Antibacterial, cytotoxic and mechanical properties of a orthodontic cement with phosphate nano-sized and phosphorylated chitosan: An in vitro study.

OBJECTIVES: Evaluate, in vitro, the effect of incorporating nano-sized sodium trimetaphosphate (TMPnano) and phosphorylated chitosan (Chi-Ph) into resin-modified glass ionomer cement (RMGIC) used for orthodontic bracket cementation, on mechanical, fluoride release, antimicrobial and cytotoxic properties. METHODS: RMGIC was combined with Chi-Ph (0.25%/0.5%) and/or TMPnano (14%). The diametral compressive/tensile strength (DCS/TS), surface hardness (SH) and degree of conversion (%DC) were determined. For fluoride (F) release, samples were immersed in des/remineralizing solutions. Antimicrobial/antibiofilm activity was evaluated by the agar diffusion test and biofilm metabolism (XTT). Cytotoxicity in fibroblasts was assessed with the resazurin method. RESULTS: After 24 h, the RMGIC-14%TMPnano group showed a lower TS value (p < 0.001); after 7 days the RMGIC-14%TMPnano-0.25%Chi-Ph group showed the highest value (p < 0.001). For DCS, the RMGIC group (24 h) showed the highest value (p < 0.001); after 7 days, the highest value was observed for the RMGIC-14%TMPnano-0.25%Chi-Ph (p < 0.001). RMGIC-14%TMPnano, RMGIC-14%TMPnano-0.25%Chi-Ph, RMGIC-14%TMPnano-0.5%Chi-Ph showed higher and similar release of F (p > 0.001). In the SH, the RMGIC-0.25%Chi-Ph; RMGIC-0.5%Chi-Ph; RMGIC-14%TMPnano-0.5%Chi-Ph groups showed similar results after 7 days (p > 0.001). The RMGIC-14%TMPnano-0.25%Chi-Ph group showed a better effect on microbial/antibiofilm growth, and the highest efficacy on cell viability (p < 0.001). After 72 h, only the RMGIC-14%TMPnano-0.25%Chi-Ph group showed cell viability (p < 0.001). CONCLUSION: The RMGIC-14%TMPnano-0.25%Chi-Ph did not alter the physical-mechanical properties, was not toxic to fibroblasts and reduced the viability and metabolism of S. mutans. CLINICAL RELEVANCE: The addition of phosphorylated chitosan and organic phosphate to RMGIC could provide an antibiofilm and remineralizing effect on the tooth enamel of orthodontic patients, who are prone to a high cariogenic challenge due to fluctuations in oral pH and progression of carious lesions.

Synthesis, Characterization, and Evaluation of the Antimicrobial Effects and Cytotoxicity of a Novel Nanocomposite Based on Polyamide 6 and Trimetaphosphate Nanoparticles Decorated with Silver Nanoparticles.

This study aimed to develop a polymeric matrix of polyamide-6 (P6) impregnated with trimetaphosphate (TMP) nanoparticles and silver nanoparticles (AgNPs), and to evaluate its antimicrobial activity, surface free energy, TMP and Ag+ release, and cytotoxicity for use as a support in dental tissue. The data were subjected to statistical analysis (p < 0.05). P6 can be incorporated into TMP without altering its properties. In the first three hours, Ag+ was released for all groups decorated with AgNPs, and for TMP, the release only occurred for the P6-TMP-5% and P6-TMP-10% groups. In the inhibition zones, the AgNPs showed activity against both microorganisms. The P6-TMP-2.5%-Ag and P6-TMP-5%-Ag groups with AgNPs showed a greater reduction in CFU for S. mutans. For C. albicans, all groups showed a reduction in CFU. The P6-TMP groups showed higher cell viability, regardless of time (p < 0.05). The developed P6 polymeric matrix impregnated with TMP and AgNPs demonstrated promising antimicrobial properties against the tested microorganisms, making it a potential material for applications in scaffolds in dental tissues.

Biomineralization and remineralizing potential of toothpastes containing nanosized ß-calcium glycerophosphate: an in vitro study.

