Removable dentures, traditionally made from polymethylmethacrylate (PMMA) due to its low cost, excellent aesthetic properties, stability, and ease of repair, can now be produced using digital methods such as additive or subtractive manufacturing [1], [2], [3], [4], [5]. Additive manufacturing by vat photopolymerization builds objects by depositing a light-curing liquid resin in successive layers, obtaining devices with high precision, in less time, and with less material waste [[1], [2], [3],[5], [6], [7]]. However, printed resin for denture bases has lower mechanical strength and higher adhesion of microorganisms than PMMA [3,4,6,8].

Filler particles such as ceramics [9], [10], [11], zirconia [2,3,7,12], titanium dioxide [1], graphene nanoplates [4], and phytochemicals [13] have been incorporated into printed resin to improve mechanical properties and prevent biofilm accumulation. Biofilm is part of the oral microbiome, a diverse environment that harbors a complex community of highly organized microorganisms surrounded by a self-secreted polysaccharide matrix [14,15]. Biofilms form on dentures due to the porous, rough, and hydrophobic nature of the resin [4,6,16], and contact with mucosal tissues causes denture stomatitis and oral candidiasis [4,6,15,16]. Proximity of dentures to the respiratory tract contributes to the aggravation of pulmonary diseases in prosthesis users who are elderly and often have systemic and immunity impairment [17], [18], [19], [20].

Candida is a genus of opportunistic fungi with more than 150 heterogeneous species, 20 of which are pathogenic [21]. Candida albicans causes oral candidiasis and denture stomatitis with its ability to adhere to biotic and abiotic surfaces, evade the host immune system by filamentation, transform from yeast to hyphae, and invade tissues [3,15,16,22]. Candida glabrata is found on the palatal mucosa and the surface of dentures in association with C. albicans [23]. Candida has synergistic interactions with the genera Streptococcus and Staphylococcus. Streptococcus mutans, a primary colonizing microorganism that facilitates the attachment of aciduric and acidogenic bacteria to cause dental caries [3,15,23,24], also provides nutrients such as lactic acid and carbohydrates for the growth of C. albicans [15]. Glycosyltransferase (gtf) B, a polysaccharide secreted by S. mutans, binds to α-mannan in the Candida cell wall and produces glucans for adhesion between the microorganisms [15]. The C. albicans cell wall adhesin Als3p binds to Staphylococcus aureus adhesins to transport them into the mucosa [22]. Production of β−1,3-glucan, extracellular DNA, and farnesol increases S. aureus resistance to drugs [25]. C. albicans and S. aureus have been co-isolated in diseases such as periodontitis, denture stomatitis, cystic fibrosis, keratitis, ventilator-associated pneumonia, urinary tract infections, and burns [22].

Despite an antagonistic relationship with Pseudomonas aeruginosa, primary lung infection with C. albicans increases the risk of secondary infection with P. aeruginosa [26]. This bacterium produces quorum sensing (QS) molecules such as pyocyanin, phenazine-1-carboximide, phenazines, and 3-oxo-HSL, which cause respiratory impairment, increase fermentation, decrease extracellular pH, and inhibit polymorphism, filamentation, and fungal metabolism [26,27]. However, Pseudomonas-Candida co-infections have increased Candida virulence and resistance to antifungal drugs. The multicellular aggregates and extracellular matrix components of Candida biofilm with these bacterial species form protective pockets that sequester antifungals, antibiotics, and antimicrobials and prevent their penetration [26].

Constant prescription of drugs for these infections can lead to antifungal and antibiotic resistance [4]. Silver nanoparticles (AgNPs) are considered nanoantibiotics that damage biofilm components; upon penetration, they interact with polysaccharides, lipids, proteins, and nucleic acids through chemical and electrostatic bonds, exerting antimicrobial activity [28]. Nanostructured silver vanadate decorated with silver nanoparticles (AgVO3) is a compound synthesized by Holtz et al. [29], whose vanadium nanowires stabilize AgNPs on their surface and release silver (Ag+) and vanadium (V4+ and V5+) ions to act on microbial structures [6,[29], [30], [31]]. These ions interact with sulfur groups in the microbial cell wall and, upon entering the cell, disrupt structures and biomolecules (ribosomes, mitochondria, proteins, and lipids), impair vital functions, induce reactive oxygen species (ROS) and free radicals, and cause lysis [14,32]. Ag+ binds DNA and coils the genetic material into a compacted structure that cannot replicate [33]. V4+ and V5+ interact with bacterial metabolic enzymes, form stable complexes, and cause oxidative stress in the cell [29].

AgVO3 has been incorporated into self-cured and heat-cured resins and other dental materials and has shown antimicrobial activity against monospecies biofilms of C. albicans, S. mutans, S. aureus and P. aeruginosa [30,31,[34], [35], [36], [37]]. In a multi-species biofilm, heat-cured resin with 10 % AgVO3 showed activity against S. mutans and did not affect physical properties related to biofilm adhesion such as roughness and wettability [6]. The incorporation of this nanomaterial into printed resin and the evaluation of its antimicrobial activity in multi-species biofilms have not yet been performed. Therefore, this study aimed to incorporate AgVO3 into heat-cured (HC) and 3D printed (3DP) resins at concentrations of 2.5 %, 5 % and 10 % and to evaluate its antimicrobial activity in two multi-species biofilms: (1) Candida albicans, Candida glabrata and Streptococcus mutans, (2) Candida albicans, Pseudomonas aeruginosa and Staphylococcus aureus, and wettability with distilled water and artificial saliva. The null hypothesis tested in this study was that the incorporation of AgVO3 does not affect the antimicrobial activity of HC and 3DP for the two biofilm models, nor the wettability with water and saliva.