Physical, mechanical and antibacterial properties of the orthodontic adhesive doped with S-TiO2.

Orthodontic adhesive doped with sulfur-modified TiO2 promotes antibacterial effect. The objective of the study was to characterize the physical, mechanical and antibacterial properties of the orthodontic bracket adhesive, doped with modified titanium dioxide nanoparticles. Sulfur-doped TiO2 was synthetized and morphological topography was analyzed with TEM and SEM imaging. The catalytic performance during the degradation of rhodamine B was assessed. Nanomaterial was added at four concentration (1, 3, 6, and 10 wt%) to a commercial orthodontic adhesive. The shear bond strength and microhardness of a resin-based orthodontic adhesive containing S-TiO2 were evaluated. The inhibitory effect of the pure and doped adhesives against Escherichia coli and Streptococcus mutans was examined. As the results, the highest antimicrobial activity and good adhesive properties were noticed for light-cured orthodontic adhesive doped with 3% of S-TiO2. In this case, orthodontic adhesives with strong and long-lasting bactericidal properties can be created through the incorporation of modified TiO2 without negatively influencing microhardnesses, and bonding ability. White spot lesion and demineralization, which occurs very often in patients during orthodontic treatment, can be therefore minimized.

Low Salivary IgA Levels Against PAc (361-386) as a Risk Factor for Root Caries in Older Adults.

OBJECTIVES: This study aimed to assess the intricate relationship between salivary IgA antibody levels to PAc (361-386) (PPA), mutans streptococci colonization, and root caries development in older adults. MATERIALS AND METHODS: This study included 307 participants aged 76 years residing in Niigata city, Japan. Clinical oral examinations were performed at baseline in 2004 and 1 year later, during which the total number of untreated and treated root caries was assessed using the root decayed, filled tooth (DFT) index. The stimulated saliva samples were collected using the spitting method during the baseline survey. Salivary IgA antibody levels to amino acid residues 361-386 of Streptococcus mutans PAc were quantified using an enzyme-linked immunosorbent assay. Statistical analyses, including the χ2 test, Mann-Whitney U test, and logistic regressions, were performed to examine the association of increased root DFT with the independent variables. RESULTS: Among the 307 participants (53.1% men), the mean root DFT at baseline was 3.77 ± 3.66, and 36.5% of the study sample exhibited increased root DFT after 1 year with a mean increment of 0.36 ± 0.48. Participants with increase in root DFT after 1 year had significantly higher rates of low PPA levels (≤ 25th percentile) than those without increased root DFT (p = 0.020). Low PPA levels (≤ 25th percentile) were significantly more likely to have an increased risk of root caries development compared with PPA levels > 25th percentile (adjusted OR: 1.88, 95% CI: 1.09-3.25). CONCLUSION: Low PPA levels and root caries incidence correlated significantly, suggesting that low levels of salivary IgA antibody to PAc (361-386) may serve as a risk factor for increased root caries in older adults.

Biological Effects of Double-Layered Hydroxyapatite and Zirconium Oxide Depositions on Titanium Surfaces.

Purpose: This study aimed to confirm the synergy effect of these two materials by evaluating osteoblast and antibacterial activity by applying a double-layered hydroxyapatite(HA) zirconium oxide(ZrO2) coating to titanium. Methods: The specimens used in this study were divided into four groups: a control group (polished titanium; group T) and three experimental groups: Group TH (RF magnetron sputtered HA deposited titanium), Group Z (ZrO2 ALD deposited titanium), and Group ZH (RF magnetron sputtered HA and ZrO2 ALD deposited titanium). The adhesion of Streptococcus mutans (S.mutans) to the surface was assessed using a crystal violet assay. The adhesion, proliferation, and differentiation of MC3T3-E1 cells, a mouse osteoblastic cell line, were assessed through a WST-8 assay and ALP assay. Results: Group Z showed a decrease in the adhesion of S. mutans (p < 0.05) and an improvement in osteoblastic viability (p < 0.0083). Group TH and ZH showed a decrease in adhesion of S. mutans (p < 0.05) and an increase in osteoblastic cell proliferation and cell differentiation (p < 0.0083). Group ZH exhibited the highest antibacterial and osteoblastic differentiation. Conclusion: In conclusion double-layered HA and ZrO2 deposited on titanium were shown to be more effective in inhibiting the adhesion of S. mutans, which induced biofilm formation, and increasing osteoblastic differentiation involved in osseointegration by the synergistic effect of the two materials.

