Apatite-type phases on MTA cements depend on soaking medium volume.

Objectives: The examination of the apatite formation (i.e.bioactivity) on a material surface dipped in a simulated body fluid is useful for predicting its in vivo bone bonding ability. The purpose of this study was to investigate the influence of the volume of DPBS (Dulbecco’s phosphate buffered saline used as simulated body fluid) on the apatite phases formed upon a commercial self-setting calcium–silicate MTA cement for endodontics that showed bioactivity. Materials and methods: White ProRoot MTA (Dentsply, Maillefer, Tulsa Dental Products, Tulsa, OK, USA)was prepared according to manufacturer directions to produce a cement paste. Cement disks (13mm diameter 1.6mm thickness) were prepared and immediately immersed in sealed containers into 5, 10 or 20mL of DPBS (i.e. 20 mL, 40mL and 80mL of medium for 1 g of cement paste, respectively). The surface of the disks was analyzed by ATR-FTIR spectroscopy after soaking for 7 days at 37◦C. Results: The B-type carbonated apatite (Ap) phase formed under the three different soaking conditions showed phosphate bands with different widths and different wavenumber positions. The amount of carbonate (C) decreased, increasing the volume of the DPBS soaking solution (i.e. the bands at about 1410 and 870cm−1 progressively decreased in intensity). Conclusions: The volume of the soaking simulated body fluid affects the nature of the apatite phase as well as the carbonate content. This must be taken into consideration in in vitro apatite-forming ability tests on biomaterials.