Trans-Cinnamaldehyde-Fighting Streptococcus mutans Using Nature.

Streptococcus mutans (S. mutans) is the main cariogenic bacterium with acidophilic properties, in part due to its acid-producing and -resistant properties. As a result of this activity, hard tooth structures may demineralize and form caries. Trans-cinnamaldehyde (TC) is a phytochemical from the cinnamon plant that has established antibacterial properties for Gram-positive and -negative bacteria. This research sought to assess the antibacterial and antibiofilm effects of trans-cinnamaldehyde on S. mutans. TC was diluted to a concentration range of 156.25-5000 µg/mL in dimethyl sulfoxide (DMSO) 0.03-1%, an organic solvent. Antibacterial activity was monitored by testing the range of TC concentrations on 24 h planktonic growth compared with untreated S. mutans. The subminimal bactericidal concentrations (MBCs) were used to evaluate the bacterial distribution and morphology in the biofilms. Our in vitro data established a TC MBC of 2500 µg/mL against planktonic S. mutans using a microplate spectrophotometer. Furthermore, the DMSO-only controls showed no antibacterial effect against planktonic S. mutans. Next, the sub-MBC doses exhibited antibiofilm action at TC doses of ≥625 µg/mL on hydroxyapatite discs, as demonstrated through biofilm analysis using spinning-disk confocal microscopy (SDCM) and high-resolution scanning electron microscopy (HR-SEM). Our findings show that TC possesses potent antibacterial and antibiofilm properties against S. mutans. Our data insinuate that the most effective sub-MBC of TC to bestow these activities is 625 µg/mL.

Biocompatibility, Surface Morphology, and Bacterial Load of Dental Implant Abutments following Decontamination Protocols: An In-Vitro Study.

The long-term success of dental implant rehabilitation depends significantly on proper peri-implant soft tissue integration. Therefore, decontamination of abutments prior to their connection to the implant is beneficial to enhance soft tissue attachment and to aid in maintaining marginal bone around the implant. Consequently, different implant abutment decontamination protocols were evaluated regarding biocompatibility, surface morphology, and bacterial load. The protocols evaluated were autoclave sterilization, ultrasonic washing, steam cleaning, chlorhexidine chemical decontamination, and sodium hypochlorite chemical decontamination. The control groups included: (1) implant abutments prepared and polished in a dental lab without decontamination and (2) unprepared implant abutments obtained directly from the company. Surface analysis was performed using scanning electron microscopy (SEM). Biocompatibility was evaluated using XTT cell viability and proliferation assays. Biofilm biomass and viable counts (CFU/mL) (n = 5 for each test) were used for surface bacterial load evaluation. Surface analysis revealed areas of debris and accumulation of materials, such as iron, cobalt, chromium, and other metals, in all abutments prepared by the lab and with all decontamination protocols. Steam cleaning was the most efficient method for reducing contamination. Chlorhexidine and sodium hypochlorite left residual materials on the abutments. XTT results showed that the chlorhexidine group (M = 0.7005, SD = 0.2995) had the lowest values (p < 0.001) (autoclave: M = 3.6354, SD = 0.1510; ultrasonic: M = 3.4077, SD = 0.3730; steam: M = 3.2903, SD = 0.2172; NaOCl: M = 3.5377, SD = 0.0927; prep non-decont.: M = 3.4815, SD = 0.2326; factory: M = 3.6173, SD = 0.0392). Bacterial growth (CFU/mL) was high in the abutments treated with steam cleaning and ultrasonic bath: 2.93 × 109, SD = 1.68 × 1012 and 1.83 × 109, SD = 3.95 × 1010, respectively. Abutments treated with chlorhexidine showed higher toxicity to cells, while all other samples showed similar effects to the control. In conclusion, steam cleaning seemed to be the most efficient method for reducing debris and metallic contamination. Bacterial load can be reduced using autoclaving, chlorhexidine, and NaOCl.

Comparison of Different Finishing and Polishing Systems on Surface Roughness and Bacterial Adhesion of Resin Composite.

