Effect of tricalcium aluminate on the properties of tricalcium silicate-tricalcium aluminate mixtures: setting time, mechanical strength and biocompatibility

P>Aim To prepare biphasic mixtures by adding Ca3Al2O6 into Ca3SiO5 and to evaluate the effect of Ca3Al2O6 on physical and ex vivo biological properties of the Ca3SiO5/Ca3Al2O6 mixtures derived from mineral trioxide aggregate (MTA). Methodology Combinations of Ca3SiO5 and Ca3Al2O6 (0, 5%, 10% and 15%) powders were mixed with deionized water. After hydration, setting time, compressive strength, ex vivo bioactivity and biocompatibility of each mixture were investigated and compared to pure Ca3SiO5. Results With the addition of Ca3Al2O6 from 0% to 15%, the initial setting time and final setting time of the Ca3SiO5/Ca3Al2O6 mixtures decreased from 110 to 43 min and from 220 to 97 min, respectively (P < 0.05). However, the compressive strength increased from 6.75 to 16.20 MPa after one day (P < 0.05) and from 17.73 to 29.13 Mpa after 28 days. Furthermore, the mixtures with 10% Ca3Al2O6 or less had similar bioactivity and biocompatibility when compared to the pure Ca3SiO5. Conclusions The addition of Ca3Al2O6 into Ca3SiO5 accelerated the hydration process, reduced the setting time and improved the compressive strength. Furthermore, these mixtures were bioactive and biocompatible and had a stimulatory effect on the L929 cell growth when the content of Ca3Al2O6 was below 10%. Therefore, the mixtures with 10% Ca3Al2O6 produced the best compromise between hydration and ex vivo biological properties.