Effect of Silver Nanoparticle-Added Pit and Fissure Sealant in the Prevention of Dental Caries in Children.

OBJECTIVE: The objective of this study was to evaluate the effects of pit and fissure sealant mixed with silver nanoparticles on dental caries, by means of monthly measurement of fluorescence with DIAGNOdent over six months. STUDY DESIGN: This study was divided in two phases: experimental and clinical. In the experimental phase, the adhesion and microleakage of the pit and fissure sealant experiment were evaluated. Two groups of 10 teeth, without serious carious lesions, were included. Conventional (group A) and silver nanoparticles (group B) were added to the pit and fissure sealant. For the clinical phase, a split-mouth study was performed on 40 children aged 6-10 years old with healthy, erupted permanent first molars. A conventional pit and fissure sealant or a silver nanoparticle-mixed sealant was randomly placed. Repeated measures analysis was performed. RESULTS: Conventional sealant presented an average microleakage of 30.6%, and the silver nanoparticle-mixed sealant showed 33.6% (P=NS). A three times greater reduction in fluorescence was found in the silver nanoparticles group compared to the conventional group (P<0.05). No sex- or age-based associations were found. CONCLUSIONS: The silver nanoparticle-mixed sealant reduced tooth demineralization significantly and likely increased remineralization, compared to the conventional sealant.

Anti-biofilm activity of silver nanoparticles against different microorganisms.

Biofilms confer protection from adverse environmental conditions and can be reservoirs for pathogenic organisms and sources of disease outbreaks, especially in medical devices. The goal of this research was to evaluate the anti-biofilm activities of silver nanoparticles (AgNPs) against several microorganisms of clinical interest. The antimicrobial activity of AgNPs was tested within biofilms generated under static conditions and also under high fluid shears conditions using a bioreactor. A 4-log reduction in the number of colony-forming units of Pseudomonas aeruginosa was recorded under turbulent fluid conditions in the CDC reactor on exposure to 100 mg ml(-1) of AgNPs. The antibacterial activity of AgNPs on various microbial strains grown on polycarbonate membranes is reported. In conclusion, AgNPs effectively prevent the formation of biofilms and kill bacteria in established biofilms, which suggests that AgNPs could be used for prevention and treatment of biofilm-related infections. Further research and development are necessary to translate this technology into therapeutic and preventive strategies.

In vitro cytotoxicity of silver nanoparticles on human periodontal fibroblasts.

UNLABELLED: Silver nanoparticles (NNPs) are extensively used for all kinds of antimicrobial applications in medical research. Their efficacy has been demonstrated against Streptococcus mutans, which is associated with dental caries. However their cytotoxic effects on human periodontal tissue are not completely understood. OBJECTIVE: The aim of this study was to evaluate the possible toxic cellular effects of different concentrations and sizes of silver nanoparticles, less than 10 nm, 15-20 nm, and 80-100 nm, respectively, on human periodontal fibroblasts. STUDY DESIGN: Primary culture cells isolated from human periodontal tissue were exposed to 0-1,000 microM silver nanoparticles of each size for 24-, 72-, and 168-hour periods. Cytotoxicity was evaluated with a nonradioactive, soluble MTS/PMS assay. RESULTS: The results demonstrated that silver nanoparticles of less than 20 nm increased cytotoxicity in human periodontal fibroblasts in a dose- and time-dependent manner. CONCLUSION: The 80-100-nm-sized nanoparticles did not modify the viability of human primary culture cells.

Atomic force microscopy observation of the enamel roughness and depth profile after phosphoric acid etching.

The aim was to compare the enamel surface roughness (ESR) and absolute depth profile (ADP) (mean peak-to-valley height) by atomic force microscopy (AFM) before and after using four different phosphoric acids. A total of 160 enamel samples from 40 upper premolars were prepared. The inclusion criterion was that the teeth have healthy enamel. Exclusion criteria included any of the following conditions: facial restorations, caries lesions, enamel hypoplasia and dental fluorosis. Evaluations of the ESR and ADP were carried out by AFM. The Mann-Whitney U-test was used to compare continuous variables and the Wilcoxon test was used to analyze the differences between before and after etching. There were statistically significant differences (P

In vitro determination of the chromatic effect of a silver nanoparticles solution linked to the gantrez S-97 copolymer on tooth enamel.

