Root Segments Research Articles

Fine root hydraulic conductivity relates to root functional traits in four coniferous species

Tree fine roots (<2 mm in diameter) are the primary organs for water acquisition from soil, yet how root traits contribute to water uptake under field conditions is not well established. In this study, we quantified the relationship between root water uptake and root functional traits in natural coniferous forests. In cool-temperate coniferous forests, we directly measured in situ hydraulic conductivity (Lp; m3 m−2 s−1 MPa−1) of fine root using a pressure chamber method. We also examined the relationship between the Lp of the intact root segments and root traits, such as morphological traits, including root diameter and tissue density, and chemical traits, such as root N content, particularly at the interspecific level. The Lp of fine root segments differed significantly among species. Fine root Lp was positively correlated with root tissue density and negatively correlated with root diameter and N content across species, suggesting it is related to actual water movement within trees. Our results show that the Lp of fine root systems in the forest field reflects and originates from both water resistance in transportation and absorption, especially a water transport rather than an absorption function. We highlight that the linkage between in situ Lp and the fine root system traits enable understanding of the complex functional balance characterizing the overall hydraulic uptake and transport capacity of water resources from the soil through exploitative root foraging.

Root System Scale Models Significantly Overestimate Root Water Uptake at Drying Soil Conditions.

Soil hydraulic conductivity (ksoil) drops significantly in dry soils, resulting in steep soil water potential gradients (ψs) near plant roots during water uptake. Coarse soil grid resolutions in root system scale (RSS) models of root water uptake (RWU) generally do not spatially resolve this gradient in drying soils which can lead to a large overestimation of RWU. To quantify this, we consider a benchmark scenario of RWU from drying soil for which a numerical reference solution is available. We analyze this problem using a finite volume scheme and investigate the impact of grid size on the RSS model results. At dry conditions, the cumulative RWU was overestimated by up to 300% for the coarsest soil grid of 4.0 cm and by 30% for the finest soil grid of 0.2 cm, while the computational demand increased from 19 s to 21 h. As an accurate and computationally efficient alternative to the RSS model, we implemented a continuum multi-scale model where we keep a coarse grid resolution for the bulk soil, but in addition, we solve a 1-dimensional radially symmetric soil model at rhizosphere scale around individual root segments. The models at the two scales are coupled in a mass-conservative way. The multi-scale model compares best to the reference solution (−20%) at much lower computational costs of 4 min. Our results demonstrate the need to shift to improved RWU models when simulating dry soil conditions and highlight that results for dry conditions obtained with RSS models of RWU should be interpreted with caution.

Preliminary Investigation on the Geometric Accuracy of 3D Printed Dental Implant Using a Monkey Maxilla Incisor Model

Additive manufacturing has proven to be a viable alternative to conventional manufacturing methodologies for metallic implants due to its capability to customize and fabricate novel and complex geometries. Specific to its use in dental applications, various groups have reported successful outcomes for customized root-analog dental implants in preclinical and clinical studies. However, geometrical accuracy of the fabricated samples has never been analyzed. In this article, we studied the geometric accuracy of a 3D printed titanium dental implant design against the tooth root of the monkey maxilla incisor. Monkey maxillas were scanned using cone-beam computed tomography, then segmentation of the incisor tooth roots was performed before the fabrication of titanium dental implants using a laser powder bed fusion (PBF) process. Our results showed 68.70% ± 5.63 accuracy of the 3D printed dental implant compared to the actual tooth (n = 8), where main regions of inaccuracies were found at the tooth apex. The laser PBF fabrication process of the dental implants showed a relatively high level of accuracy of 90.59% ± 4.75 accuracy (n = 8). Our eventual goal is to develop an accurate workflow methodology to support the fabrication of patient-specific 3D-printed titanium dental implants that mimic patients’ tooth anatomy and fit precisely within the socket upon tooth extraction. This is essential for promoting primary stability and osseointegration of dental implants in the longer term.

