Poly-(L-lactic acid)/hydroxyapatite (PLLA/HAp) composites have attracted significant attention as environmentally friendly tough materials due to their excellent biocompatibility and mechanical strength. However, the poor organic-inorganic interfacial adhesion between PLLA and HAp has been a significant challenge, often resulting in the premature elution of PLLA and a reduction in the mechanical integrity. Here, we prepared PLLA/HAp composites with a controllable interface by using etidronic acid, a bisphosphonate compound, as an interface modifier for HAp. Etidronic acid modification of HAp increased the bending strength of PLLA/E-HAp composites up to 66.7 MPa and improved the stability in phosphate buffer saline solution due to grafting of PLLA chains onto the HAp surface. The interface strengthened by chelation between etidronic acid and Ca in HAp could be dissociated in hydrochloric acid, resulting in the successful separation of PLLA and HAp.

High-solid-loading nanofluids are attractive for energy storage and related electrochemical applications but remain fundamentally limited by aggregation, sedimentation, and prohibitive viscosity growth. This work establishes that Brønsted acid site density, governed by the acidity, grafting density, and molecular structure of surface-grafted functional groups, serves as a unifying design parameter linking nanoscale surface chemistry to colloidal stability, macroscopic rheology, and electrochemical performance in metal oxide nanofluids. Using Fe2O3 nanoparticles as a model system, thiol (-SH), sulfonic acid (-SO3H), and phosphonic acid (-PO3H2) groups were systematically grafted at controlled densities, and their surface chemistry was quantitatively characterized. Systematic variation of these functional groups establishes a clear performance hierarchy of -PO3H2 ≈ -SO3H > -SH ≫ -OH across zeta potential, colloidal dispersion, nanofluid viscosity, and charge-transfer resistance. Phosphonate functionalization with etidronic acid reduces viscosity from ∼30 cP to near-water-like values (∼2-3 cP) even at a high solid loading of 40 wt %, maintains long-term dispersion stability, and improves discharge capacity from ∼130 to ∼245 mAh g-1. The identical anchoring chemistry of -SO3H and -SH confirms that functional group acidity governs surface charge development and ion accessibility, which in turn influence overall electrochemical kinetics. These results provide a transferable interfacial design framework for engineering high-loading, flowable metal oxide colloidal suspensions for semisolid flow batteries and related electrochemical technologies.

Background: Continuous chelation with etidronic acid (1-Hydroxyethylidene-1,1-diphosphonic acid, HEDP) has been proposed as a less aggressive alternative to sequential irrigation with ethylenediaminetetraacetic acid (EDTA) in endodontics. This systematic review and meta-analysis aimed to compare the effects of these two protocols on the mechanical properties and structure of root dentin. Methods: PubMed, Scopus, and Cochrane Central databases were searched up to June 2026 for in vitro studies comparing continuous chelation (NaOCl + HEDP mixture) with sequential irrigation (NaOCl and EDTA) on root dentin of permanent teeth. Studies on coronal dentin and those not using NaOCl + HEDP as a mixture were excluded. Risk of bias was assessed using the QUIN tool. Meta-analyses were performed for fracture resistance using a random-effects model. This review was registered in PROSPERO (CRD420250630663). Results: Twenty studies with a total of 572 specimens were included. Six studies had a low risk of bias and thirteen had a medium risk. The qualitative synthesis showed that HEDP generally resulted in similar or lower levels of erosion, microhardness reduction, demineralization, and collagen degradation compared to EDTA. The meta-analysis revealed no significant difference in fracture resistance (5 studies; SMD = 0.28; 95% CI: -0.37 to 0.92; p = 0.40); however, substantial heterogeneity was observed (I[2] = 66.7%). Conclusions: The evidence was limited by substantial heterogeneity and mainly medium risk of bias. Within the limitations, in vitro evidence suggests that continuous chelation with HEDP is comparable to EDTA in terms of root dentin mechanical properties and composition, supporting its use as a chelating agent in endodontic practice. This research received no external funding.

Wood's inherent flammability, arising from its cellular organic composition, demands effective protective strategies. This study aimed to develop a multifunctional bio-based wood coating simultaneously integrating flame retardancy, optical transparency, moisture-triggered self-healing, and surface hydrophobicity within a single formulation. An intumescent flame retardant (PAGHR) was synthesized via ionic assembly of a phytic acid-phosphorylated polyethylene glycol conjugate (PgP) with a piperazine-etidronic acid salt (HEPHR), subsequently blended with gelatin (G) and surface-finished with fluorosilane. The optimized coating (G/PAGHR-4) achieved a limiting oxygen index (LOI) of 37.2% and passed the UL-94 V-0 rating. Cone calorimetry demonstrated reductions of 75.1% in peak heat release rate (pHRR) and 50.0% in total heat release (THR) relative to the neat gelatin control. Char yield at 700 °C increased substantially from 17.8 wt% to 41.0 wt%, confirming effective condensed-phase char promotion. Beyond fire performance, the coating maintained high visible-light transmittance, preserved natural wood aesthetics, and achieved macroscopic scratch healing within 40 min upon ambient water contact. Fluorosilane finishing elevated the water contact angle to 122°. These results establish a scalable, environmentally friendly strategy for multifunctional bio-based protective coatings applicable to wood, textiles, and polymer substrates.

