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.

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.

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.

Antibacterial effect of composite resin foundation material incorporating quaternary ammonium polyethyleneimine nanoparticles.

STATEMENT OF PROBLEM: As caries is the most frequent cause of the failure of composite resin-based restorations, composite resins with antibacterial properties are desirable. However, whether quaternary ammonium polyethyleneimine nanoparticles can be effectively incorporated is unknown. PURPOSE: The purpose of this in vitro study was to evaluate the antibacterial activity against Streptococcus mutans and Actinomyces viscosus of a foundation material incorporating quaternary ammonium polyethyleneimine (QPEI) nanoparticles. MATERIAL AND METHODS: QPEI antimicrobial nanoparticles were incorporated in a commercially available foundation material (Q Core; BJM Laboratories Ltd) at 1% wt/wt. Antibacterial efficacy against S mutans (106 colony-forming units [CFU]/mL) and A viscosus (106 CFU/mL) was examined by the direct contact test (DCT), and the agar diffusion test (ADT) with and without surface polishing. Bacterial outgrowth was recorded with a spectrophotometer. RESULTS: Growth of S mutans and A viscosus was inhibited, showing a decrease by 6 orders of magnitude in bacterial viability in specimens incorporating the nanoparticles, even after polishing the foundation material (P<.05). Growth inhibition was not observed in specimens without nanoparticles. CONCLUSIONS: Antibacterial properties can be achieved in a commercially available foundation material by incorporating polycationic antibacterial nanoparticles. This antibacterial effect did not diminish after surface polishing.

Targeting Enterococcus faecalis biofilms with phage therapy.

Phage therapy has been proven to be more effective, in some cases, than conventional antibiotics, especially regarding multidrug-resistant biofilm infections. The objective here was to isolate an anti-Enterococcus faecalis bacteriophage and to evaluate its efficacy against planktonic and biofilm cultures. E. faecalis is an important pathogen found in many infections, including endocarditis and persistent infections associated with root canal treatment failure. The difficulty in E. faecalis treatment has been attributed to the lack of anti-infective strategies to eradicate its biofilm and to the frequent emergence of multidrug-resistant strains. To this end, an anti-E. faecalis and E. faecium phage, termed EFDG1, was isolated from sewage effluents. The phage was visualized by electron microscopy. EFDG1 coding sequences and phylogeny were determined by whole genome sequencing (GenBank accession number KP339049), revealing it belongs to the Spounavirinae subfamily of the Myoviridae phages, which includes promising candidates for therapy against Gram-positive pathogens. This analysis also showed that the EFDG1 genome does not contain apparent harmful genes. EFDG1 antibacterial efficacy was evaluated in vitro against planktonic and biofilm cultures, showing effective lytic activity against various E. faecalis and E. faecium isolates, regardless of their antibiotic resistance profile. In addition, EFDG1 efficiently prevented ex vivo E. faecalis root canal infection. These findings suggest that phage therapy using EFDG1 might be efficacious to prevent E. faecalis infection after root canal treatment.

Are anti-inflammatory agents effective in treating gingivitis as solo or adjunct therapies? A systematic review.

OBJECTIVE: Systematically review the scientific evidence for efficiency of anti-inflammatory agents against gingivitis, either as solo treatments or adjunctive therapies. METHODS: A protocol was developed aimed to answer the following focused question: "Are anti-inflammatory agents effective in treating gingivitis as solo or adjunct therapies?" RCTs and cohort studies on anti-inflammatory agents against gingivitis studies were searched electronically. Screening, data extraction and quality assessment were conducted. The primary outcome measures were indices of gingival inflammation. A sub-analysis was performed dividing the active agents into anti-inflammatory and other drugs. RESULTS: The search identified 3188 studies, of which 14 RCTs met the inclusion criteria. The use of anti-inflammatory or other agents, in general showed a higher reduction in the test than in the control in terms of gingival indexes and bleeding scores. Only two RCTs on inflammatory drugs could be meta-analysed, showing a statistically significant reduction in the GI in the experimental group [WMD = -0.090; 95% CI (-0.105; -0.074); p = 0.000]. However, the contribution of both studies to the global result was unbalanced (% weight: 99.88 and 0.12 respectively). CONCLUSIONS: Most of the tested material showed beneficial effect as anti-inflammatory agents against gingivitis, either as a single treatment modality or as an adjunctive therapy.

Teaching New Materials and Techniques for Fixed Dental Prostheses in Dental Schools in the United States and Canada: A Survey.

PURPOSE: Tooth-supported fixed dental prostheses (FDPs) remain an extensive therapeutic option, with new materials and a digital fabrication process gradually replacing traditional methods. The variety of advances calls for dental schools to expand the teaching of this field. Our aim was to examine the nature and the amount of theoretical and practical training in clinical FDP courses, and the extent to which new methods and innovations in the field are being integrated. MATERIALS AND METHODS: Data were collected using an online questionnaire including theoretical and practical teaching regarding clinical courses, restorative materials, and new fabrication methods, which was sent to 58 dental schools in North America. RESULTS: A total of 36 schools responded to the survey for a response rate of 62.1%. All the schools teach theoretical and practical porcelain-fused-to-metal (PFM) restorations, and almost all the schools teach full-metal FDPs. In more than half (57.1%) of the schools, zirconia-based FDPs are placed by students. Students place partial veneer FDPs in less than one-fifth (17.9%) of the schools. The average number of restorations required for completion of the clinical course is 7.3 FDP units. The respondents assessed that of the total FDPs placed by students in the clinical course, tooth-color coping (zirconia/alumina/porcelain) FDPs constituted 16.2%. None of the schools produce computer-assisted design/computer-assisted manufacturing copings or crowns within the school. CONCLUSIONS: All North American dental schools include teaching and placement of PFM restorations in their curriculum, but only one-third teach ceramic-based crowns. The low average number of required crowns may lead to graduates not being exposed to and trained in up-to-date dental restorative materials and techniques.

