Biofilm formation on medical devices can induce complications. Graphene oxide/silver nanoparticles (GO/AgNPs) coated nickel-titanium (NiTi) alloy has been successfully produced. Therefore, the aim of this study was to determine the anti-bacterial and anti-biofilm effects of a GO/AgNPs coated NiTi alloy prepared by Electrophoretic deposition (EPD). GO/AgNPs were coated on NiTi alloy using various coating times. The surface characteristics of the coated NiTi alloy substrates were investigated and its anti-biofilm and anti-bacterial effect on Streptococcus mutans biofilm were determined by measuring the biofilm mass and the number of viable cells using a crystal violet assay and colony counting assay, respectively. The results showed that although the surface roughness increased in a coating time-dependent manner, there was no positive correlation between the surface roughness and the total biofilm mass. However, increased GO/AgNPs deposition produced by the increased coating time significantly reduced the number of viable bacteria in the biofilm (p < 0.05). Therefore, the GO/AgNPs on NiTi alloy have an antibacterial effect on the S. mutans biofilm. However, the increased surface roughness does not influence total biofilm mass formation (p = 0.993). Modifying the NiTi alloy surface using GO/AgNPs can be a promising coating to reduce the consequences of biofilm formation.

Dental caries is the most common chronic disease in children that causes negative effects on their health, development, and well-being. Early preventive interventions are key to reduce early childhood caries prevalence. An efficient strategy is to provide risk-based targeted prevention; however, this requires an accurate caries risk predictor, which is still lacking for infants before caries onset. We aimed to develop a caries prediction model based on the salivary microbiome of caries-free 1-y-old children. Using a nested case-control design within a prospective cohort study, we selected 30 children based on their caries status at 1-y follow-up (at 2 y old): 10 children who remained caries-free, 10 who developed noncavitated caries, and 10 who developed cavitated caries. Saliva samples collected at baseline before caries onset were analyzed through 16S rRNA gene sequencing. The results of β diversity analysis showed a significant difference in salivary microbiome composition between children who remained caries-free and those who developed cavitated caries at 2 y old (analysis of similarities, Benjamini-Hochberg corrected, P = 0.042). The relative abundance of Prevotella nanceiensis, Leptotrichia sp. HMT 215, Prevotella melaninogenica, and Campylobacter concisus in children who remained caries-free was significantly higher than in children who developed cavitated caries (Wilcoxon rank sum test, P = 0.024, 0.040, 0.049, and 0.049, respectively). These taxa were also identified as biomarkers for children who remained caries-free (linear discriminant analysis effect size, linear discriminant analysis score = 3.69, 3.74, 3.53, and 3.46). A machine learning model based on these 4 species distinguished between 1-y-old children who did and did not develop cavitated caries at 2 y old, with an accuracy of 80%, sensitivity of 80%, and specificity of 80% (area under the curve, 0.8; 95% CI, 44.4 to 97.5). Our findings suggest that these salivary microbial biomarkers could assist in predicting future caries in caries-free 1-y-old children and, upon validation, are promising for development into an adjunctive tool for caries risk prediction for prevention and monitoring.

Background: It has been claimed that an alkasite restorative material can neutralize acids produced by cariogenic bacteria from released hydrogen ions and enable to remineralization via calcium and fluoride ions. However, there is no evidence to support this assertion. Therefore, the aims of this study were to investigate the effect of the alkasite restorative material on the pH ofStreptococcus mutansbiofilm and dentin hardness.Methods: Streptococcus mutansbiofilms were formed on Filtek™ Z350 (FZ, a resin composite) and Cention® N (CN, the alkasite restorative material) and their pH determined after 24 h. Hydroxide, fluoride, and calcium-ions released from the materials were determined at 6 h, 1, 3, 7, 14, and 28 days. Dentin specimens were prepared from 14 human molars and divided into four quadrants. Quadrant 1 was a sound dentin control, quadrants 2–4 were chemically demineralized, and a cylinder of FZ and CN placed on the surfaces of quadrants 2 and 4, respectively. The microhardness of quadrants 1 and 3 were measured at depths of 20, 40, and 60 µm from the occlusal surface, and similarly of quadrants 2 and 4, after 30 days. Independent t-test, Mann–Whitney-U, and repeated-measure-ANOVA were used for data analysis.Results: The pH of biofilm on CN (4.45) was significantly higher (p < 0.05) than that on FZ (4.06). The quantity of all ions released from CN was significantly higher than from FZ. The hardness of demineralized dentin under CN was significantly higher than that of demineralized dentin at all depths, and higher than that of demineralized dentin under FZ at 20 and 40 µm.Conclusions: CN released hydroxide, fluoride, and calcium ions, which was associated with raising the biofilm pH and the hardness of demineralized dentin. All results indicated that CN had the potential to reduce the incidence of secondary caries.