To evaluate the effect of 1100 ppm F toothpastes supplemented with micrometric or nanosized ß-CaGP (ß-CaGPm/ß-CaGPn) on artificial enamel remineralization, using a pH cycling model. Enamel blocks with artificial caries were randomly allocated into ten groups (n = 10), according to the toothpastes: without fluoride/ß-CaGPm/ß-CaGPn (negative control); 1100 ppm F (1100F); 1100F plus 0.125%, 0.25%, 0.5%, and 1.0% of ß-CaGPm or ß-CaGPn. The blocks were treated 2×/day with slurries of toothpastes. After pH cycling, the percentage of surface hardness recovery (%SHR); integrated loss of subsurface hardness (ΔKHN); integrated mineral loss (ΔIMR); fluoride (F), calcium (Ca), and phosphorus (P) concentrations in the enamel; polydispersity index (PdI); and zeta potential (Zp) were determined. The data were analyzed by ANOVA (p < 0.001). For Zp/PdI, no significance was observed when comparing the means (p > 0.001). The treatment with 1100F-0.25%ß-CaGPn led to %SHR ∼57 higher when compared to the 1100F group (p < 0.001). The lowest ΔKHN was observed for the 1100F-0.25%ß-CaGPn group (p < 0.001). The ΔIMR was lower (∼201%) for the 1100F-0.25%ß-CaGPn when compared to 1100F (p < 0.001). The association of ß-CaGPm and ß-CaGPn to 1100F did not influence its F concentration (p > 0.001). The highest increase in Ca and P was observed for 1100F-0.25%ß-CaGPn (p < 0.001). The addition of 0.25%ß-CaGPn to 1100F toothpaste was able to promote an additional remineralizing effect of artificial caries lesions.

Effect of nanometric ß-calcium glycerophosphate supplementation in conventional toothpaste on enamel demineralization: An in vitro study.

The aim of this study was to evaluate the effects of supplementing toothpastes containing 1100 ppm F with micrometric or nanometric [beta]-calcium glycerophosphate (ß-CaGPm/ß-CaGPn) on artificial enamel demineralization, using a pH cycling model. Bovine enamel blocks (4 mm × 4 mm, n = 120) selected using initial surface hardness were randomly allocated to ten toothpaste groups (n = 12): without fluoride or ß-CaGPm or ß-CaGPn (Negative control), 1100 ppm F (1100 F), and 1100 ppm F plus 0.125%, 0.25%, 0.5%, and 1.0% of ß-CaGPm or ß-CaGPn. Blocks were treated two times per day with toothpaste slurry and subjected to five pH cycles (demineralizing and remineralizing solutions) at 37 °C. The final surface hardness, percentage of surface hardness loss (%SH), cross-sectional hardness (ΔKHN), and profile analysis and lesion depth subsurface were analysed using polarized light microscopy (PLM). Fluoride (F), calcium (Ca), and phosphorus (P) concentrations were also measured. Data were analysed using ANOVA and Student-Newman-Keuls tests ([alpha] = 0.001). Blocks treated with 1100 F toothpaste containing 0.5%ß-CaGPm or 0.25%ß-CaGPn showed with reduced %SH values when compared with those treated with 1100 F alone (p < 0.001). Reduced lesion depths (ΔKHN and PLM) were observed for the slurry made up of 1100 F and 0.25%ß-CaGPn (p < 0.001). The addition of ß-CaGPm and ß-CaGPn did not influence the enamel F concentration, with the 1100 F/0.25%ß-CaGPn group exhibiting the highest Ca and P enamel concentrations (p < 0.001). Based on the findings of this in vitro study, we can conclude that the fluoride toothpaste produced a superior effect when combined at an appropriate ß-CaGP molar ratio. This effect was achieved with a lower proportion of ß-CaGP in the form of nanometric particles.

'Green' silver nanoparticles combined with tyrosol as potential oral antimicrobial therapy.

