Effect of Intracoronal Bleaching Agents on Sealing Ability of Cements

Objectives: To compare the sealing ability of cavit and zinc phosphate cements, each used as a temporary sealing agent for the intracoronal walking bleach technique. Methods: A cavity of 2x2x3mm were prepared on the buccal surface of 60 extracted human maxillary premolars. These teeth were randomly divided into 2 groups, A and B which were filled with Cavit G (ESPE) and zinc phosphate cement. Each group were again divided into three test groups which were exposed for 3 weeks to Sodium Perborate mixed with 30% Hydrogen Peroxide (SPHP30), Sodium Perborate mixed with 3% Hydrogen Peroxide (SPHP3), Sodium Perborate mixed into distilled water (SPW). On days 7 and 14 each group was refilled with fresh bleaching paste. The restored teeth were thermocycled for 500x between 5°C and 55°C for 15 seconds in each cycled. Microleakage was assessed by dye penetration using Indian ink. After 24 hours, teeth was sectioned longitudinally at center of the filling and the leakage were measured under measuring microscope 25x (Wild,Heerbrugg). Results: The means leakage (SD) for the experimental groups A SPHP30; A SPHP3; A SPW; B SPHP30; B SPHP3; and B SPW were: 1,76 (0,303); 0,665 (0,172); 0,62 (0,165); 1,53 (0,450); 1,8 (0,338); 1,8 (0,351). One way ANOVA test showed there were significant differences between six experimental group (p<0,01). Post hoc tests (Tuckey HSD) demonstrated that Cavit G were significantly superior to SPHP3 and SPW as bleaching agent (p<0,01). Conclusion: Cavit provided better sealing ability than zinc phosphate cement. It suggested that the use of high concentration should be limited. Sodium perborate mixed with Hydrogen Peroxide 3% or distilled water appear to be less damaging bleaching agent.