Antibiofilm Efficacy of Photosensitizer-functionalized Bioactive Nanoparticles on Multispecies Biofilm

Introduction

Newer disinfection strategies based on antibacterial nanoparticles and photodynamic therapy (PDT) aim to eliminate residual biofilm bacteria during root canal treatment. The aim of the current study was to test the newly developed rose bengal–functionalized chitosan nanoparticles (CSRBnps) for their interaction/uptake with monospecies bacteria/biofilm and assess their antibiofilm efficacy on a multispecies biofilm model in vitro.

Methods

The interaction of CSRBnps with bacterial cells was conducted using atomic force microscopy. Their membrane-damaging effect was determined by measuring the absorbance at 260 nm (OD_260nm) using Enterococcus faecalis. The penetration of CSRBnps into E. faecalis biofilms was evaluated using confocal laser scanning microscopy (CLSM). Multispecies biofilms of Streptococcus oralis, Prevotella intermedia, and Actinomyces naeslundii were grown on dentin sections for 21 days to assess the antibiofilm efficacy. The biofilms were subjected to PDT (60 J/cm²) using CSRBnps and rose bengal. The treated/untreated biofilms were examined under scanning electron microscopy and CLSM.

Results

The CSRBnps synthesized were 60 ± 20 nm and showed absorption spectra similar to rose bengal. Atomic force microscopy showed adherence of CSRBnps to bacteria, roughening of cell surface, and cell disruption after PDT. CSRBnp treatment resulted in significantly increased bacterial membrane damage (P < .05). CSRBnps exhibited deeper penetration into the biofilm structure. Scanning electron microscopy and CLSM confirmed the complete disruption of multispecies biofilm with a reduction in viable bacteria and biofilm thickness (P < .05).

Conclusions

These novel photosensitizer functionalized bioactive nanoparticles with increased affinity to bacterial cell membrane, higher penetration into biofilm structure, and enhanced ability to eliminate clinically relevant multispecies bacterial biofilm present a potential antibiofilm agent for root canal disinfection.     

Antibiofilm Effects of Endodontic Sealers Containing Quaternary Ammonium Polyethylenimine Nanoparticles

Introduction

This study evaluated the antibiofilm effects of 2 endodontic sealers incorporated with quaternary ammonium polyethylenimine (QPEI) nanoparticles at a 2% concentration (w/w).

Methods

The materials tested were AH Plus and Pulp Canal Sealer EWT (PCS) in the commercial unmodified form or containing 2% QPEI. Antibiofilm assays were conducted by using direct-contact and membrane-restricted tests for evaluation of bacterial viability in biofilms grown onto membranes or paper disks and the crystal violet microtiter-plate assay to evaluate the effects of sealer extracts on the biofilm biomass. Two Enterococcus faecalis strains (ATCC and an endodontic isolate) were used.

Results

Direct contact and membrane-restricted antibiofilm tests revealed that PCS 2% was the only material to promote total killing of E. faecalis ATCC biofilms. All the materials significantly reduced bacterial counts in E. faecalis ATCC biofilms when compared with the positive control in both tests (P < .05). In the direct test against E. faecalis RW35, PCS 2% was significantly more effective than the other materials and was the only one that showed significantly lower counts than the positive control (P < .05). In the crystal violet assay, only AH Plus 2% presented optical density readings significantly lower than the positive control of the ATCC strain (P < .05). No other significant effects on the biofilm biomass of the 2 E. faecalis strains were observed for any of the sealers tested (P > .05).

Conclusions

Addition of QPEI nanoparticles improved the killing ability of PCS against biofilms of both E. faecalis strains and the effects of AH Plus on the biomass of biofilms from the ATCC strain.     

