The anti-adherence activity and bactericidal effect of microparticulate silver additives in composite resin materials

doi:10.1016/j.archoralbio.2009.03.004

Archives of Oral Biology

Volume 54, Issue 6, June 2009, Pages 595-601

https://doi.org/10.1016/j.archoralbio.2009.03.004 Get rights and content

Abstract

Objective

Resin composite materials tend to accumulate microorganisms and dental plaque, which in turn may induce secondary caries around adhesive restorations. The aim of the present in vitro study was to evaluate the antibacterial activity of a resin composite material loaded with silver microparticles against Streptococcus mutans.

Design

Circular specimens (10.0 mm in diameter) of a resin composite matrix loaded with two different concentrations of a silver additive (Comp0.3: 0.3%; Comp0.6: 0.6%) and one unloaded reference composite matrix (Comp0: 0%) were made. Surface roughness R_a was assessed by perthometer measurements and hydrophobicity according to water contact angles was determined by computerized image analysis. The specimens were incubated in a S. mutans suspension (1 h, 37 °C) and adhering streptococci were quantified by using a biofluorescence assay (Alamar blue/Resazurin). Additionally, the viability of adhering bacteria was assessed by live/dead cell labelling in combination with fluorescence microscopy.

Results

Statistically significant differences between the median water contact angles of Comp0 (66.3°), Comp0.3 (76.7°), and Comp0.6 (89.4°) were observed (p < 0.001). A three- to fourfold higher amount of adhering S. mutans was found on reference Comp0 (12,093 relative fluorescence units) than on Comp0.3 (4258 rfu) and Comp0.6 (3292) (p < 0.001 for both). Significantly higher percentages of dead cells than on Comp0 (0.5%) were found on Comp0.3 (6.1%) and on Comp0.6 (10.1%) (p < 0.001 for both).

Conclusions

The addition of microparticulate silver to a resin composite material increased the surface hydrophobicity and reduced the number of adhering streptococci. Simultaneously it increased the percentage of dead and inactive cells on the composite surface. Thus, silver additives seem to demonstrate anti-adherence activity as well as a bactericidal effect.

Introduction

The initial adhesion of specific oral bacteria to tooth surfaces or artificial dental substrata is both the primary and the essential prerequisite for the development of cariopathogenic biofilms.¹ Within the complex formation of such biofilms, Streptococcus mutans is primarily responsible for the initiation of tooth decay as well as for the progression of an established lesion. Thus, S. mutans is regarded as a major etiological agent of dental caries.2, 3 Secondary caries under and around restorative fillings is a frequent problem and still the main reason for the replacement of direct restorations in clinical operative dentistry.4, 5 Therefore, dental materials with a low susceptibility to adhere oral microorganisms are preferable. Ideally, these materials additionally exhibit antimicrobial properties to limit the adhesion and proliferation of pathogens at a very early stage and, therefore, prevent secondary caries. Various attempts have been made to reduce plaque accumulation on the surface of restorative materials by incorporation of bactericidal agents such as chlorhexidine or antibacterial monomer MDPB (12-methacryloyloxydodecylpyridinium bromide).6, 7

For many years, silver has been known for its significant broad-spectrum antimicrobial activity. Thus, it has widely been used as an antimicrobial agent in different fields of medicine, for instance for coating devices such as catheters and cannulae.8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 Since silver has also proved to be effective against streptococci of the human oral cavity and periodontal pathogens, it might as well be useful as an antibacterial additive to dental restorations.¹² The in vivo growth of oral streptococci was inhibited around silver-containing glass ionomer cements and pure silver ions implanted in SiO₂ fillers exhibited antibacterial activity.20, 21, 22 Yoshida et al. demonstrated inhibitory effects of resin composites loaded with high concentrations of silver-containing fillers on S. mutans and assumed that this effect may be attributed to the anti-adherence activity of the silver-supported substratum.²³

A large number of experimental systems are available to study the bacteriostatic and bactericidal effects of (dental) materials containing antimicrobial additives such as silver. Most of these systems are based on the agar diffusion method, direct colony counting, or optical density measurements.8, 11, 12, 15, 19, 22, 23, 24, 25, 26, 27, 28 Besides these traditional microbial quantification methods, systems based on biofluorescence have gained increasing importance because they are simple, precise, reproducible, and highly sensitive tools for the quantification of (adhering) microorganisms.29, 30, 31, 32, 33, 34 Newly developed two-colour live/dead fluorescence staining methods complemented the investigative possibilities by providing a visual differentiation between living (active) and dead (inactive) bacteria.19, 24, 35, 36 In this context, the SYTO 9/propidium iodide staining proved to be superior in comparison to other assays because it provides a clear differentiation between dead and living bacteria without the interference of background fluorescence.³⁷

The present study was conducted to evaluate the in vitro antibacterial potential of silver additives in resin composite materials against S. mutans. Adhering bacteria were quantified by automated fluorescence quantification (Resazurin), and bacterial vitality was investigated by live/dead staining (BacLight).

