamide peroxide on discolored teeth.

Forty-two intact maxillary central incisors were selected, sectioned and artificially stained using whole blood. Color measurements were performed with a spectrophotometer: before staining (T1), after staining (T2), at 7 (T3), and 14 (T4) days postbleaching. After T1, specimens were stratified and divided randomly into two groups according to access design (N = 20): G1: contracted endodontic cavity (CEC) access performed with a #848-010M bur and G2: traditional endodontic cavity (TEC) access done with a #1157 bur. Canals were obturated, a cervical barrier was placed and 35% carbamide peroxide was sealed in the chamber for 7 days and replaced at 7 days for an additional 7 days. Data were collected based on CIELAB-CIE1976 (L^* a^* b^* ) system. Repeated measures SNK anova was used to evaluate the effects of access design and time on color change (ΔE^* ) and luminosity (L^* ) (α < 0.05).

For CEC, L^* was significantly different at all times points (P < .05). For TEC, L^* values were significantly different at all time points (P < .05) except for T0 and T4, which were similar (P > .05). There was no statistical difference for ΔE^* between CEC and TEC designs at any time point (P > .05).

In general, teeth accessed with CEC or TEC designs showed statistically similar bleaching when using 35% carbamide peroxide. However, lightness values were only reestablished with bleaching through a TEC access design.

Despite the current trend to conserve tooth structure when performing endodontic access cavities, the use of conservative access designs for bleaching discolored maxillary central incisors affected the acceptability threshold when compared with a traditional access design. These smaller accesses might not be an alternative treatment option when internal bleaching in the esthetic zone is anticipated.