Residual antibiofilm effects of various concentrations of double antibiotic paste used during regenerative endodontics after different application times

ObjectiveWe investigated the residual antibiofilm effects of different concentrations of double antibiotic paste (DAP) applied on radicular dentin for 1 or 4 weeks.DesignDentin samples were prepared (n = 120), sterilized and pretreated for 1 or 4 weeks with the clinically used concentration of DAP (500 mg/mL), low concentrations of DAP (1, 5 or 50 mg/mL) loaded into a methylcellulose system, calcium hydroxide (Ca(OH)₂), or placebo paste. After the assigned treatment time, treatment pastes were rinsed off and the samples were kept independently in phosphate buffered saline for 3 weeks. Pretreated dentin samples were then inoculated with Enterococcus faecalis and bacterial biofilms were allowed to grow for an additional 3 weeks. Biofilms were then retrieved from dentin using biofilm disruption assays, diluted, spiral plated, and quantified. Fisher’s Exact and Wilcoxon rank sum tests were used for statistical comparisons (α=0.05).ResultsDentin pretreatment for 4 weeks with 5, 50 or 500 mg/mL of DAP demonstrated significantly higher residual antibiofilm effects and complete eradication of E. faecalis biofilms in comparison to a 1 week pretreatment with similar concentrations. However, dentin pretreated with 1 mg/mL of DAP or Ca(OH)₂ did not provide a substantial residual antibiofilm effect regardless of the application time.ConclusionsDentin pretreatment with 5 mg/mL of DAP or higher for 4 weeks induced significantly higher residual antibiofilm effects in comparison to a 1 week pretreatment with the same concentrations.     

Evaluation of the Antibacterial Efficacy of Silver Nanoparticles against Enterococcus faecalis Biofilm

Introduction

The purpose of this study was to evaluate the antibacterial efficacy of silver nanoparticles (AgNPs) as an irrigant or medicament against Enterococcus faecalis biofilms formed on root dentin.

Methods

Dentin sections were inoculated with E. faecalis for 4 weeks to establish a standard monospecies biofilm model. These biofilms were tested in 2 stages. In stage 1, the biofilms were irrigated with 0.1% AgNP solution, 2% sodium hypochlorite, and sterile saline for 2 minutes, respectively. In stage 2, the biofilms were treated with AgNP gel (0.02% and 0.01%) and calcium hydroxide for 7 days. The ultrastructure of one half of the specimens from each group was evaluated by using scanning electron microscopy, whereas the structure and distribution of viable bacteria of the other half of the specimens were assessed with confocal laser scanning microscopy combined with viability staining.

Results

Syringe irrigation with 0.1% AgNP solution did not disrupt the biofilm structure, and the proportion of viable bacteria in the biofilm structures was not different from that of the saline group (P > .05) but was less than that of the control group (P < .05). The biofilms treated with 0.02% AgNP gel as medicament significantly disrupted the structural integrity of the biofilm and resulted in the least number of post-treatment residual viable E. faecalis cells compared with 0.01% AgNP gel and calcium hydroxide groups (P < .05).

Conclusions

The findings from this study suggested that the antibiofilm efficacy of AgNPs depends on the mode of application. AgNPs as a medicament and not as an irrigant showed potential to eliminate residual bacterial biofilms during root canal disinfection.     

Combined Effect of a Mixture of Silver Nanoparticles and Calcium Hydroxide against Enterococcus faecalis Biofilm

IntroductionThe aim of this study was to evaluate the antibiofilm effectiveness of calcium hydroxide (Ca[OH]₂) mixed with 0.02% silver nanoparticles (AgNPs) in comparison with 1 mg/mL triple antibiotic paste (TAP), Ca(OH)₂, and 0.02% AgNPs against Enterococcus faecalis using confocal laser scanning microscopy.MethodsNinety dentin disks were prepared, sterilized, and inoculated with E. faecalis to establish a 3-week-old biofilm model. The samples received 1 mg/mL TAP, a mixture of Ca(OH)₂ + 0.02% AgNPs, Ca(OH)₂, or 0.02% AgNPs (n = 20/group). Specimens in each group were equally subdivided into 2 groups and incubated for 2 and 4 weeks. Untreated dentin disks (n = 10) were exposed to sterile saline solution and acted as a positive control. Sterile dentin disks (n = 10) were incubated anaerobically in brain-heart infusion broth and served as a negative control. At the end of each observation period, the specimens were stained with LIVE/DEAD BacLight dye (Molecular Probes, Eugene, OR) and analyzed with confocal laser scanning microscopy to determine the proportion of dead cells in the biofilm. Statistical analysis was performed using the generalized linear model repeated measure and Tukey tests (P < .05).ResultsA significantly greater proportion of dead cells was observed in the samples treated with 1 mg/mL TAP (90.39% and 99.41%) and a mixture of Ca(OH)₂ + AgNPs (90.85% and 98.49%) than those in the samples treated with Ca(OH)₂ (76.14% and 91.71%) and AgNPs (62.83% and 88.07%) at 2 and 4 weeks, respectively. A significant difference in the antibiofilm effectiveness was observed among the groups (P < .05), except for 1 mg/mL TAP and the mixture of Ca(OH)₂ + AgNPs (P > .05). All medicaments showed a significant difference in antibiofilm efficacy at the 2 time points.ConclusionsThe mixture of Ca(OH)₂ + AgNPs showed a high antibiofilm effect and was not significantly different from 1 mg/mL TAP. Furthermore, long-term contact between intracanal medicaments and bacterial cells achieved significant antibiofilm efficacy.     

