Antimicrobial activity of Streptococcus salivarius K12 on bacteria involved in oral malodour

ObjectiveTo investigate the antimicrobial activity of the bacteriocin-producing strain Streptococcus salivarius K12 against several bacteria involved in halitosis.DesignThe inhibitory activity of S. salivarius K12 against Solobacterium moorei CCUG39336, four clinical S. moorei isolates, Atopobium parvulum ATCC33793 and Eubacterium sulci ATCC35585 was examined by a deferred antagonism test. Eubacterium saburreum ATCC33271 and Parvimonas micra ATCC33270, which have been tested in previous studies, served as positive controls, and the Gram-negative strain Bacteroides fragilis ZIB2800 served as a negative control. Additionally, the occurrence of resistance in S. moorei CCUG39336 to S. salivarius K12 was analysed by either direct plating or by passage of S. moorei CCUG39336 on chloroform-inactived S. salivarius K12-containing agar plates.ResultsS. salivarius K12 suppressed the growth of all Gram-positive bacteria tested, but the extent to which the bacteria were inhibited varied. E. sulci ATCC35585 was the most sensitive strain, while all five S. moorei isolates were inhibited to a lesser extent. Natural resistance seems to be very low in S. moorei CCUG39336, and there was only a slight decrease in sensitivity after exposure to S. salivarius K12 over 10 passages.ConclusionOur studies demonstrate that S. salivarius K12 has antimicrobial activity against bacteria involved in halitosis. This strain might be an interesting and valuable candidate for the development of an antimicrobial therapy for halitosis.     

Effect of cinnamon (Cinnamomum verum) bark essential oil on the halitosis-associated bacterium Solobacterium moorei and in vitro cytotoxicity

ObjectivesHalitosis, also known as bad breath or oral malodour, is a condition affecting a large proportion of the population. Solobacterium moorei is a Gram-positive anaerobic bacterium that has been specifically associated with halitosis. In this study, we investigated the effects of essential oils, more particularly cinnamon bark oil, on growth, biofilm formation, eradication and killing, as well as hydrogen sulfide (H₂S) production by S. moorei.MethodsA broth microdilution assay was used to determine the antibacterial activity of essential oils. Biofilm formation was assessed by a crystal violet staining assay and scanning electron microscopy. The biofilm of S. moorei was characterized by enzymatic treatments. Biofilm killing was determined by a luminescence assay monitoring ATP production. H₂S production was quantified with a colorimetric assay. The biocompatibility of cinnamon oil was investigated using a gingival keratinocyte cell line.ResultsAmong the ten essential oils tested, cinnamon oil was found to be the most powerful against S. moorei with MIC and MBC values of 0.039% and 0.156%, respectively. The biofilm formed by S. moorei was then characterized. The fact that DNase I and to a lesser extent proteinase K significantly reduced biofilm formation by S. moorei and induced its eradication suggests that the extracellular matrix of S. moorei biofilm may be mainly containing a DNA backbone associated with proteins. At concentrations below the MIC, cinnamon oil reduced S. moorei biofilm formation that resulted from an attenuation of bacterial growth. It was also found that treatment of a pre-formed biofilm of S. moorei with cinnamon oil significantly decreased its viability although it did not cause its eradication. Cinnamon oil had an inhibitory effect on the production of H₂S by S. moorei. Lastly, it was found that at concentrations effective against S. moorei, no significant loss of viability in gingival keratinocytes occurred after a 1-h exposure.ConclusionsOur study brought evidence that cinnamon oil may be a promising substance to incorporate into oral hygiene products for controlling bad breath by inhibiting growth, killing biofilm, and reducing H₂S production by S. moorei. Moreover, at the effective concentrations, cinnamon oil was found to have no toxic effects on oral keratinocytes.     

Susceptibility of oral bacteria to Melaleuca alternifolia (tea tree) oil in vitro

The in vitro activity of Melaleuca alternifolia (tea tree) oil against 161 isolates of oral bacteria from 15 genera was determined. Minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) ranged from 0.003 to 2.0% (v/v). MIC90 values were 1.0% (v/v) for Actinomyces spp., Lactobacillus spp., Streptococcus mitis and Streptococcus sanguis, and 0.1% (v/v) for Prevotella spp. Isolates of Porphyromonas, Prevotella and Veillonella had the lowest MICs and MBCs, and isolates of Streptococcus, Fusobacterium and Lactobacillus had the highest. Time kill studies with Streptococcus mutans and Lactobacillus rhamnosus showed that treatment with > or = 0.5% tea tree oil caused decreases in viability of >3 log colony forming units/ml after only 30 s, and viable organisms were not detected after 5 min. These studies indicate that a range of oral bacteria are susceptible to tea tree oil, suggesting that tea tree oil may be of use in oral healthcare products and in the maintenance of oral hygiene.     

