Effects of D-arginine on Porphyromonas gingivalis biofilm.

Porphyromonas gingivalis (P. gingivalis) is one of the major pathogenic bacteria of periodontitis or peri-implantitis. P. gingivalis tends to attach to the implant's neck with the formation of biofilm, leading to peri-implantitis. d-arginine has been shown to have a potential antimicrobial role. In this study, P. gingivalis was cultured in Brain Heart Infusion broth together with d-arginine. After 3 days (inhibition) or 6 days (dissociation), these were characterized using crystal violet (CV) staining for the biofilm, extracellular polysaccharide (EPS) production from the biofilm, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay for biofilm activation. Furthermore, the P. gingivalis biofilm was observed by scanning electron microscopy (SEM). d-arginine effectively reduced biomass accumulation and promoted dissociation at concentrations of ≥50 mM and 100 mM, respectively. Through CV staining, d-arginine concentrations of EPS production from the biofilm for inhibition and dissociation effects was ≥50 mM and 100 mM, respectively. In addition, d-arginine affected biofilm activation for the corresponding concentrations: ≥60 mM for inhibition and ≥90 mM for dispersal. Under SEM observation, d-arginine changed the P. gingivalis biofilm structure in relatively high concentrations for inhibition or dissociation, respectively. The authors concluded that d-arginine could inhibit the formation of P. gingivalis biofilm and promote the dissociation of P. gingivalis biofilm.