Sodium chloride and potassium sorbate: a synergistic combination against Enterococcus faecalis biofilms: an in vitro study

Incomplete disinfection of the root canal system is a major cause of post‐treatment disease. This study aimed to investigate the disinfecting property of organic acid salts and sodium chloride (NaCl), in a double‐hurdle strategy, on Enterococcus faecalis biofilms. First of all, the high‐throughput resazurin metabolism assay (RMA) was used to test a range of organic acid salts. Then, to gain more insight into the efficacy of sorbate salt solutions, 48‐h E. faecalis biofilms were evaluated in colony‐forming unit (CFU) assays. Chlorhexidine (CHX) and calcium hydroxide [Ca(OH)₂] were tested in parallel as controls. Sorbate salt produced the largest and most significant reduction of fluorescence intensity in the RMA assay. Neither NaCl nor potassium sorbate (KS) alone induced a clinically relevant reduction of CFU counts after 1 h. Surprisingly, the combination of the two in a single solution had a synergistic effect on the inactivation of E. faecalis. Potassium sorbate amplified the efficacy of NaCl. Of the salts tested, NaCl with KS eradicated E. faecalis biofilms within 1 h. This study showed that the double‐hurdle strategy indeed leads to synergistic efficacy and is a possible next step in the complete disinfection of endodontic infections.     

Characterisation of the efficacy of endodontic medications using a three‐dimensional fluorescent tooth model: An ex vivo study

The purpose of this study was to establish a three‐dimensional fluorescent tooth model to investigate bacterial viability against intra‐canal medicaments across the thickness and surface of root dentine. Dental microbial biofilms (Enterococcus faecalis and Streptococcus mutans) were established on the external root surface and bacterial kill was monitored over time against intra‐canal medicament (Ca(OH)₂) using fluorescent microscopy in conjunction with BacLight SYTO9 and propidium iodide stains. An Olympus digital camera fitted to SZX16 fluorescent microscope captured images of bacterial cells in biofilms on the external root surface. Viability of biofilm was measured by calculating the total pixel area of green (viable bacteria) and red (non‐viable bacteria) for each image using ImageJ® software. All data generated were assessed for normality and then analysed using a Mann–Whitney t‐test. The viability of S. mutans biofilm following Ca(OH)₂ treatment showed a significant decline compared with the untreated group (P = 0.0418). No significant difference was seen for E. faecalis biofilm between the Ca(OH)₂ and untreated groups indicating Ca(OH)₂ medicament is ineffective against E. faecalis biofilm. This novel three‐dimensional fluorescent biofilm model provides a new clinically relevant tool for testing of medicaments against dental biofilms.     

The antimicrobial properties,cytotoxicity, and differentiation potential of double antibiotic intracanal medicaments loaded into hydrogel system

Objective

This study evaluated the antimicrobial properties, cytotoxicity, and mineralization potential of methylcellulose hydrogels loaded with low concentrations of double antibiotic pastes (DAP).

Materials and methods

The direct and residual antibacterial effects of 1, 5, and 10 mg/mL of DAP loaded into hydrogels as well as calcium hydroxide (Ca(OH)₂) were tested against single-species biofilms of Enterococcus faecalis and dual-species biofilms (Enterococcus faecalis and Prevotella intermedia). The effects of DAP hydrogels on proliferation and mineralization of dental pulp stem cells (DPSC) were tested using MTT assays, alkaline phosphate activity (ALP), and alizarin red staining. Fisher’s exact tests, Wilcoxon rank sum tests, and one-way ANOVA were used for statistical analyses (α = 0.05).