In Vitro Effect of Streptococcus mutans Biofilm Produced in Sugar-Free Coca-Cola on Enamel.

OBJECTIVE: Sugary drinks such as Coca-Cola may expedite dental caries. For this reason, sugar-free drinks like Coca-Cola Zero Sugar (CZ) may be considered advantageous. This research aims to evaluate in vitro the CZ effect in the presence of Streptococcus mutans (S. mutans) biofilm on enamel demineralization. METHODS: Ninety-six human enamel slabs (4 × 4 mm) were used. S. mutans UA-159 72-hour biofilm was created over enamel surfaces. The specimens were soaked in CZ, HCl, or 10% sucrose in PBS solution, 3 times a day for 15 minutes over the course of 4 days. Viable counts (CFU/mL) and biofilm biomass (Crystal Violet staining) were evaluated. pH was measured after each exposure. After 4 days, Demineralization was evaluated clinically and by Vickers microhardness tests. Slabs were photographed using a stereomicroscope before and after exposure to caries-promoting conditions. RESULTS: Slabs that were soaked in CZ showed an increase in viable counts compared to control and almost similar counts with 10% sucrose in PBS solution exposures (1010and109CFUmL, respectivly). Biofilm biomass tests showed a 25% higher bacterial growth in the CZ group. CZ pH measures were the lowest and the only group to show a decrease in pH over time (pH ∼3). Enamel slabs that were evaluated clinically in the stereomicroscope postexposures had a chalky and matt appearance as opposed to their shiny appearance in the baseline evaluation. CONCLUSIONS: CZ creates a favourable environment for the growth of S. mutans. It may be suggested that even though CZ is sugar free it has a cariogenic effect on enamel. CLINICAL SIGNIFICANCE: Clinicians need to educate patients that sugar-free carbonated drinks may be just as harmful as regular carbonated drinks, and hence avoided. This research emphasizes the harmful effect sugar-free carbonated drinks on teeth and sheds new light on their cariogenic potential.

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.

Polyethyleneimine nanoparticles incorporated into resin composite cause cell death and trigger biofilm stress in vivo.

Incorporation of cross-linked quaternary ammonium polyethylenimine (QPEI) nanoparticles in dental resin composite has a long-lasting and wide antimicrobial effect with no measured impact on biocompatibility in vitro. We hypothesized that QPEI nanoparticles incorporated into a resin composite have a potent antibacterial effect in vivo and that this stress condition triggers a suicide module in the bacterial biofilm. Ten volunteers wore a removable acrylic appliance, in which two control resin composite specimens and two resin composite specimens incorporating 1% wt/wt QPEI nanoparticles were inserted to allow the buildup of intraoral biofilms. After 4 h, the specimens were removed and tested for bacterial vitality and biofilm thickness, using confocal laser scanning microscopy. The vitality rate in specimens incorporating QPEI was reduced by > 50% (p < 0.00001), whereas biofilm thickness was increased (p < 0.05). The ability of the biofilm supernatant to restore bacterial death was tested in vitro. The in vitro tests showed a 70% decrease in viable bacteria (p < 0.05). Biofilm morphological differences were also observed in the scanning electron microscope micrographs of the resin composite versus the resin composite incorporating QPEI. These results strongly suggest that QPEI nanoparticles incorporated at a low concentration in resin composite exert a significant in vivo antibiofilm activity and exhibit a potent broad spectrum antibacterial activity against salivary bacteria.

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.

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.

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.

Surface characterization and biocompatibility of restorative resin containing nanoparticles.

Composite resins that are used to restore hard tissues have several drawbacks including the accumulation of biofilm on teeth and restorations. Recently, quaternary ammonium poly(ethylene imine) (QA-PEI) nanoparticles were developed for additional antibacterial activity of restorative composite resins. QA-PEI nanoparticles were synthesized from cross-linked poly(ethylene imine) that was N-alkylated with octyl halide, followed by quaternary methylation with methyl iodide. QA-PEI particles that were embedded in restorative composite resin at 1% w/w resulted in the complete growth inhibition of Streptococcus mutans. Moreover, the antibacterial activity was retained for at least 3 months. The active substances on the surface of the restorative composite resin that were incorporated with QA-PEI particles were detected by X-ray photoelectron spectroscopy (XPS) and confocal microscopy measurements. The in vitro cytotoxicity tests showed a similar effect on the viability of the cell line that was tested with composites including modified and unmodified dental composite resins. In vivo toxicity studies, which were assessed on Wistar rats by the implantation of modified composite specimens, revealed no inflammation response 1 week after the implantation of restorative composite resin that was embedded with up to 2% w/w QA-PEI.