Anticaries Effects of Fluoride, Arginine, and Strontium in Chemical/Microbial Models

Objectives: Objective: The aim of this study was to evaluate the anticaries effect of fluoride (F), strontium (Sr), and arginine (Arg) in chemical and dual-species microbial models.
Methods: Methods: In the chemical model, artificial enamel caries lesions were pH cycled for 5 days with three daily treatments. Experimental groups were: deionized water (DIW), 226 ppm F (F), 452 ppm F (2F), 100 ppm Sr, 2% Arg (Arg), F+Sr, F+Arg, Sr+Arg, F+Sr+Arg. In the microbial model, a dual-species biofilm consisting of Actinomyces naeslundiiATCC12104 and Streptococcus mutans UA159 were used to form biofilm on sound enamel specimens. The experimental phase lasted 5 days, with treatments 2x/day. Experimental groups were: DIW, F, Sr, Arg, F+Sr+Arg. All lesions were characterized using Vickers surface microhardness (VHN). In the microbial model, biofilms were analyzed for log CFU of both bacteria and total biofilm dry weight. Data were analyzed using one-way ANOVA (chemical model) or both one-way ANOVA and Kruskal-Wallis tests (microbial model).
Results: Results: Chemical model: ΔVHN (mean±standard deviation/statistical groups) were: DIW/-23±56/a; F/18±39/ab; 2F/64±55/b; Sr/-21±31/a; Arg/9±85/ab; F+Sr/24±23/ab; F+Arg/31±40/ab; Sr+Arg/-12±40/a; F+Sr+Arg/39±44/ab (p≤0.005). Microbial model: Post-VHN were: DIW/240±87/a; F/210±89/a; Sr/227±59/a; Arg/224±95/a; F+Sr+Arg/180±71/a (p≤0.005). A. naeslundii log CFU/mg (mean±standard deviation/statistical groups) were: DIW/4.0±1.7/b; F/5.1±1.2/b; Sr/5.1±2.0/b; Arg/4.6±1.8/b; F+Sr+Arg/1.7±1.6/a ( p<0.0001).S. mutans log CFU/mg were: DIW/6.2±0.9/a; F/6.4±0.8/a; Sr/6.0±1.3/a; Arg/5.6±1.5/a; F+Sr+Arg/5.5±1.2/a ( p<0.1906). Total biofilm dry weight (mean±standard deviation statistical groups; all mg) were: DIW/1.0±0.6a; F/1.1±1.2/a; Sr/0.6±0.3/a; Arg/1.2±1.0/a; F+Sr+Arg/1.3±0.8/a (p<0.2553).
Conclusions: Conclusion: The combined treatment of F+Sr+Arg showed promising anticaries effect in vitro, especially in the presence of a cariogenic biofilm.