Characterization of volatile sulfur compound production by Solobacterium moorei

Objective

Solobacterium moorei is a Gram positive bacterium that has been specifically associated with halitosis. The aim of this study was to characterize volatile sulfur compound (VSC) production by S. moorei.

Methods

S. moorei was either grown or incubated in the presence of various supplements prior to determining VSC production with a Halimeter sulfide monitor. The effect of exogenous proteases or glycosidase inhibitors on VSC production by S. moorei was examined.

Results

We first showed that S. moorei can convert cysteine into hydrogen sulfide. The capacity of S. moorei to produce VSCs from serum, saliva, and mucin was dependent on the presence of an exogenous source of proteases such as pancreatic trypsin or Porphyromonas gingivalis gingipains. VSC production from mucin was inhibited by the presence of a β-galactosidase inhibitor, thus suggesting that deglycosylation of mucin by S. moorei is critical for VSC production.

Conclusion

Our study suggests that S. moorei can be a major source of malodorous compounds in halitosis by producing VSCs through a process involving the β-galactosidase activity of the bacterium and an exogenous source of proteases.     

Relationships between Solobacterium moorei and Prevotella intermedia in subgingival microbiota of periodontitis patients with halitosis: A preliminary study using qPCR

ObjectiveSolobacterium moorei is suggested to be associated with the production of volatile sulphur compounds (VSCs) and can be found in subgingival plaques of deep periodontal pockets. We examined whether this bacterium’s count was reduced in periodontitis patients with halitosis following non-surgical periodontal treatment, while the bacterial count of Prevotella intermedia was measured simultaneously as a control.Material & methodsThis clinical study included 20 adults with chronic periodontitis who complained of halitosis. The bacterial relationship in the subgingival plaque sample was measured after 8 weeks post-treatment, including the probing pocket depth (PPD). Quantitative real-time PCR (qPCR) was used to measure the proportion of S. moorei, while the concentrations of H₂S and CH₃SH were determined using oral ChromaTM.ResultsThe presence of S. moorei was consistently observed in participants with periodontitis before and after non-surgical periodontal treatment and consistent showed a significantly lower proportion compared with P. intermedia. Solobacterium moorei showed a strong positive correlation with H₂S and CH₃SH concentrations, but a negative correlation with deep periodontal pocket measurements. Conversely, reduced P. intermedia may be more associated with a deep pocket, independent of the concentration of CH₃SH.ConclusionThe study data showed that the proportion of S. moorei in the subgingival biofilm can be related to halitosis in periodontitis patients.     

Antimicrobial activity of garlic,tea tree oil,and chlorhexidine against oral microorganisms

OBJECTIVE: To compare the antimicrobial activity of tea tree oil, garlic, and chlorhexidine solutions against oral microorganisms. METHOD: The five-week study consisted of thirty subjects. The first week was considered baseline. All subjects used a control solution (second week), and were randomly divided into the three groups (third week): G1-0.12% chlorhexidine; G2 - 2.5% garlic (Allium sativum, L.); and G3 - 0.2% tea tree oil (Melaleuca alternifolia). Dishes containing blood agar and Mitis Salivarius Bacitracin agar (MSB) were inoculated with the subjects' saliva (collected twice a week). Total microorganisms and mutans streptococci were counted in blood agar and MSB, respectively. RESULTS: Chlorhexidine and garlic groups showed antimicrobial activity against mutans streptococci, but not against other oral microorganisms. The tea tree oil group showed antimicrobial activity against mutans streptococci and other oral microorganisms. Maintenance of reduced levels of microorganisms was observed only for garlic and tea tree oil during the two consecutive weeks (fourth and fifth). Unpleasant taste (chlorhexidine 40%, tea tree oil 30%, garlic 100%), burning sensation (chlorhexidine 40%, tea tree oil 60%, garlic 100%), bad breath (chlorhexidine 40%, tea tree oil 20%, garlic 90%), and nausea (chlorhexidine 0%, tea tree oil 10%, garlic 30%) were reported. CONCLUSION: Garlic and tea tree oil might be an alternative to chlorhexidine.     