Insufficient dental restoration finishing and polishing may lead to plaque accumulation, gingival inflammation, staining, caries, and esthetic impairment. Here, the effect of two finishing and polishing systems on surface roughness and bacterial adhesion were evaluated. Two finishing and polishing kits were evaluated: diamond burs (Shine 1-2, Strauss & Co, Raanana, Israel) and paper discs (Sof-Lex 3M ESPE, Seefeld, Germany) (n = 30 each). For each group surface roughness was evaluated using an optical profilometer (Contour GT-K1, Bruker, Billerica, MA, USA) (n = 10). Surface bacteria were evaluated for biofilm biomass using crystal violet (CV) staining (absorbance measured at 538 nm) and viable counts (CFU/mL) (n = 20). The control group included polymerized discs against a Mylar strip (n = 30). Student's t test and one-way ANOVA were used for statistical evaluation. Diamond burs, paper discs, and control average surface RA were 169.4 ± 45.2 µ, 364 ± 77.7 µ, and 121.2 ± 18.1 µ, respectively. There was a significant difference found between all groups (p < 0.00001). Bacterial biomass on diamond burs, paper discs, and control samples were 0.458 ± 0.161, 0.507 ± 0.139, and 0.446 ± 0.142, respectively (p = 0.257). Viable bacterial counts (CFU/mL) on diamond burs, paper discs, and control samples were 2.25 × 104, 2.95 × 104, and 2.75 × 104, respectively (p = 0.856). A comparison between two finishing and polishing kits showed that the shine 1−2 diamond bur kit produced a smoother surface than the polishing disc kit. No differences were found in the biofilm biomass quantification and bacterial viable count between the groups.

Phage Targeting Streptococcus mutans In Vitro and In Vivo as a Caries-Preventive Modality.

Dental caries is a common infectious disease worldwide. Current conventional therapies lack specific antimicrobial effects against Streptococcus mutans, a key bacterium that induces caries. A promising alternative approach is bacteriophage (phage) therapy. Recently, SMHBZ8 phage targeting S. mutans was isolated and characterized. The aim of this study was to evaluate the caries-prevention efficacy of SMHBZ8 using in vitro and in vivo caries models. Hemi-mandibles dissected from euthanized healthy mice were subjected to caries-promoting conditions in vitro. Jaws treated with phage therapy in suspension and in formulation with a sustained-release delivery system showed no carious lesions, similar to control and chlorhexidine-treated jaws. Subsequently, SMHBZ8 phage suspension also prevented carious lesion development in a murine caries model in vivo. In both models, caries lesions were analyzed clinically and radiographically by µCT scans. This study shows how SMHBZ8 phage therapy targeting S. mutans can serve as an efficient caries-prevention modality, in suspension or with a sustained-release delivery system, by in vitro and in vivo mouse models.

Isolation and Characterization of Streptococcus mutans Phage as a Possible Treatment Agent for Caries.

Streptococcus mutans is a key bacterium in dental caries, one of the most prevalent chronic infectious diseases. Conventional treatment fails to specifically target the pathogenic bacteria, while tending to eradicate commensal bacteria. Thus, caries remains one of the most common and challenging diseases. Phage therapy, which involves the use of bacterial viruses as anti-bacterial agents, has been gaining interest worldwide. Nevertheless, to date, only a few phages have been isolated against S. mutans. In this study, we describe the isolation and characterization of a new S. mutans phage, termed SMHBZ8, from hundreds of human saliva samples that were collected, filtered, and screened. The SMHBZ8 genome was sequenced and analyzed, visualized by TEM, and its antibacterial properties were evaluated in various states. In addition, we tested the lytic efficacy of SMHBZ8 against S. mutans in a human cariogenic dentin model. The isolation and characterization of SMHBZ8 may be the first step towards developing a potential phage therapy for dental caries.

Laser Tooth Preparation for Pit and Fissure Sealing.

