A Repeated State of Acidification Enhances the Anticariogenic Biofilm Activity of Glass Ionomer Cement Containing Fluoro-Zinc-Silicate Fillers

Effects of Tooth Desensitizers on Streptococcus mutans Biofilm Formation Using a Modified Robbins Device Flow Cell System

This study aimed to assess the antibiofilm effects of dentin desensitizers using a modified Robbins device flow cell system. The test desensitizers were Saforide, Caredyne Shield, and Clinpro White Varnish. Standardized dentin specimens were prepared from human single-rooted premolars, treated with one of the materials, and mounted on the modified Robbins device flow cell system. Streptococcus mutans biofilms were developed for 24 h at 37 °C under anaerobic conditions. Scanning electron microscopy, fluorescence confocal laser scanning microscopy, viable and total cell counts, acid production, and gene expression analyses were performed. A wavelength-dispersive X-ray spectroscopy electron probe microanalyzer was used to analyze the ion incorporations. Clinpro White Varnish showed the greatest inhibition, suggesting its suppression of bacterial adherence and transcription of genes related to biofilm formation. Saforide reduced only the number of viable bacteria, but other results showed no significant difference. The antibiofilm effects of Caredyne Shield were limited. The uptake of ions released from a material into dentin varies depending on the element. Clinpro White Varnish is effective for the short-term treatment of tooth sensitivity due to dentin demineralization. It prioritizes remineralization by supplying calcium and fluoride ions while resisting biofilm formation.

Antibiofilm Properties and Demineralization Suppression in Early Enamel Lesions Using Dental Coating Materials

This study aimed to investigate the effects of dental coating materials on Streptococcus mutans biofilm formation. The test materials were PRG Barrier Coat (PRG), BioCoat Ca (BioC), and FluorDental Jelly (FluorJ). Bovine enamel specimens were demineralized to mimic early enamel lesions. The biofilm was developed on a specimen treated with one of the materials by using a modified Robbins device flow-cell system. Scanning electron and fluorescence confocal laser scanning microscopy, viable and total cell counts, and gene expression assessments of the antibiofilm were performed. Ion incorporation was analyzed using a wavelength-dispersive X-ray spectroscopy electron probe microanalyzer. All materials allowed biofilm formation but reduced its volume. FluorJ was the only material that inhibited biofilm accumulation and had a bactericidal effect, revealing 0.66 log CFU in viable cells and 1.23 log copy reduction in total cells compared with the untreated group after 24 h of incubation. The ions released from PRG varied depending on the element. BioC contributed to enamel remineralization by supplying calcium ions while blocking the acid produced from the biofilm. In summary, the dental coating materials physically prevented acid attacks from the biofilm while providing ions to the enamel to improve its mechanical properties.

pH-activated antibiofilm strategies for controlling dental caries

Dental biofilms are highly assembled microbial communities surrounded by an extracellular matrix, which protects the resident microbes. The microbes, including commensal bacteria and opportunistic pathogens, coexist with each other to maintain relative balance under healthy conditions. However, under hostile conditions such as sugar intake and poor oral care, biofilms can generate excessive acids. Prolonged low pH in biofilm increases proportions of acidogenic and aciduric microbes, which breaks the ecological equilibrium and finally causes dental caries. Given the complexity of oral microenvironment, controlling the acidic biofilms using antimicrobials that are activated at low pH could be a desirable approach to control dental caries. Therefore, recent researches have focused on designing novel kinds of pH-activated strategies, including pH-responsive antimicrobial agents and pH-sensitive drug delivery systems. These agents exert antibacterial properties only under low pH conditions, so they are able to disrupt acidic biofilms without breaking the neutral microenvironment and biodiversity in the mouth. The mechanisms of low pH activation are mainly based on protonation and deprotonation reactions, acids labile linkages, and H⁺-triggered reactive oxygen species production. This review summarized pH-activated antibiofilm strategies to control dental caries, concentrating on their effect, mechanisms of action, and biocompatibility, as well as the limitation of current research and the prospects for future study.