The effect of various topical peri-implantitis antiseptics on Staphylococcus epidermidis, Candida albicans, and Streptococcus sanguinis

ObjectiveAlthough peri-implantitis has presented an ever increasing problem in modern dentistry, satisfying therapeutic strategies or scientifically based treatment recommendations are still not available. The main object of the present study was to evaluate the antibacterial efficacy of six different topical antiseptics on three test microorganisms attached to titanium implant specimens.Material and methodsFor biofilm formation, plane titan specimens were incubated either in Candida albicans, Streptococcus sanguinis, or Staphylococcus epidermidis for 2 h. The specimens were then treated with different topical antiseptics for 60 s (sodium hypochlorite 1.0%, hydrogen peroxide 3.0%, chlorhexidine gluconate 0.2%, citric acid 40.0%, Plax, or Listerine) and with sterile saline as control. Remaining vital fungi were quantified by means of a bioluminometric assay and the bacterial load and the viability of adhering S. epidermidis and S. sanguinis by live or dead cell labelling in combination with fluorescence microscopy.ResultsSodium hypochlorite was effective against all three species, whereas hydrogen peroxide was solely effective against C. albicans. CHX and Listerine showed antimicrobial activity against S. sanguinis and C. albicans and citric acid and Plax against both tested bacteria.ConclusionsNone of the tested antimicrobial agents, except for sodium hypochlorite, showed a significant in vitro effect on all three test microbes. Considering the possible toxicity of sodium hypochlorite, none of the tested – and so far widely used – antiseptics showed any broad-spectrum antimicrobial effect and could therefore not be recommended for the topical disinfection and detoxification of infected implant surfaces.     

Inhibition of Streptococcus mutans biofilm formation using extracts from Assam tea compared to green tea

ObjectiveStreptococcus mutans, a gram-positive oral bacterium, has been identified as one of the principal etiological agents of human dental caries. To clarify the nature of the difference anti-biofilm effect against S. mutans between Assam tea from Camellia sinensis var. assamica, partially fermented, and green tea from Camellia sinensis, non-fermented, active agents from the teas were purified.MethodsEffects of Assam tea and green tea samples on biofilm were assessed by using the conventional titer plate method and the human saliva-coated hydroxyapatite discs. The purification and identification of inhibitors were performed by using ultrafiltration with centrifugal filter devices and high performance liquid chromatography.ResultsAssam tea has stronger biofilm inhibition activity against S. mutans than green tea. A substance of <10 kDa in mass in Assam tea had a high concentration of galloylated catechins and a stronger biofilm inhibiting activity than green tea. In contrast, substances >10 kDa in mass from green tea included higher concentrations of polysaccharides composed of galacturonic acid, such as pectin, that enhance biofilm formation.ConclusionsThe higher concentrations of galloylated catechins in Assam tea may assist in prevention of dental caries, whereas in green tea, this mode of inhibition was likely offset by the presence of pectin. Purification of catechins in partially fermented Assam tea with lower-molecular-weight polysaccharide than pectin may be useful for developing oral care products such as toothpaste and oral care gel pastes.     

Efficiency Evaluation of Various Solvents in Retreatment of Endodontic Filling in Extracted Teeth

ObjectivesThe aim of this study was to evaluate the retreatment duration and efficacy of eucalyptol and tea tree oil in engine driven and manual retreatment of epoxy resin based endodontic filling in extracted human teeth.Methods and materialsSixty human single rooted teeth were randomly divided into two groups. The first group was prepared using hand files, and the second one using Reciproc system. Root canals were filled with gutta-percha points and AH Plus sealer. Retreatment was performed using K-reamers and Hedström files for the first group, and Reciproc instruments for the second group. Each group was divided into two subgroups (n=15) according to the retreatment solvent used (eucalyptol or tea tree oil). Root canals were longitudinaly split and analized with stereomicroscope (15x magnification). The surface of the remaining filling material was measured using an image processing software.ResultsThere were no statistically significant differences in the area of residual filling material among used solvents, nor in applied technique. Retreatment with Reciproc instruments was significantly faster compared to retreatment using hand files. The manual retreatment technique was faster when tea tree essential oil was used as a solvent compared to eucalyptol.ConclusionsAustralian tea tree oil and eucalyptus oil were equally effective in removing endodontic filling material, but none of canals were completely free of the residual filling material. Retreatment with Reciproc instruments was faster compared to retreatment using hand files. The manual retreatment technique is faster when tea tree essential oil is used as a solvent compared to eucalyptol.     

