Enamel remineralization potential of arginine-fluoride varnish in a multi-species bacterial pH-cycling model

Objectives: To examine the enamel fluoride uptake and remineralization potential of arginine-fluoride (Arg-NaF) varnishes in a simulated clinical condition using a multi-species bacterial pH-cycling model. Methods: L-Arginine (at 1 %, 2 %, and 4 % by wt.) was incorporated in a 5 % NaF varnish. Experimental and control groups were: 1 Arg-NaF; 2 % Arg-NaF; 4 % Arg-NaF; NaF and no treatment. Artificial incipient caries-like lesions were formed on 30 enamel specimen blocks (n = 6). The specimens underwent multi-species bacterial pH-cycling in an artificial mouth system using oral biofilm reactor for 72 h after treatment. The specimens were evaluated for mineral density using micro-CT, Ca/P ratio with SEM-EDX, enamel fluoride uptake (EFU) and plaque fluoride uptake (PFU). Results: Increasing concentrations of Arg in NaF varnish significantly increased the EFU of incipient caries-like lesions (p < 0.001). The PFU for 1 % Arg-NaF was significantly higher than 4 % Arg-NaF and the control NaF (p < 0.05). Post pH-cycling, Ca/P ratio with 1 %/2 % Arg-NaF was closest to hydroxyapatite (1.67). Mineral gain and % remineralization of 1 %/2 % Arg-NaF was significantly higher than the control NaF varnish (p < 0.05). Conclusion: The prebiotic L-arginine (at 1 %/2 % by wt.) in a 5 % NaF varnish enhanced the enamel fluoride uptake and remineralization potential of the conventional 5 % NaF varnish. Clinical significance: The Arg-NaF varnish addresses the limitations of fluorides on cariogenic biofilms. The Arg-NaF varnish appears a promising caries-preventive regimen that counters the pathogenic biofilms by Arg and promotes remineralization with fluorides. In high caries-risk patients, professional application of Arg-NaF varnish might aid to alleviate the global burden of dental caries.