## 1 Introduction  
Despite ongoing efforts to manage dental caries, it remains one of the most widespread chronic conditions in children and continues to represent a major global public health issue due to its high prevalence and significant social impact [1, 2]. Dental caries develops through a dynamic cycle of demineralization and remineralization, driven by acid-producing bacteria within a mature and well-organized dental biofilm that degrades tooth enamel [3].  
Fluoride remains the gold standard in caries prevention due to its ability to enhance enamel remineralization and inhibit demineralization [4]. Among the various delivery methods, fluoride varnishes are particularly effective because they adhere well to the enamel surface, allowing prolonged contact and the sustained release of fluoride ions. This interaction promotes the formation of protective compounds such as fluorapatite and calcium fluoride, which improve enamel resistance to acid attacks [5, 6]. The remineralization effect of fluoride depends largely on the presence of calcium and phosphate ions in saliva and plaque [7].  
In recent years, dental varnishes have evolved to include bioactive compounds aimed at enhancing their anticariogenic and remineralizing properties [8]. These novel formulations are designed not only to prevent tooth decay but also to promote enamel repair through the sustained release of active agents. In particular, bioactive substances with remineralizing potential have gained attention for their ability to reinforce enamel structure and reverse early carious lesions [9, 10].  
Compounds derived from plants present a broad spectrum of biological activities beneficial to dental health [11, 12, 13, 14]. Among the compounds currently under study is trans, trans-farnesol (_tt_-farnesol), found in propolis, which possess the potential to suppress the acidogenic activity of _Streptococcus mutans_ (_S. mutans_) in biofilm [14, 15]. Another natural compound currently in vogue is quercetin, a flavonoid that demonstrates the ability to inhibit the formation of _S. mutans_ biofilm by reducing its metabolic activity [16]. It also presents remineralizing activity by stabilizing the collagen matrix due to its ability to form bonds with collagen cross-links [17]. Additionally, recent research has drawn attention to theobromine, an alkaloid naturally present in cocoa beans and coffee, which belongs to the class of methylxanthines [18]. When associated with calcium and phosphate ions, theobromine can promote an enlargement of hydroxyapatite crystals, thus contributing to the enhancement of enamel microhardness and resistance to mineral dissolution during acid challenge [18, 19].  
Given the dynamic process of de-remineralization in caries development, the combination of various bioactives in dental varnishes could enable the enhancement of complementary properties, such as antimicrobial activity, remineralization potential, and adhesion to the dental surface. Such combinations may offer a more effective anticariogenic therapy. Therefore, the present study assessed the effect of varnishes containing _tt_-farnesol, quercetin, and theobromine and the combination of these compounds in two concentrations on enamel demineralization. The null hypothesis examined in the study was that there would be no meaningful difference between varnishes containing different concentrations of bioactives on enamel demineralization.