Objectives: Various approaches are available for pit and fissure sealing, including: the use of sealants, with or without mechanical preparation; the use of etching, with or without bonding; and the use of lasers as an alternative to mechanical preparation. The objective of this study is to evaluate pit and fissure sealing by comparing the retention and microleakage of sealants, between mechanical and Er:Yag laser enamel preparation. Methods: Sixty extracted sound third molars are classified into six groups: A, bur mechanical preparation and sealant application; B, bur mechanical preparation, etching and sealant; C, bur mechanical preparation, etching, bonding and sealant; D, laser mechanical preparation and sealant; E, laser mechanical preparation, etching and sealant application; F, laser mechanical preparation, etching, bonding, and sealant. Statistical analysis methods include Fisher's exact test, a general linear model for one-way analysis of variance (ANOVA) of multiple comparisons, and Bonferroni multiple comparison tests. Results: All the groups showed dye microleakage beneath the sealants. Less microleakage was observed for those that used bur rather than laser, 41 versus 44 specimens, respectively. The number of specimens without microleakage decreased as follows: group E (24), group A (18), groups B and F (17), group C (14), and group D (5). Retention was 100% in all groups except group D. Conclusion: Mechanical preparation increases retention of sealants, especially when etching material is used; additionally, bonding can help the retention. The best technique is mechanical preparation via laser and subsequent use of etching, without bonding prior to application of the dental sealant.

Eradication of Vancomycin-Resistant Enterococci by Combining Phage and Vancomycin.

Currently, effective options are needed to fight vancomycin-resistant Enterococcus faecalis (VRE). The present study shows that combinations of phage and vancomycin are highly efficient against VRE, despite being resistant to the antibiotic. Vancomycin-phage EFLK1 (anti-E. faecalis phage) synergy was assessed against VRE planktonic and biofilm cultures. The effect of the combined treatment on VRE biofilms was determined by evaluating the viable counts and biomass and then visualized using scanning electron microscopy (SEM). The cell wall peptidoglycan was stained after phage treatment, visualized by confocal microscopy and quantified by fluorescence activated cell sorting (FACS) analysis. The combined treatment was synergistically effective compared to treatment with phage or antibiotic alone, both in planktonic and biofilm cultures. Confocal microscopy and FACS analysis showed that fluorescence intensity of phage-treated bacteria increased eight-fold, suggesting a change in the peptidoglycan of the cell wall. Our results indicate that with combined treatment, VRE strains are not more problematic than sensitive strains and thus give hope in the continuous struggle against the current emergence of multidrug resistant pathogens.

Phages in a thermoreversible sustained-release formulation targeting E. faecalis in vitro and in vivo.

INTRODUCTION: Enterococcus faecalis is a key pathogen recovered from root canals when conventional treatment fails. Phage therapy has generated new interest in combating pathogens. A sustained-release formulation using specific phages against E. faecalis may offer an alternative approach. OBJECTIVES: To evaluate the efficacy of anti-E. faecalis phages formulated in a thermo- sustained-release system against E. faecalis in vitro and in vivo. METHODS: EFDG1 and EFLK1 phages were formulated with poloxamer P407. Gelation time, phage survival, activity and toxicity were evaluated. Lytic activity was evaluated in vitro against E. faecalis at various growth phases, including anti-biofilm activity. Methods included viable bacterial count (CFU/mL), biofilm biomass determination and electron microscopy (live/dead staining). Further evaluation included infected incisors in an in vivo rat model. Anti-E. faecalis phage-cocktail suspension and sustained-release phage formulation were evaluated by viable bacterial count (CFU/mL), histology, scanning electron microscopy (SEM) and 16S genome sequencing of the microbiota of the root canal. RESULTS: Gelation time for clinical use was established. Low toxicity and a high phage survival rate were recorded. Sustained-release phages reduced E. faecalis in logarithmic (4 logs), stationary (3 logs) and biofilm (4 logs) growth phases. Prolonged anti-biofilm activity of 88% and 95% reduction in biomass and viable counts, respectively, was recorded. Reduction of intracanal viable bacterial counts was observed (99% of enterococci) also seen in SEM. Phage treatment increased Proteobacteria and decreased Firmicutes. Histology showed reduced periapical inflammation and improved healing following phage treatment. CONCLUSION: Poloxamer P407 formulated with phages has an effective and long-lasting effect in vitro and in vivo targeting E. faecalis.

