**1. Introduction**

The synthesis and study of properties of new biomaterials has been emphasized lately with the improvement of nanotechnology. In this context, the development of nanomaterials has been the focus of many areas of chemistry, physics, and materials science because of the promising characteristics that these materials exhibit [1].

Nanotechnology aims to manipulate particles by creating new structures with favorable properties in many areas, such as medicine and dentistry [2], and new alternatives of treatment for oral pathologies are emerging. Metallic nanoparticles, in particular silver nanoparticles (AgNP), have been studied as an alternative antimicrobial agen<sup>t</sup> against a broad spectrum of species in the control of oral biofilms [3–5]. Although there are several studies where AgNP are used as antimicrobial agents, their mechanism of action is not completely understood. Kim et al. [6] and Besinis et al. [4] related their antimicrobial action to the toxicity resulting from free metal ions dissolution from the surface of the AgNP. In addition, AgNP would lead to oxidative stress through the generation of reactive oxygen species (ROS), interacting with cytoplasmic and nucleic acid components by inhibiting enzymes of the respiratory chain and changing the permeability of the cytoplasmatic bacterial membrane [7–11].

Among oral pathologies, dental caries is one of the most common diseases in humans that relates to genetics, saliva, and diet of the host [9]. *Streptococcus mutans* is the main cariogenic microorganism owing to its ability to produce acids and glucans from sugar metabolism, which exceed the buffering capacity of saliva [9–11] and leads by a localized and irreversible destruction of the tooth structure [9,12]. However, recent evidence indicates the presence of *C. albicans* and *S. mutans* in oral biofilms, suggesting that the interaction between them can lead to the development of caries [9,13,14]. *C. albicans* colonization depends on the presence of the bacteria, which, besides promoting adhesion sites, act as a carbon source for yeas<sup>t</sup> growth. On the other hand, yeasts reduce the levels of oxygen for streptococci [9]. Studies have shown the resistance of many microorganisms to antimicrobial agents currently used [15,16].

Studies since the 1930s [17] have reported the importance of using calcium phosphate derivatives for favouring the remineralization process in dental caries. Calcium glycerophosphate (CaGP) is an organic phosphate salt with anti-caries properties being demonstrated in studies carried out in monkeys [18] and in rats [19]. It is action in dental biofilms may be related to the increase of calcium and phosphate levels [20], buffering capacity [18], and reduction of the mass of the biofilms [21]. Becauses that it seems to interact with dental tissues [22], CaGP has been incorporated in dentifrices [23,24]. Do Amaral et al. [25] and Zaze et al. [26], when associating CaGP (0.25%) in toothpastes with fluoride at low concentrations, found the same efficacy against caries in enamel when compared to dentifrices that were supplemented with a higher concentration of fluoride demonstrating CaGP be an good option for oral products to both prevent caries and avoid fluorose in dental tissues.

The use of a biomaterial containing both an antimicrobial and a compound acting as a source of calcium phosphate for dental remineralization would have a grea<sup>t</sup> impact on the prevention and control of dental caries. Therefore, this study aimed to produce nanocompounds containing calcium glycerophosphate (CaGP) and silver nanoparticles (AgNP) by varying the reducing agen<sup>t</sup> of silver nitrate (sodium borohydride or sodium citrate), the concentration of silver (1% or 10%), and the CaGP forms (nano or microparticulated), and analyze its characterization and antimicrobial activity against ATCC strains of *Candida albicans* and *Streptococcus mutans*.
