Evaluating Antimicrobial Effectiveness of Gold Nanoparticles against Streptococcus oralis

Biofilm includes many microorganisms that causes the periodontal diseases. The increased drugs resistance against the infectious diseases is a major issue owing to excessive using of a broad spectrum of antibiotics. Recently, metallic nanoparticles (NPs) are being administered to control the growth of different types of microorganisms. For instance, gold nanoparticles (Au NPs) are found to be successful to control and limit the bacterial pathogenicity in the oral cavity without any cytotoxic effects on the human body. Aim. In this paper, it was aimed to detect the antibacterial effect of Au NPs and compare with chlorhexidine (CHX) against Streptococcus oralis (S. oralis) in dental plaque of patients with chronic periodontitis. Materials and Methods. First, supragingival and subgingival plaque samples were collected from the patients suffering from periodontal disease and incubated under aerobic or/and anaerobic conditions. Second, the morphological examination, and biochemical test by Vitec 2 machine are used to confirm the S. oralis species. Third, the synthesis of Au NPs was carried out by seed growth method and their properties were characterized. Finally, the antimicrobial effect of the Au NPs against S. oralis was evaluated by Agar well diffusion method for different Au NPs concentrations (100, 50, 25, 12.5, 6.25, 3.125, 1.562, 0.781, 0.391, 0.195, and 0.097 ppm). CHX was used as the positive control and distilled water as the negative control. The antibacterial activity data were statistically analyzed by least significant difference (LSD) using the Statistical Program for Social Science (SPSS) version 22. Results. The Au NPs with an average particles size of 43 nm, polycrystalline face-centered cubic structure were characterized. The Au NPs at 100 ppm concentration had similar antibacterial effect of CHX for inhibiting the growth of S. oralis, with no significant difference. Conclusions. The Au NPs as an antibacterial agent could be equally effective against S. oralis similar to the CHX when used at higher concentration.

Effect of Endodontic Irrigating Solutions on Radicular Dentine Structure and Matrix Metalloproteinases-A Comprehensive Review

Irrigating solutions play an important role in the eradication of intracanal microbes and debris dissolution during endodontic treatment. Different combinations of solutions and protocols have been advocated, with sodium hypochlorite (NaOCl), ethylenediamine tetra acetic acid (EDTA), and chlorhexidine (CHX) remaining the most widely used ones by many clinicians. Although these solutions provide efficient inorganic dissolution and antimicrobial capacity, their use has also been reported to cause undesired effects on root dentin composition and mechanical and biomechanical properties, such as microhardness, surface roughness, bond strength, and matrix metalloproteinase (MMP) activity. Several corroborating studies attribute these changes in mechanical properties of dentine to the use of irrigating solutions, and there are limited reports on how the solutions affect the expression of MMPs, which may be a correlating link to understanding the role of these enzymes in dentin collagen and changes in the mechanical properties of dentin. Hence, using the basis of several studies from the literature, the objective is to comprehensively review the influence of individual and combined irrigating solutions on root dentine structure and the activity of the MMPs.

Bactericidal Effect of Er:YAG Laser-Activated Sodium Hypochlorite Irrigation Against Biofilms of Enterococcus faecalis Isolate from Canal of Root-Filled Teeth with Periapical Lesions

OBJECTIVE

This study was to evaluate the bactericidal effect of Er:YAG laser-activated sodium hypochlorite irrigation (Er:YAG + NaOCl) on biofilms of Enterococcus faecalis clinical isolate.

BACKGROUND DATA

It was reported that Er:YAG + NaOCl had effective bactericidal effect on laboratory-adapted E. faecalis strain, while no study has reported its effect on the clinical isolate.

METHODS

Eighteen E. faecalis strains were isolated from 39 root-filled teeth with periapical lesions, and their biofilm formation abilities were evaluated using the crystal violet staining method. Extracted human root canals were prepared to a 40#/.04 K3 instrument and contaminated with the E. faecalis isolate that presented the strongest biofilm formation ability for 4 weeks. The infected canals then received treatments of syringe irrigation with normal saline (NS) or NaOCl, ultrasonic activated irrigations US + NS and US + NaOCl, and Er:YAG laser-activated irrigations Er:YAG + NS and Er:YAG + NaOCl. The root canals were examined using scanning electron microscopy (SEM). The bacterial reductions were evaluated using the cell count method.

RESULTS

SEM results showed that biofilm-like structures formed on the root canal walls after 4-week bacterial incubation. Er:YAG + NaOCl completely removed the E. faecalis biofilm from the root canal wall and made it the cleanest and most smooth surface among the treatment groups. Bacterial reductions in the treatment groups were presented in a descending order of Er:YAG + NaOCl (98.8%), US + NaOCl (98.6%) > NaOCl (94.0%) > Er:YAG + NS (91.9%) > US + NS (78.1%) > NS (51.1%) (p < 0.05).

