Efficacy of the Probiotic <i>L. brevis</i> in Counteracting the Demineralizing Process of the Tooth Enamel Surface: Results from an In Vitro Study

Background. Enamel plays an essential role in protecting the underlying layers of the human tooth; therefore, preserving it is vital. This experimental study aimed to evaluate the potential ability of <i>L. brevis</i> to counteract the action of a demineralizing agent on dental enamel morphology and mineral composition in vitro. Methods. The sample consisted of 12 healthy human posterior teeth. The coronal portion of each tooth was subdivided into two equal parts longitudinally. The specimens were randomly divided into four groups: artificial saliva, <i>L. brevis</i> suspension, demineralizing agent (DA), and DA plus <i>L. brevis</i>. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to evaluate the surface micromorphology and the mineral content, respectively. The statistical analysis was conducted using a one-way ANOVA, followed by Tukey’s post hoc test. Results. SEM analysis did not highlight significant changes in the enamel microstructure of <i>L. brevis</i>-treated specimens compared to the control. DA-induced damage to the enamel structure was drastically reduced when the specimens were contextually exposed to the probiotic. The treatment with DA substantially reduced the weight % of crucial enamel minerals, i.e., Ca and P. Notably, the probiotic was able to reverse the demineralization process, bringing Ca and P weight % back to basal levels, including the Ca/P ratio. Conclusions. The findings indicate that <i>L. brevis</i> is able to efficiently protect the dental enamel surface from the damage caused by DA and increase the enamel resistance to demineralization. Overall, <i>L. brevis</i> confirms its efficacy in preventing or counteracting the action of carious lesions through a novel mechanism that protects the tooth surface under a chemical challenge that mimics the caries process.