Canal Model Research Articles

Minimum Local Anesthetic Dose of Ropivacaine in Cesarean Section for Real-Time Ultrasound-Guided Spinal Anesthesia Using 24-Gauge versus 26-Gauge Needles Based on Fluid Simulation Technology: A Randomized Controlled Trial.

Previous research has demonstrated that real-time ultrasound-guided (UG) spinal anesthesia requires a higher minimum local anesthetic dose (MLAD) compared to traditional methods. However, the precise MLAD of ropivacaine for UG cesarean sections remains undetermined. In this study, we ascertained the MLAD of ropivacaine for cesarean section. We also investigated the mechanism underlying the diffusion of ropivacaine within the spinal canal using fluid simulation technology. We randomly placed 60healthy parturients undergoing elective cesarean section with real-time UG spinal anesthesia into Groups I (26-gauge spinal needle) and II (24-gauge spinal needle). For the first parturient in both groups, 15 mg of ropivacaine was administered intrathecally. Based on the effective or ineffective response of the previous parturient, the dose for the subsequent parturient was increased or decreased by 1 mg. Spinal anesthesia characteristics and side effects were recorded. A computer-generated spinal canal model was developed. Leveraging fluid dynamics simulation technology, we documented the diffusion of ropivacaine in the spinal canal using 26-and 24-gauge spinal needles. The MLADs in Groups I and II were 12.728 mg (12.339-13.130 mg) and 9.795 mg (9.491-10.110 mg), respectively. No significant difference was observed in the onset times and durations of sensory or motor blocks, incidence of complications, or neonatal Apgar scores between both groups. Fluid simulation modeling indicated that the 26-gauge spinal needle achieved a higher distribution level more quickly; however, its peak drug concentration was lower compared to the 24-gauge spinal needle. For cesarean section anesthetization, the required MLAD of ropivacaine when using a real-time UG 26-gauge spinal needle is significantly greater than that with a 24-gauge needle. The spinal needle diameter influences ropivacaine's MLAD by markedly affecting its diffusion rate within the spinal canal.

Micro-computed tomography evaluation of minimally invasive root canal preparation in 3D-printed C-shaped canal.

This study aimed to evaluate and compare the shaping abilities and minimum dentin thickness of minimally invasive rotary instruments via micro-computed tomography. Twelve 3D-printed C-shaped canal models from a mandibular molar were divided into two groups, and root canals were prepared with either XP-endo Rise (XR) or TruNatomy (TN) systems. Pre- and post-preparation evaluations included canal volume, prepared area and minimum dentin thickness. No significant differences were found in canal volume change (XR: 22.66 ± 4.28%, TN: 23.02 ± 5.10%), prepared canal area (XR: 31.86 ± 10.72%, TN: 30.26 ± 11.59%) and minimum dentin thickness (XR: 0.30 ± 0.05 mm, TN: 0.28 ± 0.05 mm) between groups (p > 0.05). The canal volume change in the middle third was significantly higher than that in the coronal and apical thirds (p < 0.05) in both groups. In conclusion, XR demonstrated comparable shaping abilities and minimum dentin thickness to TN in preparing 3D-printed C-shaped canals.

Epley Maneuver Skills in Primary Care: 3D Semicircular Canal Models for Self-Learning.

Posterior canal-type benign paroxysmal positional vertigo (BPPV) is commonly treated using the Epley maneuver; however, the maneuver's use in primary care is limited by insufficient expertise. Therefore, this study aimed to evaluate the efficacy of a three-dimensional (3D) semicircular canal model as a self-learning tool for primary care physicians to improve their Epley maneuver technique. Thirty-one participants (18 family physicians, seven residents, and six medical students) performed the Dix-Hallpike maneuver on a nursing manikin, followed by the Epley maneuver on the covered 3D models before and after a 5-minute self-study period with the uncovered 3D model. We measured the number of moved beads from posterior canal into the utricle of the 3D model, time spent on the Epley maneuver, and head suspension angle of the Dix-Hallpike maneuver. Preintervention performance was divided into a skilled group (n=7) that could move almost all the beads and an unskilled group (n=24) that could move a few beads. Postintervention, the unskilled group members significantly improved their skill: The average moved beads increased from 0.35 to 8.00, maneuver time from 26.1 to 35.8 seconds, and head suspension angle from 10.3° to 16.4°. Most participants recognized the importance of correct positioning and spent adequate time. The 3D model was effective as a self-learning tool for improving Epley maneuver performance, particularly for less experienced practitioners. This approach could bridge the gap between evidence and practice in primary care for BPPV treatment, enhancing patient outcomes and reducing the need for specialist referrals.