Cascaded neural network-based CT image processing for aortic root analysis

PurposeCareful assessment of the aortic root is paramount to select an appropriate prosthesis for transcatheter aortic valve implantation (TAVI). Relevant information about the aortic root anatomy, such as the aortic annulus diameter, can be extracted from pre-interventional CT. In this work, we investigate a neural network-based approach for segmenting the aortic root as a basis for obtaining these parameters.MethodsTo support valve prosthesis selection, geometric measures of the aortic root are extracted from the patient’s CT scan using a cascade of convolutional neural networks (CNNs). First, the image is reduced to the aortic root, valve, and left ventricular outflow tract (LVOT); within that subimage, the aortic valve and ascending aorta are segmented; and finally, the region around the aortic annulus. From the segmented annulus region, we infer the annulus orientation using principal component analysis (PCA). The area-derived diameter of the annulus is approximated based on the segmentation of the aortic root and LVOT and the plane orientation resulting from the PCA.ResultsThe cascade of CNNs was trained using 90 expert-annotated contrast-enhanced CT scans routinely acquired for TAVI planning. Segmentation of the aorta and valve within the region of interest achieved an F1 score of 0.94 on the test set of 36 patients. The area-derived diameter within the annulus region was determined with a mean error below 2 mm between the automatic measurement and the diameter derived from annotations. The calculated diameters and resulting errors are comparable to published results of alternative approaches.ConclusionsThe cascaded neural network approach enabled the assessment of the aortic root with a relatively small training set. The processing time amounts to 30 s per patient, facilitating time-efficient, reproducible measurements. An extended training data set, including different levels of calcification or special cases (e.g., pre-implanted valves), could further improve this method’s applicability and robustness.

A novel 3D X‐ray computed tomography (CT) method for spatio‐temporal evaluation of waterlogging‐induced aerenchyma formation in barley

AbstractIncreased precipitation during winter months in Western Europe is predicted from climate change. This is expected to increase the frequency of flooding events, with waterlogged conditions becoming more prevalent. A consequence of waterlogging is hypoxic conditions and dying back of roots, thereby negatively affecting plant nutrient uptake, growth, and development. Barley (Hordeum vulgare L.) forms lysigenous aerenchyma, which are air‐filled pockets within the root to facilitate O2 transport and support root respiration. Current methods for visualizing aerenchyma formation in roots are largely 2D and involve embedding a fixed root segment in resin, followed by destructive sectioning for microscopy. Here, we report the development of an X‐ray computed tomography (CT) acquisition and analytical method for spatio‐temporal identification and quantitation of aerenchyma in 2D and 3D in barley roots without the requirement for chemical fixation, resin embedding, followed by physical sectioning of the root. We demonstrated that the method we have developed can facilitate the identification and quantitation of aerenchyma in barley as early as 9 d post‐waterlogging. The method we have developed can be potentially applied to different plant species and has the potential to support the selection of breeding markers through X‐ray CT phenotyping of aerenchyma.

Vascularized pulp regeneration via injecting simvastatin functionalized GelMA cryogel microspheres loaded with stem cells from human exfoliated deciduous teeth.

Dental pulp necrosis are serious pathologic entities that causes tooth nutrition deficiency and abnormal root development, while regeneration of functional pulp tissue is of paramount importance to regain tooth vitality. However, existing clinical treatments, which focus on replacing the necrotic pulp tissue with inactive filling materials, fail to restore pulp vitality and functions, thus resulting in a devitalized and weakened tooth. Currently, dental pulp regeneration via stem cell-based therapy for pulpless teeth has raised enormous attention to restore the functional pulp. Here, a novel design of injectable simvastatin (SIM) functionalized gelatin methacrylate (GelMA) cryogel microspheres (SMS) loaded with stem cells from human exfoliated deciduous teeth (SHEDs) was established to refine SHEDs biological behaviors and promote in vivo vascularized pulp-like tissue regeneration. In this system, SIM encapsulated poly (lactide-co-glycolide) (PLGA) nanoparticles were incorporated into GelMA cryogel microspheres via cryogelation and O1/W/O2 emulsion method. SMS with sustained release of SIM promoted SHEDs adhesion, proliferation and exhibited cell protection properties during the injection process. Furthermore, SMS enhanced SHEDs odontogenic differentiation and angiogenic potential, and SHEDs loaded SMS (SHEDs/SMS) are beneficial for human umbilical vein endothelial cells (HUVECs) migration and angiogenesis, demonstrating their potential for use in promoting vascularized tissue regeneration. SHEDs/SMS complexes were injected into cleaned human tooth root segments for subcutaneous implantation in nude mice. Our results demonstrated that SHEDs/SMS could induce vessel-rich pulp-like tissue regeneration in vivo and that such an injectable nano-in-micro multistage system for the controlled delivery of bioactive reagents would be suitable for clinical application in endodontic regenerative dentistry.