Silver nanoparticles (NNPs), alone or in combination with the bioadhesive Gantrez S-97, have demonstrated their efficacy against Streptococcus mutans; however, it is not known if this combination changes the color of teeth. The aim of this work was to measure the color changes occurring after the use of a Gantrez-NNP combination on enamel tooth blocks. Two study groups were randomly formed: enamel blocks brushed with (a) the Gantrez-NNP combination and (b) conventional toothpaste, for 1 minute once daily for 4 weeks, then rinsed with distilled water and placed in thymol solution. Color changes in the enamel blocks were measured using a Minolta colorimeter CR300. Analysis of mixed models was performed with R 2.10.1 at a 95% confidence level, using the nonlinear mixed effects (NLME) package. The results showed that there were no color changes over time, only a high luminosity equal in both groups. Our study showed that the use of the Gantrez-NNP combination is safe with respect to dental esthetics in the control of S. mutans.

Bactericidal capacity of silver nanoparticles associated with Gantrez S-97 on Streptococcus mutans.

UNLABELLED: Dental caries is a worldwide public health problem. S mutans plays an important role in the etiology of caries. There have been studies that showed the antimicrobial properties of silver nanoparticles are an effective agent to diminish S. mutans. The objective of this study was to evaluate the bactericidal and bacteriostatic effects of silver nanoparticles in addition to the Gantrez S-27 copolymer, on S mutans. METHOD: We performed an in vitro experimental study using the liquid microdilution method in order to find the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) with the subcultures obtained. The mixture was obtained by preparing 98 microg/mL of silver nanoparticles (10(3)mol) with Gantrez S-27 2%, in distilled water The readings were performed 24 hours after incubation and on 3 consecutive days. The results showed an average MTC of 6.12 microg /mL and MBC of 6.12 microg /mL. CONCLUSION: The addition of Gantrez 2% to silver nanoparticles does not alter its antimicrobial effect.

Effective control of biofilms by photothermal therapy using a gold nanorod hydrogel.

Biofilms are matrices synthesized by bacteria containing polysaccharides, DNA, and proteins. The development of biofilms in infectious processes can induce a chronic inflammatory response that may progress to the destruction of tissues. The treatment of biofilms is difficult because they serve as a bacterial mechanism of defense and high doses of antibiotics are necessary to treat these infections with limited positive results. It has been demonstrated that photothermal therapy using gold nanorods (AuNRs) is an attractive treatment because of its anti-biofilm activity. The purpose of this work was to generate a novel chitosan-based hydrogel embedded with AuNRs to evaluate its anti-biofilm activity. AuNRs were synthesized by the seed-mediated growth method and mixed with the chitosan-based hydrogel. Hydrogels were characterized and tested against two bacterial strains by irradiating the produced biofilm in the presence of the nanoformulation with a laser adjusted at the near infrared spectrum. In addition, the safety of the nanoformulation was assessed with normal human gingival fibroblasts. Results showed that a significant bacterial killing was measured when biofilms were exposed to an increase of 10°C for a short time of 2 min. Moreover, no cytotoxicity was measured when normal gingival fibroblasts were exposed to the nanoformulation using the bactericidal conditions. The development of the reported formulation can be used as a direct application to treat periodontal diseases or biofilm-produced bacteria that colonize the oral cavity.

Therapeutic Use of Silver Nanoparticles in the Prevention and Arrest of Dental Caries.

Dental caries is one of the major diseases of the oral cavity affecting humans worldwide. Different alternatives have been used for its control, but its incidence and prevalence are still high. On the other hand, silver has been used for centuries due to its antimicrobial properties. With advances in nanotechnology, the use and research in nanomaterials has increased, recently, and silver nanoparticles have become an essential part of the dental practice, giving materials physical and chemical improvements in their properties, used for their antibacterial capacity preventing and arresting dental caries. The objective of this review was to examine the use of silver nanoparticles, in the treatment of dental caries in the remineralization of teeth hard tissues, as well as the antimicrobial potential, cytotoxicity, and long-term effectiveness.

The antimicrobial sensitivity of Streptococcus mutans to nanoparticles of silver, zinc oxide, and gold.

Dental caries is a worldwide public health problem for which Streptococcus mutans has been identified as the possible infectious etiology. In recent years nanotechnology has permitted the development of new properties of materials. The objective of this study was to compare the bactericidal and bacteriostatic effects of nanoparticles of silver, zinc oxide, and gold on S. mutans. We used the liquid dilution method to find the minimum inhibitory concentrations (MICs) and with subcultures obtained the minimum bactericidal concentrations (MBCs). For silver the results showed an average MIC of 4.86 +/- 2.71 microg/mL and MBC of 6.25 microg/mL; for zinc the MIC was 500 +/- 306.18 muicrog/mL and MBC of 500 microg/mL; the gold nanoparticles demonstrated an effect only at an initial concentration of 197 mug/mL. We established a higher antimicrobial effect against S. mutans of silver nanoparticles at lower concentrations than gold or zinc, which would allow achieving important clinical effects with a reduced toxicity.

Effects of silver nanoparticles on the bonding of three adhesive systems to fluorotic enamel.

