Association of arginine with a soluble source of calcium and fluoride: Anticaries and antibiofilm effect on root dentin

OBJECTIVE: The study aimed to evaluate in vitro anticaries and antibiofilm effects of combining arginine (Arg), calcium glycerophosphate (CaGP), and fluoride (F). METHODS: A saliva-derived inoculum was used to cultivate polymicrobial biofilms using an active adherence model. Bovine root dentin specimens (n = 10) were treated with: Negative Control (NC); F (110 ppm F); CaGP (0.05 %); Arg (0.8 %); F+CaGP; Arg+F; Arg+CaGP or Arg+F+CaGP. The outcomes evaluated were: biofilm acidogenicity (spent medium pH); biofilm composition (bacterial viability - total, aciduric and mutans streptococci-, alkali-soluble polysaccharides [ASP], and biofilm dry weight); and root dentin demineralization (surface Knoop hardness [KH], chemical composition, and subsurface mineral content). Data were analyzed using non-parametric mixed ANOVA, one-way ANOVA, or Kruskal-Wallis (α = 0.05). RESULTS: Arg-treated groups showed lower biofilm acidogenicity (pH>8.0) than the other groups (pH<5.5; p < 0.001, η²ₚ = 0.603). No statistical differences were found in the biofilm composition (mean or median range of microbial concentration [log 1+CFU/mL] and ASP for all the groups: total = 6.62-7.07, p = 0.189; aciduric = 4.83-5.88, p = 0.116; mutans streptococci = 4.57-5.35, p = 0.477; ASP = 0.02-1.16 μg/mg dry weight, p = 0.935). Arg+F+CaGP maintained the highest microhardness value (Mean = 61.1[SD = 10.6] KHN; %SH = 15.8) compared to F, Arg or CaGP groups (p < 0.001, η²ₚ = 0.769). Arg+F+CaGP group showed a statistically higher mineral gain compared to the other groups (Mean = 10.8[SD = 4.0] gHap.cm<sup>-3</sup>; p < 0.001, η²ₚ = 0.958). A higher amount of F ions was present in Arg+F and Arg+F+CaGP. CONCLUSION: The Arg+F+CaGP association reduced biofilm acidogenicity and root dentin demineralization (final KH and mineral content) compared to F. CLINICAL SIGNIFICANCE: As the synergistic use of arginine, fluoride, and calcium glycerophosphate helped mitigate biofilm acid production and protected dentin from demineralization, it has potential to be used in preventive and therapeutic approaches in Dentistry, especially in patients at high caries risks, as those with exposed root surfaces or reduced salivary flow.