Vegetative Propagation by Root Segments Cuttings of Sclerocarya Birrea (A. Rich.) Hochst: Effects of Substrate and Mycorrhizal Inocula on the Ability to Root Cuttings

Sclerocarya birrea (A. Rich.) Hochst is one of the woody plants of the soudano-Sahelian zones, with great socioeconomic importance. The local populations over-exploit this species for their daily socio-economic needs and this endangered its durability. The objective of this study was to contribute to the domestication of this species by the low-cost technique of Root Segments Cuttings (RSC). The substrates sand/sawdust and dark soil/Sawdust have been inoculated with 0, 10, and 20 g of mycorrhizae. The experimental design was a split plot with 4 repetitions. The experimental unit is of 10 cuttings. The results show that the best substrate for the budding of the RSC is the mixture of Sand/Sawdust (37.77±17.15%). The appropriate dose of mycorrhizae for the budding of the RSC is 10 g (33.33±21.6%). For the height of the aerial axes, a satisfactory result was obtained in the dose of mycorrhizae of 10 g (3.43±2.40 cm). Concerning the number of the leaves, the maximum is recorded in the RSC inoculated with 20 g of mycorrhizae (3.60±1.36). The analysis of variance did not show a meaningful effect for the treatments (0.54>0.05), as well as for the substrates (0.76>0.05). Regarding the rooting of the cuttings, one must notice that the best substrate for the number of newly formed roots is the mixture of Sand/Sawdust (2.22±1.01) while the dose of 20 g has much allowed the appearance of roots (3.41±1.24). The best substrate for the length of the newly formed roots is the mixture of Sand/Sawdust (2.9±1.3 cm), whiles the proportion of 10 g has permitted a lot of the growth of roots (4.24±1.69 cm) as far the plum tree of Africa is concerned. These results show that improving some parameters at S. birrea is possible by vegetative propagation.

Spatiotemporal development of suberized barriers in cork oak taproots.

The longevity and high activity of the cork cambium (or phellogen) from Quercus suber L. (cork oak) are the cornerstones for the sustainable exploitation of a unique raw material. Cork oak is a symbolic model to study cork development and cell wall suberization, yet most genetic and molecular studies on these topics have targeted other model plants. In this study, we explored the potential of taproots as a model system to study phellem development and suberization in cork oak, thereby avoiding the time constraints imposed when studying whole plants. In roots, suberin deposition is found in mature endodermis cells during primary development and in phellem cells during secondary development. By investigating the spatiotemporal characteristics of both endodermis and phellem suberization in young seedling taproots, we demonstrated that secondary growth and phellogen activity are initiated very early in cork oak taproots (approx. 8days after sowing). We further compared the transcriptomic profile of root segments undergoing primary (PD) and secondary development (SD) and identified multiple candidate genes with predicted roles in cell wall modifications, mainly lignification and suberization, in addition to several regulatory genes, particularly transcription factor- and hormone-related genes. Our results indicate that the molecular regulation of suberization and secondary development in cork oak roots is relatively conserved with other species. The provided morphological characterization creates new opportunities to allow a faster assessment of phellogen activity (as compared with studies using stem tissues) and to tackle fundamental questions regarding its regulation.

Human amniotic membrane extracellular matrix scaffold for dental pulp regeneration in vitro and in vivo.

