Antimicrobial abilities of various dentine bonding agents and restorative materials

Restorative materials containing antimicrobial agents: is there evidence for their antimicrobial and anticaries effects? A systematic review

The aim of this systematic literature review was to investigate whether the incorporation of antimicrobial agents into dental restorative materials truly exerts an antimicrobial effect against common cariogenic bacteria (primary outcome), and whether the inclusion of antimicrobial agents is able to prevent caries around restorations (secondary outcome). MEDLINE, via PubMed, was searched for papers published between 1980 and 30 November 2014. A total of 1126 articles were retrieved. After inclusion/exclusion assessment, 147 full text articles were read and included in the review, comprising 130 in vitro, 1 in situ, and 4 in vivo studies, as well as 12 literature reviews. In about 78% of in vitro studies, and in all identified in situ and in vivo studies, a positive antimicrobial effect had been found. However, the anticaries effect had not been tested in any of the selected studies. It was concluded that there is indeed evidence that restorative dental materials containing antimicrobial agents exert an antimicrobial effect, both in laboratory and in clinical studies. However, no evidence has been found regarding the role of these agents in preventing or controlling dental caries, or in preventing caries around restorations.

Activity, reduced toxicity, and scale-up synthesis of amphotericin B-conjugated polysaccharide

Amphotericin B (AMB) arabinogalactan (AG) conjugate was synthesized by the conjugation of AMB to oxidized AG by reductive amination. The conjugate was evaluated for in vitro antifungal activity and in vivo toxicity. Optimization of the conjugation process was investigated using large batches of 100 g, which are 20 times larger than previously reported for AMB-AG conjugation. The efficacy of AMB-AG conjugates was studied as a function of reaction conditions and time, aldehyde/reducing agent mole ratio, and purification procedure. The most potent AMB-AG conjugate having low minimal inhibitory concentration (MIC) and high maximal tolerated dose (MTD) was obtained following reduction with NaBH4 at 1:2 mol ratio (AG units/NaBH4) at 25 °C for 24 h. AMB-AG conjugate prepared under these conditions demonstrated MIC of 0.5 mg/L (equiv of AMB) in Candida albicans, and an MTD of 60 mg/kg (equiv of AMB) in mice, while AMB clinical formulation (Fungizone) demonstrated high toxicity (MTD = 3 mg/kg). These findings confirm the simplicity and reproducibility of the conjugation allowing this method to be applied on larger scale production.

Surface Antibacterial Properties of Compomers

AIM

This was to evaluate the antibacterial properties of four different compomers, using direct contact test (DCT) and agar diffusion test (ADT). Compomers (Polyacid Modified Composite Resin) form a group of dental restorative materials which were developed in order to improve conventional glass-ionomer and are widely used by pediatric dentists in primary dentition. Microorganisms captured under restorations or penetrating through the micro-gap at the tooth-restoration interface are the cause of secondary caries and pulpal pathology.

METHODS

For the DCT, 8 samples of Freedom (SDI), F2000 (3M-ESPE), Dyract (Dentsply) and Hytac Hplitip (3M-ESPE) were placed on the sidewalls of wells in 96 microtiter plate. After polymerization, freshly grown streptococcus mutans cells (1x10(6)) were placed on the surface of each sample for one hour at 37 degrees C, fresh media was then added to each well and bacterial growth was followed for 16 hours by temperature controlled spectrophotometer. Similarly prepared samples were aged in phosphate buffered saline for 1, or 7 days and the DCT was repeated. The ADT was performed by placing samples in uniform wells punched in agar plates.

RESULTS

In the DCT, freshly polymerized samples of F2000 showed the most potent antibacterial properties, while those of Hytac Hplitip showed moderate antibacterial phenomena. Dyract and Freedom did not show any antibacterial activity relative to the control material. None of the four aged materials showed antibacterial activity in the DCT after 1 or 7 days. In the ADT the halo in the bacterial lawn was measured after 48 hours and only F2000 demonstrated an inhibition zone of 2.15+/-0.3 mm. Statistics. Two way ANOVA indicated a significant difference in the growth rate of bacteria placed both on the different compomers (P<0.001) and in different tested time points (P<0.001).

CONCLUSION

None of the compomers tested provided significant long term antibacterial activity.

Streptococcus mutans biofilm changes surface-topography of resin composites

OBJECTIVES

Polymerized resin composites and nonpolymerized monomers are reported to accelerate bacterial growth. Furthermore, in vivo, resin composite restorations accumulate more plaque than other restorative materials. The purpose of this study was to test the hypothesis that bacteria-composite surface interaction causes changes in surface-topography.