OBJECTIVES: This study aimed to evaluate silver nanoparticles (AgNPs) obtained by a 'green' route associated or not to tyrosol (TYR) against Streptococcus mutans and Candida albicans in planktonic and biofilms states. METHODS: AgNPs were obtained by a 'green' route using pomegranate extract. The minimum inhibitory concentration (MIC) against S. mutans and C. albicans was determined for AgNPs and TYR combined and alone, and fractional inhibitory concentration index (FICI) was calculated. Single biofilms of C. albicans and S. mutans were cultivated for 24 h and then treated with drugs alone or in combination for 24 h. RESULTS: AgNPs and TYR were effective against C. albicans and S. mutans considering planktonic cells alone and combined. The MIC values obtained for C. albicans was 312.5 µg/mL (AgNPs) and 50 mM (TYR) and for S. mutans was 78.1 µg/mL (AgNPs) and 90 mM (TYR). The combination of these antimicrobial agents was also effective against both microorganisms: 2.44 µg/mL/0.08 mM (AgNPs/TYR) for C. albicans and 39.05 µg/mL /1.25 mM (AgNPs/TYR) for S. mutans. However, synergism was observed only for C. albicans (FICI 0.008). When biofilm was evaluated, a reduction of 4.62 log10 was observed for S. mutans biofilm cells treated with AgNPs (p < 0.05, Tukey test). However, the addition of TYR to AgNPs did not improve their action against biofilm cells (p > 0.05). AgNPs combined with TYR demonstrated a synergistic effect against C. albicans biofilms. CONCLUSIONS: These findings suggest the potential use of AgNPs with or without TYR against C. albicans and S. mutans, important oral pathogens. CLINICAL SIGNIFICANCE: AgNPs obtained by a 'green' route combined or not with TYR can be an alternative to develop several types of oral antimicrobial therapies and biomaterials.

Effect of the association of microparticles and nano-sized ß-calcium glycerophosphate in conventional toothpaste on enamel remineralization: In situ study.

OBJECTIVES: This in situ study aimed to assess the remineralizing effect of a fluoride toothpaste supplemented with ß-calcium glycerophosphate in both micro (ß-CaGPm) and nano-sized forms (ß-CaGPn). METHODS: This blind and cross-over study was performed in 4 phases, each spanning 3 days. Twelve volunteers utilized palatal appliances containing four bovine enamel blocks with artificial caries lesions. Volunteers were randomly assigned to the following treatment groups: Placebo (no F-ß-CaGPm-ß-CaGPn); 1100 ppm F alone (1100F); 1100F plus 0.5% micrometric ß-CaGP (1100F-0.5%ß-CaGPm); and 1100F plus 0.25%nano-sized ß-CaGP (1100F-0.25%ß-CaGPn). Participants were instructed to brush their natural teeth with the palatal appliances in the mouth for 1 min (3 times/day), ensuring that the enamel blocks were exposed to the natural toothpaste slurries. Following each phase, evaluations were conducted to determine the percentage of surface hardness recovery (%SHR), integrated recovery of subsurface hardness (ΔIHR), profile subsurface lesion through polarized light microscopy (PLM), as well as fluoride (F), calcium (Ca), and phosphorus (P) concentrations within the enamel. Data were analyzed by ANOVA and Student-Newman-Keuls test (p < 0.001). RESULTS: Treatment with 1100F-0.25%ß-CaGPn resulted in %SHR ∼69 % and ∼40 % higher when compared to 1100F and 1100F-0.5%ß-CaGPm (p < 0.001). The reduction in lesion body (ΔIHR; PLM) was ∼40 % higher with 1100F-0.25%ß-CaGPn (p < 0.001) compared to 1100F. The addition of ß-CaGPm and ß-CaGPn did not influence enamel F concentration (p > 0.001). Treatment with 1100F-0.25%ß-CaGPn led to an increase in the concentration of Ca and P in the enamel (p < 0.001). CONCLUSION: The addition of 0.25%ß-CaGPn into 1100F formulation increased the bioavailability of calcium and phosphate, promoting a higher remineralizing effect. CLINICAL SIGNIFICANCE: Toothpaste containing 1100F-0.25%ß-CaGPn showed a potential of higher remineralization to 1100 ppm F and 1100 ppm F micrometric ß-CaGP could be a strategy for patients at caries activity.