Results

All tested concentrations of DAP hydrogels as well as Ca(OH)₂ demonstrated significant direct antibacterial effects against single- and dual-species biofilms. However, only 5 and 10 mg/mL of DAP hydrogels exhibited significant residual antibacterial effects against both types of tested biofilms. Only 1 mg/mL of DAP hydrogels did not have significant negative effects on DPSC viability, ALP activity, and mineralization nodule formation. However, 5 and 10 mg/mL of DAP hydrogels caused significant negative effects on cytotoxicity and mineralization nodule formation of DPSC.

Conclusions

Hydrogels containing 1 mg/mL DAP offered significant direct antibacterial effects against single- and dual-species biofilms without causing significant negative effects on viability, ALP activity, and mineralization nodule formation of DPSC.

Clinical relevance

The methylcellulose-based hydrogel proposed in this study can be used clinically as a biocompatible system to deliver controlled low concentrations of DAP.

     

Efficacy of a combined nanoparticulate/calcium hydroxide root canal medication on elimination of Enterococcus faecalis

The purpose of this study was to evaluate the efficacy of Ca(OH)₂ with or without a silver nanoparticle suspension to eliminate Enterococcus faecalis from root canals. A total of 66 extracted human single‐rooted teeth contaminated with E. faecalis were treated with 10% Ca(OH)₂ alone, Ca(OH)₂ with nanosilver or sterile water (as a negative control). Samples were obtained with paper points and Gates‐Glidden burs at 1 and 7 days after root canal preparation and the number of colony‐forming units (CFU) was determined. The number of CFUs observed after dressing with Ca(OH)₂ + nanosilver was significantly less than the number observed with Ca(OH)₂ alone after 1 or 7 days (P < 0.001, P < 0.001). No differences in antimicrobial properties were observed between the two time points in the Ca(OH)₂ + nanosilver group (P > 0.05). Higher antimicrobial efficacy was observed in the Ca(OH)₂ group after 7 days than 1 day (P < 0.001). This study highlighted the potential advantage of using a mixture of Ca(OH)₂ and nanosilver for intracanal medicament.     

Resazurin metabolism assay for root canal disinfectant evaluation on dual-species biofilms

Introduction

Endodontic infections are caused by polymicrobial biofilms. Therefore, novel root canal disinfectants should be evaluated not only on single-species biofilms but also on dual- or mixed-species biofilms. A simple, high-throughput assay is urgently needed for this. In this study, the application of the resazurin metabolism assay was investigated for the evaluation of a root canal disinfectant on dual-species biofilms.

Methods

Enterococcus faecalis with or without Streptococcus mutans in biofilms were formed in an active attachment biofilm model for 24 hours. Subsequently, the biofilms were treated with various concentrations of NaOCl for 1 minute. After resazurin metabolism by both organisms was confirmed, treatment efficacies using 0.0016% resazurin were evaluated.

Results

During NaOCl treatments, resazurin metabolism displays a clear dose response, not only in single-species E. faecalis (or S. mutans) biofilms but also in dual-species biofilms. Notably, the assay revealed that the resistance of dual-species biofilms to NaOCl was 30-fold higher than in single-species E. faecalis biofilms. Viability counts on a selected NaOCl treatment (0.004%) confirmed this result and showed the increased resistance of E. faecalis in dual-species biofilms.

Conclusions

Clearly, the high-throughput and low cost resazurin metabolism assay has a great potential for testing novel root canal antimicrobial agents in mixed-species biofilms.     

Antibiofilm Effect of D-enantiomeric Peptide Alone and Combined with EDTA In Vitro

Introduction

The aim of this study was to evaluate the effect of DJK-5, a newly developed cationic antimicrobial peptide, on oral multispecies and Enterococcus faecalis biofilms alone or combined with the endodontic chelating agent EDTA in vitro.

Antibacterial activity of Propolis versus conventional endodontic disinfectants against Enterococcus faecalis in infected dentinal tubules

Introduction

The antibacterial activity against Enterococcus faecalis of 2 propolis samples was investigated in a dentin block model, and their effectiveness was compared with that of established endodontic disinfectants, chlorhexidine (CHX) and calcium hydroxide [Ca(OH)₂].