Antibacterial properties of mesoporous silica coated with cerium oxide nanoparticles in dental resin composite.

Cerium oxide nanoparticles are known for their antibacterial effects resulting from Ce3+ to Ce4+ conversion. Application of such cerium oxide nanoparticles in dentistry has been previously considered but limited due to deterioration of mechanical properties. Hence, this study aimed to examine mesoporous silica (MCM-41) coated with cerium oxide nanoparticles and evaluate the antibacterial effects and mechanical properties when applied to dental composite resin. Cerium oxide nanoparticles were coated on the MCM-41 surface using the sol-gel method by adding cerium oxide nanoparticle precursor to the MCM-41 dispersion. The samples were tested for antibacterial activity against Streptococcus mutans via CFU and MTT assays. The mechanical properties were assessed by flexural strength and depth of cure according to ISO 4049. Data were analyzed using a t-test, one-way ANOVA, and Tukey's post-hoc test (p = 0.05). The experimental group showed significantly increased antibacterial properties compared to the control groups (p < 0.005). The flexural strength exhibited a decreasing trend as the amount of cerium oxide nanoparticle-coated MCM-41 increased. However, the flexural strength and depth of cure values of the silane group met the ISO 4049 standard. Antibacterial properties increased with increasing amounts of cerium oxide nanoparticles. Although the mechanical properties decreased, silane treatment overcame this drawback. Hence, the cerium oxide nanoparticles coated on MCM-41 may be used for dental resin composite.

Preventive effects of probiotics on dental caries in vitro and in vivo.

BACKGROUND: Dental caries is a common disease in the oral cavity, and the microorganisms in the cavity are colonized in the form of dental plaque biofilm. Streptococcus mutans is the main pathogen causing dental caries. Using probiotics to inhibit the growth and colonization of pathogenic bacteria, regulate mucosal immunity and improve oral microecological balance is an effective way to prevent or treat dental caries. The aim of this study was to evaluate the caries-prevention of probiotics in vitro and in rat caries models. METHODS: The probiotics used in this study are a combination of 4 strains of bacteria. After the fermentation of 4 strains (L. plantarum, L. salivarius, L. rhamnosus, and L. paracasei) was completed, they were mixed in equal volume proportions and used as samples to be tested. The mixture was then assessed the ability to inhibit the growth of S. mutans in vitro and in vivo. SPSS Statistics 22.0 (SPSS, Inc., Chicago, IL, USA) was used for analysis. RESULTS: In vitro the probiotics mixture could inhibit the growth of S. mutans and was able to remove biofilms formed by S. mutans. In a 42-day in vivo experiment, the probiotics group significantly reduced the level of S. mutans on the tooth surface of rats, reducing more than half the bacterial quantities compared with the caries model group (P < 0.05). The amount of S. mutans in the antagonist group was low and highly significant compared with the caries model group. Moreover, the mixture of 4 strains significantly reduced the caries scores (modified Keyes scoring method) in both the probiotic and antagonist groups (p < 0.05). CONCLUSIONS: The study showed that the combination of the four strains can reduce the cavity scores, and the four strains can be used as products in oral care products. At the same time, the study also suggests that probiotic therapy can be an effective way to prevent dental caries.

Evaluation of probiotics' efficiency on cariogenic bacteria: randomized controlled clinical study.

BACKGROUND: Probiotics are live beneficial bacteria to human health and their efficiency on oral health is still being investigated. The purpose of this study was to evaluate the level of Streptococcus mutans and Lactobacillus species with and without the use of probiotics for six-months after the treatment of all dental caries under general anesthesia. METHODS: Fifty-eight pediatric patients without any systemic diseases, whose dental treatments were completed under general anesthesia (GA), were included in the study. The patients were recruited in two-groups; Group A: Patients started using probiotics after GA and Group B: Patients did not use probiotics after GA. Saliva samples were taken from all patients on the day before GA (T0), at one-month (T1), three-month (T2) and six-month (T3) follow-up after GA. The counts of cariogenic bacteria were determined by the analysis of saliva samples using real-time polymerase chain reaction. Statistical significance level was accepted as p < 0.05. RESULTS: There was statistically significant difference between Group A and B for T0, T1, T2 and T3 regarding S. mutans (p = 0.001, p = 0.04, p = 0.04, p = 0.03; p < 0.05). However, there was no statistically significant difference between groups regarding Lactobacillus species (p ≥ 0.05). CONCLUSIONS: Probiotic use and treatment of all caries significantly reduced the level of S. mutans but not Lactobacillus species. Furthermore, S. mutans decreased after cessation of probiotics, but it was not statistically significant. TRIAL REGISTRATION: Study was registered as "Effects of Probiotics on Streptococcus mutans and Lactobacillus species" with the registration number of NCT05859646 (16/05/2023) at https://www. CLINICALTRIALS: gov Protocol Registration and Results System.