Section snippets

Preparation of specimens

The antibacterial additive used in this study was microparticulate silver with a specific surface area of 3–5 m²/g and a particle size ranging from 3.5 to 18 μm (HyMedic 4000; Bio-Gate AG, Nuremberg, Germany). This microparticulate silver was used because of its high specific surface area capable of releasing reasonable amounts of silver.¹⁸ Two experimental composite restorative materials were assessed in the present study, containing 0.3% by weight (Comp0.3) and 0.6% by weight silver additive (

Surface roughness R_a and hydrophobicity

No statistically significant differences were found between the median R_a of Comp0 (0.08 μm), Comp0.3 (0.11 μm), and Comp0.6 (0.08 μm) (p > 0.017 for all comparisons). In contrast, Kruskal–Wallis rank analysis of variance revealed significant differences between the measured contact angles (p < 0.001) of the three test materials. Increasing content of microparticulate silver resulted in an increase of hydrophobicity (Comp0 (66.3°), Comp0.3 (76.7°), and Comp0.6 (89.4°); cf. Fig. 1).

Enumeration of adhering streptococci (Resazurin staining)

Fig. 2 shows the

Discussion

Bacterial biofilms are responsible for dental diseases, such as caries and periodontitis.1, 3 Dental restorations may be regarded as artificial predilection sites for the accumulation of oral microorganisms, and the ability of a specific substratum to foster biofilms is an important pathogenic factor. Consequently, the control of bacterial adhesion and biofilm formation on dental materials is now understood as a crucial factor for determining the longevity of an incorporated material. Resin

Acknowledgement

We are grateful to Monika Schoell for the linguistic revision of the manuscript.

Funding: None.

Competing interests: The first part of the present study (Resazurin staining) was financially supported by the BioGate AG (Nuremberg, Germany). All other parts (live/dead staining, perthometer measurements, statistical analysis) were not financially supported by any Institution. Additionally, all scientific work (production and mixture of composites, laboratory work, analysis, and writing) was done

References (46)

R. Kumar et al.
Silver ion release from antimicrobial polyamide/silver composites
Biomaterials
(2005)
M. Kawashita et al.
Antibacterial silver-containing silica glass prepared by sol–gel method
Biomaterials
(2000)
A.D. Russell et al.
Antimicrobial activity and action of silver
Prog Med Chem
(1994)
J.J. Morrier et al.
Antimicrobial activity of amalgams, alloys and their elements and phases
Dent Mater
(1998)
A. Balamurugan et al.
An in vitro biological and anti-bacterial study on a sol–gel derived silver-incorporated bioglass system
Dent Mater
(2008)
V. Alt et al.
An in vitro assessment of the antibacterial properties and cytotoxicity of nanoparticulate silver bone cement
Biomaterials
(2004)
K. Yamamoto et al.
Antibacterial activity of silver ions implanted in SiO₂ filler on oral streptococci
Dent Mater
(1996)
A. Al-Ahmad et al.
Effects of commonly used food preservatives on biofilm formation of Streptococcus mutans in vitro
Arch Oral Biol
(2008)
S.J. Ahn et al.
Experimental antimicrobial orthodontic adhesives using nanofillers and silver nanoparticles
Dent Mater
(2009)
J.P. Ruparelia et al.
Strain specificity in antimicrobial activity of silver and copper nanoparticles
Acta Biomater
(2008)

S. Gaines et al.

A novel spectrofluorometric microassay for Streptococcus mutans adherence to hydroxylapatite

J Microbiol Methods

(2003)

M. Grivet et al.

Automatic enumeration of adherent streptococci or actinomyces on dental alloy by fluorescence image analysis

J Microbiol Methods

(1999)

R. Buergers et al.

Streptococcal adhesion to novel low-shrink silorane-based restorative

Dent Mater

(2009)

L. Boulos et al.

LIVE/DEAD BacLight: application of a new rapid staining method for direct enumeration of viable and total bacteria in drinking water

J Microbiol Methods

(1999)

C. Hannig et al.

Fluorescence microscopic visualization and quantification of initial bacterial colonization on enamel in situ

Arch Oral Biol

(2007)

R. Buergers et al.

Bacterial adhesion of Streptococcus mutans to provisional fixed prosthodontic material

J Prosthet Dent

(2007)

S. Hahnel et al.

Influence of saliva substitute films on initial Streptococcus mutans adhesion to enamel and dental substrata

J Dent

(2008)

C.J. Whittaker et al.

Mechanisms of adhesion by oral bacteria

Annu Rev Microbiol

(1996)

J.D. De Stoppelaar et al.