METHODS

Resin composite disks were polymerized between two glass slides. Streptococcus mutans cells were brought in contact with and grown on the disks for 1 day, 1 week or 1 month. The disks were analyzed using atomic force microscopy. One-month-aged composite specimens were assayed for changes in micro-hardness and bacterial outgrowth.

RESULTS

Atomic force microscopy analysis revealed a time-dependent increase in root mean square (RMS) roughness (p<0.0001). S. mutans outgrowth was accelerated following direct contact with the surface of aged composites, with no changes in micro-hardness.

SIGNIFICANCE

Our results show that S. mutans growth on resin composite increases surface roughness without affecting micro-hardness. The change in surface integrity may further accelerate biofilm accumulation.

Surface antibacterial properties of glass ionomer cements used in atraumatic restorative treatment

BACKGROUND

Atraumatic restorative treatment (ART) is recommended for use worldwide, not only in developing countries where resources are not readily available, but also in more industrialized countries. The antibacterial properties of restorative dental materials may improve the restorative treatment outcome. Glass ionomer cement (GIC) has been advocated as the preferred restoration material for ART. The authors evaluated the antibacterial properties of restorative materials-three GICs and a zinc oxide eugenol (ZOE)-in vitro.

METHODS

Streptococcus mutans, Actinomyces viscosus and Enterococcus faecalis were the test microorganisms. The authors used a quantitative microtiter spectrophotometric assay to evaluate the antibacterial effect of the restorative materials using the direct contact test (DCT) of freshly prepared and one-week-aged materials.

RESULTS

The freshly prepared GICs and ZOE showed no bacterial growth in all tested bacteria compared with a control. This effect lasted for at least one week for S. mutans and A. viscosus but not for E. faecalis.

CONCLUSIONS

Conventional GICs used in ART showed antibacterial surface properties against cariogenic bacteria for at least one week. Further study on the long-term antimicrobial effects of GICs is needed.

CLINICAL IMPLICATIONS

The antimicrobial properties of freshly prepared restorative materials and aged restorative materials used in ART have a potent effect against cariogenic bacteria. These properties have crucial importance in preventing secondary caries.

Antibacterial properties of self-etching dental adhesive systems

BACKGROUND

Dental adhesives with antibacterial properties may reduce recurrent or secondary caries. The authors conducted a study to examine the immediate and long-lasting antibacterial properties of four self-etching adhesive systems.

METHODS

The authors used the agar diffusion test (ADT) and direct contact test (DCT) to measure the antibacterial properties of AdheSe (Ivoclar Vivadent, Schaan, Liechtenstein), Adper Prompt L-Pop (3M ESPE, Seefeld, Germany), Clearfil Protect Bond (Kuraray, Kurashiki, Okayama, Japan) and Xeno III (Dentsply, Konstanz, Germany) on Streptoccocus mutans after aging samples in phosphate-buffered saline for one, two, seven and 14 days.

RESULTS

Only Clearfil Protect Bond showed an inhibition halo in the ADT. In the DCT, fresh samples of all of the tested materials exhibited potent antibacterial properties, which were maintained by AdheSe for one day and Clearfil Protect Bond for seven days. None of the adhesive systems exhibited any antibacterial properties after 14 days.

CONCLUSIONS

All of the tested adhesives had an immediate bactericidal effect on S. mutans. None, however, had long-lasting antibacterial properties.

CLINICAL IMPLICATIONS

The application of self-etching adhesive materials could contribute to the immediate elimination of residual bacteria. The likelihood of developing secondary caries as a consequence of bacterial microleakage may not be affected by the use of the adhesive systems tested in this study.

An in vitro quantitative antibacterial analysis of amalgam and composite resins

OBJECTIVES

Antibacterial properties of restorative dental materials such as amalgam and composite resins may improve the restorative treatment outcome. This study evaluates the antibacterial properties of three composite resins: Z250, Tetric Ceram, P60 and a dental amalgam in vitro.

METHODS

Streptococcus mutans and Actinomyces viscosus served as test microorganisms. Three quantitative microtiter spectrophotometric assays were used to evaluate the effect of the restorative materials on: (i) early-stage biofilm using a direct contact test (DCT); (ii) planktonic bacterial growth; (iii) bacterial growth in the materials' elute. For comparison purposes, agar diffusion test (ADT) was also performed.