Application of Sponge City Ecological Landscape Design in Residential District

In response to the escalating challenges posed by rapid urbanization, this article conducts a comprehensive exploration of innovative models for urban water management. Through a comparative analysis, we delve into the principles, methodologies, and potential outcomes of three prominent models: the Sustainable Urban Drainage Systems (SUDS), Water-Sensitive City Model (WSUD), and Depression-Infiltration Canal System Model. Each model offers a unique perspective on addressing urban water challenges, emphasizing sustainability, adaptability, and environmental protection. The SUDS model emphasizes replicating natural ecological drainage systems to mitigate urban waterlogging, enhance water quality, and promote sustainable water management practices. Incorporating green infrastructure, natural ecological restoration, and community participation, the WSUD model integrates various aspects of water management to achieve effective utilization and recycling of water resources while enhancing urban resilience. This paper is helpful to promote a more sustainable and flexible future.

Localized Canal Development Model Based on Titled Landscapes on the Grand Canal, Hangzhou Section, China

After the decline of water transportation along the Grand Canal, the integration of urban development and the preservation of cultural heritage along the canal has become imperative. This paper takes the titled landscape as its research perspective and investigates the cultural significance of the canal through its historical, spatial, artistic, and spiritual dimensions, identifying the “Ten Canal Scenes” (TCS) that encapsulate both the canal’s heritage and the unique characteristics of Hangzhou, with the aim of establishing notable urban cultural landmarks. Archival analysis, average nearest neighbor (ANN) analysis, nuclear density analysis, and clustering of resource sites are first used to identify cultural landscape features. Evaluation and decision-making techniques are then used to comprehensively assess and categorize the conservation and utilization value for the TCS based on the value evaluation framework. Finally, it proposes strategies for enhancing the comprehensive values of titled landscapes and addressing socio-economic and cultural dimensions. These efforts seek to reconcile the preservation of the canal’s cultural heritage with the ongoing regeneration and development of the city and propose references for a localized canal development model based on titled landscapes.

Modeling Reliability Analysis for the Branch-Based Irrigation Water Demands Due to Uncertainties in the Measured Surface Runoff

This study aims to model the uncertainty and reliability quantification of estimating the planning irrigation water demands in the multi-canal irrigation zone, named the RA_IWD_Canal model. The proposed RA_IWD_Canal could estimate the zone-based and branch-based water demands and quantify their uncertainties and reliabilities via the weighted frequency quantile curves. The historical planning irrigation water demands and measured surface runoff from 2019 to 2024 in the Zhudong irrigation zone are utilized in the model development and application. Using the proposed RA_IWD_Canal model, the estimated branch-based irrigation water demands exhibit a significant variation (on average, from 0.02 m3/s to 1.7 m3/s) in time and space attributed to uncertainties in the historical gauged surface runoff. Also, the Zhudong Canal zone is demonstrated to be sufficiently supplied irrigation water subject to existing introduced water demands with a high reliability of 0.85; instead, the associated branches have considerable difficulty achieving the expected irrigation efficiency based on the desired water requirements with low reliability (nearly 0.25). To keep all branches in the irrigation zone consistent in irrigation efficiency, the probabilistic-based water demands could be introduced via the proposed RA_IWD_Canal model with the desired reliability.

Presence and distribution of voids after using the single cone obturation technique with different sealer placement methods in canals with an isthmus