Effects of nano-sized sodium hexametaphosphate on the viability, metabolism, matrix composition, and structure of dual-species biofilms of Streptococcus mutans and Candida albicans.

This study evaluated the effects of micrometric or nano-sized sodium hexametaphosphate (HMPnano), combined or not with fluoride (NaF, 1100 ppm), on dual-species biofilms of Streptococcus mutans and Candida albicans. Biofilms were treated with solutions containing the polyphosphates at 0.5% or 1.0%, with/without fluoride (F), in addition to positive and negative controls. Biofilms were analysed by colony-forming units (CFU) counting, metabolic activity, production of biomass, composition of extracellular matrix, and structure. 1% HMPnano + F led to the lowest S. mutans CFU, while C. albicans CFU counts were not affected by any solution. 1% HMPnano led to the lowest metabolic activity, except for 1% HMPnano + F. All solutions promoted reductions in biofilm biomass compared to controls. Also, 1% HMPnano + F promoted the lowest concentrations of carbohydrates in the biofilm matrix, besides substantially affecting biofilms' structure. In conclusion, HMPnano and F promoted higher antibiofilm effects compared with its micrometric counterpart for most of the parameters assessed.

Activity of Sodium Trimetaphosphate Nanoparticles on Cariogenic-Related Biofilms In Vitro.

In light of the promising effect of sodium trimetaphosphate nanoparticles (TMPn) on dental enamel, in addition to the scarce evidence of the effects of these nanoparticles on biofilms, this study evaluated the activity of TMPn with/without fluoride (F) on the pH, inorganic composition and extracellular matrix (ECM) components of dual-species biofilms of Streptococcus mutans and Candida albicans. The biofilms were cultivated in artificial saliva in microtiter plates and treated with solutions containing 1% or 3% conventional/microparticulate TMP (TMPm) or TMPn, with or without F. After the last treatment, the protein and carbohydrate content of the ECM was analyzed, and the pH and F, calcium (Ca), phosphorus (P), and TMP concentrations of the biofilms were determined. In another set of experiments, after the last treatment, the biofilms were exposed to a 20% sucrose solution, and their matrix composition, pH, and inorganic component contents were evaluated. 3% TMPn/F significantly reduced ECM carbohydrate and increased biofilm pH (after sucrose exposure) than other treatments. Also, it significantly increased P and F levels before sucrose exposure in comparison to 3% TMPm/F. In conclusion, 3% TMPn/F affected the biofilm ECM and pH, besides influencing inorganic biofilm composition by increasing P and F levels in the biofilm fluid.

Green and Chemical Silver Nanoparticles and Pomegranate Formulations to Heal Infected Wounds in Diabetic Rats.

Infected cutaneous ulcers from diabetic rats with Candida albicans and Streptococcus aureus were treated with spray formulations containing green silver nanoparticles (GS), chemical silver nanoparticles (CS), or pomegranate peel extract (PS). After wound development and infection, the treatments were performed twice per day for 14 days. The wound healing was analyzed on days 2, 7, and 14 through the determination of CFUs, inflammatory infiltrate, angiogenesis, fibroplasia, myeloperoxidase, and collagen determination. Expressive improvement in wound healing was noted using both silver nanoparticles for 7 days. All the treatments were superior to controls and promoted significant S. aureus reduction after 14 days. CS presented better anti-inflammatory results, and GS and CS the highest number of fibroblasts. Despite the techniques' limitations, GS and CS demonstrated considerable potential for managing infected wounds, especially considering no early strategies prior to the drugs, such as the debridement of these wounds, were included.

The potential of nanomaterials associated with plant growth-promoting bacteria in agriculture.