Methods

Standardized dentin blocks were infected with E. faecalis ATCC 29212. The root canal space was filled with one of the ethanolic extracts of propolis (Artvin or Tekirda? mix [TM]), CHX 2%, Ca(OH)₂, or ethanol or phosphate-buffered saline for control. Canal dentin was sampled after 1 or 7 days by using a standard-size bur. The dentinal shavings were vortexed vigorously in phosphate-buffered saline, and aliquots were cultured on tryptone soy agar plates. Colonies were counted after 2 days of incubation. Statistical significance was set to 5%.

Results

All experimental agents significantly reduced the number of the cultivable bacteria. CHX was the most potent disinfectant at both times. Compared with the ethanol control, no significant reduction in the number of colonies was found for the propolis extracts at day 1; however, significant reduction was found at day 7. The 2 propolis samples were statistically similar to each other and to Ca(OH)₂, but the TM sample was also similar to CHX at day 7. This has been linked to the greater concentration of flavonoids, a group of antibacterially active compounds, in the TM sample as determined by gas chromatography-mass spectrometry analysis.

Conclusions

The antimicrobial activity of the propolis samples tested in this study was between Ca(OH)₂ and CHX. Both propolis samples were antimicrobially effective; however, their activity did not exceed CHX.     

Antimicrobial Activity of a Sodium Hypochlorite/Etidronic Acid Irrigant Solution

Introduction

The aim of this study was to evaluate the antimicrobial activity of a 2.5% sodium hypochlorite (NaOCl)/9% etidronic acid (HEBP) irrigant solution on Enterococcus faecalis growing in biofilms and a dentinal tubule infection model.

Methods

The antimicrobial activity of the solutions 2.5% NaOCl and 9% HEBP alone and associated was evaluated on E. faecalis biofilms grown in the Calgary biofilm model (minimum biofilm eradication concentration high-throughput device). For the dentinal tubule infection test, the percentage of dead cells in E. faecalis–infected dentinal tubules treated with the solutions for 10 minutes was measured using confocal laser scanning microscopy and the live/dead technique. Available chlorine and pH of the solutions were also measured. Distilled water was used as the control. Nonparametric tests were used to determine statistical differences.

Results

The highest viability was found in the distilled water group and the lowest in the NaOCl-treated dentin (P < .05). Both NaOCl solutions killed 100% of the E. faecalis biofilms and showed the highest antimicrobial activity inside dentinal tubules, without statistical differences between the 2 (P < .05). The HEBP isolated solution killed bacteria inside dentinal tubules but did not present any significant effect against E. faecalis biofilms. The incorporation of HEBP to NaOCl did not cause any loss of available chlorine within 60 minutes.

Conclusions

HEBP did not interfere with the ability of NaOCl to kill E. faecalis grown in biofilms and inside dentinal tubules.     

Antimicrobial effect of grape seed extract as a potential intracanal medicament combined with Nd:YAG laser

This study evaluated the antimicrobial efficacy of grape seed extract medicament combined with Nd:YAG laser, against Enterococcus faecalis, Staphylococcus aureus and Candida albicans biofilms. Root canals infected with 4-week-old biofilms were divided into five groups (n = 11): calcium hydroxide, 6.5% GSE, Nd:YAG laser (1064 nm, 1.5 w, 15 Hz and 100 mj) and 6.5% GSE followed by Nd:YAG laser and normal saline (control). Dentin chips were collected using Gates–Glidden and cultured to obtain colony-forming units. Statistical analysis was performed using Kruskal–Wallis and Mann–Whitney U test. GSE showed higher antibacterial activity against all species investigated compared to Ca(OH)₂. However, the lowest microbial count was obtained using a combination of GSE and Nd:YAG laser (p < 0.001). No significant difference in the susceptibility of tested pathogens to each of the protocols was observed (p > 0.05). Application of Nd:YAG laser following GSE medicament is efficient against endodontic biofilms; also, GSE can be considered as an alternative to Ca(OH)₂ dressing.     

