Effect of Internal Bleaching on Discoloration Caused by 4 Different Materials

Objectives :

In endodontics, mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM cement) are commonly used bioceramic materials. Regenerative endodontics often involves the use of double or triple antibiotic pastes (DAP or TAP), which are effective but may cause discoloration. This study aims to examine the effectiveness of internal bleaching in addressing discoloration caused by 4 different materials.

Methods:

 This in vitro study was conducted on 40 single-rooted anterior and premolar human teeth that did not have caries, restorations, obvious discoloration, or fractures and were extracted due to periodontal disease or orthodontic treatment. The teeth were randomly assigned to 4 groups (n=10). After root canal instrumentation, the baseline color of the specimens was measured using a spectrophotometer. After applying the aforementioned materials in the canals, access cavities were sealed with glass ionomer (GI), and the color of the specimens was measured again after 1 month to calculate color change (∆E). Internal bleaching was performed with 35% hydrogen peroxide 3 times within 3 weeks, and values were calculated at each time point. Data were analyzed using paired t-tests and 1-way analysis of variance (ANOVA).

Results:

 Clinically noticeable discoloration (∆E>3.7) occurred in the MTA Angelus (∆E=4.88) and TAP (∆E=17.3) groups. The ∆E of the TAP group was significantly higher than that of all other groups (P<0.05). The discoloration was borderline detectable in the CEM group (∆E=3.89) and clinically undetectable in the DAP group (∆E=2.02). Discoloration significantly improved after 3 rounds of bleaching in the TAP group (P<0.05), as well as after 2 rounds of bleaching in the MTA (P<0.05) and CEM (P<0.05) groups. In all groups, ∆E increased after each round of bleaching.

Conclusion :

The CEM cement may yield better results with lower discoloration compared to MTA and exhibit a more favorable response to internal bleaching. For canal disinfection using antibiotic paste, DAP is a good alternative to TAP.