The impacts of chemical fertilizers and pesticides have raised public concerns regarding the sustainability and security of food supplies, prompting the investigation of alternative methods that have combinations of both agricultural and environmental benefits, such as the use of biofertilizers involving microbes. These types of microbial inoculants are living microorganisms that colonize the soil or plant tissues when applied to the soil, seeds, or plant surfaces, facilitating plant nutrient acquisition. They can enhance plant growth by transforming nutrients into a form assimilable by plants and by acting as biological control agents, known as plant growth-promoting bacteria. The potential use of bacteria as biofertilizers in agriculture constitutes an economical and eco-friendly way to reduce the use of chemical fertilizers and pesticides. In this context, nanotechnology has emerged as a new source of quality enrichment for the agricultural sector. The use of nanoparticles can be an effective method to meet the challenges regarding the effectiveness of biofertilizers in natural environments. Given the novel sustainable strategies applied in agricultural systems, this review addresses the effects of nanoparticles on beneficial plant bacteria for promoting plant growth.

Novel Colloidal Nanocarrier of Cetylpyridinium Chloride: Antifungal Activities on Candida Species and Cytotoxic Potential on Murine Fibroblasts.

Nanocarriers have been used as alternative tools to overcome the resistance of Candida species to conventional treatments. This study prepared a nanocarrier of cetylpyridinium chloride (CPC) using iron oxide nanoparticles (IONPs) conjugated with chitosan (CS), and assessed its antifungal and cytotoxic effects. CPC was immobilized on CS-coated IONPs, and the nanocarrier was physico-chemically characterized. Antifungal effects were determined on planktonic cells of Candida albicans and Candida glabrata (by minimum inhibitory concentration (MIC) assays) and on single- and dual-species biofilms of these strains (by quantification of cultivable cells, total biomass and metabolic activity). Murine fibroblasts were exposed to different concentrations of the nanocarrier, and the cytotoxic effect was evaluated by MTT reduction assay. Characterization methods confirmed the presence of a nanocarrier smaller than 313 nm. IONPs-CS-CPC and free CPC showed the same MIC values (0.78 µg mL-1). CPC-containing nanocarrier at 78 µg mL-1 significantly reduced the number of cultivable cells for all biofilms, surpassing the effect promoted by free CPC. For total biomass, metabolic activity, and cytotoxic effects, the nanocarrier and free CPC produced statistically similar outcomes. In conclusion, the IONPs-CS-CPC nanocarrier was more effective than CPC in reducing the cultivable cells of Candida biofilms without increasing the cytotoxic effects of CPC, and may be a useful tool for the treatment of oral fungal infections.

Novel nanocarrier of miconazole based on chitosan-coated iron oxide nanoparticles as a nanotherapy to fight Candida biofilms.

Overexposure of microorganisms to conventional drugs has led to resistant species that require new treatment strategies. This study prepared and characterized a nanocarrier of miconazole (MCZ) based on iron oxide nanoparticles (IONPs) functionalized with chitosan (CS), and tested its antifungal activity against biofilms of Candida albicans and Candida glabrata. IONPs-CS-MCZ nanocarrier was prepared by loading MCZ on CS-covered IONPs and characterized by physicochemical methods. Minimum inhibitory concentration (MIC) of the nanocarrier was determined by the microdilution method. Biofilms were developed (48 h) in microtiter plates and treated with MCZ-carrying nanocarrier at 31.2 and 78 µg/mL, in both the presence and absence of an external magnetic field (EMF). Biofilms were evaluated by total biomass, metabolic activity, cultivable cells (CFU), extracellular matrix components, scanning electron microscopy and confocal microscopy. Data were analyzed by two-way ANOVA and Holm-Sidak test (p < 0.05). A nanocarrier with diameter lower than 50 nm was obtained, presenting MIC values lower than those found for MCZ, and showing synergism for C. albicans and indifference for C. glabrata (fractional inhibitory concentration indexes of <0.12 and <0.53, respectively). IONPs-CS-MCZ did not affect total biomass and extracellular matrix. IONPs-CS-MCZ containing 78 µg/mL MCZ showed a superior antibiofilm effect to MCZ in reducing CFU and metabolism for single biofilms of C. albicans and dual-species biofilms. The EMF did not improve the nanocarrier effects. Microscopy confirmed the antibiofilm effect of the nanocarrier. In conclusion, IONPs-CS-MCZ was more effective than MCZ mainly against C. albicans planktonic cells and number of CFU and metabolism of the biofilms.