Antimicrobial effect of two fluoride-releasing adhesive tapes on Streptococcus mutans biofilm.

Fluoride-releasing adhesive tapes have been developed as a new fluoride delivery agent. However, application as caries prevention agents remains underexplored. This study aimed at evaluating the antimicrobial activity of two fluoride-releasing adhesive tapes against S. mutans biofilm. Two polyvinyl alcohol (PVA) tapes were investigated: (i) a fluoride-PVA (F-PVA) tape, (ii) a pullulan incorporated F-PVA (PF-PVA) tape. S. mutan strains were cultured and treated with the tapes. Antimicrobial effects were evaluated using the agar diffusion test, field-emission scanning electron microscopy (FE-SEM), and confocal laser scanning microscopy (CLSM). F-PVA tapes showed higher inhibition-zone diameters than PF-PVA at 48 h and 72 h. However, there were no significant differences (p > 0.05) between the effects of F-PVA and PF-PVA. The bio-volume of S. mutans and extracellular polymeric substances significantly decreased in the F-PVA tapes than in the PF-PVA tapes (p < 0.05). FE-SEM micrographs revealed less S. mutans colonization in F-PVA. F-PVA exhibited better antimicrobial activity against S. mutans than PF-PVA.

PH VALUE AND ANTIBACTERIAL EFFECT OF ALKASITE RESTORATIVE MATERIALS.

This (in vitro) investigation was conducted to evaluate PH value and antibacterial effect of Alkasite restorative materials against important oral pathogens Streptococcus mutans and lactobacillus plantarum. MATERIAL AND METHODS: Four groups were made of three different type ion releasing materials Cention N= group 1, Primer free Cention Forte=group 2, Primer applied Cention Forte=group 3 and Fuji IX= group 4. A total number of 72 discs in form samples (2 mm height and 5mm diameter) were constructed in polyethylene mold divided according to the evaluating parameters. 32 specimens for PH measurements (n=8) and 40 specimens were utilized for antibacterial effect (n=5) for each bacterial species. The antibacterial properties of groups were assessed by direct contact test. An adjusted diluted broth culture of each bacterium (Streptococcus mutans) and (Lactobacillus plantarum) were prepared. RESULTS: At all intervals of time both Cention N and Primer free Cention Forte has significantly higher PH value in comparison with Fuji IX. Primer applied Cention Forte. There was no significant difference between Cention N, Primer free Cention and Fuji IX in terms of their effect in reducing viable colony count in both bacterial species. CONCLUSION: Along period of (28day) Alkasite material groups (Cention N and Primer free Cention Forte) showed the ability to increase the storage solution PH value. Also, both groups have antibacterial effect against (Streptococcus mutans) and (Lactobacillus plantarum) by inhibiting their numbers. Applying Cention primer showed negative effect on both PH value and the antibacterial effect of the material.

The antimicrobial activity of an antiseptic soap against Candida Albicans and Streptococcus Mutans single and dual-species biofilms on denture base and reline acrylic resins.

