Mutans Biofilm Research Articles

Small cyclic dipeptide produced by Lactobacillus rhamnosus with anti-biofilm properties against Streptococcus mutans biofilm

The human oral cavity harbors many bacterial species collectively termed the oral microbiome and is integral for maintaining oral health. Dysbiosis of oral microbiota leads to common oral diseases, including dental caries, gingivitis, and periodontitis. Streptococcus mutans is the primary causative agent of dental caries. Studies have explored the use of probiotic Lactobacillus spp. to mitigate S. mutans biofilms. In the present study, we have tested the use of Lactobacillus rhamnosus extracts/metabolites for anti-biofilm properties. A small organic compound/metabolite was isolated from the cell-free supernatant of L. rhamnosus, and this metabolite resulted in a dose-dependent inhibition of S. mutans biofilms. Confocal microscopy revealed that the thickness of S. mutans biofilms was severely reduced upon metabolite treatment. With the help of FTIR spectra and mass spectrometry analysis, the molecular formula (C11H19O2N2) was deduced. The inhibitor compound was further identified as a small cyclic peptide, cyclo (-L-Leu-L-Pro). Our data also revealed that isolated metabolite impedes S. mutans biofilms by modulating gene expression of several essential genes involved in biofilm establishment.

The anti-caries effects of copper tetraamine fluoride on enamel: An in vitro study

ObjectiveTo investigate the antibacterial, remineralising, and discolouring effects of copper tetraamine fluoride (CTF) on artificial enamel caries. MethodHuman enamel blocks with artificial caries were treated with CTF, silver diamine fluoride (SDF, positive control) and water (negative control) before being challenged with Streptococcus mutans. The morphology, viability, and growth kinetics of biofilm were evaluated using scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), and colony-forming unit (CFU) counting. The lesion depths, mineral loss, micro-hardness, and crystal characteristics were assessed using micro-computed tomography, Knoop Hardness Tester, and X-ray diffraction (XRD), respectively. The discolouring property was assessed by spectrophotometry. ResultsSEM showed that bacteria completely covered the enamel surface treated with water, but not the enamel surface treated with CTF and SDF. CLSM showed dead-to-live ratio of biofilm treated with CTF, SDF and water were 0.8 ± 0.1, 0.9 ± 0.2 and 0.5 ± 0.1 (p < 0.001, CTF, SDF>Water). Log10 CFU values of biofilm treated with CTF, SDF and water were 7.7 ± 0.2, 7.7 ± 0.1 and 8.1 ± 0.1 (p < 0.001, CTF, SDF<Water). Lesion-depths (μm) of the CTF, SDF and water groups were 93 ± 6, 92 ± 7 and 152 ± 29 (p < 0.001, CTF, SDF<Water). Mineral loss (gHApcm−3) of the CTF, SDF and water groups were 0.4 ± 0.1, 0.4 ± 0.2 and 1.0 ± 0.2 (p < 0.001, CTF, SDF<Water). Knoop hardness of the CTF, SDF and water groups were 70 ± 23, 68 ± 16 and 21 ± 10 (p < 0.05, CTF, SDF>Water). XRD revealed well-crystallised hydroxyapatite in enamel treated with CTF and SDF, but not water. Spectrophotometry showed ΔE values of the CTF, SDF and water groups were 5 ± 3, 54 ± 6 and 6 ± 2 (p < 0.001, CTF, water<SDF). ConclusionCTF inhibited Streptococcus mutans biofilm and remineralised artificial enamel caries without discolouration. Clinical significanceIf CTF is successfully translated into clinical use, it can be a simple agent for clinicians to arrest enamel caries.

Dietary carbohydrates modulate Streptococcus mutans adherence and bacterial proteome.