In order to obtain a 3-dimentional scaffold with predictable clinical results for pulp regeneration, this study aims to fabricate and characterize a porous decellularized human amniotic membrane (HAM) extracellular matrix (ECM) scaffold, and evaluate its potential to promote pulp regeneration in vitro and in vivo. The HAM was decellularized, and its histology and DNA content were analysed to confirm decellularization. The scaffolds were synthesized with 15, 22.5 and 30mg/ml concentrations. The porosity, pore size, phosphate-buffered saline (PBS) absorption and degradation rate of the scaffolds were assessed. In vitro experiments were performed on human dental pulp stem cells (hDPSCs) to assess their viability, proliferation, adhesion and migration on the scaffolds. The optimal group was selected for in vivo immunogenicity assessment and was also used as the cell-free or cell-loaded scaffold in root segment models to evaluate pulp regeneration. All nonparametric data were analysed with the Kruskal-Wallis test followed by Dunn's post hoc test, whilst quantitative data were analysed with one-way anova. Decellularization of HAM was confirmed (p<.05). The porosity of all scaffolds was more than 95%, and the pore size decreased with an increase in ECM concentration (p<.01). PBS absorption was not significantly different amongst the groups, whilst 30mg/ml ECM scaffold had the highest degradation rate (p<.01). The hDPSCs adhered to the scaffold, whilst their proliferation rate increased over time in all groups (p<.001). Cell migration was higher in 30mg/ml ECM scaffold (p<.05). In vivo investigation with 30mg/ml ECM scaffold revealed mild to moderate inflammatory response. In root segments, both cell-free and cell-loaded 30mg/ml scaffolds were replaced with newly formed, pulp-like tissue with no significant difference between groups. Immunohistochemical assessments revealed high revascularization and collagen content with no significant difference amongst the groups. The 30mg/ml HAM ECM scaffold had optimal physical properties and better supported hDPSC migration. The HAM ECM scaffold did not interfere with formation of pulp-like tissue and revascularization within the root canal when employed as both cell-free and cell-loaded scaffold. These results highlight the potential of HAM ECM membrane for further investigations in regenerative endodontics.

Co-localised phosphorus mobilization processes in the rhizosphere of field-grown maize jointly contribute to plant nutrition

Understanding phosphorus (P) dynamics in the rhizosphere is crucial for sustainable crop production. P mobilization processes in the rhizosphere include the release of plant and microbially-derived protons and extracellular phosphatases. We investigated the effect of root hairs and soil texture on the spatial distribution and intensity of P mobilizing processes in the rhizosphere of Zea mays L. root-hair defective mutant (rth3) and wild-type (WT) grown in two substrates (loam, sand). We applied 2D-chemical imaging methods in custom-designed root windows installed in the field to visualize soil pH (optodes), acid phosphatase activity (zymography), and labile P and Mn fluxes (diffusive gradients in thin films, DGT).The average rhizosphere extent for phosphatase activity and pH was greater in sand than in loam, while the presence of root-hairs had no impact. Acidification was significantly stronger at young root tissue (<2 cm from root cap) than at older root segments (>4 cm from root cap) and stronger in WT than rth3. Accompanied with stronger acidification, higher P flux was observed mainly around young, actively growing root tissues for both genotypes. Our results indicate that acidification was linked to root growth and created a pH optimum for acid phosphatase activity, i.e., mineralization of organic P, especially at young root tissues which are major sites of P uptake. Both genotypes grew better in loam than in sand; however, the presence of root hairs generally resulted in higher shoot P concentrations and greater shoot biomass of WT compared to rth3. We conclude that soil substrate had a larger impact on the extent and intensity of P solubilization processes in the rhizosphere of maize than the presence of root hairs. For the first time, we combined 2D-imaging of soil pH, phosphatase activity, and nutrient gradients in the field and demonstrated a novel approach of stepwise data integration revealing the interplay of various P solubilizing processes in situ.

How to Define the Appropriate Spatial Resolution of Root Segments When Solving Water Flow in Root System Hydraulic Architectures.

In this chapter, we discuss the issue of balance between spatial resolution and computational efficiency in the context of the R-SWMS model. Based on the equations governing the water fluxes within the model, we propose here an objective and quantitative criterion which can help fix root segment size to both minimize computational load and achieve simulation according to a given accuracy degree.