To evaluate the effect of antiseptic soap on single and dual-species biofilms of Candida albicans and Streptococcus mutans on denture base and reline resins. Samples of the resins were distributed into groups (n = 9) according to the prevention or disinfection protocols. In the prevention protocol, samples were immersed in the solutions (Lifebuoy, 0.5% sodium hypochlorite solution and PBS) for 7, 14 and 28 days before the single and dual-species biofilms formation. Overnight denture disinfection was simulated. In the disinfection protocol, samples were immersed in the same solutions during 8 hours after the single and dual-species biofilms formation. Antimicrobial activity was analyzed by counting colony-forming units (CFU/mL) and evaluating cell metabolism. Cell viability and protein components of the biofilm matrix were evaluated using confocal laser scanning microscopy (CLSM). Data were submitted to ANOVA, followed by Tukey's post-test (α = 0.05) or Dunnett's T3 multiple comparisons test. In the prevention protocol, Lifebuoy solution effectively reduced the number of CFU/mL of both species. In addition, the solution decreased the cell metabolism of the microorganisms. Regarding disinfection protocol, the Lifebuoy solution was able of reduce approximately of 2-3 logs for all the biofilms on the denture base and reline resin. Cellular metabolism was also reduced. The images obtained with CLSM corroborate these results. Lifebuoy solution was effective in reducing single and dual-species biofilms on denture base and reline resins.

Effect of Acetylsalicylic Acid on Biological Properties of Novel Cement Based on Calcium Phosphate Doped with Ions of Strontium, Copper, and Zinc.

This study aimed to compare the biological properties of newly synthesized cements based on calcium phosphate with a commercially used cement, mineral trioxide aggregate (MTA). Strontium (Sr)-, Copper (Cu)-, and Zinc (Zn)-doped hydroxyapatite (miHAp) powder was obtained through hydrothermal synthesis and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive X-ray spectrometry (EDX). Calcium phosphate cement (CPC) was produced by mixing miHAp powder with a 20 wt.% citric acid solution, followed by the assessment of its compressive strength, setting time, and in vitro bioactivity. Acetylsalicylic acid (ASA) was added to the CPC, resulting in CPCA. Biological tests were conducted on CPC, CPCA, and MTA. The biocompatibility of the cement extracts was evaluated in vitro using human dental pulp stem cells (hDPSCs) and in vivo using a zebrafish model. Antibiofilm and antimicrobial effect (quantified by CFUs/mL) were assessed against Streptococcus mutans and Lactobacillus rhamnosus. None of the tested materials showed toxicity, while CPCA even increased hDPSCs proliferation. CPCA showed a better safety profile than MTA and CPC, and no toxic or immunomodulatory effects on the zebrafish model. CPCA exhibited similar antibiofilm effects against S. mutans and L. rhamnosus to MTA.

Postbiotic mediators derived from Lactobacillus species enhance riboflavin-mediated antimicrobial photodynamic therapy for eradication of Streptococcus mutans planktonic and biofilm growth.

BACKGROUND: Streptococcus mutans has been implicated as a primary causative agent of dental caries and one of its important virulence properties is an ability to form biofilm on tooth surfaces. Thus, strategies to prevent and control S. mutans biofilms are requested. The present study aimed to examine the eradication of S. mutans planktonic and biofilm cells using riboflavin (Rib)-mediated antimicrobial photodynamic therapy (aPDT) enhanced by postbiotic mediators derived from Lactobacillus species. MATERIALS AND METHODS: Minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of Rib and postbiotic mediators were determined. The antimicrobial and anti-biofilm effects of Rib-mediated aPDT (Rib plus blue light), Rib-mediated aPDT in combination with postbiotic mediators derived from Lactobacillus casei (LC) (aPDT+ LC), and Rib-mediated aPDT in combination with postbiotic mediators derived from Lactobacillus plantarum (LP) (aPDT+ LP) were evaluated. The anti-virulence potential of Rib-mediated aPDT, aPDT+ LC, and aPDT+ LP were assessed by measuring the expression of the gtfB gene using quantitative real-time polymerase chain reaction (qRT-PCR) at the highest concentrations of Rib, LC, and LP, at which the S. mutans had proliferation as the same as in the control (non-treated) group. RESULTS: According to the results, the MIC doses of LC, LP, and Rib were 64 µg/mL, 128 µg/mL, and 128 µg/mL, respectively, while the MBC values of LC, LP, and Rib were 128 µg/mL, 256 µg/mL, and 256 µg/mL, respectively. Rib-mediated aPDT, aPDT+ LP, and aPDT+ LC showed a significant reduction in Log10 CFU/mL of S. mutans compared to the control group (4.2, 4.9, and 5.2 Log10 CFU/mL, respectively; all P < 0.05). The most destruction of S. mutans biofilms was observed after treatment with aPDT+ LC followed by aPDT+ LP and Rib-mediated aPDT (77.5%, 73.3%, and 67.6%, respectively; all P < 0.05). The concentrations of 31.2 µg/mL, 62.5 µg/mL, and 62.5 µg/mL were considered as the highest concentrations of LC, LP, and Rib, respectively, at which S. mutans replicates as same as the control group and were used for gtfB gene expression assay using qRT-PCR during Rib-mediated aPDT, aPDT+ LP, and aPDT+ LC treatments. Gene expression results revealed that aPDT+ LP and aPDT+ LC could decrease the gene expression level of gtfB by 6.3- and 5.7-fold, respectively (P < 0.05), while only 5.1-fold reduction was observed after Rib-mediated aPDT (P < 0.05). CONCLUSION: Our findings indicate that aPDT+ LP and aPDT+ LC hold promise for use as a treatment to combat S. mutans planktonic and biofilms growth as well as anti-virulence as a preventive strategy to inhibit biofilms development via reduction of gtfB gene expression.