Incorporation of chlorhexidine and nano-sized sodium trimetaphosphate into a glass-ionomer cement: Effect on mechanical and microbiological properties and inhibition of enamel demineralization.

OBJECTIVE: To evaluate the antimicrobial/antibiofilm and mechanical properties, and the effect on enamel demineralization of a resin-modified GIC (RMGIC) containing CHX and nano-sized sodium trimetaphosphate (TMP). METHODS: RMGIC was associated with CHX (1.25 or 2.5%) and/or TMP (7 or 14%). Antimicrobial and antibiofilm activity were assessed using agar diffusion test and evaluation of biofilm metabolism, respectively. In addition, fluoride (F) and TMP releases as well as the diametral tensile (DTS) and compressive (CS) strength were determined. The percentage of mineral loss (%SH), integrated loss of subsurface hardness (ΔKHN) and enamel F concentrations were also evaluated. RESULTS: RMGICs containing CHX associated or not with TMP presented higher inhibition zones and effect on S. mutans biofilm. A reduction on CS was observed only for RMGIC + 2.5%CHX and on DTS for RMGIC + 2.5%CHX + 14%TMP. The highest F and TMP releases and lowest %SH and ΔKHN values were detected for RMGIC + 1.25%CHX + 14%TMP and RMGIC + 2.5%CHX + 14%TMP. Higher enamel F concentrations were observed for TMP groups. CONCLUSION: 1.25%CHX and 14%TMP increased antimicrobial/antibiofilm action and the ability to prevent enamel demineralization, with minimal effect on the mechanical properties of RMGIC. CLINICAL SIGNIFICANCE: RMGIC containing CHX and TMP is an alternative material for patients at high risk for dental caries and can be indicated for low-stress regions or provisional restorations.

Antimicrobial Activity of Compounds Containing Silver Nanoparticles and Calcium Glycerophosphate in Combination with Tyrosol.

Nanocomposites containing antimicrobial agents and calcium phosphates have been developed. Thus, this study assessed the effects of two compounds containing silver nanoparticles (AgNPs) and ß-calcium glycerophosphate (CaGP), associated or not with tyrosol (TYR), against planktonic cells and biofilms of Candida albicans and Streptococcus mutans. The nanocompounds were synthesized through chemical and 'green' processes and characterized by scanning electron microscopy. The minimum and fractional inhibitory concentrations of each compound were determined for planktonic cells. Next, 24-h single biofilms of C. albicans and S. mutans were treated for 24 h with the nanocompounds alone or in combination with TYR, and the antibiofilm effect was assessed through enumeration of colony forming units. Biofilm data were statistically examined using one-way ANOVA and the Kruskal-Wallis test (α = 0.05). The chemically synthesized nanocompound in combination with TYR demonstrated a synergistic effect against planktonic cells of C. albicans and S. mutans. For the nanocompound obtained through the 'green' route associated with TYR, a synergistic effect was observed only against C. albicans. For biofilms, only the combination obtained through the 'green' route + TYR demonstrated a synergistic effect against C. albicans. Our results may contribute to the development of oral care products containing AgNPs-CaGP and TYR to combat oral infections.

Antibiofilm effect of chlorhexidine-carrier nanosystem based on iron oxide magnetic nanoparticles and chitosan.

