Search Results (25)

Growing demand for greener and more sustainable materials in cultural heritage conservation has prompted the investigation of bio-based alternatives for cleaning applications. This study presents a preliminary evaluation of bacterial nanocellulose (BNC) membranes for the removal of acrylic resins from mural paintings, comparing commercial medical-grade and laboratory-produced BNC with conventional gel systems under simulated application conditions. Both BNC types were characterized in terms of composition, pH, electrical conductivity, Water Holding Capacity and Water Retention Rate. Acetone loading via solvent exchange was assessed by thermogravimetric analysis (TGA), while mechanical behavior before and after solvent loading was evaluated through tensile testing and optical density measurements of the immersion media. The performance of BNCs and reference delivery systems was comparatively assessed in terms of solvent retention, solvent penetration depth into the substrate and residue release. Cleaning performance was investigated through FTIR spectroscopy and semi-quantitative image analysis as indirect indicators of residual resin content, on both mock-up samples and in situ applications. Under the tested conditions, both BNC membranes were compatible with acetone loading and maintained mechanical integrity after solvent exposure. FTIR analysis showed a reduction in the acrylic carbonyl band after treatment with acetone-loaded BNC, which exhibited greater solvent diffusion depth; the underlying removal mechanism, including the possible contribution of solvent-driven redistribution phenomena, remains to be clarified. Differences in reproducibility were observed between medical-grade and laboratory-produced BNC. Overall, the study provides experimental data contributing to the assessment of BNC membranes as bio-based solvent delivery systems for conservation practice. Full article

Purpose: Preclinical studies report low-intensity ultraviolet C (UVC) light to be safe and effective in treating murine bacterial keratitis, however, limbal impacts of UVC have yet to be investigated directly. This study evaluated the depth and density of UVC-induced DNA damage in the porcine and human limbus following UVC exposures of varying supratherapeutic dose. Methods: The corneoscleral junction (limbus) of full-thickness porcine corneas was exposed to supratherapeutic doses of UVC light (265 nm, 1.93 mW/cm²) for 5, 10, 15, 30, or 60 min (exposure groups) or remained unexposed for the same durations (control groups), with a sample size of 6 per group. In parallel, human corneal tissue was exposed to UVC for 1 or 5 min and processed identically. Following exposure, all tissues were frozen, dissected, and analysed using immunohistochemistry to detect cyclobutane pyrimidine dimers (CPDs) as markers of DNA damage. CPD distribution, depth, and density were subsequently evaluated. Results: CPDs were localised predominantly in the superficial corneal epithelial layers, irrespective of the UVC dose. The mean ± SD thickness of the corneal epithelium in the UVC-exposed groups was 38.9 ± 18.9 µm, and the average depth of CPD formation was 13.3 ± 8.43 µm. The proportions of cells affected by CPDs within the corneal epithelium (mean ± SD) were 47.8 ± 25.6%, 58.5 ± 16.2%, 39.9 ± 26.4%, 41.3 ± 27.3%, and 38.9 ± 28.3% for exposure durations of 5, 10, 15, 30, and 60 min, respectively (p > 0.05). Human cornea showed similarly limited penetration, with no difference in CPD proportions between the 1 and 5 min UVC exposures (p = 0.70). Conclusions: UVC-induced DNA damage in both species was confined to the superficial cellular layers of the cornea, with no detectable damage observed in deeper tissues, including those where limbal stem cells reside, even after supratherapeutic doses of up to one hour of exposure. Full article

This study investigates the bactericidal efficacy and penetration ability inside dentinal tubules of calcium hydroxide (CH) and a modified tri-antibiotic paste (ciprofloxacin, metronidazole, clarithromycin) (TAP) during regenerative endodontic procedures (REPs). The blood clot serving as a biological scaffold was introduced into the root canal to assess its influence on bacterial regrowth. Forty-four human extracted teeth were infected with E. faecalis and divided in four experimental groups (N = 10) with positive and negative controls (N = 4). Samples were treated with either CH or TAP as intracanal dressing. Bacterial viability and depth of penetration were evaluated using confocal laser scanning microscopy (CLSM) after fluorescent vital staining. The same analysis was performed with or without blood clot exposure and the data were analyzed by one-way ANOVA and a post hoc Bonferroni test (p < 0.05). TAP demonstrated significantly stronger bactericidal activity than CH (p = 0.008). However, its efficacy significantly decreased in the presence of blood clot (p = 0.032). CH showed a moderate antibacterial effect, with its efficacy reduced in the presence of blood. Blood clot exposure consistently reduced the bactericidal efficacy in both groups (p = 0.01) and the dye penetration in CH group (p = 0.041). In conclusion, TAP demonstrated superior antibacterial performance compared to CH and blood clot exposure seemed to decrease antimicrobial efficacy and depth of disinfection during REPs. Full article