Background/purposeThe obturation of canals with irregular structures is still a challenge for single cone obturation technique (SC). The purpose of this study was to evaluate the presence and distribution of voids using SC with different sealer placement methods in the canal with a simulated band-shaped isthmus. Materials and methods3D-printed root canal models with band-shaped isthmuses were randomly divided into four groups according to different obturation methods. Group 1: sealer placement by single cone passively (SCP); Group 2: bi-directional spiral-supported sealer placement (BS); Group 3: ultrasound-supported sealer placement (U). Group 4: vertical compaction obturation (VC). In each group, 10 of 14 models were sliced and the remaining four were scanned by micro-CT. The percentage area of voids (PAV) and the percentage volume of voids (PVV) of fillings were calculated. ResultsAt all slice levels, using BS and U to support sealer placement reduced voids with an average PAV of 21%, and in the VC and SCP groups were 33% and 45% respectively. Based on the micro-CT scans, nearly half of the porosity decreased by the BS and ultrasound in the isthmus with PVV of 25% and 29% respectively, compared with 46% in the SCP group. However, in the main canal, when the PVV was 22% in the SCP group, the porosity decreased to 14% in the U group and 18% in the BS group. ConclusionBi-directional spiral or ultrasound-supported sealer placement can improve the performance of single cone obturation in canals with an isthmus.

Comprehensive mathematical model for efficient and robust control of irrigation canals

Linear control-oriented models are important to represent canal dynamics for designing controllers. This study focuses on hydraulic control structure (gate) modelling to address the complex interdependent behavior inherent in irrigation canals. A comprehensive mathematical model that incorporates the water level with gate-opening to model discharge is introduced for single and multiple canal pool scenarios. The proposed model captures the hydraulic coupling within and among canal pools, a key finding. The model is evaluated extensively under uniform and non-uniform flows across three distinct canals, highlighting the model's applicability to various systems. The uncertainty inherent within the nominal model is also assessed for varying operating conditions and hydraulic parameters. The proposed model is compared with the existing and the Saint-Venant (SV) model, showing improved accuracy in water-level predictions. This advancement in hydraulic modelling contributes to adaptable canal models essential in developing robust controllers to enhance water management in irrigation canals.

Irrigant dynamics of a back-to-back double side-vented needle in root canals with various tapers: a computational fluid dynamics study

Understanding the apical pressure and irrigant flow patterns in root canals is crucial for safe and effective irrigation. Therefore, this study aimed to assess the flow characteristics of irrigants in root canal models with varying tapers during final irrigation by employing various needle designs, including a back-to-back double-side-vented needle, through computational fluid dynamics. The root canal model was configured as a closed geometrical cone with a simulated apical zone (size 30) and features tapers of 4%, 6%, and 8%. Three needle types—open-ended needle (OEN), single side-vented needle (SSVN), and double side-vented needle (DSVN)—were investigated. The results indicated that for the 4% taper models, the open-ended needle generated the maximum apical pressure, followed by the double side-vented needle and the single side-vented needle. However, in the 6% and 8% tapering root canal models, the double-side-vented needle applied the lowest maximum apical pressure. Consequently, the DSVN can pose a risk for irrigant extrusion in minimally prepared canals due to heightened apical pressure. In wider canals, the DSVN exhibited lower apical pressure. The maximum irrigant replacement was observed with OEN compared to that of the closed-ended group for both flow rates. Additionally, compared with OENs, closed-ended needles exhibited nonuniform and lower shear wall stress.

Phase-locked µPIV analysis of flow dynamics in a simulated root canal with different laser-activated irrigations.

To measure the dynamic characteristics of the flow field in a complex root canal model activated by two laser-activated irrigation (LAI) modalities at different activation energy outputs: photon-induced photoacoustic streaming (PIPS) and microshort pulse (MSP). A phase-locked micro-scale Particle Image Velocimetry (µPIV) system was employed to characterise the temporal variations of LAI-induced velocity fields in the root canal following a single laser pulse. The wall shear stress (WSS) in the lateral root canal was subsequently estimated from the phase-averaged velocity fields. Both PIPS and MSP were able to generate the 'breath mode' of the irrigant current under all tested conditions. The transient irrigation flush in the root canal peaked at speeds close to 6 m/s. However, this intense flushing effect persisted for only about 2000 µs (or 3% of a single laser-pulse activation cycle). For MSP, the maximum WSS magnitude was approximately 3.08 Pa at an activation energy of E = 20 mJ/pulse, rising to 9.01 Pa at E = 50 mJ/pulse. In comparison, PIPS elevated the WSS to 10.63 Pa at E = 20 mJ/pulse. Elevating the activation energy can boost the peak flushing velocity and the maximum WSS, thereby enhancing irrigation efficiency. Given the same activation energy, PIPS outperforms MSP. Additionally, increasing the activation frequency may be an effective strategy to improve irrigation performance further.