Hydroalcoholic extracts of Myracrodruon urundeuva All. and Qualea grandiflora Mart. leaves on Streptococcus mutans biofilm and tooth demineralization

ObjectivesThis study evaluated the effect of the hydroalcoholic extracts of Myracrodruon urundeuva All. and Qualea grandiflora Mart. leaves (alone or combined) on the viability of Streptococcus mutans biofilm and on the prevention of enamel demineralization.MethodsStrain of S. mutans (ATCC 21175) was reactivated in BHI broth. Minimum inhibitory concentration, minimum bactericidal concentration, minimum inhibition biofilm concentration and minimum eradication biofilm concentration were determined in order to choose the concentrations to be tested under biofilm model. S. mutans biofilm (5 × 10⁵ CFU/ml) was produced on bovine enamel, using McBain saliva under 0.2% sucrose exposure, for 3 days. The biofilm was daily treated with the extracts for 1 min. The biofilm viability was tested by fluorescence and the enamel demineralization was measured using TMR.ResultsMyracrodruon urundeuva All. (Isolated or combined) at the concentrationsc ≥0.625 mg/ml was able to reduce bacteria viability, while Qualea Grandflora Mart. alone had antimicrobial effect at 5 mg/ml only (p < 0.05). On the other hand, none of the extracts were able to reduce enamel demineralization.ConclusionsThe hydroalcoholic extracts of Myracrodruon urundeuva All. and Qualea grandiflora Mart. leaves (isolated or combined) have antimicrobial action; however, they do not prevent enamel caries under S. mutans biofilm model.     

Fungicidal amounts of antifungals are released from impregnated denture lining material for up to 28 days

ObjectivesThe aim of this study was to investigate the efficacy of a polymeric delivery system impregnated with chlorhexidine or fluconazole against Candida species.MethodsSelf-cure poly-ethyl methacrylate and tetrahydro-furfuryl methacrylate (PEM/THFM) discs impregnated with pure fluconazole substance (FLUp), fluconazole powder from capsules (FLUc) or chlorhexidine powder (CHX) were incubated in water for up to 28 days at 37 °C. The water was replaced at 24 h and 3, 7, 14, 21, 28 days. The amount of released drugs and antifungal activity of the leachates was measured by bioassay. The minimal inhibitory concentration (MIC) of each drug for 46 Candida isolates was determined and compared to the released concentrations.ResultsA total of 53.0% of CHX, 38.5% of FLUc and 13.2% of FLUp impregnated into the discs was leached during the 28-day incubation. Of the total amount leached, 71.8% of CHX, 75.1% of FLUc and 70.5% of FLUp was released during the first week of incubation. Antifungal activity was confirmed for up to 28 days.ConclusionBoth chlorhexidine and fluconazole become readily leached from PEM/THFM polymer up to four weeks and that the polymerisation of the acrylic does not affect the antimicrobial activity of the agents. Importantly, the amount of drugs released exceeded the MICs of most isolates also during the fourth week of incubation.Clinical significanceThese findings indicate the feasibility of this treatment modality for oral candidal infections, especially denture stomatitis. But further in vivo work is warranted to determine its clinical relevance and applicability.     

Development of tissue conditioner containing cetylpyridinium chloride montmorillonite as new antimicrobial agent: Pilot study on antimicrobial activity and biocompatibility

PurposeThe mechanical properties, antimicrobial activity, and biocompatibility of a novel antimicrobial tissue conditioner containing cetylpyridinium chloride with montmorillonite (CPC-Mont) were evaluated.MethodsTo examine the mechanical properties of the novel material, hardness, consistency, and penetration tests were conducted. Antimicrobial activity against Candida albicans (C. albicans) and Staphylococcus aureus (S. aureus) was evaluated. Cell viabilities of fibroblasts and epithelial cells using eluates from materials were measured to evaluate cytotoxicity. In addition, to assess tissue response, animal experiments were conducted.ResultsThe hardness test results were similar to those of other commercially available materials. The novel tissue conditioner showed good antimicrobial activity against C. albicans and S. aureus compared with other materials. This effect was sustained for a week for C. albicans. In the case of S. aureus, microbial growth was suppressed for up to 3 weeks. Cell viability of the novel material for the eluate at 1 day was significantly less than those of other material for both cells. However, the cell viability at 7 days showed no significant difference. Animal experiments demonstrated that inflammatory responses around materials were not observed on the oral mucosa as other material.ConclusionWithin the limitations of this in vitro and in vivo study, the results suggest that the newly developed tissue conditioner containing CPC-Mont has not only excellent antimicrobial properties, but also the same mechanical properties and biocompatibility as tissue conditioners on the market.     