Streptococcus mutans adherence to the tooth surface and subsequent biofilm development is modulated by the carbohydrate source, but the corresponding effect on bacterial proteome has not been previously studied. This study aimed to assess the effect of different carbohydrates on S. mutans viability and bacterial proteome at two-time points, early attachment (8 h) and biofilm maturation (24 h). Hydroxyapatite (HAp) discs coated with parotid saliva proteins were inoculated with S. mutans UA159 in Tryptone Soy Broth without dextrose supplemented with one of the following carbohydrates (n=12/treatment/time point): 1% Sucrose (S); 0.525% Glucose + 0.525% Fructose (G+F); 10% Xylitol (X); 10% Xylitol + 1% Sucrose (X+S); or culture medium without supplementation as negative control (C). Once inoculated, HAp discs were incubated for 8 h or 24 h at 37 °C and 10% CO2. After each incubation period, adhered bacteria were quantified using the plate-counting method for 6 HAp discs/group, and the remaining 6 HAp discs/group were used to extract bacterial cell wall proteins. Extracted proteins were analyzed using liquid chromatography coupled with mass spectrometry and then classified by their biological process. The study was conducted in three independent assays and the number of bacteria adhered to the HAp discs was determined at each time point and analyzed by two-way ANOVA followed by Bonferroni test (=5%). The results suggest that xylitol significantly repressed bacterial adherence and metabolism at 8 h and 24 h; however, bacterial adherence and metabolism were significantly enhanced when xylitol was combined with sucrose, showing no negative effect on S. mutans at both time points. Bacterial proteome was modulated by the carbohydrate source. The cariogenicity of S. mutans biofilms may be reduced by the alternative sweetener xylitol; however, the combination with fermentable sugars may inhibit such a beneficial effect.

Effect of glycerol monolaurate nanocapsules on Streptococcus mutans biofilm in vitro

This study aimed to prepare and apply nanocapsules containing glycerol monolaurate for eradicating Streptococcus mutans biofilms. The interfacial deposition method of the preformed polymer synthesized the nanocapsules characterized for mean diameter, polydispersity index, zeta potential, pH, and morphology by transmission electron microscopy. The microdilution method investigated antimicrobial activity. Crystal violet staining determined biomass quantification and the ability to inhibit biofilm formation. The study also measured exopolysaccharide production and the number of viable colonies. The characterization outcomes indicated acceptable values for the mean diameter 198.1 ± 2, a polydispersity index of 0.087 ± 0.018, a zeta potential of -21.30 ± 2.00 mV, a pH of 6.19 ± 0.12, and typical nanostructure morphology. The evaluations of minimum inhibitory and bactericidal concentrations of glycerol monolaurate (free and nanoencapsulated) revealed their ineffectiveness in inhibiting microorganisms. Only free glycerol monolaurate inhibits S. mutans growth with 125 µg/mL. Biomass, exopolysaccharide content, and viable colonies in the biofilm were analyzed to assess the compounds' ability to inhibit biofilm formation. The tested compounds did not significantly reduce the formed biofilm. Despite unfavorable outcomes of the formulated preparation, further experimentation with a new formulation is encouraged to explore alternative strategies and potential improvements.

Novel Antibacterial Resin Coating for Dental Provisional Crowns to Suppress Biofilms and Inhibit Secondary Caries

Provisional crowns are often used in dentistry for prolonged periods, but bacterial attachment and dental plaque often lead to gingival inflammation and secondary caries. The aims of this research were to develop a novel resin-based antibacterial provisional crown coating to prevent secondary caries and investigate the physical properties and antibacterial efficacy. The resin-based coating was prepared by addition of triethylene glycoldivinylbenzyl ether and urethane dimethacrylate, with the antibacterial monomer dimethylaminododecyl methacrylate (DMADDM) incorporated at different mass fractions. Surface characteristics including surface roughness and contact angle were assessed. The antibacterial effects were evaluated by 48 h biofilms of Streptococcus mutans (S. mutans) on provisional crowns coated with the resin-based coating. No statistically significant difference was observed in surface roughness across all groups (p &gt; 0.05), showing that adding DMADDM did not have a negative impact on surface roughness. The contact angle results revealed a significant difference in hydrophilicity between different concentrations of DMADDM (p &lt; 0.01), but overall hydrophilicity did not negatively affect the performance of the coating. The incorporation of 5% DMADDM demonstrated a significant antibiofilm effect on S. mutans biofilm CFU with a 4-log reduction compared to controls (p &lt; 0.01). Significant reductions of 4–5 folds were observed in biofilm metabolic activity and lactic acid production (p &lt; 0.01). The findings suggest that the novel coating material could enhance the long-term performance and clinical outcomes of provisional crowns, contributing to better patient oral health.

