Association between Salivary Hormones, Dental Caries, and Cariogenic Microorganisms during Pregnancy.

Objective: This study aimed to identify the salivary levels of six hormones (progesterone, estradiol, testosterone, cortisol, thyroxine T3, and triiodothyronine T4) in pregnant women, and to assess the association between salivary hormones, dental caries, and cariogenic microorganisms. Methods: This cross-sectional study included 181 low-income US pregnant women who were in their third trimester. Demographic details, oral hygiene practices, and medical backgrounds were obtained via questionnaires and medical records. Calibrated dentists obtained data on plaque index and caries status through comprehensive oral examinations. Unstimulated saliva was collected 2 h before eating and brushing. Salivary hormones were measured with a multiplex assay. Oral Streptococcus mutans (S. mutans) and Candida albicans (C. albicans) were quantified via colony-forming unit (CFU) counts. A latent model was used to generate clusters of pregnant women based on salivary hormone levels, followed by post-clustering analysis. Factors associated with salivary cariogenic microorganisms were further evaluated via multiple regression analyses. Results: Estradiol, progesterone, testosterone, cortisol, T3, and T4 in saliva were detectable at rates of 92%, 97%, 77%, 99%, 71%, and 50%, respectively. Three distinct participant clusters (high, intermediate, and low) were identified based on salivary hormone levels. Intermediate-level and high-level clusters had increased numbers of decayed teeth, decayed surfaces, ICDAS scores, and salivary S. mutans and C. albicans, compared to the low-level cluster (p < 0.05). Covariate analysis demonstrated that the high-level cluster was positively associated with salivary carriage of S. mutans (CFU/mL) (p < 0.05). Participants with higher levels of progesterone, estradiol, testosterone, and cortisol were associated with a high carriage status of S. mutans in saliva (>105 CFU/mL) (p < 0.05). Conclusions: This study demonstrated the feasibility of detecting salivary hormones during pregnancy and revealed the positive association between salivary steroid hormones and cariogenic pathogens.

Effects of Nystatin oral rinse on oral Candida species and Streptococcus mutans among healthy adults.

OBJECTIVES: To examine the effect of Nystatin oral rinse on oral Candida species and Streptococcus mutans carriage. MATERIALS AND METHODS: Twenty healthy adults with oral candidiasis participated in the single-arm clinical trial and received Nystatin oral rinse for 7 days, 4 applications/day, and 600,000 International Units/application. Demographic-socioeconomic-oral-medical conditions were obtained. Salivary and plaque Candida species and Streptococcus mutans were assessed at baseline and 1-week and 3-month follow-ups. Twenty-four salivary cytokines were assessed. Candida albicans isolates underwent Nystatin susceptibility test. RESULTS: Half of participants (10/20) were free of salivary C. albicans after using Nystatin rinse. Salivary S. mutans was significantly reduced at 3-month follow-up (p < 0.05). Periodontal status reflected by bleeding-on-probing was significantly improved at 1-week and 3-month follow-ups (p < 0.05). Plaque accumulation was significantly reduced at 1-week follow-up (p < 0.05). Interestingly, the responses to Nystatin oral rinse were not associated with race, gender, age, oral hygiene practice, adherence to Nystatin rinse, or sweet consumption (p > 0.05). No C. albicans isolates were resistant to Nystatin. Furthermore, salivary cytokine eotaxin and fractalkine were significantly reduced at 3-month follow-up among participants who responded to Nystatin rinse (p < 0.05). CONCLUSIONS: The study results indicate that oral antifungal treatment had an effect on S. mutans salivary carriage. Future clinical trials are warranted to comprehensively assess the impact of antifungal treatment on the oral flora other than S. mutans and Candida. CLINICAL RELEVANCE: Due to the potential cariogenic role of oral Candida species, antifungal approaches shed new light on the prevention and management of dental caries from a fungal perspective.

Effect of Probiotic Lactobacillus plantarum on Streptococcus mutans and Candida albicans Clinical Isolates from Children with Early Childhood Caries.

