Antimicrobial action, cytotoxicity and erosive potential of hypochlorous acid obtained from an electrolytic device compared with sodium hypochlorite.

OBJECTIVES: This study aimed to compare the antimicrobial action, cytotoxicity, cleaning ability, and erosion of dentine of hypochlorous acid (HClO) obtained from an electrolytic device at two different concentrations (Dentaqua) and three concentrations of sodium hypochlorite (NaOCl). METHODS: Microbiological test-The root canals of sixty single-rooted extracted human teeth were inoculated with Enterococcus faecalis and divided into 6 groups (n = 10), according to decontamination protocol: DW (control); 1% NaOCl; 2.5% NaOCl; 5.25% NaOCl; 250 ppm HClO and 500 ppm HClO. The colony-forming units were counted to evaluate the decontamination potential of each group, calculating the reduction in bacterial percentage. Cytotoxicity test-Cytotoxicity was evaluated after inoculation of the same tested protocols in fibroblastic cells for 3 min, calculating the cell viability percentages. Specifical statistical analysis was performed (α = 5%). Cleaning ability and erosion-Fifty-six single-rooted bovine lower incisors were divided into seven groups of 8 roots each, being the test groups 1% NaOCl; 2.5% NaOCl; 5,25% NaOCl; 250 ppm HClO and 500 ppm HClO, and a negative and positive control. Negative control was not contaminated, and the other groups were inoculated with Enterococcus faecalis. SEM images were ranked as from the cleanest to the least clean. Erosion was also assessed, being ranked from the least to the most eroded dentine. RESULTS: The highest bacterial reduction was observed in experimental groups, with no statistical differences between them (p > 0.05). The highest number of viable cells was observed in control group, followed by 250 ppm HClO and 500 ppm HClO groups, with statistical differences between them (p < 0.05). 1% NaOCl; 2.5% NaOCl; 5.25% NaOCl and 500 ppm HClO displayed the cleanest areas. All sodium hypochlorite groups displayed erosion with higher ranks with greater concentration, while hypochlorous acid did not display any erosion regardless the concentration. CONCLUSIONS: It is possible to conclude that HClO obtained from an electrolytic device presented high antimicrobial activity and low cytotoxicity in both tested concentrations. 500 ppm HClO did not display erosion and showed great cleaning ability. CLINICAL RELEVANCE: The use of 500 ppm hypochlorous acid may reduce unfavorable behavior of sodium hypochlorite whilst maintaining its antimicrobial action.

How Does Ethylenediaminetetraacetic Acid Irrigation Affect Biodentine? A Multimethod Ex Vivo Study.

The activity of biomaterials used during endodontic treatment can be affected by various factors. One of them is the chemical action of the irrigant that they are exposed to. The aim of this multimethod ex vivo study was to evaluate the influence of ethylenediaminetetraacetic acid (EDTA) on the surface appearance and chemical composition of Biodentine used in perforation repair. Twenty material specimens were prepared according to manufacturers' recommendations and divided into two setting-time-based groups, tested after 45 min (group A) and 24 h (group B) of setting. Material was irrigated with 17% EDTA solution with or without simultaneous ultrasonic activation. The surface characteristics and the chemical composition analysis of the Biodentine specimens were performed with the aid of a scanning electron microscope (SEM) and an energy dispersive spectroscopy (EDS) method, respectively. The volumetric loss of material was measured by dedicated digital software in an optical microscope. Statistical analysis was performed. The EDS study confirmed that after the rinsing protocol, the percentage content of elements differed between the groups. The EDTA rinse, whether ultrasonically activated or not, visibly affected the surface appearance and chemical composition of Biodentine. The specimens' surface subjected to irrigation was more irregular under SEM than in a control group. The US activation of the liquid amplified its impact on the tested material. The average volume loss in group A after 5 min irrigation was 3.98 µm3 for each µm2 of the chosen area and it increased up to 7.74 µm3/µm2 after the ultrasonic activation. In group B, indicated volume loss values were 6.30 and 11.70 µm3/µm2 for 5 min irrigation without and with US activation, respectively. Using a 20 min irrigation time and ultrasonic activation increased it up to 32.71 µm3/µm2. Each rinsing protocol involving irrigation with ethylenediaminetetraacetic acid modified the surface features and the chemical composition of the evaluated hydraulic tricalcium silicate cement. Further research is needed to indicate the possible impact of the observed changes on its long-term clinical performance.