Next generation of dentists moving to amalgam-free dentistry: Survey of posterior restorations teaching in North America.

OBJECTIVES: The dental field is gradually reducing the use of amalgam and moving towards adhesive restoration. This change is in accordance with the advancement and improvement of composite resin materials and adhesion systems. Consequently, posterior cavity preparations teaching should be re-examined to determine whether dental schools are adapting their curriculum to fit the current trends in dentistry and what rationale supports their decisions. METHODS: An online questionnaire was constructed to assess the time dedicated to teaching composite materials and amalgam, in addition to the principles of posterior preparations, for composite restorations in North American dental schools. RESULTS: A total 33 schools responded to the questionnaire. A large variation was found in teaching methods and techniques of posterior restorations. The reasoning for teaching amalgam restorations was diverse as were the principles of composite resin preparation taught. CONCLUSION: No agreed principles of cavity preparation for resin composite restorations were found, as opposed to explicit agreement on amalgam cavity preparations. The results demonstrate a lack of clear guidelines for cavity preparation of resin composite restorations. Dental schools may benefit when a consensus on this topic is achieved.

Influence of jaw opening on occlusal vertical dimension between incisors and molars.

STATEMENT OF PROBLEM: Modification of the occlusal vertical dimension (OVD) is a significant procedure in prosthodontics. Improper estimation of the space available between opposing teeth may lead to an improper framework design. PURPOSE: The purpose of this clinical study was to evaluate the average opening ratio in the molar area in relation to the extent of opening in the incisor area. MATERIAL AND METHODS: A total 34 adults with a complete dentition and stable occlusion participated in the study. The change in vertical distance was evaluated in 3 areas: between the maxillary and mandibular central incisors, between the maxillary and mandibular canines, and between the maxillary and mandibular first molars. Digital photographs were made at the intercuspal position (ICP) and at a 2-mm and 8-mm OVD increase. The OVD opening was standardized with the aid of a Woelfel sliding guide device. The measurements were made by recording the distance between the maxillary and mandibular teeth at different openings. For calibration and quantitative evaluation of the photographs, image-processing analysis was used. RESULTS: The collected data showed that the average ratio of the opening between the first molars and the opening between the central incisors was 0.73. The average ratio of the opening between the canines and the opening between the central incisors was 0.95. The values were plotted, and a mathematical model was derived. CONCLUSIONS: A vertical dimension opening of 1 mm between the central incisors resulted in 0.73 mm of occlusal clearance in the first molar region and 0.95 mm in the canines.

Antibacterial Orthodontic Cements and Adhesives: A Possible Solution to Streptococcus mutans Outgrowth Adjacent to Orthodontic Appliances.

PURPOSE: To assess the antibacterial effect of orthodontic cements containing 1% insoluble antibacterial polycat-ionic nanoparticles against Streptococcus mutans. MATERIALS AND METHODS: Polycationic polyethyleneimine (PEI)-based nanoparticles were incorporated into GC Fuji Ortho LC (GC), CX-plus (Shofu) orthodontic cements and in Neobond Transbond plus (Denstply) and Transbond XT (3M) orthodontic adhesives. The samples were evaluated immediately after setting, as well as after two weeks and one month of aging. The antibacterial effect against S. mutans was evaluated with the direct contact test and the agar diffusion test. In addition, the antibacterial properties of the eluate from the examined materials was tested. Four-way ANOVA followed by Tukey's test was used to determine bacterial growth rates. RESULTS: S. mutans outgrowth was substantially reduced (p < 0.05) following direct contact with the surface of Neobond adhesives (95%, i.e. 5-6 log reduction) and GC Fuji Ortho LC cement samples (97% reduction) containing PEI nanoparticles. CX-plus cement, Transbond plus and Transbond XT adhesives with and without PEI showed no antibacterial effect, and S. mutans outgrowth was similar to that of the controls. CONCLUSIONS: Neobond adhesive and GC Fuji Ortho LC cement with 1% incorporated insoluble antibacterial polycat-ionic nanoparticles exhibited stable antibacterial properties, particularly after immediate contact between the cement and the adhesive, and thus may prevent S. mutans outgrowth adjacent to orthodontic appliances. Further studies are needed to evaluate the efficacy, physical properties and possible side effects of the PEI nanoparticles in vivo.