Diversity of vam in soils used to cultivate sugarcane (Saccharum spp.) in Tabasco, Mexico

E Objective: A study was carried out in the Ingenio Santa Rosalía sugar mill supply area with the aim of identifying the soil subunits cultivated with sugar cane and to quantify the degree of mycorrhization of Saccharum officinarum. Design/Methodology/Approach: Rhizosphere samples were collected at a depth of 0-30 cm and root segments with diameters of ≤ 1 mm and 1-2.0 mm were studied. The intersect method and the fungal structures method were comparatively analyzed to determine the mycotrophic state of the roots. The study also quantified the number of spores in the soils and classified the morpho-species of vesicular-arbuscular mycorrhiza (VAM). Results: The results show that seven soil subunits exist in the area, but the intersect method did not detect differences in colonization by root diameter or by root colonization ( = 68.5%). For its part, the fungal structures method showed differences in colonization between soil subunits ( = 69.5%), being higher in thin roots, and statistical differences wer found for vesicles and spores. At the sites, an average of 696 spores was quantified per 100 g of soil, which indicates a high presence of vesicular-arbuscular mycorrhizal fungi in the study area. Finally, six species of mycorrhizae were identified, of which four are present in various soil subunits: Glomus aff. deserticola, Glomus etunicatum, Glomus viscosum, and Paraglomus occultum. Study Limitations/Implications: This was an exploratory study that indicates the potential of VAM. Findings/Conclusions: The presence of hyphae, vesicles, arbuscules, and spores indicates that there is an active mycotrophic process between VAM and sugarcane cultivation in the soils of the study area.

Japanese knotweed control with winter soil injection of chemicals targeting the rhizome system

AbstractTo achieve chemical control of aggressive creeping perennial weeds and avoid the disadvantages of conventional foliar applications, we established a winter soil‐injection method using soil‐active herbicides. Our previous study demonstrated the feasibility of the practical use of this method by showing that the regeneration from rhizomes or creeping root segments was inhibited by direct contact with chemicals in the soil. Then, a field trial was conducted on a population of Japanese knotweed. A stand of 148 plants growing on a railway bank was used for the experiment involving two herbicide treatments and an untreated control. In early March 2016, 1 L of chlorpropham (230 mg/L) or tebuthiuron (100 mg/L) was injected 15–25 cm deep into the base of each dead shoot clump. New shoot growth started in late April and became senescent in November. Aerial growth, determined as total shoot length and shoot number, significantly decreased throughout the season under both chemical treatments, without showing any injury symptoms (shoot dieback, leaf desiccation, or yellowing) that make unsightly views. In November, rhizome number was as low as 6 and 18% of the untreated control in the chlorpropham and tebuthiuron treatments, respectively. Sprouting and rooting abilities were reduced by treatment with tebuthiuron. Such marked reductions in rhizome number and viability, as well as the reduction in food reserves as estimated from diminished aerial growth, suggested probable substantial growth inhibition in the following season. Further improvement of the injection methodology would be attained from the consolidation of practical application data.

Profiling the Proteome of Cyst Nematode-Induced Syncytia on Tomato Roots.

Cyst nematodes are important herbivorous pests in agriculture that obtain nutrients through specialized root structures termed syncytia. Syncytium initiation, development, and functioning are a research focus because syncytia are the primary interface for molecular interactions between the host plant and parasite. The small size and complex development (over approximately two weeks) of syncytia hinder precise analyses, therefore most studies have analyzed the transcriptome of infested whole-root systems or syncytia-containing root segments. Here, we describe an effective procedure to microdissect syncytia induced by Globodera rostochiensis from tomato roots and to analyze the syncytial proteome using mass spectrometry. As little as 15 mm2 of 10-µm-thick sections dissected from 30 syncytia enabled the identification of 100–200 proteins in each sample, indicating that mass-spectrometric methods currently in use achieved acceptable sensitivity for proteome profiling of microscopic samples of plant tissues (approximately 100 µg). Among the identified proteins, 48 were specifically detected in syncytia and 7 in uninfected roots. The occurrence of approximately 50% of these proteins in syncytia was not correlated with transcript abundance estimated by quantitative reverse-transcription PCR analysis. The functional categories of these proteins confirmed that protein turnover, stress responses, and intracellular trafficking are important components of the proteome dynamics of developing syncytia.

Apical Sealing Ability of Two Calcium Silicate-Based Sealers Using a Radioactive Isotope Method: An In Vitro Apexification Model.