Gel-based delivery systems have emerged as versatile platforms in dentistry due to their biocompatibility, injectability, tunable rheology, and ability to localize therapeutic agents at the site of application. This review synthesizes current evidence on hydrogels, thermosensitive gels, mucoadhesive gels, nanoparticle-loaded gels, and stimuli-responsive systems, highlighting their structural characteristics, mechanisms of drug release, and clinical relevance. Mucoadhesive formulations demonstrate prolonged retention in periodontal pockets and oral mucosa, improving the efficacy of antimicrobials and anti-inflammatory agents. Thermosensitive gels enable minimally invasive administration and in situ gelation, supporting controlled release at body temperature. Nanoparticle-loaded gels exhibit enhanced drug stability and deeper tissue penetration, while “smart” gels respond to environmental stimuli such as pH or temperature to modulate release profiles. Clinical findings indicate reductions in probing depth, improved wound healing, decreased bacterial load, and better patient comfort when gel systems are used as adjuncts to mechanical therapy or regenerative procedures. However, despite these advances, challenges such as variability in gel stability, manufacturing reproducibility, regulatory approval pathways, and limited long-term clinical evidence still constrain widespread adoption of these systems in routine practice. Full article

The increasing incidence of hospital-acquired infections and antimicrobial-resistant pathogens poses a major clinical challenge. Nearly all medical devices are vulnerable to bacterial biofilm formation, which acts as a protective coating against the host defense systems and antibiotics. The persistence of biofilm infections, accounting for around 65% of all microbial infections, and poor conventional treatment outcomes has driven interest in alternative approaches like bacteriophage therapy. This review encompasses key aspects of biofilm biology, taking into account the clinically significant ESKAPE pathogens, and provides an in-depth analysis of the role of phage agents in biofilm control as a new biofilm control strategy. Diving deeper into the mechanisms of phage-mediated processes, the review examines how bacteriophages penetrate and disrupt biofilm architecture and evaluates current therapeutic strategies that exploit these actions, acknowledging their limitations and considering possible future directions. Full article

Biofilm-associated infections caused by Gram-negative bacteria, especially multidrug-resistant strains, frequently occur in intensive care units and represent a major therapeutic challenge. The economic burden of biofilm-associated infections is considerable, making the search for new treatment approaches a focal point for policymakers and scientific funding bodies. Biofilm formation is regulated by quorum sensing (QS), a population density-dependent communication mechanism between cells mediated by small diffusible signaling molecules. QS modulates various intracellular processes, and some features of QS are common to all Gram-negative bacteria. While there are differences in the QS regulatory networks of different Gram-negative bacterial species, a common feature of most Gram-negative bacteria is the ability of N-acylhomoserine lactones (AHL) as inducers to diffuse across the bacterial membrane and interact with receptors located either in the cytoplasm or on the inner membrane. Targeting QS by inhibiting the synthesis, transport, or perception of signaling molecules using small molecules, quorum quenching enzymes, antibodies, combinatorial therapies, or nanoparticles is a promising strategy to combat virulence. In-depth knowledge of biofilm biology, antibiotic susceptibility, and penetration mechanisms, as well as a deep understanding of anti-QS agents, will contribute to the development of antimicrobial therapies to combat biofilm infections. Advancing antimicrobial therapies against biofilm infections requires a deep understanding of biofilm biology, antibiotic susceptibility, penetration mechanisms, and anti-QS strategies. This can be achieved through in vivo and clinical studies, supported by state-of-the-art tools such as machine learning and artificial intelligence. Full article