Antimicrobial properties,mechanics, and fluoride release of ionomeric cements modified by red propolis

ObjectivesTo evaluate the antimicrobial activity, mechanical properties, and fluoride release capacity of glass ionomer cement (GIC) used for cementing orthodontic bands and modified by ethanolic extract of red propolis (EERP) in different concentrations.Materials and MethodsTwo orthodontic GICs containing EERP at 10%, 25%, and 50%, were used. The following assays were carried out: cell viability tests against Streptococcus mutans and Candida albicans, diametral tensile strength, compressive strength, shear bond strength, microhardness, and fluoride release capacity. The statistical analyses of the antimicrobial tests, fluoride release, diametral tensile strength, compressive strength, and microhardness were performed using two-way analysis of variance and Tukey test (P < .05). Shear bond strength data were analyzed using one-way analysis of variance followed by Tukey test (P < .05).ResultsAt the concentrations of 25% and 50%, EERP was shown to be a promising antimicrobial agent incorporated into GICs against C albicans (P < .001) and S mutans (P < .001). The fluoride release capacity of the GICs was not affected, and the EERP concentration of 25% was the one that least affected the mechanical properties of the cements (P > .05).ConclusionsThe GICs containing EERP at 25% showed a significant increase in their antimicrobial activity against S mutans and C albicans, while mechanical properties and fluoride release remained without significant changes.     

Chemical composition of Pistacia vera L. oleoresin and its antibacterial,anti-virulence and anti-biofilm activities against oral streptococci,including Streptococcus mutans

ObjectiveThe aim of this study was to characterize the chemical composition of oleoresin of Pistacia vera L. and to determine its antimicrobial and anti-virulence activity versus selected oral streptococci.DesignA gaschromatografic analysis of the oleoresin was performed. The antimicrobial and anti-virulence activity of the oleoresin and its fractions was evaluated by the Minimum Inhibitory Concentration (MIC) and/or Minimum Bactericidal Concentration (MBC), biofilm production and haemolytic activity inhibition experiments.ResultsThe oleoresin MBCs were ≥1024 μg/mL for all tested strains; the neutral and acidic fraction MBCs ranged from 128 to 2048 μg/mL. Essential oil’s MBCs (from 256 to 2048 μg/mL) were almost identical to MICs, suggesting a bactericidal effect. P. vera oleoresin at sub-lethal concentrations significantly reduced biofilm production by Streptococcus mutans (up to 49.4%) and by Streptococcus sanguinis (up to 71.2%). In addition, the acidic fraction showed a specific anti-biofilm activity against S. mutans (up to 41.3% reduction). A significant dose-dependent reduction in the haemolytic activity of S. mutans (up to 65.9%) and of S. anginosus (up to 78.3%) was observed after growth in the presence of oleoresin at sub-lethal concentrations. The acidic fraction reduced haemolytic activity (up to 54.3% at 64 μg/mL) of S. mutans only.ConclusionsGiven the anti-virulence activity of the P. vera oleoresin and its acidic fraction against S. mutans, our findings suggest their potential use in oral hygiene. These data represent the first step in the exploitation of P. vera L. oleoresin.     

New Bacterial Compositions in Root-filled Teeth with Periradicular Lesions

The aim of this study was to isolate and detect microorganisms of root-filled teeth associated with periradicular lesions. Specimens were sampled from patients undergoing root canal retreatment. The bacteria were characterized by morphologic and biochemical analysis and by 16S rRNA gene sequencing. Microorganisms were detected in 10 of 18 teeth. The majority of positive samples revealed a mixed culture of 2–8 species. In 2 teeth Enterococcus faecalis was the only detected species. For the first time Vagococcus fluvialis was detected in root canals. Solobacterium moorei and Fusobacterium nucleatum were the most prevalent species. Presence of F. nucleatum was associated with the presence of S. moorei in 5 of 7 cases. In all teeth with Parvimonas micra and Dialister invisus, F. nucleatum and S. moorei were found. Moreover, members of additional different genera were detected delivering bacterial compositions that have been not described yet.     