The Biofilm Removal and Bactericidal Effect of an 810-nm High-Power Laser on an Orthodontic Bracket Surface: An In Vitro Study.

Objective: The present study aimed to analyze the biofilm removal and bactericidal effect of laser treatment alone and laser combined with ultrasonic scaling on orthodontic brackets. It also assessed whether the use of a laser can improve the efficiency of biofilm removal and bactericidal effect compared with traditional ultrasonic instrumentation. Background Data: Streptococcus mutans (S. mutans) can lead to white spots and dental caries. Orthodontic brackets make teeth cleaning more difficult, and biofilms or bacteria on the surface of brackets worsen the oral environment, which may cause some oral diseases. Laser can be used for biofilm removal and killing bacteria on the surface of an object through thermal, photochemical, and pressure effects, which is widely used in the treatment of oral diseases. Methods: A total of 600 mandibular incisor brackets were collected for this study. Among these, 320 unused brackets were used for the S. mutans crystal violet assay (n = 160) and for S. mutans live/dead bacterial staining (n = 160). Another 280 brackets, obtained from patients who had undergone therapy for over two years, were used for the mature multispecies biofilms removal assay (n = 120) and multispecies bacterial live/dead bacterial staining (n = 160). Ultrasonic scaling, laser, and laser combined with ultrasonic scaling were applied to the labial surface of brackets covered by S. mutans biofilm or mature multispecies biofilms. Specifically, we used the following three methods: ultrasonic scaling for 10 sec without laser; 810-nm laser (Doctor Smile, Italy, LA5D0 001.1) with 0.3-mm spot size at total 21.2 kJ/cm2 for 10 sec; and 810-nm laser at total 10.6 kJ/cm2 for 5 sec, followed by ultrasonic scaling for 5 sec. The 810-nm diode laser removed biofilms with a power of 1.5 W and a power density of 2.12 kW/cm2. The S. mutans biofilm was examined using crystal violet assay, and scanning electron microscopy (SEM) was used for mature multispecies biofilms to evaluate the effect of the three methods on biofilm removal. Live/dead bacterial staining was used to examine the bactericidal effect on remaining biofilms by confocal laser scanning microscopy (CLSM). Results: For S. mutans biofilm, the optical density (OD) value and live/dead bacterial ratio in the laser and the laser combined with ultrasonic scaling groups were significantly lower than those in the ultrasonic scaling group (p < 0.05); moreover, the OD value and the live/dead bacterial ratio in laser treatment combined with ultrasonic scaling and laser treatment alone showed no significant difference (p > 0.05). For mature multispecies biofilms, the percentage of biofilm coverage after treatment was higher in the laser group than in the ultrasonic scaling group (p < 0.05) and lower in the laser combined with ultrasonic scaling group than in the ultrasonic scaling group (p < 0.05), and live/dead bacterial staining showed that laser treatment alone killed the most bacteria, followed by laser treatment combined with ultrasonic scaling, while ultrasonic scaling alone seldom killed bacteria. Conclusions: Laser treatment alone has a better bactericidal effect and can also remove more S. mutans biofilm than ultrasonic scaling alone, but it fails to remove more mature multispecies biofilms. Laser treatment combined with ultrasonic scaling can remove more S. mutans biofilm and mature multispecies biofilms than ultrasonic scaling alone and also has a better bactericidal effect than ultrasonic scaling alone on a bracket surface.