PERFORMANCE IMPROVEMENT OF TRANSIENT PULSATING FLOW IN ROOT CANAL IRRIGATION AND FLOW MECHANISM ANALYSIS

Inflow conditions dominate the process of root canal irrigation, and the application of pulsating inflow in dentistry is necessary to be explored due to its mass transfer enhancement capability. A prepared root canal model with a 30G side-vented needle is numerically investigated under pulsating inflow with different frequencies and amplitudes. Root canal apical pressure, extending depth, and effective cleaning area are adopted to evaluate the safety, mass transfer capacity, and clean efficiency of the irrigation system. Time-averaged results show that the irrigation performance is improved with pulsating flow maintaining safety. Compared with steady cases, the extending depth and effective cleaning area are increased by up to 43.6% and 11.42%, respectively. Three typical cases with significant improvement are selected for transient analysis. Transient results show that the apical pressure and extending depth have instant response features, while the effective cleaning area has a time-lag response characteristic. It is convinced that the transient characteristic of the system results from the coupling effects of the pulsating effect, instantaneous flow rate, and Coanda effect. The internal flow distribution of root canal system is prompted under the optimal parameters combinations of pulsating conditions, in which mass transfer capacity and clean efficiency are enhanced with guaranteed safety.

Comparative evaluation of cyclic fatigue resistance of thermomechanically treated NiTi rotary instruments in simulated curved canals with two different radii of curvature: An in vitro Study.

This study aimed to compare the effect of heat treatment on the cyclic fatigue resistance of three different nickel-titanium rotary file systems: TruNatomy, HyFlex CM, and NeoEndo flex in simulated curved canals at two different radii of curvatures. A total of 60 NiTi rotary files of three types were used, and the samples were divided into three groups TruNatomy, HyFlex CM, and NeoEndo flex. All the instruments were subjected to cyclic fatigue testing using a stainless steel custom-made canal model with a 60° angle of curvature and two radii of curvature 5 mm and 3 mm; the number of cycles to fracture and length of the fractured segment was measured. The separated instruments were subjected to fractographic analysis under scanning electron microscope. The number of cycles to failure to fracture a file at a 3 mm radius of curvature is significantly less as compared to a 5 mm radius of curvature (HCM > TRN > NE). Within the limitation of the present study, there was a positive correlation between the radius of curvature and fatigue life of NiTi files.

Deep CANALs: a deep learning approach to refining the canalization theory of psychopathology.

Psychedelic therapy has seen a resurgence of interest in the last decade, with promising clinical outcomes for the treatment of a variety of psychopathologies. In response to this success, several theoretical models have been proposed to account for the positive therapeutic effects of psychedelics. One of the more prominent models is "RElaxed Beliefs Under pSychedelics," which proposes that psychedelics act therapeutically by relaxing the strength of maladaptive high-level beliefs encoded in the brain. The more recent "CANAL" model of psychopathology builds on the explanatory framework of RElaxed Beliefs Under pSychedelics by proposing that canalization (the development of overly rigid belief landscapes) may be a primary factor in psychopathology. Here, we make use of learning theory in deep neural networks to develop a series of refinements to the original CANAL model. Our primary theoretical contribution is to disambiguate two separate optimization landscapes underlying belief representation in the brain and describe the unique pathologies which can arise from the canalization of each. Along each dimension, we identify pathologies of either too much or too little canalization, implying that the construct of canalization does not have a simple linear correlation with the presentation of psychopathology. In this expanded paradigm, we demonstrate the ability to make novel predictions regarding what aspects of psychopathology may be amenable to psychedelic therapy, as well as what forms of psychedelic therapy may ultimately be most beneficial for a given individual.

In vitro antibiofilm effect of different irradiation doses in infected root canal model

BackgroundEradication of endodontic biofilms from the infected root canal system is still the main concern in endodontics. In this study, the role of the power density parameter in the efficacy of antimicrobial photodynamic therapy (PDT) with toluidine blue O (TBO) and phycocyanin (PC) activated by a 635 nm diode laser (DL) against Enterococcus faecalis biofilm in the root canal model was investigated. Materials and methodsThe E. faecalis biofilm in the root canal was treated with TBO and PC with different power densities (636, 954, 1273, and 1592 W/cm2). The untreated biofilm represented the control group. After the treatments, the biofilms were analyzed based on the number of colonies per milliliter. ResultsTBO and PC activated with 635 nm DL with a power density of 1592 W/cm2 were more efficient in removing E. faecalis biofilms within the root canals than those with a power density of 636 W/cm2 (p = 0.00). ConclusionThe light power density optimized the bacterial reduction of E. faecalis biofilms in the root canal spaces. These results provide information on the decisive parameters for performing PDT on intracanal biofilms.

