Z-form extracellular DNA is a structural component of the bacterial biofilm matrix.

Biofilms are community architectures adopted by bacteria inclusive of a self-formed extracellular matrix that protects resident bacteria from diverse environmental stresses and, in many species, incorporates extracellular DNA (eDNA) and DNABII proteins for structural integrity throughout biofilm development. Here, we present evidence that this eDNA-based architecture relies on the rare Z-form. Z-form DNA accumulates as biofilms mature and, through stabilization by the DNABII proteins, confers structural integrity to the biofilm matrix. Indeed, substances known to drive B-DNA into Z-DNA promoted biofilm formation whereas those that drive Z-DNA into B-DNA disrupted extant biofilms. Importantly, we demonstrated that the universal bacterial DNABII family of proteins stabilizes both bacterial- and host-eDNA in the Z-form in situ. A model is proposed that incorporates the role of Z-DNA in biofilm pathogenesis, innate immune response, and immune evasion.

Evaluation of the caries-preventive effect of toothpaste containing surface prereacted glass-ionomer filler.

AIM: Although fluoride interventions have the most consistent benefit in preventing caries, caries still develop in high-risk individuals. Authors have evaluated the effectiveness of toothpastes containing surface prereacted glass-ionomer (S-PRG) filler in preventing tooth demineralization. METHODS: Human tooth enamel blocks were randomly assigned to six groups (30 blocks/group): no treatment (a), and toothpaste containing either 1500 ppm fluoride as sodium monofluorophosphate (NaMFP) (b), 0 wt% S-PRG (b), 1 wt% S-PRG (d), 5 wt% S-PRG (e), or 20 wt% S-PRG (f). Early caries developed on each block by 7-days demineralization using a microbial caries model. Mineral loss (Δz) and lesion depth (LD) were determined using transverse microradiography. RESULTS: Relative to the control, all toothpastes, except 0% S-PRG, significantly (analysis of variance, Tukey's, P<.0001) reduced Δz and LD at varying percentages. With regard to Δz, all comparisons were significant (P<.0001), except 0% S-PRG vs the control. Otherwise, S-PRG 1%, 5%, and 20% had 0.50, 0.37, and 0.27 times Δz compared to the control, respectively, while NaMFP had 0.61 times Δz compared to the control. LD followed an almost similar trend as Δz. CONCLUSIONS: The findings of the present study demonstrate the effectiveness of toothpaste containing S-PRG filler in inhibiting tooth demineralization in the presence of bacterial plaque, thus highlighting its potential as an effective caries-control tool for individuals at high risk of developing caries.