Effect of Using Mouthwash Containing Cibotium barometz J. Smith on Cariogenic Bacteria and Acid-producing Ability of Saliva: A Randomised Blinded Clinical Trial.

PURPOSE: To examine the anti-caries effect of mouthwashes containing Cibotium barometz J. Smith (CB), a natural substance, and compare it with chlorhexidine and saline solution. MATERIALS AND METHODS: A randomised, blinded clinical trial was conducted on 76 study participants. The differences between the 3 gargle groups (saline gargle: SAL; chlorhexidine gargle: CHX; CB gargle group: CB) and the differences over time (baseline, after 1 week, after 2 weeks) were compared. To this end, ANOVA was performed on caries-related clinical indicators (e.g. O'Leary plaque index, caries activity, and satisfaction). RESULTS: The O'Leary index, caries activity, and saliva tests, gradually improved in group CB at one and two weeks. In the case of bacterial tests, unlike SAL and CHX, only in group CB did the decrease occur one and two weeks later. The caries-related indicators decreased significantly over time in group CB compared to SAL and CHX groups, and there was also a statistically significant difference in interaction between groups and time (p<0.05). CONCLUSIONS: The mouthwash containing CB extract showed statistically significant improvement in biofilm adhesion as well as the saliva and bacterial tests compared to SAL and CHX. However, since there were differences in the initial oral conditions of the three groups, additional long-term research is needed through crossover clinical trials to supplement these.

The effect of antimicrobial peptide-added adhesive resins on shear bond strength and the adhesive remnant index of orthodontic brackets.

OBJECTIVES: The aim of this study was to evaluate the effect of in-vivo produced Nisin which is an antimicrobial peptide (AMP) added to adhesive resin on shear bond strength (SBS) and the adhesive remnant index (ARI) of orthodontic brackets. METHODS: Bacterial AMP was produced by fermentation and the ideal AMP/Bond concentration and antimicrobial efficacy of the mixture were tested. To evaluate the SBS and ARI scores of AMP-added adhesive resins, 80 maxillary premolar teeth extracted for orthodontic purposes were used and randomly assigned into 2 groups (n = 40). Group 1: Control Group (teeth bonded with standard adhesive resin); Group 2: Experimental Group (teeth bonded with AMP-added adhesive resin). Statistical analysis was performed using the SPSS package program and applying the Mann-Whitney U and Fisher's exact tests. P < 0.05 was considered as statistically significant. RESULTS: Nisin synthesized in-vivo from Lactococcus lactis (L. lactis) (ATCC 7962) bacteria was provided to form a homogenous solution at an ideal concentration To find the minimum AMP/Bond mixture ratio that showed maximum antimicrobial activity, AMP and Bond mixtures were tested at various concentration levels between 1/160 and 1/2 (AMP/Bond). As a result, the optimum ratio was determined as 1/40. The antimicrobial efficacy of Nisin-added adhesive resin was tested against Streptococcus mutans (S. mutans) (ATCC 35,688) and Lactobacillus strains (cariogenic microorganisms). AMP formed a 2.7 cm diameter zone alone, while 1/40 AMP-bond mixture formed a 1.2 cm diameter zone. SBS values of the teeth bonded with Nisin added adhesive (17.49 ± 5.31) were significantly higher than the control group (14.54 ± 4.96) (P = 0.004). According to the four point scale, Nisin added adhesive provided a higher ARI score in favour of the adhesive and tooth compared to the control group (ARI = 3, n = 20). CONCLUSIONS: Nisin produced from L. lactis (ATCC 7962) had greater antimicrobial effects after mixing with adhesive bond against cariogenic microorganisms S. mutans (ATCC 35,688) and Lactobacillus strains. Nisin added adhesive increased shear bond strength (SBS) of orthodontic brackets and ARI scores in favor of adhesive & teeth. CLINICAL RELEVANCE: Clinicians should take into account that using Nisin-added adhesive resin in orthodontic treatments can provide prophylaxis against tooth decay, especially in patients with poor oral hygiene.

