Arginine-fluoride varnish helps modulate biochemical composition of biofilm on treated enamel: Study

The study is published in the Journal of Dentistry.

Mohammed Nadeem Bijle and colleagues from the Paediatric Dentistry, Faculty of Dentistry, The University of Hong Kong, Hong Kong conducted the present study to examine the biochemical components of multi-species biofilm on the arginine (Arg)-sodium fluoride (NaF) varnish-treated enamel following bacterial pH-cycling.

l-arginine (at 1%, 2%, & 4% w/v.) was incorporated in a 5% NaF varnish. The experimental and control groups were: 1%, 2%, 4% Arg-NaF, NaF, and no treatment. Enamel blocks were prepared, acid-etched, varnish-treated and then subjected to 72 h bacterial pH-cycling in an oral biofilm reactor.

The organic (carbohydrates, proteins, amyloids, and eDNA) and inorganic components (calcium, inorganic phosphate, F) were assayed for the obtained biofilm suspensions. The biofilms were stained for exopolysaccharides (EPS)/bacteria and the respective proportions of live/dead bacteria was determined using confocal imaging.

The following results were seen-

a. The total carbohydrate content of the biofilm was the lowest for the 2% and 4% Arg-NaF (p < 0.05).

b. Except for 2% Arg-NaF, the biofilm proteins for 4% Arg-NaF were significantly higher than the other groups (p < 0.05).

c. The amyloids for Arg-NaF groups were significantly lower than the controls (p < 0.05).

d. The eDNA for 4% Arg-NaF was significantly higher than the controls (p < 0.05). e. The 2% and 4% Arg-NaF-treated enamel had increased biofilm Pi and F compared to the NaF-treated enamel (p < 0.05).

f. The proportion of biofilm EPS matrix to bacteria was significantly reduced in Arg-NaF groups compared to the controls (p < 0.05).

g. The dead bacterial proportions of 4% Arg-NaF were significantly higher than the controls (p < 0.05).

Hence, the authors concluded that "Higher concentrations (i.e. 2%/4%) of Arg in 5% NaF varnish have the potential to modulate the biochemical composition of the biofilm growing on the treated enamel."