The Inhibitory Effect of Agastache rugosa Essential Oil on the Dental Biofilm

This study aimed to identify the inhibitory effect of Agastache rugosa essential oil (AREO) on the cariogenic properties of Streptococcus mutans, which causes dental caries and dental plaque formation. After extracting the AREO, their effects on the growth and acid production of S. mutans were examined. Furthermore, S. mutans biofilm formation was observed on the resin teeth surface. The effect on the expression of biofilm-related genes of S. mutans was measured using real-time PCR. AREO components were analyzed using gas chromatography (GC) and GC-mass spectrometry (MS). The growth and acid production of S. mutans were significantly inhibited at concentrations of 0.02 mg/mL or higher of AREO. At 0.04 mg/mL, inhibition was similar to that of the positive control, 0.1% NaF. AREO suppressed the expression of virulence factors such as gtfB, gtfC, gtfD, gbpB, SpaP, brpA, relA, and vicR at concentrations of 0.02 mg/mL or higher. As a result of GC and GC-MS analyses, the main components of AREO included estragole, limonene, and β-caryophyllene. These results suggest that A. rugosa may be a useful agent for inhibiting the cariogenic properties of S. mutans.

A comparative evaluation of the antimicrobial efficacy of Chlorhexidine and Chlorine dioxide on self-ligating brackets contaminated with Streptococcus mutans biofilm- An In vitro study

ObjectiveTo evaluate and compare antimicrobial efficacy of Chlorhexidine and Chlorine dioxide mouthwashes on S.mutans biofilm created on metal and ceramic self-ligating brackets. Materials and methodsA total of 162 metal and ceramic self-ligating brackets (3M™ SmartClip™ & Clarity SL™) were randomly divided into 3 groups and 2 subgroups. Standard procedures were followed to coat all brackets with S.mutans biofilm. The biofilms were cultivated which were then subjected to the effects of the mouthwashes. Quantitative assessment was carried out by comparing the number of viable colonies of S.mutans. A Mann-Whitney U test was used to compare the data between the experimental and control groups. (p < 0.05). ResultWhen compared to untreated controls the antimicrobial efficacy of Chlorhexidine Digluconate and Chlorine Dioxide mouthwashes was found to be statistically significant (p = 0.00). The comparison between Chlorhexidine digluconate and Chlorine dioxide mouthwashes was not statistically significant in Ceramic self-ligating group (p = 0.502) and statistically significant in Metal self-ligating group (p = 0.001) ConclusionS mutans colonies on metal and ceramic self-ligating brackets can be reduced effectively by Chlorhexidine digluconate and Chlorine dioxide mouthwashes. Chlorhexidine digluconate more effective for metal bracket group. Both mouthwashes had comparable antimicrobial effectiveness, with the difference in the number of viable colonies following exposure for ceramic bracket groups.

Are glass ionomer cements bioactive? Analysis of ions release, pH, hydroxyapatite nanoprecursors formation, antibacterial activity, and cytotoxicity

ObjectiveThis study assessed the release of F−, Ca+2, PO4−3, alkalinizing activity, cytotoxicity, antibacterial activity, and the hydroxyapatite nanoprecursor formation of six commercial glass ionomer cements (GICs). Materials and methodsBioglass (Biodinâmica), Gold label 9 (GC), Vitrofil (DFL), Maxxion (FGM), Vidrion (SS WHITE) and Ionglass (Maquira) were evaluated. pH analysis was performed at different times in initial pH (pHi) 4 and 7 for 28 days. At day-28, the release of Ca+2, PO4−3 and F− was analyzed. Fibroblastic cells were used for cytotoxicity tests. Samples were evaluated at 24, 48 and 72 h. The hydroxyapatite precipitate formation was analyzed using SEM/EDS, FTIR/ATR and XRD, after 28 days. S. mutans biofilms were cultured over GIC disks to antibacterial activity assessment. ResultspH of all GIC were acidic over 28 days. Bioglass had greater F− release when compared to Gold Label (p < 0.05), at pHi 4. At pHi 7, there was no difference on F− release between GICs. Ionglass and Vitro fill had the highest Ca+2 and PO4−3 release. SEM indicated the presence of precipitates on the surface of all GICs and FTIR showed the presence of carbonate (1080/1413/1453 cm−1). XRD did not indicate crystalline hydroxyapatite precursors peaks. All GICs presented cytotoxicity when compared to the control group in 72h (p < 0.05). The GICs did not have antibacterial activity against S. mutans (p < 0.05). SignificanceGICs released ions that are important for tooth remineralization. However, GICs showed low pH, cytotoxicity, lack of antibacterial activity and the absence of precursors of hydroxyapatite indicated that materials were not bioactive.

