The purpose of this study was to investigate mechanistically the mechanical alterations, chemical dissolution, and interelated phenomenon of a commercially available calcium phosphate cement intended for use as a bone substitute. A controlled size fraction cement starting powder was characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive spectroscopy (EDS), and electric sensity zone technique, demonstrating that it was constituted primarily of tetracalcium phosphate (TTCP) and dicalcium phosphate anhydre (DCPA), with traces of hydroxyapatite (HA) and Type B CO{dollar}sb3{dollar} apatite.; The setting time of the cement was evaluated as a function of the powder/liquid (P/L) ratio and type of solution used as a liquid phase, according to specification number 8 of American Dental Association, and the results showed significant differences, with values ranging from 4 to 87 min. The diametral tensile strength, compressive strength, and flexural strength of the material were evaluated as a function of the P/L ratio, type of solution used, method of delivery, and exposure to physiological-like conditions. The results showed that the cement has a tensile and compressive strength of 7.22 and 46.71 MPa 3 h after the mixing which varies as a function of the P/L ratio and type of mixing solution. Strengths increase to an average of 9.74 and 56.51 MPa after a 24-hour time interval, which are greater comparatively than strengths known for cancellous bone; the flexural strength of the cement in four-point beading tests show values ranging from 10.53 to 13.50 MPa.; Finally, the compositional and structural alterations of the calcium phosphate cement were evaluated as a function of physiological-like solution and of physiological-like solution under applied cyclic load. It was observed that when the material was immersed in a neutral (pH 7.4) physiological-like solution, there was a gradual decrease of Ca and PO{dollar}sb4{dollar} concentrations, indicating deposition of a calcium phosphate layer (growth), characterized as phosphate substituted apatite. When the material was submitted to physiological simulated acidic conditions (pH 4.5), the Ca and PO{dollar}sb4{dollar} concentrations gradually increased, showing a dissolution process. The effect of applied cyclic load (1 Hz, 5 to 18 N) was evaluated under neutral and acidic conditions, and noticeable differences existed between loaded and non-loaded groups for neutral (pH 7.4) and acidic (pH 4.5) situations. Statistical analysis showed significant differences for the acidic conditions, which were associated with an increase in surface area due to microcrack formation and pits, probably resulting from higher ion diffusivity.
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