Calcium-Rich 13X Zeolite as a Filler with Remineralizing Potential for Dental Composites

A zeolite with high ion-exchange potential was used as an active filler with remineralizing potential in composites that can be applied in restorative dentistry. Two calcium-rich forms of the 13X zeolite were obtained by sodium to calcium ion exchange and mineralization of a hydroxyapatite layer. These fillers were also silanized and mixed with methacrylic resins and photoinitiators to obtain composite materials. First, the effectiveness of the filler preparation and silanization was confirmed by X-ray diffractometry, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, nitrogen adsorption/desorption measurements, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The physicochemical characteristics of composites with silanized and nonsilanized forms of sodium- and calcium-rich 13X zeolite fillers were examined. The degree of conversion, depth of cure, flexural and compressive strength, mass stability, and remineralizing potential, understood as the ability to release calcium ions in the conditions simulating a natural oral environment, were determined. The effect of ion exchange, hydroxyapatite mineralization, and silanization of fillers on the final composites' properties was examined. Composites with calcium-rich fillers proved to show the ability to release Ca2+ during incubation in saline for 14 days at 36.6 degrees C showing therefore remineralizing potential with good values of other parameters.