Introduction: Successful root canal therapy relies on thorough cleaning and disinfection to eliminate microorganisms and residual pulp tissue. Advanced irrigation activation techniques, including Sonic, Ultrasonic, and Diode Laser activation, have improved cleaning efficacy, bacterial reduction, smear layer removal, and irrigant hydrodynamics. On the other hand, these irrigation activation techniques may lead to a temperature rise that may risk the surrounding periodontal tissue. Thus, this study aimed to investigate the temperature rise during different irrigation activation techniques at various time intervals and evaluate the efficacy of these techniques in removing biofilm-mimicking hydrogel BMH of a simulated root canal system in 3D-printed tooth models. Methods: Ten extracted human mandibular premolars, prepared to size 40/0.04 taper, and a hundred 3D-printed resin premolars with simulated main (0.25 mm) and lateral canals (0.15 mm at 3, 7, 11 mm from apex) were used; 50 of them were filled with biofilm-mimicking hydrogel (BMH). Five irrigation activation techniques were evaluated: Diode Laser, Ultrasonic, Sonic, XP-Finisher, and Control (n = 10). Temperature rises were measured on the extracted premolars after 30 and 60 s of activation using a thermographic camera in a controlled environment (23 ± 2 °C). Irrigant penetration, with and without BMH, was assessed in 3D-printed premolars using a 2.5% sodium hypochlorite-contrast medium mixture, visualized with a CMOS radiographic sensor. Penetration was scored (main canal: 3 points; lateral canals: 0–2 points) and analyzed with non-parametric tests. Results: Diode Laser activation technique resulted in the highest temperature rise on the external root surface, followed by the Ultrasonic, with no statistically significant difference observed among the remaining groups. In terms of efficacy, Ultrasonic and Sonic activation achieved significantly greater irrigant penetration in samples without BMH, and greater BMH removal in samples with BMH, compared to Diode Laser, XP-Finisher, and Control groups. Conclusions: In this in vitro study, Diode Laser caused the highest temperature rise, followed by Ultrasonic, with significant increases from 30 to 60 s. Temperature rise did not significantly affect penetration or BMH removal. Ultrasonic and Sonic irrigation techniques achieved the highest depth of penetration (without BMH) and biofilm-mimicking Hydrogel removal (with BMH) compared to Diode Laser, XP-Finisher, and Control. Full article

Antibiotic resistance poses a significant global health challenge, undermining the effectiveness of conventional treatments and increasing mortality rates worldwide. Factors such as the overuse and misuse of antibiotics in healthcare and agriculture, along with poor infection control practices, have accelerated the emergence of resistant bacterial strains. The stagnation in the development of new antibiotics, compounded by economic and biological challenges, has necessitated alternative approaches to combat resistant infections. Nanotechnology provides a promising solution using nanoparticles (NPs), which combat bacteria through mechanisms like membrane disruption and reactive oxygen species (ROS) generation. Metal-based nanoparticles such as silver and zinc oxide possess intrinsic antimicrobial properties, while polymer- and carbon-based nanoparticles enhance drug delivery and biofilm penetration. Unlike conventional antibiotics, nanoparticles operate through multi-mechanistic pathways, reducing the likelihood of resistance development and improving treatment efficacy. This review aims to provide an updated, in-depth look at recent advances in nanoparticle research targeting antibiotic resistance, discussing different types of nanoparticles, mechanisms of action, and current challenges and opportunities. By exploring the evolving role of nanotechnology in addressing this crisis, this review intends to highlight the potential for nanoparticles to transform the treatment landscape for resistant bacterial infections and inspire further research into these innovative solutions. Full article

Formaldehyde, sulfuric acid and salicylic acid were combined to create a 3,3′-methylenebis(2-hydroxybenzoic acid) (MHB) ligand, which was subsequently permitted to bind with zinc(II) ions. The ligand and its zinc(II) complex (Zn–MHB) have been described by a combination of elemental analyses, spectral analyses (UV–Vis, IR, MS and NMR), XRD, TEM, as well as TGA measurement. The ligand has been suggested to coordinate to the zinc center in a tetradentate manner forming the binuclear tetrahedral complex. An X-ray analysis indicated a considerable difference between MHB (crystalline) and Zn–MHB (amorphous). The UV–Vis spectra were used to determine the optical properties such as bandgap, refractive index, optical conductivity and penetration depth. The possibility of employing the samples for optoelectronic applications was indicated from the band gap values which underlie the range of semiconductors. TEM revealed the spherical shapes and mutation of ligand particles into the nano-scale by complexation. The antimicrobial potential of the MHB towards Gram-positive and Gram-negative bacterial growths has been investigated. The results suggested that it would be possible to employ MHB to prevent bacterial development, particularly that of salmonella typhimurium. The cytotoxicity of the MHB was assessed against two types of mammalian cells: VERO (the kidney of an African green monkey) and HFB4 (human skin melanocytes). Lower sensitivity was observed in VERO cells. Full article