Antibacterial activity of endosequence root repair material and proroot MTA against clinical isolates of Enterococcus faecalis

Introduction

Endodontic repair materials such as mineral trioxide aggregate (MTA) are used for various endodontic procedures. An alternative material to MTA with purportedly improved handling properties is EndoSequence Root Repair Material, which is available as premixed putty (ESP) or syringeable paste (ESS) and is described as possessing antibacterial activity during its setting reaction due to its highly alkaline pH. The aim of this in vitro study was to determine whether ESP and ESS possess antibacterial properties against a collection of Enterococcus faecalis strains recovered from root canal infections. The hypotheses tested were that (1) ESP and ESS possess antibacterial activity during their setting reaction, (2) there is no difference between ESP, ESS, and MTA in antibacterial activity, and (3) E. faecalis strains isolated from root canals differ in susceptibility to the materials.

Methods

The direct contact test was used. ESP, ESS, and white MTA were preincubated at 37°C in >95% humidity for 30 minutes and 24 hours before 1-hour direct contact exposure to E. faecalis strains (n = 10). Absence of antibacterial carryover effect from the materials to the bacterial cultures was confirmed. Log₁₀ viable counts were compared by using analysis of variance with significance level at P ≤ .05.

Results

Combining data for all strains, the mean (± standard deviation) log₁₀ viable counts for ESP (4.55 ± 0.85), ESS (4.5 ± 0.95), and MTA (4.12 ± 1.26) were significantly lower than for untreated controls (7.40 ± 0.33) (P < .0001). The reduction in viable counts ranged from 1.86 ± 0.24 to 4.78 ± 0.42, with no statistically significant differences between the materials or preincubation periods. One strain was significantly more susceptible than 4 other strains.

Conclusions

ESP, ESS, and MTA had similar antibacterial efficacy against clinical strains of E. faecalis. Clinical strains varied in their susceptibility to the root repair materials.     

The Radiopacity and Antimicrobial Properties of Different Radiopaque Double Antibiotic Pastes Used in Regenerative Endodontics

Introduction

We evaluated the radiopacity and antibacterial properties of various concentrations of double antibiotic paste (DAP) containing barium sulfate (BaSO₄) or zirconium oxide (ZrO₂) radiopaque agents.

Effect of sodium fluoride on the virulence factors and composition of Streptococcus mutans biofilms

Objective

This study aimed to evaluate the influence of NaF (2, 10, 50 and 125 ppm F⁻) on the virulence factors and composition of Streptococcus mutans biofilms.

Methods

S. mutans UA159 biofilms were formed on saliva-coated hydroxyapatite discs. To assess the influence of NaF on the virulence factors of S. mutans biofilm cells, glycolytic pH drop, proton-permeability and F-ATPase activity assay were performed using 74 h old S. mutans biofilms. Glucosyltransferase (GTF) activity assay in suspension was also performed. To examine the influence of NaF on S. mutans biofilm composition, the biofilms were treated twice daily (5 min exposure/treatment) a total of five times during biofilm formation. After a total of 5 treatments, the biomass, colony forming unit (CFU) and polysaccharide composition of the treated 74 h old S. mutans biofilms were analysed by microbiological and biochemical methods, and scanning electron microscopy.

Results

NaF showed inhibitory effects on the acid production and acid tolerance of S. mutans biofilm cells at 10, 50 and 125 ppm F⁻, compared to the vehicle control (P < 0.05) and the treatments at these concentrations also affected the biomass, water-insoluble extracellular polysaccharides and intracellular iodophilic polysaccharides of the biofilms, compared to the vehicle control (P < 0.05).

Conclusions

These results indicate that NaF (10, 50 and 125 ppm F⁻) has inhibitory effects on the virulence factors and composition of S. mutans biofilms, suggesting the potential use of these concentrations as an effective measure for controlling dental biofilms.     

In vitro study of the inactivation by dentine of some endodontic medicaments and their bases