How Do Phages Disrupt the Structure of Enterococcus faecalis Biofilm?

Biofilms are composed of multicellular communities of microbial cells and their self-secreted extracellular polymeric substances (EPS). The viruses named bacteriophages can infect and lyze bacterial cells, leading to efficient biofilm eradication. The aim of this study was to analyze how bacteriophages disrupt the biofilm structure by killing bacterial cells and/or by damaging extracellular polysaccharides, proteins, and DNA. The use of colorimetric and spectrofluorimetric methods and confocal laser scanning microscopy (CLSM) enabled a comprehensive assessment of phage activity against E. faecalis biofilms. The impact of the phages vB_Efa29212_2e and vB_Efa29212_3e was investigated. They were applied separately or in combination on 1-day and 7-day-old biofilms. Phages 2e effectively inhibited the growth of planktonic cells with a limited effect on the biofilm. They did not notably affect extracellular polysaccharides and proteins; however, they increased DNA levels. Phages 3e demonstrated a potent and dispersing impact on E. faecalis biofilms, despite being slightly less effective than bacteriophages 2e against planktonic cells. Phages 3e reduced the amount of extracellular polysaccharides and increased eDNA levels in both 1-day-old and 7-day-old biofilm cultures. Phage cocktails had a strong antimicrobial effect on both planktonic and biofilm-associated bacteria. A significant reduction in the levels of polysaccharides, proteins, and eDNA in 1-day-old biofilm samples was noted, which confirms that phages interfere with the structure of E. faecalis biofilm by killing bacterial cells and affecting extracellular polymer levels.

Benefits and Challenges of the Use of Two Novel vB_Efa29212_2e and vB_Efa29212_3e Bacteriophages in Biocontrol of the Root Canal Enterococcus faecalis Infections.

Bacteriophage therapy has emerged as a strategy supplementing traditional disinfection protocols to fight biofilms. The aim of the study was to isolate the phages against E. faecalis and to characterize its biological features, morphology, and lytic activity in a formed biofilm model. METHODS: E. faecalis ATCC 29212 strain was used for the trial. Two novel vB_Efa29212_2e and vB_Efa29212_3e virulent phages were isolated from urban wastewater and characterized. The E. faecalis biofilm was established in 15 bovine teeth for 21 days. Transmission (TEM) and scanning electron (SEM) microscopes with the colony-forming unit (CFU) counting were used for assessment. RESULTS: Isolated phages differed in morphology. Taxonomy for vB_Efa29212_2e (Siphoviridae, Efquatovirus) and for vB_Efa29212_3e (Herelleviridae, Kochikohdavirus) was confirmed. Both phages were stable at a temperature range of 4-50 °C and showed a different tolerance to chemicals: 15% EDTA, 1-3% sodium hypochlorite, and chlorhexidine. SEM analysis showed distortion of bacteria cells after phage inoculation, which proved the lytic activity against E. faecalis. A 54.6% reduction in the E. faecalis biofilm confirmed bacteriophage efficacy against isolates in the ex vivo model. CONCLUSIONS: Results strongly support the concept that phage therapy has a real therapeutic potential for the prevention and treatment of E. faecalis-associated infections.

The Effect of Irrigation with Citric Acid on Biodentine Tricalcium Silicate-Based Cement: SEM-EDS In Vitro Study.

There are various factors that may interfere with the activity of biomaterials during endodontic therapy. One of them is the canal system irrigation procedure with different rinsing solutions performed after the placement of bioactive cements. The authors investigate the influence of citric acid, a chelating agent, on the surface and the chemical composition of Biodentine tricalcium silicate-based cement using a multimethod approach. Twenty samples were divided into two groups based on the material setting time. They were subjected to citric acid irrigation with or without ultrasonic activation for 5 and 20 min. The chemical analysis was made with energy dispersive spectroscopy (EDS). The visual assessment of Biodentine surface was carried out in scanning electron microscope (SEM). The volume of material loss during the procedure was measured with Keyence optic microscope and dedicated digital software. Statistical analysis was performed. The results of the study show that the irrigation with citric acid influenced the surface appearance of the material and changed its chemical composition in both investigated groups. The ultrasonic activation (US) of the liquid has also aggravated its impact. Further research is needed to assess if that fact may change the sealing properties of the material influencing the long-term clinical outcome.