The aim of this study was to evaluate and compare the sealing ability of two calcium silicate-based sealers (TotalFill BC RRM Fast Set Putty and White ProRoot MTA) when used as apical plugs in immature teeth through nuclear medicine. Single-rooted extracted teeth (n = 34) had their crowns and root tip sectioned to obtain 14 mm long root segments to simulate an in vitro apexification model. Were created two experimental groups, namely MTA (n = 12) and BC (n = 12), and two control groups, PG (positive group, n = 5) and NG (negative group, n = 5). On the 4th day after placing the respective apical plug, the apical portions of the teeth were submerged in a solution of sodium pertechnetate (99mTcNaO4) for 3 h. Statistical analysis showed a significant difference between the MTA group and the controls (p < 0.05). The BC group had a significant difference regarding the negative control (p < 0.001) but showed no statistical significance regarding the positive control (p = 0.168). There was a statistically significant difference (p = 0.009) between the BC group (7335.8 ± 2755.5) and the MTA group (4059.1 ± 1231.1), where the last showed less infiltration. Within the limitations of this study, White ProRoot MTA had a significantly better sealing ability than TotalFill BC RRM Fast Set Putty.

CBCT Visualization of Furcation Perforation Repair Materials Using Different Voxel Sizes

Background: Three-dimensional cone-beam computed tomography is gaining popularity as an imaging modality aiding the performance of difficult endodontic treatment procedures. For this reason, we assessed the visualization of bioactive furcal perforation repair materials in an ex vivo study using CBCT with different voxel sizes and determined which voxel size yielding the best images with least artefacts. Visualization of endodontic restorative material is affected by the appearance of various artifacts. This study was conducted to evaluate the CBCT visualization of three perforation repair materials using five different voxel sizes.&#x0D; Methods: This study was performed with 84 mandibular molars that had been extracted for various reasons. All samples were measured with a digital caliper (Digimess, São Paulo, Brazil), marked at 3 mm above the cementoenamel junction, and decoronized at this line. The root segments were amputated at 3 mm below the furcation site using diamond discs under water cooling. Endodontic access cavities were then created, and the perforations were formed. Biodentine, MTA, and EndoSequence were mixed following the manufacturers’ instructions and applied to the perforation sites. Five image sets were obtained: 0.075 mm3; 0.1 mm3; 0.15 mm3; 0.2 mm3; and 0.4 mm3. Each scan was evaluated by 2 observers with 8 to 12 years of experience in CBCT imaging.&#x0D; Results: The best image quality for repair all materials was achieved with a voxel size of 0.1 mm3. Image clarity of repair materials was no statistically difference between voxel sizes of 0.075 mm3 and 0.15 mm3. Image quality was significantly reduced at voxel sizes of 0.2 mm3 and 0.4 mm3, and was the worst quality at 0.4 mm3 voxels in all groups.&#x0D; Conclusions: CBCT imaging can be used to examine endodontic repair materials with adjustment of the effective radiation dose rate and selection of the appropriate voxel size.

Mesoscopic characteristics and macroscopic mechanical properties of coral aggregates

Coral aggregate is a type of porous and light-weight construction material with intense prospects for the engineering applications in remote ocean islands. However, its macroscopic properties is directly determined by the mesoscopic characteristics, such as texture, porosity, etc. Thus, the mesoscopic characteristics and macroscopic properties of coral aggregates are investigated in the present work. Three types of coral aggregates sampled at different positions of coral clusters, such as the tip-, stem- and root segments, are selected for investigation. The zoom-stereo microscope and X-ray computed tomography (XCT) facility are used to conduct the morphology observations for coral aggregates. Afterwards, the pore information (i.e., size, number and connectivity) of different coral aggregates are tested and analyzed quantitatively according to the XCT scanning data. Besides, the uniaxial compressive properties of coral aggregates are studied using cylinder aggregate samples with dimension of φ10mm × 20 mm. The effect of porosity characteristic on the compressive strengths of coral aggregates is discussed comprehensively. Furthermore, based on the XCT scanning data, a series of algorithms are developed to establish the mesoscale models for different coral aggregate samples. Employing the established mesoscale models and the Mohr-Coulomb criterion, the uniaxial compressive tests of coral aggregates are simulated. Results indicate that there are high reliabilities for the developed mesoscale model and the determined material model parameters of different coral aggregates, providing further insights into the mechanical properties of coral aggregates.