Bioactivity and antibacterial effect of star anise biosynthesized silver nanoparticles against Streptococcus mutans: an in vitro study.

BACKGROUND: Silver nanoparticles (AgNPs) are receiving a lot of attention as a prospective antibacterial agent for use in caries prevention. The objective of this study was to investigate the bioactivity and antibacterial effect of silver nanoparticles biosynthesized using Star Anise against Streptococcus mutans (S.mutans). METHODS: The bioactive components of the Star Anise were assessed by employing the gas chromatography-mass spectrometry technique. The antibacterial activities of Star Anise Biosynthesized Silver Nanoparticles against S.mutans bacteria were evaluated using Bauer and Kirby's disc diffusion mechanism and the minimum inhibitory concentration. RESULTS: Silver nanoparticles biosynthesized using Star Anise revealed high antioxidant activity. AgNPs inhibited S. mutans with a 16 mm inhibition zone diameter and demonstrated an 80 µg/ml minimum inhibitory concentration. CONCLUSIONS: Biologically synthesized AgNPs made from aqueous extract of Star anise appear to be a potential and effective bactericidal agent against S.mutans that can be used to prevent dental caries.

Efficiency of the photodynamic therapy on viability of Streptococcus mutans in the oral cavity using chitosan nanoparticles: an in vitro study.

PURPOSE: This study aimed to investigate the efficiency of antimicrobial photodynamic therapy (aPDT) on Streptococcus mutans biofilm in the oral cavity using the photosensitizer chloroaluminum phthalocyanine encapsulated in chitosan nanoparticles (ClAlPc/Ch) at three preirradiation times. METHODS: Biofilms of Streptococcus mutans strains (ATCC 25,175) were cultivated on bovine tooth blocks and exposed to a 10% sucrose solution three times a day for 1 min over three consecutive days. The samples were randomly distributed into five treatment groups (n = 5): (I) aPDT with ClAlPc/Ch with a preirradiation time of 5 min (F5), (II) aPDT with ClAlPc/Ch with a preirradiation time of 15 min (F15), (III) aPDT with ClAlPc/Ch with a preirradiation time of 30 min (F30), (IV) 0.12% chlorhexidine digluconate (CHX), and (V) 0.9% saline solution (NaCl). After treatment, the S. mutans biofilms formed on each specimen were collected to determine the number of viable bacteria (colony-forming units (CFU)/mL). Data were analyzed for normality using the Shapiro-Wilk test and the analysis of variance (ANOVA) and Tukey HSD tests to analyze the number of viable bacteria (α = 0.05). RESULTS: The one-way ANOVA showed a difference between the groups (p = 0.0003), and the Tukey HSD posttest showed that CHX had the highest microbial reduction of S. mutans, not statistically different from the F5 and F15 groups, whereas the NaCl group had the lowest microbial reduction statistically similar to the F30 group. CONCLUSION: The results demonstrate that aPDT mediated by ClAlPc/Ch when used at preirradiation times of 5-15 min can be an effective approach in controlling cariogenic biofilm of S. mutans, being an alternative to 0.12% CHX.

Colloidal chitosan-silver nanoparticles-fluoride nanocomposite as an antibacterial mouthwash against salivary Streptococcus mutans in orthodontic patients (a randomized clinical trial).