Reducing apical voids for intra-canal sealer injection using a modified passive deflation needle.

The aim of the study was to evaluate the ability of a modified passive deflation needle to reduce the apical voids during the intra-canal iRoot SP sealer injection. A modified passive deflation injection needle was designed. Forty 20°-curved and twenty S-shaped single-canal resin block models were allocated into six groups. Each group was mechanically prepared to #25/04 or #25/06 file; then the root canals were injected with iRoot SP sealer using a modified needle or a normal plastic needle. Radiographs were taken to measure the length of apical void in each specimen. Similarly, twenty single-canal extracted premolars were collected and randomly divided into four groups. Each group was prepared to #25/04 or #25/06 file; then the root canals were injected with iRoot SP sealer using a modified needle or a normal plastic needle. Roots were then scanned using micro-computed tomography (micro-CT), and the volume of voids in root canals was analyzed and compared among groups. Statistical analysis demonstrated that the length and the volumetric percentage of voids were much lower in the modified needle group in both resin block root canal models and extract teeth than the normal plastic needle group (P < 0.05). The modified passive deflation needle can efficiently reduce apical voids during the intra-canal iRoot SP sealer injection.

Evaluation the stress distribution in root canals by 3D finite element analysis after the materials used in reattaching the vertically root fractured fragments.

The aim was to evaluate the effect of stress distribution on vertical, horizontal, and oblique forces on the tooth model after reattaching the fragments of the maxillary incisor with vertical root fracture (VRF) using different materials, by 3D finite element analysis (FEA). Tooth with a root canal, spongious, and cortical bone models were designed. VRF was modeled on a tooth with 4 different re-attachment models: Group 1: dual-cure cement (DC)+fiber reinforced composite (FRC), Group 2: DC+polyethylene fiber, Group 3: DC+glass fiber, and Group 4:DC. 100 N force was applied in 3 different directions. Maximum principal stresses (σmax) of dentin, and re-attachment materials were evaluated on colored images. The highest σmax values ​​were on the repair materials under vertical forces for Groups 1 and 4, respectively; Groups 2 and 3 showed similarity. The highest σmax values in repair materials under horizontal and oblique forces were observed in Group 3 however the lowest σmax values in repair materials under oblique and horizontal forces were observed in Group 1. The stress values ​​on repair materials gradually increased respectively starting from horizontal to vertical. As the elasticity modulus of the repair materials increased, the stress values ​​on root dentin increased. Through all force directions, except vertical forces, lower stress values were observed with FRC. The fracture resistance was bigger when using solely FRC or dual-cure resin cement in comparison to fiber-supported designs. Adding polyethylene fiber to re-restorations decreased stress values ​​compared to glass fiber addition. Therefore, when adding fibers, polyethylene fiber will be advantageous.

Effect of curvature on sound propagation in the ear canal.

In this paper, we investigate the effect of the curvature and torsion of the ear canal on its resonance through a comparison between several ear canal models. Utilizing Stinson's ear canal geometries as a reference, we build and analyze several ear canal models using both transmission matrix and numerical methods for the purpose of comparative assessment. A conical transmission unit, which considers visco-thermal effects, is employed for the modeling of the human ear canal. While the transfer matrix and numerical method agree well for a straight axis model, this simplification results in up to 20% deviation from a curved canal. We propose the curve twist ratio as a metric to quantify the influence of curvature on the ear canal and find that our proposed metric can effectively express the error introduced by the simplified straight axis model. Upon this metric, an empirical equation is proposed for incorporating the curvature effect in the transmission matrix method, enabling it to generate comparable results to those of the numerical method, which considers the effect of the curvature and torsion, thus dramatically accelerating computation.