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.

The Influence of Streptococcus mutans Biofilm Formation in a Polymicrobial Environment (Streptococcus gordonii & Porphyromonas gingivalis).

Biofilms play a vital role in the occurrence or worsening of an infectious disease. Streptococcus mutans is a bacterium with the ability to form biofilms that plays a key role in the development of infectious diseases such as dental caries. The formation of biofilms in S. mutans is mediated by quorum sensing. Inhibiting quorum sensing can be considered as one of the approaches to prevent caries. This study aims to investigate the ability of Streptococcus gordonii and Porphyromonas gingivalis bacteria to inhibit the formation of S. mutans biofilm. This research was conducted to analyze bacterial biofilm formation and metabolism. The bacteria used are S. mutans (serotype C), S. gordonii (ATCC 5165), and P. gingivalis (ATCC 33277). Biofilm formation was analyzed using the crystal violet assay. Bacterial metabolism was analyzed using the methylthiazol tetrazolium (MTT) assay. The results of the crystal violet assay indicate a decrease in biofilm formation in S. mutans when in the presence of S. gordonii and S. mutans in the presence of P. gingivalis. The results of the MTT assay show no significant change in the bacterial metabolism of S. mutans in the presence of S. gordonii and S. mutans in the presence of P. gingivalis. However, S. mutans with the presence of S. gordonii and P. gingivalis show an increase in biofilm formation and bacterial metabolism. S. gordonii and P. gingivalis are each capable of inhibiting the formation of S. mutans biofilm in a polymicrobial environment.

Comparing The Antibacterial Effectiveness Of Indigenously Derived Propolis In Various Vehicles Against Streptococcus Mutans Biofilm Formation: A Study With Contemporary Pulp Capping Agents

Comparing The Antibacterial Effectiveness Of Indigenously Derived Propolis In Various Vehicles Against Streptococcus Mutans Biofilm Formation: A Study With Contemporary Pulp Capping Agents

Comparative Evaluation of Biofilm Formation on Temporization Crown Materials Used in the Rehabilitation of Primary Dentition With Different Polishing Materials: An In Vitro Study.

Introduction Advancements in dental materials have enhanced aesthetic treatments for managing dental caries and injuries in primary dentition. Bis-acryl composite-based temporization materials are now preferred for restoring primary crowns due to their superior properties. However, prolonged exposure to dietary and hygienic factors can lead to discoloration and roughness, making efficient polishing essential to prevent plaque buildup. Objective This study aims to evaluate Streptococcus mutans biofilm formation on temporization material polished with different polishing systems. Methods This study tested bis-acryl methacrylate temporization material. Thirty disk-shaped specimens were prepared and divided into three groups according to the polishing system used (n = 10 per group): Shofu Super Snap mini kit (Shofu, San Marcos, CA), aluminum oxide polishing paste, and propol polishing paste. Each group's specimens were polished according to the manufacturer's instructions. Surface roughness (SR), scanning electron microscopy (SEM) morphological analysis, and Streptococcus mutans biofilm formation were assessed for each group. Results The results showed significant differences in roughness average (Ra) values among the polishing materials, with the Shofu Super Snap mini kit having the highest roughness (Ra = 2.04), followed by propol polishing paste (Ra = 1.30)and aluminum oxide paste (Ra = 0.75). Additionally, polishing methods significantly affected mean colony-forming unit (CFU) levels, with the first group having the highest mean CFU value (0.24), with SEM images showing substantial biofilm formation by Streptococcus mutans. Conclusion Bacterial biofilm formation on the aluminum oxide paste group's surface differed from that on the propol polishing paste and aluminum oxide disc groups. The polishing techniques that we tested significantly influenced surface properties and biofilm formation. These findings suggest that selecting an appropriate polishing system can reduce the risk of gingival inflammation associated with temporization materials.

