Among the available methods of enamel strengthening, fluoride varnish (FV) treatment has relatively better results. On the other hand, cold plasma technology has shown promising capacities in sterilizing the environment, surface modification, and improving adhesion. Accordingly, this study aimed to increase the adhesion of FV to the enamel surface to prolong the enamel interaction with FV with subsequently increased fluoride uptake by enamel. Emphasizing that the change in adhesion is evidence-based and has not been explicitly measured. For this purpose, we randomly divided twenty bovine teeth into two groups A (consisting of four teeth) and B (composed of four subgroups, each containing four teeth). Samples of group A and one specimen of each subset B investigated the effect of using Helium-DBD (He-DBDJ), Argon (ArJ), and Air-DBD jet on the enamel surface. Other B specimens are devoted to studying the release of FV fluoride ions from processed enamel. Two diagnostic techniques, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), have been utilized to examine the samples' surface morphology and chemical analysis, respectively. Finally, the release of fluoride ions into distilled water was measured by an ion-selective electrode (ISE). SEM images showed that ArJ and Air-DBD significantly damaged enamel hexagonal structures, whereas, in the case of He-DBDJ, the hexagonal structures have only altered from convex to concave. EDX indicated an increase in calcium to phosphorus ratio and the amount of fluoride and sodium uptake on the enamel surface layer in the group processed with He-DBDJ plasma. The latter helps restore the damaged parts of the enamel. Analysis of fluoride released from the FV did not show a significant change owing to plasma processing (P ≤ 0.112). The combination of cold plasma and fluoride varnish treatment on the enamel surface might be considered as a more promising approach to increasing enamel resistance to tooth decay.

Enamel strengthening to prevent the first stage of caries has been an essential issue in oral health recently. Among the available methods to increase enamel strength, fluoride varnish treatment has relatively better results in preventing tooth decay. Cold plasma capabilities in sterilizing the environment, surface modification, and improving adhesion are well known. Accordingly, this study aims to increase the enamel layer's adhesion hoping that the intensity and time of enamel interaction with FV and the absorption of fluoride ions will increase. Accordingly, we randomly divided twenty bovine teeth into two groups A (consisting of four teeth) and B (composed of four subgroups, each containing four teeth). Samples of group A and one specimen of each subset B investigate the effect of using Helium-DBD (He-DBDJ), Argon (ArJ), and Air-DBD jet on the enamel surface. Other B specimens are devoted to the study of the release of FV fluoride ions from processed enamel. The scanning electron microscope (SEM) images show that although ArJ and Air-DBD have significantly damaged the enamel's hexagonal structures, they are only changed from convex to concave in the He-DBDJ case. For this reason, enamel effectively enhances the capacity to accept more FV. The energy-dispersive X-ray spectroscopy (EDX) indicates an increase in calcium ratio to phosphorus and the amount of fluoride and sodium absorption in the enamel layer in processing with He-DBDJ plasma. The latter helps restore the damaged parts of the enamel. Analysis of fluoride released from the FV did not show a significant change owing to plasma processing. The combination of Cold plasma and varnish fluoride on treatment enamel could be unique ability to improve reinforcement of tooth enamel against of tooth decay.