Dispersion and Demineralization Inhibition Capacity of Novel Magnesium Oxide Nanoparticles Varnish on Enamel Surfaces against Streptococcus mutans (an In Vitro Study)

Abstract

This research analyzed the dispersion and impact of magnesium oxide nanoparticles (MgONPs) varnish on inhibiting enamel demineralization. A novel MgONPs varnish was prepared in absolute ethanol with rosin in 10%, 5%, 2.5%, and 1.25% concentrations. The samples were classified into six groups, including four tested with MgONPs varnish, one commercial 5% NaF varnish, and control groups of non-protected and sound dental enamel groups. Each group included five enamel samples and three broths of 20 mL per sample. The examinations were started by applying different concentrations of varnishes on the enamel surfaces, which were then exposed to Streptococcus mutans (S. mutans) in three sequences of time for 144 h. A scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to examine the MgONPs’ dispersion. Inductively coupled plasma optical emission spectroscopy (ICP-OES) was used to quantify the calcium (Ca) released from the enamel. The SEM and EDX evaluations of the enamel samples showed a significantly increased dispersion for the 5% MgONPs varnish, with the highest median. The ICP-OES test showed significant inhibition levels of the Ca release capacity in the 2.5% and 1.25% MgONPs varnishes, similar to the 5% NaF varnish. The MgONPs varnish revealed increasing dispersion of MgONPs, from 1.25% to 5%, and the maximum protection capacity was associated with the 1.25% and 2.5% varnishes, which was similar to the 5% NaF varnish in inhibiting the demineralization effect on enamel.