Effects of a Novel Magnetic Nanomaterial on Oral Biofilms

Dental caries is one of the most common oral chronic infectious diseases, and novel antibacterial materials must be developed to control plaque and inhibit formation of dental caries. Combining magnetic nanomaterials with antibacterial agents to decrease the formation of bacterial biofilm has been a hot topic in the biomedical field. The present study developed a novel magnetic nanomaterial chemically combined with dimethylaminododecyl methacrylate (DMADDM) and initially investigated its inhibiting effects on biofilms by using traditional caries-related bacteria and saliva flora models. The novel magnetic nanomaterials successfully loaded DMADDM according to thermogravimetric analysis, Fourier transform infrared spectroscopy, x-ray diffraction, vibrating sample magnetometry, scanning electron microscopy, and transmission electron microscopy results. Further, the novel nanoparticle Fe3O4@SiO2@DMADDM with concentration of 8 mg/mL could effectively reduce Streptococcus mutans biofilm and decrease the production of lactic acid. The 16S rDNA sequencing revealed that Fe3O4@SiO2@DMADDM could depress the proportion of caries-related bacteria in saliva-derived biofilm, such as Streptococcus, Veillonella, and Neisseria. Therefore, Fe3O4@SiO2@DMADDM is a novel effective antibacterial magnetic nanomaterial and has clinical potential in plaque control and dental caries prevention.

The Inhibition of Cyanobacteria Spirulina Extract on S. Mutans Biofilm as an Ingredient in Mouthwash

Background: The main cause of dental caries is Streptococcus mutans (S. mutans), to suppress the growth of cariogenic bacteria can be done by using mouthwash containing antibacterial ingredients such as chlorhexidine. Cyanobacteria spirulina extract contains compounds that have secondary metabolites which act as antibacterial and antioxidant including tannins, flavonoids, saponins and terpenoids. Objective: This study aimed to find out he inhibition of Cyanobacteria spirulina against S. mutans biofilm. Materials and Methods: The research sample consisted of 6 groups. Group K(-) was the S. mutans biofilm with aquadest, K(+) was Chlorhexidine 0.2% and four treatment groups (P1, P2, P3, P4), which were Cyanobacteria spirulina extract with a concentration of 60 , 70, 80 and 90 mg/ml. The sample was applied to a well microtiter plate, then incubated overnight at 37°C for 1 x 24 hours, then painted with 0.1% crystal violet. After that, it was rinsed with sterile distilled water, then given 0.2 mL of Tween 80 concentration of 2% and measured Optical Density with an ELISA Reader with a wavelength of 570 nm, then biofilm inhibition percentage as calculated. Results: The mean value of the percentage of S. mutans biofilm inhibition in group K(+): -131,694(SD 10,758) ; P1: -12,234(SD 2,402) ; P2: 11,076(SD 6,387) ; P3: 19.7020(SD 11,670) ; P4: 40,214(12,057) there were significant differences between P2 and P4 also between P3 and P4. Conclusion: Cyanobacteria spirulina at concentrations of 70, 80 and 90 mg/ml had S. mutans biofilm inhibition, while Chlorhexidine 0.2% and Cyanobacteria spirulina 60 mg/ml did not.

The impact of Streptococcus mutans biofilms on the color stability and topographical features of three lithium disilicate ceramics.

