Color Stability of Calcium Silicate-based Materials After Contact With Endodontic Solutions

Objectives: Bismuth oxide has been responsible for color discoloration of calcium silicate-based materials. MTA Angelus (Angelus, Londrina, Brazil) was modified with calcium tungstate (MTA HP Repair) and MTA Plus (Avalon Biomed, Bradenton, FL, USA) was modified with tantalum oxide as radiopacifier (NeoMTA Plus).The aim of this study was to evaluate the influence of endodontic solutions on color stability of White MTA Angelus, MTA HP Repair, MTA Plus and NeoMTA Plus.
Methods: Samples with 10 mm diameter and 1 mm height (n = 5) were immersed in distilled water (DW), 2.5% sodium hypochlorite (NaOCl) or 2% chlorhexidine (CHX) for 24 h. Color was evaluated by digital photography and spectrophotometry after immersion and after 7 days. Data were analyzed by ANOVA, Tukey-Krammer and paired t-test (p<0.05).
Results: The immersion in NaOCl promoted higher ΔE for MTA and MTA Plus than for MTA HP and NeoMTA Plus (p<0.05) resulting in dark discoloration after 24 h. After 7 days, MTA exhibited higher ΔE in comparison to other materials (p<0.05). The MTA Plus color was also influenced by CHX in both periods (p<0.05). The comparison between periods showed that MTA Angelus color was similar after 7 days (p < 0.05) while MTA Plus exhibited an increase on ΔE (p<0.05). The MTA HP and the NeoMTA Plus showed lower ΔE for all solutions, except Neo MTA Plus in DW, which presented higher ΔE values (p < 0.05) and it resulted in bright discoloration after 7 days (p < 0.05). The exposure of MTA HP and Neo MTA Plus to NaOCl and CHX also increased ΔE (p<0.05).
Conclusions: It could be concluded that MTA and MTA Plus resulted in a dark discoloration and they were affected by sodium hypochlorite and chlorhexidine solutions. The replacement of bismuth oxide as radiopacifier increases the color stability of materials.