The relationship between extracellular polysaccharide-producing streptococci and smooth surface caries in 13-year-old children

Caries Res

(1969)

W.J. Loesche

Role of Streptococcus mutans in human dental decay

Microbiol Rev

(1986)

K.H. Friedl et al.

Placement and replacement of composite restorations in Germany

Oper Dent

(1995)

D.C. Sarrett

Prediction of clinical outcomes of a restoration based on in vivo marginal quality evaluation

J Adhes Dent

(2007)

J.R. Jedrychowski et al.

Antibacterial and mechanical properties of restorative materials combined with chlorhexidines

J Oral Rehabil

(1983)

Cited by (101)

Current trends and future perspectives on dental nanomaterials – An overview of nanotechnology strategies in dentistry
2022, Journal of King Saud University - Science
The field of nanotechnology or nanoscience encompasses research and development in the applied sciences at the atomic or molecular levels and has a huge impact on nearly every aspect of human health and well-being, including pharmacological studies, clinical diagnosis, and supplemental immune system treatments. The numerous dental uses of nanotechnology have led to the development of the field of nanodentistry. The efficacy of dental operations and the field’s possibilities have grown greatly over the years as a result of extensive research in the fields of biomaterials and nanotechnology. Materials with nanoscale dimensions can display features not found in their larger-scale equivalents. Endodontic procedures are time-consuming and usually require multiple visits to attain the best results. The eradication of primary bacterial infection from dental root canals is still a serious concern in dentistry. Nanoparticles have been shown to be more efficient than standard materials and to have superior capabilities in terms of surface chemistry and bonding. Their antimicrobial characteristics are also promising in all medical procedures, particularly in endodontics. Because of their versatility, nanomaterials are a useful tool in dental clinics for a variety of operations including pulp regeneration, drug administration, root restoration, cleaning, obturation, and canal filling. This review provides an overview of the synthesis and characteristics of nanomaterials and their potential applications in dentistry and describes future perspectives of nanotechnology in dentistry with an updated literature review.
Nanoparticles as antibacterial agent for dental restorative materials and their antibacterial activity evaluation
2022, Handbook of Microbial Nanotechnology
Challenge in combating microbial adhesion in dental application is continuously significant nowadays. A plethora of microbes exists in an oral environment, which adhere to the surfaces in the oral cavity including teeth and restorative materials. Surface roughness of tooth restorative materials is one of the factor that will contribute to the microbial adhesion at early stage. The consequences of the microbial adhesion are dental caries and failure of the dental restoration due to secondary dental caries. A classic approach of fluoride-containing restorative material as an antibacterial agent that could inhibit bacterial growth is still inadequate to combat the bacteria in the oral environment and could not sustain for a long period. Hence, modern approach is to incorporate nanoparticles in restorative materials as an antibacterial agent. The efficiency of the nanoparticles acting as antibacterial agent will be elaborated. Several techniques to evaluate the antibacterial activities will be briefly discussed.
A General Strategy for Efficiently Constructing Multifunctional Cluster Fillers Using a Three-Fluid Nozzle Spray Drying Technique for Dental Restoration
2022, Engineering
Multifunctional fillers are greatly required for dental resin composites (DRCs). In this work, a spray dryer with a three-fluid nozzle was applied for the first time to construct high-performance complex nanoparticle clusters (CNCs) consisting of different functional nanofillers for dental restoration. The application of a three-fluid nozzle can effectively avoid the aggregation of different nanoparticles with opposite zeta potentials before the spray drying process in order to construct regularly shaped CNCs. For a SiO₂–ZrO₂ binary system, the SiO₂–ZrO₂ CNCs constructed using a three-fluid nozzle maintained their excellent mechanical properties ((133.3 ± 4.7) MPa, (8.8 ± 0.5) GPa, (371.1 ± 13.3) MPa, and (64.5 ± 0.7) HV for flexural strength, flexural modulus, compressive strength, and hardness of DRCs, respectively), despite the introduction of ZrO₂ nanoparticles, whereas their counterparts constructed using a two-fluid nozzle showed significantly decreased mechanical properties. Furthermore, heat treatment of the SiO₂–ZrO₂ CNCs significantly improved the mechanical properties and radiopacity of the DRCs. The DRCs containing over 10% mass fraction ZrO₂ nanoparticles can meet the requirement for radiopaque fillers. More importantly, this method can be expanded to ternary or quaternary systems. DRCs filled with SiO₂–ZrO₂–ZnO CNCs with a ratio of 56:10:4 displayed high antibacterial activity (antibacterial ratio > 99%) in addition to excellent mechanical properties and radiopacity. Thus, the three-fluid nozzle spray drying technique holds great potential for the efficient construction of multifunctional cluster fillers for DRCs.
Biocompatible silver nanoparticles incorporated in acrylic resin for dental application inhibit Candida albicans biofilm
2021, Materials Science and Engineering C
Although silver nanoparticles (SNP) have proven antimicrobial activity against different types of microorganisms, the effect of SNP incorporation into acrylic resin to control Candida albicans biofilm formation aiming at the prevention of Candida-associated denture stomatitis has not yet been fully elucidated.
This study aimed to evaluate the antimicrobial effect of an acrylic resin containing SNP on C. albicans biofilm growth, the flexural strength of this material and tissue reaction in the subcutaneous connective tissue of rats to SNP.
SNP were synthesized through silver nitrate reduction by sodium citrate. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to verify the size and colloidal stability. SNP were added to acrylic resin monomer (Lucitone 550) at 0.05, 0.5 and 5 vol%. The antimicrobial effect against C. albicans (ATCC 10231) was investigated by the enumeration of colony-forming units (CFUs) and SEM. The three-point bending test was performed to analyze the flexural strength. Tissue reaction was evaluated after 7 and 60 days of implantation in the connective tissue of Wistar rats.
Spherical particles of 5 and 10 nm were obtained. SNP at 0.05 and 0.5% incorporated into acrylic resin was effective in reducing C. albicans biofilm growth (p < .001). SEM revealed that the material was able to disrupt C. albicans biofilm formation and did not reduce the flexural strength compared to control (p > .05). The inflammatory response observed 60 days after implantation SNP in the subcutaneous tissue was similar to control.
It was concluded that SNP addition at 0.05 and 0.5% into acrylic resin exhibited antimicrobial effects against C. albicans biofilm, did not interfere in the flexural strength and may be considered biocompatible.
Setting time, mechanical and adhesive properties of magnesium oxide nanoparticles modified glass-ionomer cement
2020, Journal of Materials Research and Technology
Nanoparticle modifications of glass-ionomer cement are interesting research subjects. This study investigated the effect of MgO nanoparticles on the setting time, compressive and diametral tensile strength, and adhesive properties of glass-ionomer cement. A conventional GIC was modified by the incorporation of MgO nanoparticles at 1%, 2.5%, 5%, and 10% (w/w) ratios with an unmodified GIC used as the control group. The data were analysed using a one-way analysis of variance (ANOVA) and Tukey's HSD test (p < 0.05). Although the GICs with 1% and 2.5% MgO nanoparticles were still within the ISO standard range specified for the GIC setting time, increasing the MgO nanoparticle concentration significantly increased the setting time of the tested cement (p < 0.05). GICs with 1% MgO nanoparticles had the highest compressive and diametral tensile strength values. Increasing the nanoparticle content from 5% and more significantly decreased the cement strength (p < 0.05). The shear bond strength (SBS) of enamel and dentine showed statistically significant differences among the tested groups (p < 0.05). However, the addition of MgO nanoparticles up to 5% (w/w) did not have an unfavourable effect on the cement adhesiveness. Although cohesive and mixed type failure modes were more common than adhesive failure modes, no statistically significant associations were found between the failure mode and type of GIC (p > 0.05).
Within the limitations of this study, the current findings suggest that modifying GICs by incorporating MgO nanoparticles up to 2.5% (w/w) could be a promising restorative material for clinical dental applications.
Antifungal Activity of Chitosan/Poly(Ethylene Oxide) Blend Electrospun Polymeric Fiber Mat Doped with Metallic Silver Nanoparticles
2023, Polymers