Secondary caries around ceramic restorations is the most common reason for the replacement of fixed dental prostheses (FDPs). Therefore, it is important to examine the susceptibility of different ceramic materials to biofilm formation. This study aimed to evaluate biofilm development and associated roughness and color alterations in three lithium disilicate ceramics: Emax CAD (EC), Emax Press (EP), and LiSi Press (LP). Streptococcus mutans biofilms were grown on the three ceramics (n = 10 per group) for 7 days. Surface roughness values and color alteration were assessed before and after the biofilm using a non-contact profilometer and spectrophotometer, respectively. Biofilm growth was evaluated using colony-forming units (CFUs) and scanning electron microscope (SEM) images. The data were analyzed using one-way ANOVA and Tukey tests. There was a significant (p≤0.001) growth of S. mutans colonies on EC (6.75 ± 0.56) and EP (6.72 ± 0.54) specimens compared to LP, which showed no biofilm growth. The change in average surface roughness (∆Ra, nm) was significantly lower (p < 0.001) in the EC specimens (0.029 ± 0.003) compared to the EP (0.055 ± 0.012) and LP (0.041 ± 0.010). When the changes in the Rv and Rt values were investigated, no significant difference was observed among the groups. Following the biofilm challenge, the change in color (∆E00) was significantly lower (p = 0.005) in the LP group (1.68 ± 1.45) compared to the EC group (3.89 ± 1.50) and no significant difference was observed between the EP group (2.74±1.01) and the other two ceramics (p ≥ 0.05). LP ceramics exhibited superior resistance to S. mutans biofilm formation and associated changes in surface roughness and color compared to the Emax CAD and Emax Press ceramics. These findings suggest that the LiSi Press material may be more favorable to mitigate the risk of secondary caries.

Real-time acid production and extracellular matrix formation in mature biofilms of three Streptococcus mutans strains with special reference to xylitol

BackgroundAcidogenicity and production of an extracellular matrix (ECM) are important virulence factors for the dental caries-associated bacteria, such as Streptococcus mutans, that live in biofilms on tooth surface. The ECM protects the bacteria from the flushing and buffering effects of saliva resulting in highly acidic microenvironments inside the biofilm. Materials and methodsIn this in vitro study, we applied real-time assays to follow biofilm formation and pH decrease in a growth medium and saliva by three S. mutans strains, as well as acid neutralization inside the mature biofilm. Results were compared with the biofilm composition. Effects of a non-fermentable polyol, xylitol, on acid production and acid neutralization in mature biofilms were evaluated by real-time pH measurements and confocal microscopy. ResultsCombination of real-time pH measurements with biofilm accumulation assays revealed growth media dependent differences in the pH decrease and biofilm accumulation, as well as strain differences in acid production and biofilm formation but not in the buffer diffusion through ECM. The presence of xylitol reduced the pH drop during biofilm formation of all strains. In addition, with strain Ingbritt xylitol reduced the amount of ECM in biofilm, which increased the rate of acid neutralization inside the biofilm after buffer exposure. ConclusionOur results stress the importance of biofilm matrix in creating the acidic environment inside a S. mutans biofilm, especially in the presence of saliva. In addition, our results suggest a novel mechanism of xylitol action. The observed increase in the permeability of the S. mutans ECM after xylitol exposure may allow acid-neutralizing saliva to reach deeper layer of the biofilms and thus, in part, explain previous clinical observations of reduced plaque acidogenicity after frequent xylitol use.

S. mutans Antisense vicK RNA Over-Expression Plus Antibacterial Dimethylaminohexadecyl Methacrylate Suppresses Oral Biofilms and Protects Enamel Hardness in Extracted Human Teeth.

Streptococcus mutans (S. mutans) antisense vicK RNA (ASvicK) is a non-coding RNA that regulates cariogenic virulence and metabolic activity. Dimethylaminohexadecyl methacrylate (DMAHDM), a quaternary ammonium methacrylate used in dental materials, has strong antibacterial activity. This study examined the effects of S. mutans ASvicK on DMAHDM susceptibility and their combined impact on inhibiting S. mutans biofilm formation and protecting enamel hardness. The parent S. mutans UA159 and ASvicK overexpressing S. mutans (ASvicK) were tested. The minimum inhibitory concentration (MIC) and minimum bactericidal concentrations for planktonic bacteria (MBC-P) and biofilms (MBC-B) were measured. As the ASvicK MBC-B was 175 μg/mL, live/dead staining, metabolic activity (MTT), colony-forming units (CFUs), biofilm biomass, polysaccharide, and lactic acid production were investigated at 175 μg/mL and 87.5 μg/mL. The MIC, MBC-P, and MBC-B values for DMAHDM for the ASvicK strain were half those of the UA159 strain. In addition, combining S. mutans ASvicK with DMAHDM resulted in a significant 4-log CFU reduction (p < 0.05), with notable decreases in polysaccharide levels and lactic acid production. In the in vitro cariogenic model, the combination achieved the highest enamel hardness at 67.1% of sound enamel, while UA159 without DMAHDM had the lowest at 16.4% (p < 0.05). Thus, S. mutans ASvicK enhanced DMAHDM susceptibility, and their combination effectively inhibited biofilm formation and minimized enamel demineralization. The S. mutans ASvicK + DMAHDM combination shows great potential for anti-caries dental applications.

