Biointeractivity-related versus chemi/physisorption-related apatite precursor-forming ability of current root end filling materials

Abstract

Commercial root end filling materials, namely two zinc oxide eugenol-based cements [intermediate restorative material (IRM), Superseal], a glass ionomer cement (Vitrebond) and three calcium-silicate mineral trioxide aggregate (MTA)-based cements (ProRoot MTA, MTA Angelus, and Tech Biosealer root end), were examined for their ability to: (a) release calcium (Ca(2+) ) and hydroxyl (OH(-) ) ions (biointeractivity) and (b) form apatite (Ap) and/or calcium phosphate (CaP) precursors. Materials were immersed in Hank's balanced salt solution (HBSS) for 1-28 days. Ca(2+) and OH(-) release were measured by ion selective probes, surface analysis was performed by environmental scanning electron microscopy/energy dispersive X-ray analysis, micro-Raman, and Fourier transform infrared spectroscopy. IRM and Superseal released small quantities of Ca(2+) and no OH(-) ions. Uneven sparse nonapatitic Ca-poor amorphous CaP (ACP) deposits were observed after 24 h soaking. Vitrebond did not release either Ca(2+) or OH(-) ions, but uneven nonapatitic Ca-poor CaP deposits were detected after 7 days soaking. ProRoot MTA, MTA Angelus, and Tech Biosealer root end released significant amounts of Ca(2+) and OH(-) ions throughout the experiment. After 1 day soaking, nanospherulites of CaP deposits formed by amorphous calcium/magnesium phosphate (ACP) Ap precursors were detected. A more mature ACP phase was present on ProRoot MTA and on Tech Biosealer root end at all times. In conclusion, zinc oxide and glass ionomer cements had little or no ability to release mineralizing ions: they simply act as substrates for the possible chemical bonding/adsorption of environmental ions and precipitation of nonapatitic Ca-poor ACP deposits. On the contrary, calcium-silicate cements showed a high calcium release and basifying effect and generally a pronounced formation of more mature ACP apatitic precursors correlated with their higher ion-releasing ability.

Push-out bond strength of MTA HP, a new high-plasticity calcium silicate-based cement

“…Atmeh et al 18 demonstrated that Ca-Si cements facilitate the permeation of Ca and OH ions into the dentine, due to their caustic effect. It can be assumed that the improved ability to release remineralizing Ca and OH ions by Biodentine 19 is responsible for the improved formation of apatite at the interface 19,20 , and for micromechanical anchorage 21 . MTA HP showed improved push-out bond strength values compared with those of White MTA (p < 0.05).…”

Physicochemical properties of calcium silicate cements associated with microparticulate and nanoparticulate radiopacifiers

“…The hydroxyl ions released by the material are responsible for increasing the pH of the surrounding tissues. Biologically active materials, such as calcium silicate cements, can promote bone regeneration, and, for this reason, are recommended for healing periapical bone defects [41]. Furthermore, the release of hydroxyl ions during the hydration reaction creates an unfavorable environment for bacterial survival and proliferation [37].…”

Bioactivity of Mineral Trioxide Aggregate and Mechanism of Action

“…Although it is possible that some of these represent calcium-deficient apatite with variable degrees of lattice substitutions by cations such as Na + and Mg 2+ and anions such as Cl − , it is likely some of these crystalline morphologies represent the intermediate octacalcium phosphate (OCP) phase described in classic calcium phosphate characterisation studies. Formation of an intermediate OCP phase by MTA or MTA-like materials was sparsely discussed in the endodontic literature except in a couple of studies [52,128]. Indiscriminate use of the term 'hydroxyapatite' (HA) in most of these endodontic studies is reflected by the inadequate chemo-analytical techniques employed for characterising the calcium phosphate precipitates.…”