Antibacterial Effect of a Temporary Cement-Dissolving Liquid.

PURPOSE: Methods for removing temporary cement with an antibacterial effect might improve prosthetic treatment prognosis. MATERIALS AND METHODS: Three removal methods were assessed: (1) immersion of an acrylic provisional restoration in a temporary cement dissolver (Temp-off); (2) mechanical removal with a dental explorer; and (3) sandblasting. Two temporary cements, one with eugenol (Temp-Bond) and one without eugenol (Temp-Bond NE) and of two thicknesses (100 µm and 250 µm), were examined. RESULTS: Immersion in Temp-off produced the most effective bacterial count decrease compared to the other methods (P < .05). No significant difference was found between the two cement types, although the decrease in count was more evident in the thicker (250 µm) cement layer. CONCLUSION: Temp-off dissolving liquid used for removal of temporary cement exhibited an antibacterial effect and nonmechanical cleaning ability.

Defeating Antibiotic- and Phage-Resistant Enterococcus faecalis Using a Phage Cocktail in Vitro and in a Clot Model.

The deteriorating effectiveness of antibiotics is propelling researchers worldwide towards alternative techniques such as phage therapy: curing infectious diseases using viruses of bacteria called bacteriophages. In a previous paper, we isolated phage EFDG1, highly effective against both planktonic and biofilm cultures of one of the most challenging pathogenic species, the vancomycin-resistant Enterococcus (VRE). Thus, it is a promising phage to be used in phage therapy. Further experimentation revealed the emergence of a mutant resistant to EFDG1 phage: EFDG1r. This kind of spontaneous resistance to antibiotics would be disastrous occurrence, however for phage-therapy it is only a minor hindrance. We quickly and successfully isolated a new phage, EFLK1, which proved effective against both the resistant mutant EFDG1r and its parental VRE, Enterococcus faecalis V583. Furthermore, combining both phages in a cocktail produced an additive effect against E. faecalis V583 strains regardless of their antibiotic or phage-resistance profile. An analysis of the differences in genome sequence, genes, mutations, and tRNA content of both phages is presented. This work is a proof-of-concept of one of the most significant advantages of phage therapy, namely the ability to easily overcome emerging resistant bacteria.

Antibacterial Activity of Orthodontic Cement Containing Quaternary Ammonium Polyethylenimine Nanoparticles Adjacent to Orthodontic Brackets.

Enamel demineralization is a common problem found in patients using orthodontic devices, such as orthodontic braces. It was found that Streptoccocus mutans growth increases adjacent to orthodontic devices, which may result in caries development. Incorporated antibacterial quaternary ammonium polyethylenimine (QPEI) nanoparticles were previously shown to be highly efficacious against various bacteria. Combining antibacterial materials in orthodontic cement may be advantageous to prevent bacterial outgrowth adjacent to orthodontic brackets. The aim was to evaluate the efficiency of orthodontic cement containing QPEI nanoparticles in reducing S. mutans and Lactobacillus casei outgrowth adjacent to orthodontic brackets. Orthodontic brackets were bonded to the buccal surfaces of extracted lower incisors. The antibacterial effect on S. mutans and L. casei outgrowth of Neobond bracket adhesive orthodontic cement with and without QPEI nanoparticles was compared. The antibacterial effect was evaluated using crystal violet staining and bacterial count (CFU/mL). The teeth in the experimental group, with the QPEI nanoparticles cement, showed significantly lower optical density (OD) values and CFU counts of S. mutans and L. casei than the teeth in the control group (p < 0.05). Based on the results, it can be concluded that orthodontic cement containing QPEI nanoparticles significantly inhibits S. mutans and L. casei growth around orthodontic brackets.

