Bioadhesive liquid crystal system containing citral: effect against cariogenic biofilm and on dental enamel

This study evaluated the effects of a bioadhesive liquid crystal system containing citral on cariogenic biofilm and enamel demineralisation. Citral (C) at 10× and 15× the minimum inhibitory concentration (MIC) was incorporated into the formulation (F) (30% oleic acid, 50% alkoxylated cetyl alcohol, and 20% aqueous dispersion of poloxamer 1%), FC1 and FC2, respectively. Both formulations underwent physicochemical characterisation, including polarised light microscopy, rheology, adhesive strength, and citral release. For biofilm and enamel demineralisation analyses, polymicrobial biofilms were cultivated for 4 days on bovine enamel blocks and treated with the formulations (n = 14/group). Analyses included pH measurement, total bacteria, aciduric bacteria, and mutans streptococci quantification. Enamel demineralisation was assessed via surface hardness loss (SH%) and integrated hardness loss (KHN × µm). Data were analyzed using appropriate statistical tests, with significance set at 5%. FC1 and FC2 exhibited Newtonian fluid characteristics, releasing 22.9% and 40.7% of citral, respectively, over 24 h. FC2 released citral near the MIC between 1-3 h. FC2 treatment showed antimicrobial activity in biofilms, maintained pH levels closer to neutrality for longer periods, and reduced SH% and KHN × µm values. Thus, FC2 demonstrated adequate physicochemical properties, antimicrobial efficacy, and the ability to reduce enamel mineral loss under cariogenic conditions.