CONCLUSIONS

The Er:YAG + NaOCl showed an effective bactericidal effect on biofilms of E. faecalis isolate, which may be considered an effective protocol for root canal treatment.

Detection of HCV Persistent Infections in the Dental Pulp: A Novel Approach for the Detection of Past and Ancient Infections

The dental pulp is a sterile highly vascularized tissue and has been commonly used as a biological material to detect the genome of infectious agents that reach the dental tissue. Indeed, the pulp is also used to reveal past and ancient infections in the field of paleomicrobiology. The present study aimed to detect the presence of Hepatitis C virus (HCV) in a small community (approximately 400 inhabitants) in the Amazon region of Brazil (Nossa Senhora do Perpetuo Socorro, Vizeu, Para, Brazil) and standardize a technique for the detection of the virus in the dental pulp. Serum samples were collected from 48 patients whose teeth were clinically recommended for surgical extraction. The group comprised an equal number of males and females, mostly agriculture workers and housewives, respectively. The majority (64.6%) received less than one minimum wage and were ill educated (less than four years of school years). An enzyme immune assay was used to detect antibodies to HCV and the 9 (18.8%) positive samples were submitted to nucleic acid extraction in the blood (using the EXTRAzol) and the pulp (QIAamp DNA Micro Kit e kit RNeasy Plus Micro). The pulp was removed using a modified protocol without the use of liquid nitrogen. Nucleic acid was found in 8 of the dental pulp, but in 7 of the blood samples. Sequencing of one of the samples showed the presence of genotype 1.

CONCLUSIONS

A novel simplified methodology for the extraction and amplification of HCV nucleic acid was successful to detect the presence of persistent infections of the virus within the dental pulp tissue. The protocol may be helpful to detect past and ancient infections and to better understand the natural history of HCV.

Antimicrobial efficacy of a high-power diode laser, photo-activated disinfection, conventional and sonic activated irrigation during root canal treatment

AIM

To evaluate the antimicrobial effect of a diode laser irradiation, photo-activated disinfection (PAD), conventional and sonic activated irrigation with 2.5% sodium hypochlorite (NaOCl) on Enterococcus faecalis.

METHODOLOGY

Root canals of 120 human extracted teeth with single straight canals were prepared with ProTaper files, sterilized, contaminated with an E. faecalis suspension and incubated for 7 days. They were then randomly distributed into six groups: G1, diode laser irradiation (2 W, 3 × 20 s); G2, PAD (100 mW, 60 s); G3, PAD with 3D Endoprobe (100 mW, 60 s); G4, 30-gauge syringe irrigation with NaOCl (60 s); G5, sonic agitation of NaOCl with the EndoActivator system (60 s); G6, 30-gauge syringe irrigation with NaCl (60 s). The pattern of colonization was visualized by scanning electron microscopy. The root canals were sampled by flushing with saline solution at baseline and after the treatments. The number of bacteria in each canal was determined by plate count. The presence and the absence of E. faecalis in root canals were also demonstrated by polymerase chain reaction (PCR).

RESULTS

There was a significant reduction in the bacterial population after all treatments (P < 0.001). The PAD, using both laser systems, and the sonic activated NaOCl irrigation were significantly more effective than diode irradiation and single NaOCl irrigation in reducing CFUs (P < 0.05). High-power diode laser and single NaOCl irrigation had an equal antibacterial effect (P > 0.05).

CONCLUSIONS

The PAD and EndoActivator system were more successful in reducing the root canal infection than the diode laser and NaOCl syringe irrigation alone.

Cell lysis and DNA extraction of gram-positive and gram-negative bacteria from whole blood in a disposable microfluidic chip

Sepsis caused by gram positive and gram negative bacteria is the leading cause of death in noncoronary ICUs and the tenth leading cause of death in the United States. We have developed a microfluidic sample preparation platform for rapid on-chip detection of infectious organisms for point-of-care diagnostics. The microfluidic chips are made of a robust thermoplastic and can be easily multiplexed for high throughput applications. Bacteria are lysed on-chip via hybrid chemical/mechanical method. Once lysed, the bacterial DNA is isolated using a microscale silica bead/polymer composite solid-phase-extraction (SPE) column. Lysis was confirmed using off-chip real time PCR. We isolated and detected both gram-negative (Escherichia coli) and gram-positive (Bacillussubtilis and Enterococcus faecalis) bacterial genomic DNA from microliter scale spiked whole human blood samples. The system performs better for gram-negative bacteria than it does for gram-positive bacteria, with limits of detection at 10(2) CFU/ml and 10(3)-10(4) CFU/ml, respectively. Total extraction times are less than one hour and can be further decreased by altering the channel geometry and pumping configuration.