In-vitro evaluation of various solvents for retrieval of mineral trioxide aggregate and their effect on microhardness of dentin

AIM: Organic acids have the potential to decrease the strength of mineral trioxide aggregate (MTA) during retreatment. However, this might cause alterations in dentin composition and structure. The aim of this study was to assess the efficacy of chemicals on surface microhardness of white MTA (WMTA) and dentin. MATERIALS AND METHODS: White MTA-Angelus(®) was mixed and packed into tooth molds. Six experimental groups (n = 15) were formed and exposed to 2% carbonic acid, 2% chlorhexidine gluconate, 5.25% sodium hypochlorite, 10% citric acid, 20% tartaric acid, and normal saline for 10 min and 20 min intervals on 1 and 21 days of setting, respectively. Vickers microhardness of WMTA and dentin for each specimen was measured before and after exposure. Data were subjected to repeated-analysis of variance (ANOVA) and post-hoc tests. RESULTS: Carbonic acid was effective in significantly reducing the surface hardness of WMTA on both 1 and 21 days; followed by citric and tartaric acid (P < 0.05). Two percent chlorhexidine gluconate and NaOCl were effective on 1-day set WMTA. All chemicals, except 2% chlorhexidine, decreased microhardness of dentin significantly (P < 0.05) at 20 min interval. CONCLUSION: Cautious use of these chemicals not exceeding 10 min is mandatory to prevent significant alterations in mechanical properties of tooth during MTA retrieval.