RESULTS

The effect of the composite resins on bacterial growth was minimal and limited to a few days only. One-week-aged composites promoted growth of S. mutans and A. viscosus. The antibacterial properties in direct contact were more potent than in planktonic bacterial growth. Amalgam showed complete inhibition of both bacteria in all phases, and the effect lasted for at least 1 week. The materials' elute had no effect on both bacterial growth with the exception of complete inhibition of S. mutans in amalgam. The later results correlated with the ADT.

CONCLUSIONS

The present findings demonstrate potent and lasting antibacterial properties of amalgam, which are lacking in composite resins. This may explain the clinical observation of biofilm accumulated more on composites compared to amalgams. It follows that the assessment of antibacterial properties of poorly-soluble materials has to employ more than one assay.

Antibacterial Properties of Temporary Filling Materials

The purpose of this study was to investigate the antibacterial properties of temporary fillings. The direct contact test (DCT) was used to evaluate the antibacterial properties of Revoltek LC, Tempit, Systemp inlay, and IRM. These were tested in contact with Streptococcus mutans and Enterococcus faecalis. The materials were examined immediately after setting, 1, 7, 14, and 30 days after aging in phosphate buffered saline (PBS). Statistical analysis included two-way ANOVA, one-way ANOVA, and Tukey multiple comparison. Systemp inlay, Tempit, and IRM exhibited antibacterial properties when in contact with S. mutans for at least 7 days, Tempit and IRM sustained this ability for at least 14 days. When in contact with E. faecalis Tempit and IRM were antibacterial immediately after setting, IRM sustained this ability for at least 1 day. Our study suggests that the difference in temporary filling materials may influence which microorganism will be able to invade the root canal system.

Antibacterial activity of glass-ionomer cements, compomers and resin composites: relationship between acidity and material setting phase

Agar diffusion testing was used with four different media to evaluate the antibacterial activity of six products (one conventional glass-ionomer cement (GIC), two light-activated glass-ionomers, two polyacid-modified resin composites and one resin composite) on Streptoccoccus mutans. Their respective antibacterial activities were also compared during and after setting. The relationship between product acidity and antibacterial activity was evaluated. All the GICs demonstrated antibacterial properties in contrast to the polyacid-modified resin composites and resin composite which did not shown any antibacterial effects. Vitrebond GIC exhibited higher antibacterial action, probably because of a cytotoxic photo-initiator diphenyliodoniumchloride. A direct relationship between material acidity and growth inhibition of S. mutans was observed.

Antibacterial properties of resin composites and dentin bonding systems

This paper reviews the research conducted on the evaluation of antibacterial properties of commercial composites and adhesive systems, in addition to the discussion on many attempts to achieve antibacterial composites or adhesives. With regard to composites, commercially available products including fluoride-releasing materials have no antibacterial effect after being cured, which may explain why composites accumulate more plaque than other filling materials. The attempts to provide composites with antibacterial properties involve alterations to the resin components and filler components, and the trials can be subsequently classified into two groups based on the release profile of antibacterial components; agent-releasing or non-agent-releasing materials. Each type of antibacterial composite has advantages and disadvantages, and further modifications are needed to achieve clinically useful materials. Among proprietary dentin bonding systems (DBS), the products which contain glutaraldehyde or have an acidic property exhibit some antibacterial effects. However, the antibacterial properties shown by these products are only side-effects which are derived from the constituents included to produce superior bonding characteristics, and appear to be unreliable. Inclusion of antibacterial components into DBS has also been attempted using several methods, and the results of in vitro tests indicate that some of the trials seem promising. It is worthy of continuing the attempts to develop DBS which can inhibit invading bacteria after the placement of restoration as well as residual bacteria in the cavity. Achievement of bio-functional composites or DBS with therapeutic effects would contribute to prevent secondary caries.

The effect of orthodontic bonding materials on dental plaque accumulation and composition in vitro

The aim of this study was to investigate the accumulation and composition of microcosm dental plaque on different orthodontic bonding materials using an in vitro model. Microcosm plaques were grown on discs of a range of bonding materials in a constant depth film fermentor. The biofilms were derived from human saliva and supplied with artificial saliva as a source of nutrients. The number of viable bacteria in the biofilms was determined and the streptococci present were identified to species level. The results showed that there was no significant difference in bacterial accumulation between different bonding materials, however, biofilms grown on materials which were fluoride releasing, did not contain Streptococcus mutans. This in vitro study has shown that the use of fluoride-releasing bonding materials may support the growth of supragingival plaque, which does not contain S. mutans.