Cocktail Approach with Polyserotonin Nanoparticles and Peptides for Treatment of Streptococcus mutans.

Dental plaque, formed by a Streptococcus mutans biofilm, is a major contributor to cavity formation. While antimicrobial strategies exist, the growing risk of antibiotic resistance necessitates alternative therapeutic solutions. Polyserotonin nanoparticles (PSeNPs), recently recognized for their photothermal property and promising biomedical applications, open up a new avenue for antimicrobial use. Here, we introduced a UV-initiated synthetic route for PSeNPs with improved yield. Using these PSeNPs, a cocktail treatment to reduce the viability of this cavity-causing bacteria was developed. This cocktail comprises an S. mutans-targeting antimicrobial peptide (GH12), an intraspecies competence-stimulating peptide that triggers altruistic cell death in S. mutans, and laser-activated heating of PSeNPs. The "peptide + PSeNP + laser" combination effectively inhibits S. mutans growth in both planktonic and biofilm states. Moreover, the cocktail approach remains effective in reducing the viability of S. mutans in a more virulent dual-species biofilm with Candida albicans. Overall, our results reinforce the utility of a multipronged therapeutic strategy to reduce cariogenic bacteria in the complex model oral biofilm.

In vitro assessment of NaF/Chit supramolecular complex: Colloidal stability, antibacterial activity and enamel protection against S. mutans biofilm

ObjectivesThis study assessed the effect of NaF/Chit suspensions on enamel and on S. mutans biofilm, simulating application of a mouthrinse. MethodsThe NaF/Chit particle suspensions were prepared at molar ratio [NaF]/Chitmon]≈0.68 at nominal concentrations of 0.2 % and 0.05 % NaF and characterized by Fourier transform infrared spectroscopy (FTIR), dynamic light scattering and zeta potential. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were measured. The S. mutans biofilm was formed for 7 days on eighty human enamel blocks that were divided into eight groups (n = 10/group): i) 0.05 % NaF solution; ii) 0.31 % Chit solution; iii) NaF/Chit(R=0.68) suspension at 0.05 % NaF; iv) 1.0 % HAc solution (Control); v) 0.2 % NaF solution; vi) 1.25 % Chit solution; vii) NaF/Chit(R=0.68) suspension at 0.2 % NaF; viii) 0.12 % chlorhexidine digluconate. The substances were applied daily for 90 s. S. mutans cell counts (CFU/mL) were performed, and the Knoop microhardness (KHN) of enamel samples were measured before and after biofilm formation. The KHN and CFU/mL data were analyzed by repeated measure ANOVA and Tukey's test (α = 0.05). ResultsInteractions between NaF and Chit were evidenced in solid state by FTIR spectra. The NaF/Chit complexes showed spontaneous microparticle formation and colloidal stability. The MIC and MBC ranged from 0.65 to 1.31 mg/mL. The NaF/Chit(R=0.68) suspension at 0.2 %NaF Group showed lower CFU/mL values than other groups. The NaF/Chit(R=0.68) suspensions Groups had the highest KHN values after biofilm formation. ConclusionsThe NaF/Chit(R=0.68) complexes exhibited an antibacterial effect against S. mutans biofilm and reduced the enamel hardness loss. Clinical significanceThe NaF/Chit(R=0.68) suspensions showed potential to be used as a mouthrinse for caries prevention.