This study synthesized and characterized a chlorhexidine (CHX)-carrier nanosystem based on iron oxide magnetic nanoparticles (IONPs) and chitosan (CS), and evaluated its antimicrobial effect on mono- and dual-species biofilms of Candida albicans and Streptococcus mutans. CHX was directly solubilized in CS-coated IONPs and maintained under magnetic stirring for obtaining the IONPs-CS-CHX nanosystem. Antimicrobial susceptibility testing for planktonic cells was performed by determining the minimum inhibitory concentration (MIC) of the nanosystem and controls. The effects of the IONPs-CS-CHX nanosystem on the formation of mono- and dual-species biofilms, as well as on pre-formed biofilms were assessed by quantification of total biomass, metabolic activity and colony-forming units. Data were analyzed by the Kruskal-Wallis' test or one-way analysis of variance, followed by the Student-Newman-Keuls' or Holm-Sidak's tests (α = 0.05), respectively. Physico-chemical results confirmed the formation of a nanosystem with a size smaller than 40 nm. The IONPs-CS-CHX nanosystem and free CHX showed similar MIC values for both species analyzed. In general, biofilm quantification assays revealed that the CHX nanosystem at 78 µg/mL promoted similar or superior antibiofilm effects compared to its counterpart at 39 µg/mL and free CHX at 78 µg/mL. These findings highlight the potential of CS-coated IONPs as preventive or therapeutic agents carrying CHX to fight biofilm-associated oral diseases.

Anticaries effect of toothpaste with nano-sized sodium hexametaphosphate.

OBJECTIVE: To evaluate the effect of a fluoride toothpaste containing nano-sized sodium hexametaphosphate (HMPnano) on enamel demineralization on the biochemical composition and insoluble extracellular polysaccharide (EPS) in biofilm formed in situ. METHODS: This crossover double-blind study consisted of four phases (7 days each), in which 12 volunteers wore intraoral appliances containing four enamel bovine blocks. The cariogenic challenge was performed using 30% sucrose solution (6×/day). Blocks were treated 3×/day with the following toothpastes: no F/HMP/HMPnano (Placebo), conventional fluoride toothpaste, 1100 ppm F (1100F), 1100F + 0.5% micrometric HMP (1100F/HMP), and 1100F + 0.5% nano-sized HMP (1100F/HMPnano). The percentage of surface hardness loss (%SH), integrated loss of subsurface hardness (ΔKHN), and enamel calcium (Ca), phosphorus (P), and fluoride (F) were determined. Moreover, biofilms formed on the blocks were analyzed for F, Ca, P, and insoluble extracellular polysaccharide (EPS) concentrations. Data were analyzed using one-way ANOVA, followed by Student-Newman-Keuls' test (p < 0.001). RESULTS: 1100F/HMPnano promoted the lowest %SH and ΔKHN among all groups (p < 0.001). The addition of HMPnano to 1100F significantly increased Ca concentrations (p < 0.001). The 1100F/HMPnano promoted lower values of EPS when compared with 1100F (~ 70%) (p < 0.001) and higher values of fluoride and calcium in the biofilms (p < 0.001). CONCLUSION: 1100F/HMPnano demonstrated a greater protective effect against enamel demineralization and on the composition of biofilm in situ when compared to 1100F toothpaste. CLINICAL RELEVANCE: This toothpaste could be a viable alternative to patients at high risk of caries.

In situ effect of fluoride toothpaste supplemented with nano-sized sodium trimetaphosphate on enamel demineralization prevention and biofilm composition.

OBJECTIVE: To evaluate the effect of a fluoride toothpaste containing nano-sized sodium trimetaphosphate (TMPnano) on enamel demineralization in situ and composition of the biofilm. DESIGN: This crossover double-blind study consisted of four phases (seven days each) and 12 volunteers who wore oral appliances containing four enamel bovine blocks. The cariogenic challenge was performed by 30% sucrose solution (6x/day). The toothpaste treatments (3x/day) were as follows: no F/TMP/TMPnano (Placebo), 1100 ppm F (1100F), 1100F plus 3% micrometric or nano-sized TMP (1100F/TMP; 1100F/TMPnano). Percentage of surface hardness loss (%SH), and integrated loss of subsurface hardness (ΔKHN), as well as enamel calcium (Ca), phosphorus (P), and fluoride (F) were determined. Moreover, biofilm formed on the blocks were analyzed for F, Ca, P, and insoluble extracellular polysaccharide (EPS) concentrations. Data were analyzed using one-way ANOVA, repeated measures followed by Fisher LSD test (p < 0.001). RESULTS: 1100F/TMPnano promoted the lowest %SH and ΔKHN among all groups (p < 0.001). Regarding the F concentrations in the enamel and in the biofilm, there were no significant differences between 1100 F and 1100 F/TMPnano, but significantly increased enamel Ca concentrations (p < 0.001). 1100F/TMPnano showed lower values of EPS concentration when compared with 1100F (∼80%) (p < 0.001). CONCLUSION: 1100F/TMPnano promoted a greater protective effect against enamel demineralization and significantly affected the composition of biofilm formed in situ when compared to 1100F toothpaste.

