Physicochemical properties and apatite precipitation behavior of experimental calcium silicate-based cements doped with phosphate compounds

Abstract

<p>Objectives: This study aims to evaluate the solubility, pH, Ca^{2 +} release, setting time, and hydroxyapatite (HAp) formation of the tested materials. Methods: Four study groups were tested: NEX-MTA (NMTA; GC, Japan), NMTA with phosphorylated pullulan (MTA-PPL), NMTA with poly-PS (MTA-polyPS), and Biodentine (BD; Septodont, France). Solubility was measured after 7 and 28 days at 37 °C in deionized water. Ca²⁺ release and pH evaluation were performed after immersion in deionized water at 3 h, 24 h, 7 days, and 28 days using pH and Ca²⁺ meters. Setting times were determined with a Vicat apparatus, and apatite precipitation was evaluated through scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/ EDS) and Fourier transform infrared spectroscopy (FTIR) analysis 28 days in phosphate-buffered saline. Results: NMTA showed the lowest solubility; however, there was no statistically significant difference between NMTA and MTA-polyPS (P > 0.05). NMTA exhibited the most alkaline pH at all measured time points. Although MTA-polyPS consistently showed lower pH values than NMTA throughout the observation periods, no statistically significant differences were observed among MTA-polyPS, BD, and MTA-PPL at 28 days (P > 0.05). BD released the most Ca²⁺, with MTA-polyPS releasing the least. BD exhibited the shortest initial and final setting time (9.2 and 42 min, respectively), followed by MTA-polyPS, MTA-PPL, and NMTA. SEM/ EDS and FTIR indicated that MTA-polyPS had the highest apatite precipitation, with Ca/P ratios of 1.70 (NMTA) and 1.79 (MTA-polyPS). MTA-PPL and BD showed no significant apatite precipitation, with Ca/P ratios of 3.93 and 34.9, respectively. Significance: The incorporation of polyPS into calcium silicate-based cement may enhance apatite precipitation and accelerate the setting without altering the pH and solubility property.</p>