Effectiveness of dentine bonding agents against cariogenic bacteria in vitro: a comparison of two methods

Data obtained from studies on the antimicrobial properties of bonding agents are the subject of controversy, probably because of methodological differences. This study compared two commonly used in vitro methods, the disc agar diffusion test and the well agar diffusion test. Agar plates were seeded with Streptococcus sobrinus, Lactobacillus gasseri, or Actinomyces naeslundii. For the well diffusion test, wells cut out of the agar were filled with the test material, and for the disc method, discs impregnated with the test material were applied to the agar; the discs and wells were both 9 mm in diameter. After incubation, measurements of the zones of inhibition showed little agreement between the two methods when bonding agents were tested; the mean differences (+/- sdiff) in the zones of inhibition between the methods were 0.7 +/- 3.4 mm (P = 0.40, one sample t-test against zero), 4.9 +/- 4.4 mm (P = 0.97), and 0.8 +/- 4.3 mm (P = 0.47) for S. sobrinus, L. gasseri, and A. naeslundii, respectively. Mean differences were less contrasting when chlorhexidine and pure components were tested (P < 0.05 for S. sobrinus and L. gasseri). These results indicate the need for a gold standard method to evaluate the antimicrobial properties of bonding agents.

Comparison of antibacterial activity of two dentin bonding systems using agar well technique and tooth cavity model

OBJECTIVE

This study compared the antibacterial activities of two dentin bonding systems (ABF, Kuraray and Reactmer Bond, Shofu) by a conventional agar well technique and a newly designed in vitro test using tooth model.

METHODS

In the agar well technique, the test materials were filled in the wells of Muller Hinton agar plates inoculated with Streptococcus mutans NCTC10449, and the diameters of inhibition zones produced around the materials were measured after 24h of incubation. For the tooth model test, three cavities (diameter 1mm, depth 2mm) were prepared in the flat occlusal dentin of human extracted molar. After sterilization, the teeth were left in broth culture of 1.56 x 10(8)CFU/ml of S. mutans at 37 degrees C for 72h for allowing bacteria to invade the cavity. The dentin bonding systems were applied separately to each of the two infected cavities, and the third cavity was left unapplied for control. After sealing the occlusal surfaces, the teeth were kept in physiologic saline solution at 37 degrees C for 72h. The standardized amounts of dentin chips (120+/-5mg) were obtained from the cavity walls and the number of bacteria recovered was determined. The results were analyzed by One Way ANOVA, Kruskal Wallis and Mann-Whitney's U tests.

RESULTS

The primer of ABF and Reactmer Bond produced inhibition zones with similar sizes (p>0.05), but the bonding resin of ABF did not produce any inhibition. When tested by the model cavity method, the application of ABF resulted in significantly less bacterial recovery than Reactmer Bond (p<0.05), demonstrating substantial antibacterial effects.

CONCLUSIONS

The tooth model method used in this study was effective for evaluating the substantial antibacterial effects of dentin bonding agents, and the experimental dentin bonding system ABF was demonstrated to be able to inactivate the bacteria in the cavity effectively in comparison with little antibacterial activity shown by Reactmer Bond.

Factors influencing pulpal response to cavity restorations

OBJECTIVES

The purposes of this retrospective work were: (1) to determine the relative importance of bacteria on cavity walls, remaining dentin thickness and post-operative time on pulpal inflammation after cavity restoration; (2) to compare the respective influences of bacterial microleakage and the restorative material itself on pulp reaction severity.

METHODS

317 class V cavities, in human bicuspids scheduled for extraction for orthodontic reasons were used for this study. Nine different materials were included. The severity of the pulpal reaction was ranked on hematoxylin/eosin stained sections according to FDI standards. The further parameters recorded were: (1) the presence or absence of bacteria on the cavity walls was noted on Brown and Brenn stained sections; (2) the remaining dentin thickness was measured and the teeth classified into three groups (< 500, 500-1000, > 1000 microns); and (3) the post-operative delay before extraction was recorded and classified as short time (< 5 weeks) or long time (> 5 weeks). Three two-way analyses of variance (ANOVA) followed by Kruskall and Wallis tests evaluated the influence of the three parameters on pulpal reaction severity. The third ANOVA also compared pulpal reactions under the different materials when the teeth were pooled, on bacteria free teeth and on bacteria contaminated teeth.

RESULTS

The first ANOVA ranked by decreasing order of importance: the presence of bacteria (p < 0.0001), the remaining dentin thickness (p = 0.02) and the post-operative delay (p = 0.04). The second ANOVA showed no difference among the restorative materials when bacteria were present on the cavity walls.

SIGNIFICANCE

The presence of bacteria on the cavity walls is the main factor influencing pulpal reaction under restorative materials, but does not account for 100% of the cases.