Evaluation of the stress generated during biomechanical preparation with nickel–titanium rotary endodontic file using finite element analysis

Introduction: Adequate biomechanical preparation of root canals is the essence of successful endodontic therapy. Roots with curved canal framework led to endodontic complexity. The hassles in the preparation of such complex canals have prompted the inauguration of nickel–titanium (Ni-Ti) instruments with properties of shape memory and superelasticity. They benefit root canal preparation with causing less aberration, yet intracanal separation due to fatigue remains a concern. The study was intended to evaluate and compare the stresses developed during biomechanical preparation with Ni-Ti rotary file in straight, moderate, and severely curved root canals using finite element analysis (FEA). Materials and Methods: Six real sizes, three-dimensional root models were designed in SolidWorks software with varying angles of curvature (2°–45°), and using the same software, ProTaper Gold F2 rotary file was developed. All the designed root models with the rotary file inserted into each model were subjected to FEA. ANSYS Software (version 17.2 Company, Commonwealth of Pennsylvania, USA) 2015 was used to simulating root canal shaping, and the stresses generated in all the root canal models were observed. Results: Highest mean stress was observed with 45° models which was 235.95 MPa, followed by a 30° simulated model showed 220.36 MPa and least stress of 125.22 MPa was observed with 2° models (P &gt; 0.05). Conclusions: Increased canal curvature has definitely resulted in generation of more amount of stress.

Computational fluid dynamics and artificial neural networks for modelling lined irrigation canals with low‐density polyethylene and cement concrete liners

AbstractThis study numerically investigated the lining effect on the discharges and seepage losses of five reaches which belong to the El‐Sont Canal, Asyut, Egypt, using FLOW‐3D and Slide2 models, respectively. Two lining materials were considered, cement concrete (CC) and CC with low‐density polyethylene (LDPE) film. A cost analysis was performed to explore the feasibility of the proposed lining materials. Moreover, a parametric study was conducted by the Slide2 model to investigate the effect of canal geometry and liner properties on seepage losses. An artificial neural network (ANN) model was developed based on the Slide2 model scenarios to estimate the seepage losses from lined irrigation canals. The results showed that reach the discharge calculated from the FLOW‐3D model increased by 92%–97% and 149%–156%, while the calculated seepage losses from the Slide2 model decreased by 81%–87% and approximately 97% under CC and CC with LDPE film liners, respectively. Cost analysis revealed that the overall cost of CC with LDPE film was higher by 14% than CC. Relying on the importance of saving irrigation water and conveying water to the last reaches, CC with LDPE film is recommended for lining irrigation canals. A parametric study showed that the seepage losses were reduced by more than 96% when the ratio between liner and soil hydraulic conductivities was less than 0.01. A thick liner could maximally decrease the seepage losses by 68%, regardless of the canal geometry. As the developed ANN model showed a close agreement with the Slide2 results with coefficient of determination (R2) and mean squared error values of 0.99 and 0.05, respectively, the ANN model is recommended as a robust and rapid tool for estimating seepage losses from lined irrigation canals.

Metal-Phenolic Network with Pd Nanoparticle Nodes Synergizes Oxidase-Like and Photothermal Properties to Eradicate Oral Polymicrobial Biofilm-Associated Infections.

Designing an effective treatment strategy to combat oral diseases caused by complex polymicrobial biofilms remains a great challenge. Herein, a series of metal-phenolic network with Pd nanoparticle nodes using polyphenols as stabilizers and reducing agents is constructed. Among them, sulfonated lignin-Pd (SLS-Pd) with ultrafine size palladium nanoparticles and broadband near infrared absorption exhibit excellent oxidase-like activity and stable photothermal effect. In vitro experiments demonstrate that the superoxide radical generated by SLS-Pd oxidase-like activity exhibits selective antibacterial effects, while its photothermal effect induced hyperthermia exhibits potent antifungal properties. This difference is further elucidated by RNA-sequencing analysis and all-atom simulation. Moreover, the SLS-Pd-mediated synergistic antimicrobial system exhibits remarkable efficacy in combating various biofilms and polymicrobial biofilms. By establishing a root canal model and an oropharyngeal candidiasis model, the feasibility of the synergistic antimicrobial system in treating oral biofilm-related infections is further validated. This system provides a promising therapeutic approach for polymicrobial biofilm-associated infections in the oral cavity.