Surface-modified nanoparticles as anti-biofilm filler for dental polymers.

The objective of the study was to synthesis silica nanoparticles modified with (i) a tertiary amine bearing two t-cinnamaldehyde substituents or (ii) dimethyl-octyl ammonium, alongside the well-studied quaternary ammonium polyethyleneimine nanoparticles. These were to be evaluated for their chemical and mechanical properties, as well for antibacterial and antibiofilm activity. Samples were incorporated in commercial dental resin material and the degree of monomer conversion, mechanical strength, and water contact angle were tested to characterize the effect of the nanoparticles on resin material. Antibacterial activity was evaluated with the direct contact test and the biofilm inhibition test against Streptococcus mutans. Addition of cinnamaldehyde-modified particles preserved the degree of conversion and compressive strength of the base material and increased surface hydrophobicity. Quaternary ammonium functional groups led to a decrease in the degree of conversion and to low compressive strength, without altering the hydrophilic nature of the base material. In the direct contact test and the anti-biofilm test, the polyethyleneimine particles exhibited the strongest antibacterial effect. The cinnamaldehyde-modified particles displayed antibiofilm activity, silica particles with quaternary ammonium were ineffective. Immobilization of t-cinnamaldehyde onto a solid surface via amine linkers provided a better alternative to the well-known quaternary ammonium bactericides.

Antibacterial Effect of Provisional Cements with Incorporated Polyethyleneimine Nanoparticles: An In Vivo Study.

PURPOSE: Provisional restorations exhibit various degrees of microleakage when cemented. Incorporation of quaternized polyethyleneimine nanoparticles (QPEI) into provisional cements may be effective against bacteria in vivo. MATERIALS AND METHODS: Nine polymethylmethacrylate provisional restorations in human volunteers were evaluated after cementation with and without QPEI nanoparticles. Bacterial load in the provisional cement was assessed after 1 week of cementation. RESULTS: The number of colony-forming units in the cement with QPEI was significantly lower (P < .05) than in the control cement. CONCLUSION: The results of this in vivo study clearly indicate that provisional cement incorporating QPEI nanoparticles significantly reduces viable bacterial counts in the provisional cement in all patients.

Antibacterial Orthodontic Adhesive Incorporating Polyethyleneimine Nanoparticles.

PURPOSE: To evaluate the antibacterial, mechanical and biocompatibility characteristics of an orthodontic adhesive that contains quaternary ammonium polyethyleneimine (QPEI) nanoparticles. MATERIALS AND METHODS: QPEI nanoparticles were added to an orthodontic adhesive at 0%, 1% and 1.5% wt/wt. Antibacterial activity was tested after aging for 14 days using the direct contact test (DCT). The degree of monomer conversion (DC) was measured using Fourier transform infrared (FTIR) spectroscopy. Shear bond atrength (SBS) was tested on the etched enamel of extracted human teeth. Biocompatibility was tested using keratinocyte and neutrophil cell lines in the XTT assay. RESULTS: The DCT results showed significant bacterial growth inhibition in the test group incorporating 1.5% wt/wt QPEI nanoparticles (p < 0.05). The DC of the 0%, 1%, and 1.5% wt/wt samples measured immediately and after 10 min was 62.2-71.0%, 59.1-68.7%, and 52.9-58.6%, respectively, and the average SBS were 9.25 MPa, 11.57 MPa, and 9.10 MPa, respectively. Keratinocyte and neutrophil viability did not change following the addition of QPEI to the orthodontic adhesives. CONCLUSIONS: The incorporation of QPEI nanoparticles into orthodontic cement provides long-lasting antibacterial activity against Streptococcus mutans without reducing the strength of adhesion to enamel, the degree of double bond conversion during the polymerisation, or the biocompatibility of the orthodontic cement.