Antimicrobial Potential and Cytotoxicity of Silver Nanoparticles Phytosynthesized by Pomegranate Peel Extract.

The phytosynthesis of metal nanoparticles is nowadays attracting the increased attention of researchers and is much needed given the worldwide matter related to environmental contamination. The antimicrobial activity of colloidal and spray formulation of silver nanoparticles (AgNPs) synthesized by pomegranate peel extract against Candida albicans and Staphylococcus aureus, and their cytotoxicity in mammalian cells were tested in the present study. Dry matter, pH, total phenolics, and ellagic acid in the extract were determined. Then, AgNPs were phytosynthesized and characterized by X-ray diffraction, electron transmission microscopy, dynamic light scattering, zeta potential, and Ag⁺ dosage. Spray formulations and respective chemical-AgNP controls were prepared and tested. The peel extract reduced more than 99% of Ag⁺, and produced nanoparticles with irregular forms and an 89-nm mean size. All AgNP presented antimicrobial activity, and the spray formulation of green-AgNP increased by 255 and 4 times the effectiveness against S. aureus and C. albicans, respectively. The cytotoxicity of colloidal and spray green-AgNP was expressively lower than the respective chemical controls. Pomegranate peel extract produced stable AgNP with antimicrobial action and low cytotoxicity, stimulating its use in the biomedical field.

Fluoride toothpastes containing micrometric or nano-sized sodium trimetaphosphate reduce enamel erosion in vitro.

OBJECTIVE: To evaluate the effect of fluoride toothpastes supplemented with micrometric or nano-sized sodium trimetaphosphate (TMP or TMPnano, respectively) on enamel erosion in vitro, as well as the influence of salivary acquired pellicle and saliva. MATERIAL AND METHODS: Bovine enamel blocks (n = 120) were randomly assigned into the following experimental toothpastes: no F/TMP/TMPnano (Placebo); 1100 ppm F (1100 ppm F); 1100 ppm F plus 3% TMP or 3% TMPnano (1100 TMP or 1100 TMPnano, respectively) and 5000 ppm F (5000 ppm F). Erosive challenge was performed by immersion of the blocks in citric acid for 5 min, followed by 2 h immersion in human or artificial saliva, 4×/day, during 5 days. After each erosive challenge, blocks were exposed to slurries of the toothpastes. Enamel erosion (µm), surface hardness (SHf) and cross-sectional hardness (ΔKHN) were analyzed as response variables and the data were submitted to two-way ANOVA, followed by the Student-Newman-Keuls test (p < .05). RESULTS: 1100 TMPnano significantly reduced enamel loss when compared to 1100 TMP (p = .002), reaching values similar to those promoted by 5000 ppm F (p = .96). 1100 ppm F presented significantly lower enamel loss than Placebo (p < .001), and higher than 1100 TMP (p < .001). Significantly higher SHf and lower ΔKHN was observed for 1100 TMPnano and 5000 ppm F when compared with the other groups (p < .001). The type of saliva did not influence enamel erosion, SHf and ΔKHN for the groups treated with TMP-containing toothpastes. CONCLUSION: The addition of 3% TMPnano to 1100 ppm F toothpastes significantly increases the protective effect against enamel erosion in vitro when compared with its counterparts with micrometric TMP or without TMP. This effect was not influenced by the presence of acquired enamel pellicle and saliva.