OBJECTIVES: This study aimed to synthesize and characterize colloidal chitosan-silver nanoparticles-fluoride nanocomposite (CCAgNPF) and evaluate its efficacy compared to chlorhexidine on salivary Streptococcus mutans in orthodontic patients. MATERIALS AND METHODS: AgNPs stabilized with chitosan were synthesized by chemical reduction of AgNO3. The nanoparticles were characterized with SEM, FTIR, DLS and ICP-OES. The MIC and MBC against S. mutans and IC50 concentration of CCAgNPF were obtained for antibacterial and cytotoxicity evaluations, respectively. For the clinical study, a total of 45 orthodontic patients were divided into three groups of 15 and used the following mouthwashes twice a day for 1 month: CCAgNPF, chlorhexidine 0.2% and the combination of these mouthwashes. The colony count of salivary S. mutans was evaluated before and after using the mouthwashes. The data were analyzed using One-way ANOVA and Tukey's test. RESULTS: Stabilized AgNPs were spherical with a diameter of 25.3 ± 3.3 nm. The MIC, MBC and IC50 of CCAgNPF were 4.42, 8.85 and 18.89 µg/ml. All mouthwashes reduced the salivary S. mutans of the orthodontic patients, however, no significant difference was found between the efficacy of CCAgNPF and chlorhexidine (P-value > 0.05). The best results were achieved by the combination of CCAgNPF and chlorhexidine mouthwashes (P-value < 0.05). CONCLUSION: The CCAgNPF and its combination with chlorhexidine present potent bactericidal, biocompatible and effective anti-carious mouthwashes for orthodontic patients. CLINICAL RELEVANCE: This study proved CCAgNPF as an antibacterial mouthwash with lower cytotoxicity and side effects for patients undergoing orthodontic treatments to maintain oral hygiene and reduce salivary S. mutans.

Trans-Cinnamaldehyde Inhibition of Pyruvate Dehydrogenase: Effects on Streptococcus mutans Carbohydrate Metabolism.

Dental caries is a chronic oral infectious disease, and Streptococcus mutans (S. mutans) plays an important role in the formation of dental caries. Trans-cinnamaldehyde (CA) exhibits broad-spectrum antibacterial activity; however, its target and mechanism of action of CA on S. mutans needs to be further explored. In this study, it was verified that CA could inhibit the growth and biofilm formation of S. mutans. Further proteomic analysis identified 33, 55, and 78 differentially expressed proteins (DEPs) in S. mutans treated with CA for 1, 2, and 4 h, respectively. Bioinformatics analysis showed that CA interfered with carbohydrate metabolism, glycolysis, pyruvate metabolism, and the TCA cycle, as well as amino acid metabolism of S. mutans. Protein interactions suggested that pyruvate dehydrogenase (PDH) plays an important role in the antibacterial effect of CA. Moreover, the upstream and downstream pathways related to PDH were verified by various assays, and the results proved that CA not only suppressed the glucose and sucrose consumption and inhibited glucosyltransferase (GTF) and lactate dehydrogenase (LDH) activities but also decreased the ATP production. Interestingly, the protein interaction, qRT-PCR, and molecular docking analysis showed that PDH might be the target of CA to fight S. mutans. In summary, the study shows that CA interferes with the carbohydrate metabolism of bacteria by inhibiting glycolysis and the tricarboxylic acid (TCA) cycle via binding to PDH, which verifies that PDH is a potential target for the development of new drugs against S. mutans.

Intraspecies interactions of Streptococcus mutans impact biofilm architecture and virulence determinants in childhood dental caries.

Early childhood dental caries (ECC) is the most common chronic disease among children, especially among low socioeconomic populations. Streptococcus mutans is most frequently associated with initiation of ECC. Although many studies report children with multiple S. mutans strains (i.e., genotypes) have greater odds of developing ECC, studies investigating intraspecies interactions in dental caries are lacking. This study investigates the impact of intraspecies interactions on cariogenic and fitness traits of clinical S. mutans isolates using in vitro and in vivo approaches. Association analysis evaluated if presence of multiple S. mutans genotypes within the first year of colonization was associated with caries. Initially, clinical S. mutans isolates from 10 children were evaluated. S. mutans strains (G09 and G18, most prevalent) isolated from one child were used for subsequent analysis. Biofilm analysis was performed for single and mixed cultures to assess cariogenic traits, including biofilm biomass, intra-polysaccharide, pH, and glucan. Confocal laser scanning microscopy (CLSM) and time-lapse imaging were used to evaluate spatial and temporal biofilm dynamics, respectively. A Drosophila model was used to assess colonization in vivo. Results showed the mean biofilm pH was significantly lower in co-cultured biofilms versus monoculture. Doubling of S. mutans biofilms was observed by CLSM and in vivo colonization in Drosophila for co-cultured S. mutans. Individual strains occupied specific domains in co-culture and G09 contributed most to increased co-culture biofilm thickness and colonization in Drosophila. Biofilm formation and acid production displayed distinct signatures in time-lapsed experiments. This study illuminates that intraspecies interactions of S. mutans significantly impacts biofilm acidity, architecture, and colonization.IMPORTANCEThis study sheds light on the complex dynamics of a key contributor to early childhood dental caries (ECC) by exploring intraspecies interactions of different S. mutans strains and their impact on cariogenic traits. Utilizing clinical isolates from children with ECC, the research highlights significant differences in biofilm architecture and acid production in mixed versus single genotype cultures. The findings reveal that co-cultured S. mutans strains exhibit increased cell density and acidity, with individual strains occupying distinct domains. These insights, enhanced by use of time-lapsed confocal laser scanning microscopy and a Drosophila model, offer a deeper understanding of ECC pathogenesis and potential avenues for targeted interventions.