Probiotics interfere with pathogenic microorganisms or reinstate the natural microbiome. Streptococcus mutans and Candida albicans are well-known emerging pathogenic bacteria/fungi for dental caries. In this study, three probiotic Lactobacilli strains (Lactobacillus plantarum 8014, L. plantarum 14917, and Lactobacillus salivarius 11741) were tested on S. mutans and C. albicans clinical isolates using a multispecies biofilm model simulating clinical cariogenic conditions. The ten pairs of clinical isolates of S. mutans and C. albicans were obtained from children with severe early childhood caries. Our study findings show a remarkable inhibitory effect of L. plantarum 14917 on S. mutans and C. albicans clinical isolates, resulting in significantly reduced growth of S. mutans and C. albicans, a compromised biofilm structure with a significantly smaller microbial and extracellular matrix and a less virulent microcolony structure. FurTre, plantaricin, an antimicrobial peptide produced by L. plantarum, inhibited the growth of S. mutans and C. albicans. The mechanistic assessment indicated that L. plantarum 14917 had a positive inhibitory impact on the expression of S. mutans and C. albicans virulence genes and virulent structure, such as C. albicans hypha formation. Future utilization of L. plantarum 14917 and/or its antimicrobial peptide plantaricin could lead to a new paradigm shift in dental caries prevention.

Effect of Nystatin on Candida albicans - Streptococcus mutans duo-species biofilms.

OBJECTIVE: To assess the effect of Nystatin on Candida albicans and Streptococcus mutans duo-species biofilms using an in vitro cariogenic biofilm model. DESIGN: Biofilms were formed on saliva-coated hydroxyapatite discs under high sugar challenge (1 % sucrose and 1 % glucose), with inoculation of 105CFU/ml S. mutans and 103CFU/ml C. albicans. Between 20 and 68 h, biofilms were treated with 28,000 IU Nystatin solution, 5 min/application, 4 times/day, to mimic the clinical application. Biofilm's three-dimensional structure was assessed using multi-photon confocal microscopy. The expression of C. albicans and S. mutans virulence genes was assessed via real-time PCR. Duplicate discs were used in 3 independent repeats. t-test and Mann-Whitney U test were used to compare outcomes between treatment and control group. RESULTS: Nystatin treatment eliminated C. albicans in biofilms at 44 h. Nystatin-treated group had a significant reduction of biofilm dry-weight and reduced S. mutans abundance by 0.5 log CFU/ml at 44 and 68 h (p < 0.05). Worth noting that biomass distribution across the vertical layout was altered by Nystatin treatment, resulting in less volume on the substrate layers in Nystatin-treated biofilms compared to the control. Reduction of microcolonies size and volume was also observed in Nystatin-treated biofilms (p < 0.05). Nystatin-treated biofilms formed unique halo-shaped microcolonies with reduced core EPS coverage. Furthermore, Nystatin-treated biofilms had significant down-regulations of S. mutans gtfD and atpD genes (p < 0.05). CONCLUSIONS: Nystatin application altered the formation and characteristics of C. albicans and S. mutans duo-species biofilms. Therefore, developing clinical regimens for preventing or treating dental caries from an antifungal perspective is warranted.

The effect of Er:YAG laser treatment on biofilm formation on titanium and zirconia disc surfaces.

BACKGROUND: Lasers represent a promising method for implant decontamination, but evidence on implant surface changes and subsequent biofilm formation is limited. This study aimed to assess the effect of erbium-doped yttrium aluminum garnet (Er:YAG) laser treatment on zirconia and titanium discs, and the differences in biofilm formation as a result of surface alterations. METHODS: A two-stage (in vitro and in vivo) experiment utilizing Er:YAG laser on titanium and zirconia discs was performed. In vitro, surface alterations, roughness, and elemental-material weight differences following laser treatment were assessed using scanning electron microscopy and atomic force microscopy. In vivo, four participants wore custom-made intra-oral stents, embedded with laser-treated and untreated titanium and zirconia discs overnight. Biofilm-coated discs were stained using nucleic acid fluorescence dye and visualized using multiphoton confocal laser scanning microscopy. Biofilm 3D structure, biomass, thickness, and live-to-dead bacteria ratio were assessed. RESULTS: Both titanium and zirconia discs treated with Er:YAG laser resulted in visual surface alterations, but showed no significant change in average surface roughness (titanium P = 0.53, zirconia P = 0.34) or elemental-material-weight (titanium, P = 0.98), (zirconia, P = 0.96). No significant differences in biofilm biomass, average thickness, and live-to-dead bacteria ratio of laser-treated titanium and zirconia discs were identified compared to untreated groups (titanium P > 0.05, zirconia P > 0.05). Generally, zirconia discs presented with a lower live-to-dead bacteria ratio compared to titanium discs, regardless of laser treatment. CONCLUSION: Er:YAG laser treatment of titanium and zirconia implant surfaces does not significantly affect surface roughness, elemental material weight, or early biofilm formation in the oral cavity.