Influence of orthodontic brackets design and surface properties on the cariogenic Streptococcus mutans adhesion

ObjectiveTo compare the surface properties of self-ligating metallic (SLM), ceramic esthetic, and conventional metallic (CM) brackets, and evaluate the adhesion of Streptococcus mutans biofilms to their surface, attempting to interpret the correlation between bracket type and enamel demineralization from a microbiological perspective.Materials and methodsTwenty-two brackets of each group were used. The brackets’ surface roughness was defined and the bacterial adhesion was performed using the strain S. mutans ATCC25175 with 8 h or 24 h of incubation time. The total bacterial adhesion (TBA) of biofilms was assessed using optical density (OD) methodology. To quantify bacteria viability (BV), the colony forming units (CFU) were counted. A scanning electron microscopy (SEM) observation of biofilms was also performed. Results: Ceramic brackets exhibited significantly higher roughness (0.304) compared to CM (0.090) and SLM (0.067) ones (C > CM = SLM). The data obtained with the TBA and BV tests showed that S. mutans biofilm formed on bracket groups exhibited similar results for both incubation periods. From the SEM images it is possible to observe that biofilm structure formed for 24 h was denser than that for 8 h of incubation with significantly more aggregates and cells for three groups.ConclusionThis in vitro study suggests that despite the higher surface roughness of ceramic brackets, this alone does not influence the adhesion of the S. mutans biofilms.Clinical relevanceFrom a microbiological perspective, the bracket's design may be more relevant than its surface roughness with respect to the adhesion of cariogenic bacteria biofilm with potential risk to dental enamel integrity.     

In vitro antimicrobial effect of the tissue conditioner containing silver nanoparticles

PURPOSE

The aim of this study was to identify in vitro antimicrobial activity of the tissue conditioner containing silver nanoparticles on microbial strains, Staphylococcus aureus, Streptococcus mutans and Candida albicans.

MATERIALS AND METHODS

Experimental disc samples (20.0×3.0 mm) of tissue conditioner (GC Soft-Liner, GC cooperation, Tokyo, Japan) containing 0.1 - 3.0% silver nanoparticles (0%: control) were fabricated. Samples were placed on separate culture plate dish and microbial suspensions (100 µL) of tested strains were inoculated then incubated at 37℃. Microbial growth was verified at 24 hrs and 72 hrs and the antimicrobial effects of samples were evaluated as a percentage of viable cells in withdrawn suspension (100 µL). Data were recorded as the mean of three colony forming unit (CFU) numerations and the borderline of the antimicrobial effect was determined at 0.1% viable cells.

RESULTS

A 0.1% silver nanoparticles combined to tissue conditioner displayed minimal bactericidal effect against Staphylococcus aureus and Streptococcus mutans strains, a 0.5% for fungal strain. Control group did not show any microbial inhibitory effect and there were no statistical difference between 24 hrs and extended 72 hrs incubation time (P > .05).

CONCLUSION

Within the limitation of this in vitro study, the results suggest that the tissue conditioner containing silver nanoparticles could be an antimicrobial dental material in denture plaque control. Further mechanical stability and toxicity studies are still required.     

Antimicrobial and physicochemical characterization of endodontic sealers after exposure to chlorhexidine digluconate

ObjectivesAssess the antibacterial, physical and chemical properties of AH Plus, BioRoot RCS and Pulp Canal Sealer (PCS) in contact with 2% chlorhexidine digluconate (CHX) used as final irrigant prior to root canal obturation.MethodsThe antimicrobial properties were investigated by direct contact tests for planktonic and biofilm growth of E. faecalis, S. mutans, S.epidermidis and S.aureus in vitro. The setting time, wettability, microhardness and surface roughness were also assessed. The sealers were studied in no contact, 1-minute (short-term) and continuous contact (long-term) with CHX. Chemical characterization of sealers was performed by scanning electron microscopy, X-ray diffraction analysis and Fourier-transform infrared spectroscopy after CHX or saline used as the last irrigant in an ex vivo tooth model and in endo training blocks.ResultsCHX increased the antibacterial activity of all the sealers investigated against planktonic bacteria and biofilms with PCS exerting the highest antimicrobial activity with and without the presence of CHX. The setting of AH Plus and BioRoot RCS was retarded, while for PCS accelerated in the presence of CHX. AH Plus and PCS were more hydrophilic after contact with CHX, whilst BioRoot RCS was hydrophobic in a time-dependent manner. The microhardness of sealers was compromised and the surface roughness increased after CHX exposure for AH Plus and BioRoot RCS, and decreased for PCS. CHX did not affect the sealers’ chemistry, but PCS that exhibited two extra phases.SignificanceCHX improved the antibacterial efficacy of endodontic sealers but further evidence is needed to confirm its suitability as a final irrigant prior to root canal obturation.     