Synthesis and Characterization of a Sustained Nitric Oxide-Releasing Orthodontic Elastomeric Chain for Antimicrobial Action.

The acidic byproducts of bacteria in plaque around orthodontic brackets contribute to white spot lesion (WSL) formation. Nitric oxide (NO) has antibacterial properties, hindering biofilm formation and inhibiting the growth of oral microbes. Materials that mimic NO release could prevent oral bacteria-related pathologies. This study aims to integrate S-nitroso-acetylpenicillamine (SNAP), a promising NO donor, into orthodontic elastomeric ligatures, apply an additional polymer coating, and evaluate the NO-release kinetics and antimicrobial activity against Streptococus mutans. SNAP was added to clear elastomeric chains (8 loops, 23 mm long) at three concentrations (50, 75, 100 mg/mL, and a control). Chains were then coated, via electrospinning, with additional polymer (Elastollan®) to aid in extending the NO release. NO flux was measured daily for 30 days. Samples with 75 mg/mL SNAP + Elastollan® were tested against S. mutans for inhibition of biofilm formation on and around the chain. SNAP was successfully integrated into ligatures at each concentration. Only the 75 mg/mL SNAP chains maintained their elasticity. After polymer coating, samples exhibited a significant burst of NO on the first day, exceeding the machine's reading capacity, which gradually decreased over 29 days. Ligatures also inhibited S. mutans growth and biofilm formation. Future research will assess their mechanical properties and cytotoxicity. This study presents a novel strategy to address white spot lesion (WSL) formation and bacterial-related pathologies by utilizing nitric oxide-releasing materials. Manufactured chains with antimicrobial properties provide a promising solution for orthodontic challenges, showing significant potential for academic-industrial collaboration and commercial viability.

Effect of Different Isolation Methods on Bioaerosol Distribution: An In Vitro Study.

Purpose: The purposes of this in vitro study were to evaluate the effect of three isolation methods to mitigate bioaerosols during stainless steel crown (SSC) preparations and assess the distribution of Streptococcus mutans by aerosolization in closed-room operatories. Methods: Melamine teeth coated in laboratory-grown S. mutans biofilm were prepared for SSCs using three different isolation methods. Agar plates were placed in five locations throughout the operatory and opened during each preparation as well as for 10 minutes immediately following to collect aerosolized S. mutans. Bacterial colonies were counted after incubating plates for 48 hours. Data were analyzed for differences between the isolation method and plate locations. Results: Bacterial colony counts for teeth prepared using high-volume evacuation suction (HVE) with dental dam (DD) isolation were statistically significantly higher than for those prepared using HVE with a DryShield®(DS) and HVE with no isolation at the assistant (A) (P<0.001), operator face shield (FS) (P<0.001), and patient (Pt) (P=0.002) locations. No significant differences were found among isolation methods for parent (Pa) or rear delivery (RD) locations. The location that produced the most bacterial colony counts using HVE with DD isolation was FS (P<0.001), followed by A (P=0.04), Pt (P<0.001), and RD and Pa (P<0.001). Counts produced from teeth prepared with DS isolation were significantly higher at the Pt location than the A (P<0.001), FS (P=0.002), RD (P<0.001), and Pa (P=0.008) locations. Conclusion: The use of dental dam with high-volume evacuation suction during stainless steel crown preparations increased bioaerosols near the procedure, while dental evacuation systems (DryShield®) may effectively limit their spread.