Comparison of solubility rate of WMTA (white mineral trioxide aggregate) in acidic and neutral environment

Abstract

Solubility is an important characteristic of dental materials, with a direct effect on the sealing potential and longevity of the materials influence. MTA, as an endodontic filling material, may be used in various environmental conditions, including an environment with a low pH value, which influences its physical and chemical properties. The aim of the present study was to evaluate solubility of WMTA in an acidic environment. Methods: Twenty-four metal rings measuring 2 mm 20 mm were prepared, filled with 1 gr of WMTA and randomly divided into two groups of 12. The samples in groups 1 and 2 were placed in synthetic tissue fluid with pH values of 7.4 and 4.4, respectively. The samples were then allowed to set in an incubator at 37C and 100% relative humidity for 24 hours. After desiccating the samples and calculating the initial dry weights, the samples in groups 1 and 2 were transferred to beakers containing 50 mL of synthetic tissue fluid with pH values of 7.7 and 4.4. Solubility of WMTA samples were calculated at 1-, 2-, 5-, 9-, 14-, 21-, 30-, 50 and 78-day intervals by calculating the ratio of desiccated samples after retrieval from the beakers subsequent to evaporating the content to the initial weight of each sample. In addition, at the end of the study weight change of each sample was calculated. Data was analyzed with one way ANOVA and Bonferroni and P < 0.03 was considered significant. Results: The total solubility of WMTA in groups 1 and 2 were -9.1796% 1.9158 and -1.1192%2.6236, (p=0.028) with weight changes of 9.1574% 2.1432 and 7.3276%1.5823, respectively(p=0.002). Statistical analysis revealed significant differences between the two groups. Conclusion: According to the results of the present study, solubility of WMTA increases in acidic environments. Therefore, additional therapeutic precautions should be taken to decrease inflammation; otherwise, WMTA should be placed at greater thicknesses.