Role of Riboflavin; Curcumin photosensitizers and Ozone when used as canal disinfectant on push-out bond strength of glass fiber post to radicular dentin.

AimTo assess the efficacy of photosensitizers (CP, riboflavin) and gaseous ozone in comparison to the conventional radicular dentin disinfectant (NaOCl) on push-out bond strength (PBS) of PFRC post cemented to radicular dentin. Material and methodHuman single-rooted teeth were collected, steriled implanted in polyvinyl pipes up to a cement-o-enamel junction and de coronated. Cleaning and shaping of the canal were performed using the crown down technique followed by obturation of the canal space. Canal space was prepared using peso reamers and samples were divided into four groups based on types of canal disinfectant protocols. Group 1: Riboflavin+ 17%EDTA; group 2: Curcumin Photosensitizer + 17% EDTA; group 3: Gaseous Ozone disinfection (O3) +17% EDTA and group 4 control 2.5% NaOCl +17% EDTA. Within the canal space, fiber post was cemented and cured, and thermocycled. PBS was evaluated using a Universal testing machine (UTM) and failure modes using a stereomicroscope at 40x magnification. One-way analysis of variance (ANOVA) was used to determine the mean and standard deviation of push-out bond strength (PBS). The Tukey multiple comparison tests (p = 0.05) was used to compare the means of PBS. ResultsThe highest PBS was displayed in group 2 CP+ 17% EDTA at all three root levels, coronal (8.81±0.61), middle (7.77±0.55), and apical (5.25±0.61). The lowest PBS was revealed in group 4, disinfected with 2.5% NaOCl +17% EDTA (control) at coronal (6.12±0.54), middle (5.46±0.84), and apical (3.00±1.88) levels. The most prevailed fracture mode was an adhesive failure (cement-dentin interface). ConclusionRadicular dentin disinfected with PDT using CP, riboflavin, and O3 displayed similar PBS at all root segments. NaOCl is a convenient, traditional, and commonly used disinfectant, and it's effects on PBS is still controversial.

THREE-DIMENSIONAL PRINTING OF CUSTOM SEMIFLEXIBLE AORTIC ROOT MODELS FOR OPERATIVE PLANNING AND SURGICAL PROCTORING OF PERCEVAL VALVE IMPLANTATION

<h3>BACKGROUND</h3> The Perceval Valve (LivaNova, London, United Kingdom) is a rapid-deployment aortic bioprosthesis with a stentless self-expanding design conducive to minimally-invasive approaches. Uptake of this valve may be limited by sizing-related nuances and its unique implantation technique. Three-dimensional modeling and printing of custom patient-specific models can be used for surgical teaching and preoperative planning. Herein, we describe our method for 3D-printing aortic roots using a semi-flexible material and demonstrate their utility for sizing and surgical planning before Perceval Valve Implantation. <h3>METHODS AND RESULTS</h3> Semiflexible models of aortic roots were virtually modelled and 3D-printed from DICOM files containing contrast-enhanced ECG-gated CTA images of the thoracic aorta obtained in patients awaiting surgical aortic valve replacement via right anterior minithoracotomy. Segmentation of the aortic root, annulus and the left ventricular outflow tract was performed using a free, open source, multi-platform software package (http://slicer.org). In Slicer, a three-dimensional shell was generated around the luminogram model and then hollowed out, replicating the interior of the aortic root. After converting the aortic surfaces to standard tessellation language (STL), the models were printed using Thermoplastic Polyurethane (NinjaFlex, NinjaTek, PA,USA) in a direct drive extruder desktop 3D printer (Printrbot Simple Metal, Printrbot, USA). Preliminary model validation was performed in a prospective and blinded manner. Surgeons sized two de-identified aortic roots prior to the patient's operation. Implantation was then performed in the operating room without knowledge of the model sizing. The same size selected in the model corresponded to the size implanted in the operating room. The root models correctly predicted the size of the implanted valve. They also demonstrated the consequences of incorrect sizing (Image). Undersizing resulted in poor leaflet coaptation. Oversizing resulted in pinwheeling or buckling of the Perceval valve, both oversizing-related complications. A prototype holder was developed for simulation of the implantation procedure, including guiding suture placement, traction-countertraction of the sutures and balloon expansion. <h3>CONCLUSION</h3> Custom 3D-printed semiflexible aortic roots allowed for simulation of intraoperative sizing and can reproduce surgically relevant signs of inappropriate sizing, including oversizing (pinwheeling and buckling) and undersizing (suboptimal coaptation). This model will be of use for preoperative planning, sizing and surgical proctoring for the Perceval valve. Custom modeling may accelerate the learning curve associated with this valve and improve uptake for use in minimally invasive aortic valve surgery, combined cases, and patients with small roots.