Artificial intelligence-powered smartphone application, AICaries, improves at-home dental caries screening in children: Moderated and unmoderated usability test.

Early Childhood Caries (ECC) is the most common childhood disease worldwide and a health disparity among underserved children. ECC is preventable and reversible if detected early. However, many children from low-income families encounter barriers to dental care. An at-home caries detection technology could potentially improve access to dental care regardless of patients' economic status and address the overwhelming prevalence of ECC. Our team has developed a smartphone application (app), AICaries, that uses artificial intelligence (AI)-powered technology to detect caries using children's teeth photos. We used mixed methods to assess the acceptance, usability, and feasibility of the AICaries app among underserved parent-child dyads. We conducted moderated usability testing (Step 1) with ten parent-child dyads using "Think-aloud" methods to assess the flow and functionality of the app and analyze the data to refine the app and procedures. Next, we conducted unmoderated field testing (Step 2) with 32 parent-child dyads to test the app within their natural environment (home) over two weeks. We administered the System Usability Scale (SUS) and conducted semi-structured individual interviews with parents and conducted thematic analyses. AICaries app received a 78.4 SUS score from the participants, indicating an excellent acceptance. Notably, the majority (78.5%) of parent-taken photos of children's teeth were satisfactory in quality for detection of caries using the AI app. Parents suggested using community health workers to provide training to parents needing assistance in taking high quality photos of their young child's teeth. Perceived benefits from using the AICaries app include convenient at-home caries screening, informative on caries risk and education, and engaging family members. Data from this study support future clinical trial that evaluates the real-world impact of using this innovative smartphone app on early detection and prevention of ECC among low-income children.

Lactobacillus plantarum Disrupts S. mutans-C. albicans Cross-Kingdom Biofilms.

Dental caries, an ecological dysbiosis of oral microflora, initiates from the virulent biofilms formed on tooth surfaces where cariogenic microorganisms metabolize dietary carbohydrates, producing acid that demineralizes tooth enamel. Forming cariogenic biofilms, Streptococcus mutans and Candida albicans are well-recognized and emerging pathogens for dental caries. Recently, probiotics have demonstrated their potential in treating biofilm-related diseases, including caries. However, limited studies have assessed their effect on cariogenic bacteria-fungi cross-kingdom biofilm formation and their underlying interactions. Here, we assessed the effect of four probiotic Lactobacillus strains (Lactobacillus rhamnosus ATCC 2836, Lactobacillus plantarum ATCC 8014, Lactobacillus plantarum ATCC 14917, and Lactobacillus salivarius ATCC 11741) on S. mutans and C. albicans using a comprehensive multispecies biofilm model that mimicked high caries risk clinical conditions. Among the tested probiotic species, L. plantarum demonstrated superior inhibition on the growth of C. albicans and S. mutans, disruption of virulent biofilm formation with reduced bacteria and exopolysaccharide (EPS) components, and formation of virulent microcolonies structures. Transcriptome analysis (RNA sequencing) further revealed disruption of S. mutans and C. albicans cross-kingdom interactions with added L. plantarum. Genes of S. mutans and C. albicans involved in metabolic pathways (e.g., EPS formation, carbohydrate metabolism, glycan biosynthesis, and metabolism) were significantly downregulated. More significantly, genes related to C. albicans resistance to antifungal medication (ERG4), fungal cell wall chitin remodeling (CHT2), and resistance to oxidative stress (CAT1) were also significantly downregulated. In contrast, Lactobacillus genes plnD, plnG, and plnN that contribute to antimicrobial peptide plantaricin production were significantly upregulated. Our novel study findings support further assessment of the potential role of probiotic L. plantarum for cariogenic biofilm control.