The objective was to evaluate the effect of adding silver nanoparticles into three commercial adhesive systems (Excite™, Adper Prompt L-Pop™ and AdheSE™). Nanoparticles were prepared by a chemical method then mixed with the commercial adhesive systems. This was later applied to the fluorotic enamel, and then micro-tensile bond strength, contact angle measurements and scanning electron microscopy observations were conducted. The commercial adhesive systems achieved the lowest micro-tensile bond strength (Excite™: 11.0±2.1, Adper Prompt L-Pop™: 14.0±5.4 and AdheSE™: 16.0±3.0 MPa) with the highest adhesive failure mode related with the highest contact angle (46.0±0.6º, 30.0±0.5º and 28.0±0.4º respectively). The bond strength achieved in all the experimental adhesive systems (19.0±5.4, 20.0±4.0 and 19.0±3.5 MPa respectively) was statistically higher (p<0.05) than the control and showed the highest cohesive failures related to the lowest contact angle. Adding silver nanoparticles in order to decrease the contact angle improve the adhesive system wetting and its bond strength.

Antimicrobial Properties of Biofunctionalized Silver Nanoparticles on Clinical Isolates of Streptococcus mutans and Its Serotypes.

(1) Background: Streptococcus mutans (S. mutans) is the principal pathogen involved in the formation of dental caries. Other systemic diseases have also been associated with specific S. mutans serotypes (c, e, f, and k). Silver nanoparticles (SNP) have been demonstrated to have good antibacterial effects against S. mutans; therefore, limited studies have evaluated the antimicrobial activity of biofunctionalized SNP on S. mutans serotypes. The purpose of this work was to prepare and characterize coated SNP using two different organic components and to evaluate the antimicrobial activity of SNP in clinical isolates of S. mutans strains and serotypes; (2) Methods: SNP with bovine serum albumin (BSA) or chitosan (CS) coatings were prepared and the physical, chemical and microbiological properties of SNP were evaluated; (3) Results: Both types of coated SNP showed antimicrobial activity against S. mutans bacteria and serotypes. Better inhibition was associated with smaller particles and BSA coatings; however, no significant differences were found between the different serotypes, indicating a similar sensitivity to the coated SNP; (4) Conclusion: This study concludes that BSA and CS coated SNP had good antimicrobial activity against S. mutans strains and the four serotypes, and this study suggest the widespread use of SNP as an antimicrobial agent for the inhibition of S. mutans bacteria.

Antimicrobial activity, cytotoxicity and inflammatory response of novel plastics embedded with silver nanoparticles.

AIM: Infections associated with medical devices are an important cause of morbidity and mortality. Microorganisms are responsible for catheter infections that may then result in the local or systemic dissemination of the microorganism into the bloodstream. The aim of this study was to evaluate the antimicrobial activity of silver nanoparticles (AgNPs) embedded in polyurethane plastics, commonly used for catheter fabrication. MATERIALS & METHODS: AgNPs in the range of 25-30 nm were synthesized and embedded in polyurethane plastics at different concentrations. The antimicrobial activities of these plastics were tested against the three pathogenic microorganisms, Escherichia coli, Staphylococcus epidermidis and Candida albicans, frequently associated with catheter infections. The cytotoxicity of the plastics was evaluated on human-derived macrophages using propidium iodide and the secretion of the pro- and anti-inflammatory cytokines IL-6, IL-10 and TNF-a was measured using ELISA. RESULTS: A significant reduction of 6- to 7-log in the number of bacteria was measured, while a reduction of 90% was measured in the case of C. albicans. Neither cytotoxic effect on macrophages nor immunological response was observed. CONCLUSION: Plastics embedded with AgNPs have great potential to limit microbial colonization of implanted medical devices.

Effectiveness of bonding resin-based composite to healthy and fluorotic enamel using total-etch and two self-etch adhesive systems.

The aim of this study was to evaluate the bond strength of three adhesive systems: Excite™, Adper Prompt L-Pop™ and AdheSE One™ to varying degrees of fluorotic enamel using micro-tensile bond strength (µTBS) tests. Human enamel was classified according to the Thylstrup and Fejerskov Index. The interface resin-enamel was observed using stereoscopic and electron microscopy. The Excite™, achieved the highest µTBS when bonded to healthy enamel and decreased as the degree of fluorosis increased (p<0.05). The Prompt L-Pop™ improved the bonding on moderate and severe fluorosis. The µTBS of the AdheSE One™, was significantly lower in all degrees of fluorotic enamel (p<0.05) indicating a very poor bonding ability to enamel. These results will provide clinicians with preliminary data to assist them in the selection of the most effective adhesive systems for treatment of fluorosis enamel, resulting in more successful restorative care.