Analysis of the Surface Condition and Changes in Crystallographic Structure of Zirconium Oxide Affected by Mechanical Processing.

Zirconium oxide is a material commonly used in dental prosthetics for making cups of permanent prosthetic restorations. In order to properly prepare the surface of zirconium oxide for prosthetic treatment, it must be veneered with ceramics. The quality of cup-veneered ceramics is dependent on many factors, including the surface free energy (SFE) and transformation of zirconium oxide. The aim of the study was to investigate the type of phase transition and the value of free energy of the surface subjected to machining (wet and dry grinding, polishing). Quantitative and qualitative phase identification measurements showed that mechanical treatment causes transformation of the tetragonal phase into a monoclinic phase in the zirconium oxide surface. Prepared samples were analyzed by means of X-ray diffraction (XRD), which confirmed the phenomenon of transition. Measurements of the wetting angle and the calculated values of the surface free energy (SFE) showed no significant differences between the samples subjected to each treatment.

The Pulp Stones: Morphological Analysis in Scanning Electron Microscopy and Spectroscopic Chemical Quantification.

Background and objectives: Pulp stones are hard tissue structures formed in the pulp of permanent and deciduous teeth. Few studies have evaluated their morphology and chemical composition. However, their formation, composition, configuration and role played in overall health status are still unclear. Clinically, they may be symptomatic; technically, they impede access during endodontic therapy, increasing the risk of treatment errors. Thus, this study aimed to morphologically analyze pulp stones and present their chemical quantification, identifying their main chemical elements. It also correlates the results with their possible induction mechanisms. Materials and Methods: Seven pulp nodules were collected from molar teeth needing endodontic treatment. The morphology of the stones was analyzed by scanning electron microscopy (SEM), and their chemical composition was determined by X-ray dispersive energy spectroscopy (EDX). Results: These structures varied considerably in shape, size and topography. The site of the stones in the pulp cavity was the factor that most affected the morphology. The majority of the stones found in the pulp chambers presented nodular morphology, while those in the root canals presented a diffuse shape, resembling root canal anatomy. The topography of the nodules showed heterogeneous relief, revealing smooth and compact areas contrasting with the rugged and porous ones. The chemical composition varied depending on the location of the nodule in the pulp cavity and the relief of the analyzed area. Radicular stones presented considerably lower calcium and phosphorus content than coronary nodules. Conclusions: The high cellularity rate of the coronal pulp predisposes this region to nodular mineralizations around injured cells. The presence of larger caliber vascular bundles and higher collagen fiber content in radicular pulp determines a diffuse morphological pattern in this region. Understanding the morphology and chemical composition of the pulp stones allows future translational pathways towards the prevention or treatment of such conditions.

Historical Perspectives on Mechanical Teeth Separators - Evolution and Function.

Ingenious dental professionals created teeth separators over 130 years ago that enabled the effective access to and restoration of interproximal tooth decay. Many companies claimed superiority in their products and key individuals expounded on their use. Because separators were often intertwined with matrix bands, confusion was present as both the separators and matrix bands were often referred jointly as matrices in textbooks, journal publications and dental catalogues. However, these authors who focused exclusively on teeth separation for restorative purposes, detailed the concepts of separation quite clearly. In time the use of these entities was replaced by other methods to manage these secluded tooth surfaces. However, orthodontic tooth movement picked up on the use of different types of non-mechanical separators in the early 1900s in their simplicity to create space to facilitate band placement. Further evolution coincided with material development that enabled ease of placement for both the dentist and the patient.

Influence of sodium hypochlorite and ultrasounds on surface features and chemical composition of Biodentine tricalcium silicate-based material.