The aim of this study was to weigh dissolving versus physical effects of laser-activated irrigation (LAI) when cleaning simulated human root canals. Dentin debris was selected as the composite organic/inorganic substrate. The cleaning effects of plain 3% sodium hypochlorite (NaOCl, proteolytic), plain 9% 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP, decalcifying), or combined 3% NaOCl + 9% HEDP (NaOCl+HEDP, combined effect) were compared to those of deionized water (no dissolving effect on substrate). Properties of test and control solutions were assessed, including their absorption of infrared light and their viscosity. The isthmus of transparent root canal models (n = 22) was filled with dentin debris obtained from bovine tooth roots. Activated irrigation was done on the models in random order in 3 cycles of 30 s each, at 612 mW/18 Hz. The area of removed debris was measured using digital microscopy. The influence of the irrigating solution on debris removal was assessed by one-way ANOVA and Tukey's HSD, alpha = 0.05. Infrared absorbance spectra were similar between solutions. Density and viscosity increased cumulatively with the solutes under investigation. The combined NaOCl+HEDP solution displayed a significantly (p = 0.002) better cleaning effect than the plain counterparts, which did not remove more debris from the isthmus than water (p>0.05). Under current conditions, the known dissolving effects by NaOCl and HEDP per se did not affect dentin debris removal by LAI, which was mainly due to physical dislodgment of the debris. The enhanced LAI-endorsed cleaning by the combined NaOCl+HEDP irrigant could be related to altered fluid properties and should be explored in further experiments.

The effectiveness of an adjunctive SAF Infinitum procedure performed under continuous chelation was evaluated for reducing hard-tissue debris (HTD) after single-file root canal preparation. Thirty mandibular incisors with flattened canals were pair-matched and prepared using Reciproc Blue R25 or XP-endo Rise Shaper under irrigation with 2.5% sodium hypochlorite combined with etidronic acid. Micro-computed tomography scans were obtained at baseline, after preparation and after supplementary SAF instrumentation for 2 min under continuous NaOCl/HEDP delivery. Canal volume, surface area, HTD volume and percentage reduction were quantified. Baseline morphology and post-preparation HTD did not differ between groups. The adjunctive SAF procedure significantly reduced HTD in both groups. Final residual HTD volumes after SAF use were comparable between preparation protocols, although the percentage reduction was greater after Reciproc Blue preparation. Adjunctive SAF Infinitum with continuous chelation enhanced debris removal in flattened canals irrespective of the initial shaping system.

E. faecalis is one of the most important microbiological factors responsible for the failures after root canal treatment. The knowledge about the efficacy of HEBP and PAA with different concentrations, when they are used alone or associated with NaOCl on E. faecalis biofilms is limited. In the present study, the efficacy of 17% ethylenediaminetetraacetic acid (EDTA), 9% and 18% etidronic acid (HEBP), and 1% and 2% peracetic acid (PAA), used alone or in combination with sodium hypochlorite (NaOCl), was evaluated on dentine discs experimentally infected with Enterococcus faecalis biofilms using a laser scanning confocal microscope. Irrigation of the samples using HEBP solutions in combination with NaOCl decreased the viability of E.faecalis more effectively compared with the sole use of 9% HEBP and 18% HEBP solutions. The use of two different concentrations of peracetic acid (1–2%) and etidronic acid (9–18%) resulted in similar biofilm elimination when these chelators were used alone or in combination with NaOCl. The sole use of 2% peracetic acid in the experimentally infected samples eliminated more biofilm than the use of 9% and 18% HEBP. Lower concentrations of peracetic acid and etidronic acid can be recommended to remove the E.faecalis biofilms from root canals to decrease the irrigation solutions’ potential harmful effects.

BACKGROUND: The adhesion of root canal sealers to dentin is critical for preventing microleakage and ensuring long-term endodontic success. Irrigating agents influence dentin surface characteristics and thus affect sealer bond strength. This study aimed to compare the effects of continuous chelating (NaOCl + HEDP) and sequential chelating (NaOCl followed by EDTA) protocols on the bond strength of AH Plus and AH Plus Bioceramic root-canal sealers. METHODS: Fifty-two extracted human mandibular premolars were decoronated and divided into two groups. Chemo-mechanical preparation was completed using 2.5% NaOCl (Group 1) and a mixture of 2.5% NaOCl + 9% HEDP (Dual Rinse, Group 2) up to ProTaper Next X3. Final irrigation was performed with 17% EDTA in Group 1 and 9% Dual Rinse HEDP in Group 2. Each group was further divided into two subgroups according to the sealer used: AH Plus or AH Plus Bioceramic. Root sections (1.5 mm thick) were taken from apical, middle, and coronal thirds. Bond strength was evaluated using a universal testing machine at 1 mm/min in the apico-coronal direction. Failure modes were also evaluated. Data were analysed using a three-way mixed-effects ANOVA with irrigation protocol and sealer type as between-subject factors and anatomical region as a within-subject factor, followed by post hoc comparisons based on estimated marginal means. RESULTS: Continuous chelation significantly increased the bond strength of AH Plus but had no effect on AH Plus Bioceramic. Cohesive failure was dominant in AH Plus, while no dominant mode was observed in AH Plus Bioceramic. Bond strength increased toward the apical region in all groups. CONCLUSION: Irrigation protocols influence the bond strength of root canal sealers. Continuous chelation may enhance adhesion, particularly for epoxy resin–based sealers, while it does not appear to significantly affect the bond strength of AH Plus Bioceramic.