Elimination of microbes in the root canal system is crucial for achieving long-term success in endodontic treatment. Further efforts in study design and standardization are needed in order to improve the validity and comparability of in vitro results on endodontic disinfection procedures, in turn improving clinical outcomes. This study optimizes two models at all steps: tooth selection, pretreatment, inoculation method (by growth or centrifugation), and confocal laser scanning microscopy (CLSM)-guided imaging of LIVE/DEAD-stained specimens. Individual anatomical conditions lead to substantial differences in penetration depth. Sclerosis grading (SCG), a classification system introduced in this study, provides information about the sclerosis status of the dentine and is helpful for careful, specific, and comparable tooth selection in in vitro studies. Sonically activated EDTA for the pretreatment of roots, inoculation of Enterococcus faecalis in an overflow model, 3–4 weeks of incubation, as well as polishing of dentine slices before staining, led to advances in the visualization of bacterial penetration and irrigation depths. In contrast, NaOCl pretreatment negatively affected performance reproducibility and should be avoided in any pretreatment. Nonsclerotized teeth (SCG0) can be used for microbial semilunar-shaped inoculation by centrifugation as a “quick-and-dirty” model for initial orientation. In conclusion, CLSM-guided imaging for quantifying endodontic infection/disinfection is a very powerful method after the fine-tuning of materials and methods. Full article

Different sands have significant influences on MICP reinforcement effects. Using calcium carbonate production and bioflocculation lag period as evaluation criteria, this study investigates the optimal theoretical pH values of bacterial solutions with different concentrations. We reinforced four different sands using MICP at the optimal theoretical pH, and based on permeability, moisture retention, raindrop erosion, wind erosion, penetration, and SEM tests, the influence of sand properties on low-pH MICP reinforcement was analyzed and the low-pH MICP mechanism was revealed. The results indicate the following: (1) The optimal theoretical pH values for bacterial solutions with concentrations of 0.67 × 10⁸ cells/mL, 3 × 10⁸ cells/mL, and 10 × 10⁸ cells/mL are 4.5, 3, and 4, respectively. (2) With 0.67 × 10⁸, 3 × 10⁸, and 10 × 10⁸ cells/mL bacterial solutions, the strength of tailings sand containing calcium salt was 21.15%, 44.42%, and 13.61% higher than that of quartz sand, respectively. The effective reinforcement depth of alkaline reclaimed sand was 10, 8, and 6 mm lower than that of neutral calcareous sand, respectively. The strength of fine tailings sand was 70.41%, 58.04%, and 22.6% higher than that of coarse reclaimed sand. The effective reinforcement depth of fine quartz sand was 6, 4, and 4 mm lower than that of coarse calcareous sand. (3) Low pH temporarily suppresses urease activity, delaying calcium carbonate flocculation and enhancing reinforcement uniformity. To achieve optimal reinforcement effects, adjusting the actual optimal pH values of bacterial solution based on sand properties is essential in engineering applications. Full article

Membrane-active molecules provide a promising strategy to target and kill pathogenic bacteria. Understanding how specific molecular features drive interactions with membrane components and subsequently cause disruption that leads to antimicrobial activity is a crucial step in designing next-generation treatments. Here, we test a library of lipid-like compounds (lipidoids) against Gram-negative bacteria Escherichia coli to garner in-depth structure–activity relationships using antimicrobial assays. Modular lipidoid molecules were synthesized in high-throughput, such that we could analyze 104 compounds with variable combinations of hydrophobic tails and cationic headgroups. Antibacterial activity was strongly correlated to specific structural features, including tail hydrophobicity and headgroup charge density, and also to the overall molecular shape and propensity for self-assembly into curved liquid crystalline phases. Dye permeabilization assays showed that E. coli membranes were permeabilized by lipidoids, confirming their membrane-active nature. The reduced permeabilization, as compared to Gram-positive Bacillus subtilis, alludes to the challenge of permeabilizing the additional outer membrane layer of E. coli. The effect of headgroup solubility in gemini-type lipidoids was also demonstrated, revealing that a headgroup with a more hydrophilic spacer between amine groups had enhanced activity against B. subtilis but not E. coli. This provides insight into features enabling outer membrane penetration and governing selectivity between bacterial species. Full article