Laser-enhanced cytotoxicity of zoledronic acid and cisplatin on primary human fibroblasts and head and neck squamous cell carcinoma cell line UM-SCC-3

IntroductionLow-level laser therapy (LLLT) is used in parodontitis treatment in combination with an antimicrobial photosensitizer. The purpose of this study was to investigate the combination of LLLT with cisplatin and zoledronic acid as potential photosensitizer in-vitro.Materials and methodsPrimary human fibroblasts (PHF) and head and neck squamous cell carcinoma cells (HNSCC, exactly UM-SCC-3) were treated with different concentrations of zoledronatic acid and cisplatin and irradiated twice with a diode laser (wavelength 670 nm, 2 min). Cell viability was tested by XTT assay and histomorphological analysis with HE staining.ResultsLLLT increased bioviability for both cell lines (p < 0.001). LLLT lowered PHF viability at the highest concentrations of cisplatin (p = 0.027 and p = 0.005) and zoledronic acid (p < 0.001). For HNSCCs, LLLT reduced cell viability at every concentration of cisplatin (all p < 0.05). In cases of incubation with zoledronic acid, similar to fibroblasts, laser therapy lowered cell viability at the highest concentration only (p < 0.001).ConclusionsWithin the limits of this study, it can be concluded that LLLT enhances the effect of cisplatin and zoledronic acid in the discussed cells in order to develop new therapeutic options for cysts in the cranio-maxillofacial region and other appropriate indications.     

Photocrosslinkable methacrylated gelatin hydrogel as a cell-friendly injectable delivery system for chlorhexidine in regenerative endodontics

ObjectivesThis work sought to formulate photocrosslinkable chlorhexidine (CHX)-laden methacrylated gelatin (CHX/GelMA) hydrogels with broad spectrum of action against endodontic pathogens as a clinically viable cell-friendly disinfection therapy prior to regenerative endodontics procedures.MethodsCHX/GelMA hydrogel formulations were successfully synthesized using CHX concentrations between 0.12 % and 5 % w/v. Hydrogel microstructure was evaluated by scanning electron microscopy (SEM). Swelling and enzymatic degradation were assessed to determine microenvironmental effects. Compression test was performed to investigate the influence of CHX incorporation on the hydrogels’ biomechanics. The antimicrobial and anti-biofilm potential of the formulated hydrogels were assessed using agar diffusion assays and a microcosms biofilm model, respectively. The cytocompatibility was evaluated by exposing stem cells from human exfoliated deciduous teeth (SHEDs) to hydrogel extracts (i.e., leachable byproducts obtained from overtime hydrogel incubation in phosphate buffer saline). The data were analyzed using One- and Two-way ANOVA and Tukey’s test (α = 0.05).ResultsCHX/GelMA hydrogels were effectively prepared. NMR spectroscopy confirmed the incorporation of CHX into GelMA. The addition of CHX did not change the micromorphology (pore size) nor the swelling profile (p > 0.05). CHX incorporation reduced the degradation rate of the hydrogels (p < 0.001); whereas, it contributed to increased compressive modulus (p < 0.05). Regarding the antimicrobial properties, the incorporation of CHX showed a statistically significant decrease in the number of bacteria colonies at 0.12 % and 0.5 % concentration (p < 0.001) and completely inhibited the growth of biofilm at concentration levels 1 %, 2 %, and 5 %. Meanwhile, the addition of CHX, regardless of the concentration, did not lead to cell toxicity, as cell viability values were above 70 %.SignificanceThe addition of CHX into GelMA showed significant antimicrobial action against the pathogens tested, even at low concentrations, with the potential to be used as a cell-friendly injectable drug delivery system for root canal disinfection prior to regenerative endodontics.