Biomaterials are subjected to various factors during endodontic workflow. The aim was to evaluate the influence of different concentrations of sodium hypochlorite and ultrasound activation on the features and chemical composition of Biodentine. Fifty-four Biodentine samples were divided into 3 groups based on the material setting time. They were subjected to different modes and times of 2% and 5.25% NaOCl irrigation with or without ultrasounds, 12 min (group I), 45 min (group II) and 24 h (group III) after the material mixing. Visual assessment of the sample's surface was performed using the scanning electron microscope and chemical analysis was made with energy dispersive spectroscopy. Both NaOCl irrigation and ultrasounds affected the surface of the material; however, they did not change its chemical composition. The irrigation enhanced by ultrasounds following the placement of Biodentine should be performed after a longer material setting time. The immediate use of ultrasounds is not recommended.

Targeted Endodontic Microsurgery: Computed Tomography-based Guided Stent Approach with Platelet-rich Fibrin Graft: A Report of 2 Cases.

Endodontic microsurgery is a predictable alternative to nonsurgical treatment of persistent and recurrent apical periodontitis. The modern endodontic microsurgical procedure has been evolving in pace with technological advances. The introduction of modern innovations such as cone-beam computed tomographic (CBCT) imaging, 3-dimensional (3D) printing technology, and a 3D surgical guide designed with computer-aided software has allowed for a novel approach to the surgical site. The aim of these case reports was to describe root-end surgery with the use of the implant DDS-Pro planning software (Natrodent Polska, Poland), a 3D-printed surgical guide precisely positioned according to the preoperative CBCT scan measurements (CS 8100; Carestream Dental, Atlanta, GA), and a modified soft tissue access. A hollow trephine bur was used to perform the osteotomy, resection of the root, and enucleation of the lesion. The intact cortical plate was salvaged and used as a graft along with plasma-rich fibrin acquired preoperatively from the patient's blood. The positioning guide allowed the clinicians to precisely achieve targeted tissues and shorten the procedure time. Modified soft tissue management helped achieve a small surgical wound for uneventful healing. A less than 12-month CBCT follow-up of both cases showed complete 3D healing of the surgical site.

Fibrinogen, bFGF and VEGF levels during antibiotic therapy in gynecologic cancer: a preliminary report.

The role of angiogenesis in the development of neoplasia has been identified and characterized. However, antiangiogenic therapeutic intervention still requires more evidence to become recognized and successful. The aim of this study was to evaluate levels of selected proangiogenic factors, such as fibrinogen, vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in serum of patients with the gynecologic cancer on the first, third and sixth day of antibiotic therapy, routinely administered as a perioperative treatment. In addition, serum concentrations of gamma-gamma dimers and alpha-polymers of cross-linked fibrin structure and the degree of bFGF binding with the fibrin network were investigated. Immunohistochemistry staining of the excised tumor tissue was also performed. We observed higher levels of bFGF, VEGF, as well as fibrinogen in patients with gynecologic malignancy, as compared to healthy women. In cancer patients, the concentration of alpha-polymers and gamma-gamma dimers of fibrin network increased. Further only gamma-gamma dimers fraction of fibrin was found to bind to bFGF. Immunohistochemical analysis indicated the presence of bFGF in an excised tumor tissue. In conclusion, the decrease of proangiogenic bFGF and fibrinogen levels in a clinical trial of gynecologic patients may confirm anti-angiogenic properties of selected antibiotic therapy.

Scanning electron microscope appearances of fretting in the fixed orthodontic appliances.

Fretting is one of the types of a tribologic wear. It is a process that occurs at a nominally immovable junction of elements. In dentistry, such elements can be brackets and archwires of fixed orthodontic appliances. They meet all the criteria for fretting to occur, i.e., they are nominally immovable, are subjected to initial loadings and they work in aggressive environment. Chrome-nickel stainless steel Elite Opti-Mim brackets (Trachem) working in vivo in oral cavity environment in combination with NiTi and stainless steel archwires were investigated. Scanning electron micrographs of bracket's working surfaces showed the presence of fretting damaged areas. This research also confirmed that there were almost all the types of fretting wear on the elements of the orthodontic appliances under examination.