View all citing articles on Scopus

View full text

The anti-adherence activity and bactericidal effect of microparticulate silver additives in composite resin materials

Abstract

Objective

Design

Results

Conclusions

Introduction

Section snippets

Preparation of specimens

Surface roughness Ra and hydrophobicity

Enumeration of adhering streptococci (Resazurin staining)

Discussion

Acknowledgement

Biomaterials

Biomaterials

Prog Med Chem

Dent Mater

Dent Mater

Biomaterials

Dent Mater

Arch Oral Biol

Dent Mater

Acta Biomater

J Microbiol Methods

J Microbiol Methods

Dent Mater

J Microbiol Methods

Arch Oral Biol

J Prosthet Dent

J Dent

Mechanisms of adhesion by oral bacteria

Annu Rev Microbiol

The relationship between extracellular polysaccharide-producing streptococci and smooth surface caries in 13-year-old children

Caries Res

Role of Streptococcus mutans in human dental decay

Microbiol Rev

Placement and replacement of composite restorations in Germany

Oper Dent

Prediction of clinical outcomes of a restoration based on in vivo marginal quality evaluation

J Adhes Dent

Antibacterial and mechanical properties of restorative materials combined with chlorhexidines

J Oral Rehabil

Surface roughness R_a and hydrophobicity