The aim of this study was to investigate the antimicrobial efficacy of different disinfection protocols in a novel Enterococcus faecalis biofilm model based on a visualization method and to evaluate the potential alteration of dentinal surface. A total of 120 extracted human premolars were allocated to 6 groups with different irrigation protocols. The assessment of the effectiveness of each protocol and the alteration of dentinal surface were visualized by using SEM and fluorescence microscopy (DAPI). A dense E. faecalis biofilm with a penetration depth of 289 μm (medial part of the root canal) and 93 μm (apical part) validated that the biofilm model had been successfully implemented. A significant difference between the 3% NaOCl groups and all the other groups in both observed parts of the root canal (p < 0.05) was detected. However, the SEM analysis revealed that the dentinal surface in the 3% NaOCl groups was severely altered. The established biofilm model and the visualization method based on DAPI are appropriate for bacterial quantification and evaluation of the depth effect of different disinfection protocols in the root canal system. The combination of 3% NaOCl with 20% EDTA or MTAD with PUI allows the decontamination of deeper dentine zones within the root canal but simultaneously alters the dentinal surface. Full article

Restorative dentistry aims to create a favorable environment to arrest caries with minimal operative intervention. The Hall technique (HT) involves the seating and cementation of stainless steel crowns (SSC) on primary molars without any tooth preparation, caries removal, or local anesthesia. In this manner, it entombs bacteria and arrests caries’ progress. We compared bacterial distribution and quantity among primary molars affected with caries and restored with SSC using the HT (n = 10), the conventional technique (CT; n = 10), or not restored at all (control; n = 10). The teeth were contaminated with Enterococcus faecalis to mimic the clinical situation in the oral cavity and then incubated for 21 days. They were then cut mesiodistally and evaluated with confocal laser scanning microscopy. Total bacterial load (live + dead) in the mesial and distal areas of the crown showed no significant difference between the groups (p = 0.711), but there were significantly more dead than live bacteria in the CT and control groups versus the HT group (p = 0.0274 and p = 0.0483, respectively). Inside the pulp chamber and the crown area, the total bacterial load was significantly higher in the HT compared to the CT group (p < 0.001). Significantly more dead than live bacteria were observed in all tooth areas treated with the HT (p = 0.0169). Bacterial penetration depth was significantly correlated with bacterial load (p = 0.0167). In conclusion, although more bacteria were present in teeth that had undergone the HT versus those treated with the CT, they were mainly unviable. Additionally, the CT and the HT showed a similar performance in terms of marginal leakage, indicating that complete caries removal is not essential to achieve good sealing. Full article

(1) The objective of the study is to conduct a comprehensive systematic review of in vitro studies in order to assess the depth to which E. faecalis bacteria penetrate human dentinal tubules after the use of various irrigation solutions. (2) Methods: A literature search of the MEDLINE, Scopus, Cochrane CENTRAL, and Embase databases was conducted, as well as a backward and forward citation search. Two independent reviewers then selected suitable studies based on inclusion and exclusion criteria. Data were extracted and the risk of bias and methodology of the studies were evaluated. (3) Results: Out of a total of 504 papers evaluated following the removal of duplicates, 7 studies met the inclusion criteria and were included in the systematic review. The heterogeneity of the studies made it impossible to perform a meta-analysis. The majority of the studies reported that sodium hypochlorite (NaOCl) and chlorhexidine digluconate (CHX) can affect the penetration depth of E. faecalis suspensions. The studies included in this review possess a moderate to high risk of bias and thus represent moderate evidence that the antimicrobial activity of NaOCl and CHX affects the intra-tubular penetration of bacteria. (4) Conclusions: The evidence indicates that irrigants may affect the bacteria inside human dentinal tubules. Standardized high-quality methods are needed to evaluate bacterial penetration in in vitro studies. Full article