Background: The aim of this study was to investigate the antimicrobial effect of endodontic medicaments and their bases in the presence of dentine powder. Methods: The medicaments tested were Ledermix paste, Pulpdent paste, a 50:50 combination of the Pulpdent:Ledermix and their bases. The test organism was Enterococcus faecalis ATCC 29212. The presence or absence of dentine was examined as well as the effect of autoclaving dentine. Serial dilutions of samples at 1 hour, 1 day and 3 days were used for colony counting. The effects of dentine powder on pH for saturated Ca(OH)₂ solution and Pulpdent paste at 1 hour and 24 hours were also measured. Results: Pulpdent and the 50:50 combination of Pulpdent:Ledermix completely inhibited the growth of E. faecalis from 1 hour onwards, and these results were not affected by the presence/absence of dentine powder, pre‐incubation period, timing of autoclaving, or exposure time. Saturated solutions of Ca(OH)₂ are prone to inactivation by dentine powder unlike Pulpdent paste. Ledermix paste took 3 days to exert a significant effect on the growth of E. faecalis. Conclusions: In this laboratory study, both Pulpdent and the 50:50 mixture of Pulpdent with Ledermix were effective medicaments against E. faecalis in the presence of dentine powder.     

Influence of Calcium Hydroxide–loaded Microcapsules on Osteoprotegerin and Receptor Activator of Nuclear Factor Kappa B Ligand Activity

Introduction

Calcium hydroxide (Ca[OH]₂) microcapsules were synthesized to allow controlled release of Ca(OH)₂. The aim of this study was to evaluate the influence of Ca(OH)₂ microcapsules on osteoprotegerin (OPG) activity, receptor activator of nuclear factor kappa B ligand (RANKL) activity, and the OPG/RANKL ratio compared with pure Ca(OH)₂ powder and Vitapex (Neo Dental Chemical Products Co Ltd, Tokyo, Japan).

Methods

One formula of Ca(OH)₂ microcapsules was evaluated, and pure Ca(OH)₂ powder was used as a control. A commonly used Ca(OH)₂ medication containing an oily vehicle (Vitapex) was also evaluated, and the in vitro release profile of Vitapex was studied. The human osteosarcoma cell line MG63 was used to evaluate the influence of Ca(OH)₂ microcapsules, pure Ca(OH)₂ powder, and Vitapex on OPG and RANKL activity. The relative messenger RNA (mRNA) expression of OPG and RANKL was determined by real-time polymerase chain reaction. The protein expression of OPG and RANKL in supernatants was measured using enzyme-linked immunosorbent assay.

Results

Vitapex prolonged the release of Ca(OH)₂ compared with pure Ca(OH)₂ powder, and the release rate of Vitapex was faster than that of the microcapsules. The OPG/RANKL ratio in the microcapsules group was up-regulated at both the mRNA and protein levels compared with the negative control group and the pure Ca(OH)₂ powder group. The ratio in the Vitapex group was lower than the microcapsule group both at the mRNA and protein levels.

Conclusions

Ca(OH)₂ microcapsules increased the expression of OPG although they did not increase the expression of RANKL compared with pure Ca(OH)₂ powder and Vitapex. This increase in expression led to an increase in the OPG/RANKL ratio and eventual inhibition of osteoclast activity.     

Dental materials with antibiofilm properties

Objectives

Oral bacteria have evolved to form biofilms on hard tooth surfaces and dental materials. The antibiofilm effect of materials used for the restoration of oral function affects oral health. In this review we describe the features involved in the formation of oral biofilms on different surfaces in the oral cavity and the antibiofilm properties of dental materials.

Methods

An electronic search of scientific papers from 1987 to 2013 was performed with PubMed, ScienceDirect and Google search engines using the following search terms: antibiofilm, dental material, dental hard tissue, endodontic material, implant material, oral biofilm, and restorative material.

Results

Selected inclusion criteria resulted in 179 citations from the scientific, peer-reviewed literature. Oral biofilms form not only on dental hard tissue, but also on a wide range of dental materials used in cariology, endodontics, restorative dentistry and periodontology, resulting in destruction of dental hard tissue and even infection. Therefore, there has been a continuous effort to develop the antibiofilm properties of dental materials used for different purposes. Specific antimicrobial design in the composition and application of new materials (e.g. bioceramic sealer, resin composite, implant coating) demonstrates an improvement of the antibiofilm properties of these materials compared to earlier generations.

Significance

A significant number of dental materials have been shown to affect biofilm growth by inhibiting the adhesion of bacteria, limiting their growth or killing microbes in the biofilms formed in vitro. Incorporation of an appropriate amount of antibacterial agent could provide dental materials with antibiofilm activity without significantly influencing their mechanical properties. However, more randomized and double-blind clinical studies of sufficient length with these materials are needed to confirm long term success following their use in the dental clinic.