First Report of white root rot of hemp (Cannabis sativa L.) caused by Dematophora necatrix in Campania region (Southern Italy).

Industrial hemp (Cannabis sativa L.) was cultivated in Italy until the end of the Second World War. Since then, it has been abandoned and substituted with other crops mainly due to legal restrictions and public concerns. Public legislation passed in 2016, has allowed for the production of hemp seeds, flowers and fibers (law n. 242/2016). During a 2019 survey on hemp sanitary status in the province of Naples (40°57'6"12 N, 14°22'37"56 E), hemp 'Kompolty' with symptoms of root rot were observed at a private farm and collected for further analysis at the phytosanitary laboratory of CREA in Caserta. Death generally occurred within 2-3 weeks after the appearance of the first symptoms, occurring on ca. 10% of plants, consisting of yellowing, canopy wilt and signs of roots covered with white mycelium and fan-like mycelium under the bark. The causal agent, was isolated from small root segments, excised from symptomatic plants, the surface was disinfected with 2% sodium hypochlorite, placed on potato dextrose agar (PDA) amended with streptomycin sulphate (100mg/L) and incubated in the dark at 25°C for 5 days. Small pieces (2-3 mm) at the edge of the resulting colonies were sub-cultured onto PDA and incubated at 25°C in the dark for one week. The mycelia from 15 isolates showed pear-shaped swellings adjacent to the septa. The conidia were aseptate, hyaline, ellipsoid to ovoid, and 3-5 × 2.5-3 µm (n=50). Based on the morphological characteristics, the fungus was identified as Rosellinia necatrix Berl. ex Prill. (Singleton et al., 1992) a fungus taxonomically revised to Dematophora necatrix R. Hartig (Wittstein et al., 2020). To confirm the identification, total DNA was extracted from five isolates using a DNeasy Plant Mini Kit (Qiagen, Hilden, Germany) and the ITS spacer was PCR-amplified with primers ITS1-ITS4 (White et al., 1990). The size-expected amplicons of 536 bp were purified and sequenced, the resulting sequence was trimmed and deposited in GenBank under the accession number MK937913. BLAST-n analysis revealed 98.83% nucleotide identity with some representative isolates of D. necatrix (MK888684.1; KT343972.1). To fulfill Koch's postulates, the pathogenicity tests were carried out on fifteen 4-weeks-old potted hemp plants 'Kompolty'. The inoculation was performed by adding 3 g of millet seeds inoculated with ten mycelial plugs, taken from the margins of a D. necatrix actively growing colony, per liter of sterile peat and perlite substrate in single pots. Moreover, ten hemp plants were inoculated with sterilized millet seed and served as negative controls. All plants were incubated at 25°C. After three weeks, inoculated plants exhibited foliar chlorosis, apical wilting, and death in two weeks, similar to what was observed in the field. Control plants did not show any symptoms. The fungus was isolated from the roots in all fifteen inoculated plants and confirmed to be D. necatrix based on morphological and molecular analysis, carried out with a second primer pair EF1-983F/ EF1-2218R targeting the transcription elongation factor 1- (Rehner and Buckley., 2005) (MW541068) that showed 99.67% nt in BLAST-n analysis. To our knowledge, this is the first report of D. necatrix infecting hemp in Europe. The farm where the problem arose has a history of cultivation for the production of apples for over 30 years. Therefore, an adaptation of D. necatrix to the new host is hypothesized. An in-depth knowledge on the diseases of hemp will be needed to relaunch hemp cultivation in this area.