Phage Therapy: A New Horizon in the Antibacterial Treatment of Oral Pathogens.

Dental diseases are perhaps the most prevalent infection-related diseases in humans. Biofilm is involved in almost every infectious disease compromising oral health, notably caries, periodontal disease, gingivitis, endodontic infections and peri-implantitis. Current therapies of biofilm-derived oral infections lack sensitivity; they are not species-specific and kill pathogenic species as well as commensal species, which are protective against the formation of pathogenic biofilms. Moreover, antibiotics have a limited effect on biofilm and are almost unused in oral diseases. A promising alternative approach is bacteriophage (phage) therapy. Phages play a key role in the natural balance in a predator-prey relationship with bacteria and thus have the potential to be efficient anti-bacterial agents. Phages are highly efficient against biofilm, strain specific and easy to isolate and manipulate. Thus, like in many other medicinal fields, phage therapy offers new horizons to dentistry, both therapeutics and research. The present review presents the etiology of common oral diseases, characterization of the infection and the treatment challenges of phage therapy in dentistry. Recent findings and development in the use of phages for prevention, control, and treatment of oral infections as well as possibilities of engineering the oral microbiome are discussed.

Sustained Release of Antibacterial Lipopeptides from Biodegradable Polymers against Oral Pathogens.

The development of antibacterial drugs to overcome various pathogenic species, which inhabit the oral cavity, faces several challenges, such as salivary flow and enzymatic activity that restrict dosage retention. Owing to their amphipathic nature, antimicrobial peptides (AMPs) serve as the first line of defense of the innate immune system. The ability to synthesize different types of AMPs enables exploitation of their advantages as alternatives to antibiotics. Sustained release of AMPs incorporated in biodegradable polymers can be advantageous in maintaining high levels of the peptides. In this study, four potent ultra-short lipopeptides, conjugated to an aliphatic acid chain (16C) were incorporated in two different biodegradable polymers: poly (lactic acid co castor oil) (PLACO) and ricinoleic acid-based poly (ester-anhydride) (P(SA-RA)) for sustained release. The lipopeptide and polymer formulations were tested for antibacterial activity during one week, by turbidometric measurements of bacterial outgrowth, anti-biofilm activity by live/dead staining, biocompatibility by hemolysis and XTT colorimetric assays, mode of action by fluorescence-activated cell sorting (FACS) and release profile by a fluorometric assay. The results show that an antibacterial and anti-biofilm effect, as well as membrane disruption, can be achieved by the use of a formulation of lipopeptide incorporated in biodegradable polymer.

Phage therapy against Enterococcus faecalis in dental root canals.

Antibiotic resistance is an ever-growing problem faced by all major sectors of health care, including dentistry. Recurrent infections related to multidrug-resistant bacteria such as methicillin-resistant Staphylococcus aureus, carbapenem-resistant Enterobacteriaceae, and vancomycin-resistant enterococci (VRE) in hospitals are untreatable and question the effectiveness of notable drugs. Two major reasons for these recurrent infections are acquired antibiotic resistance genes and biofilm formation. None of the traditionally known effective techniques have been able to efficiently resolve these issues. Hence, development of a highly effective antibacterial practice has become inevitable. One example of a hard-to-eradicate pathogen in dentistry is Enterococcus faecalis, which is one of the most common threats observed in recurrent root canal treatment failures, of which the most problematic to treat are its biofilm-forming VRE strains. An effective response against such infections could be the use of bacteriophages (phages). Phage therapy was found to be highly effective against biofilm and multidrug-resistant bacteria and has other advantages like ease of isolation and possibilities for genetic manipulations. The potential of phage therapy in dentistry, in particular against E. faecalis biofilms in root canals, is almost unexplored. Here we review the efforts to develop phage therapy against biofilms. We also focus on the phages isolated against E. faecalis and discuss the possibility of using phages against E. faecalis biofilm in root canals.