Tooth Model Research Articles

Impact of optical fiber-based photo-activation on dental composite polymerization

ObjectivesThe study aimed to introduce a novel two-step optical fiber-based photo-activation of dental resin-based composites (RBCs) for reducing polymerization shrinkage stress (PSS). MethodsProposed protocol design – in the first step, two flexible plastic optical fibers connected to a dental light curing unit (LCU), were used as light guides inserted into the filling to initiate low-irradiance polymerization from within; in the second step, fibers were extracted and remaining voids were filled with RBC, followed by conventional high-irradiance curing to finalize polymerization. Three bulk-fill RBCs were tested (Beautifil-Bulk Restorative, Filtek Bulk-fill Posterior, Tetric PowerFill) using tooth cavity models. Three non-invasive examination techniques were employed: Digital Holographic Interferometry, Infrared Thermography, and Raman spectroscopy for monitoring model deformation, RBC temperature change, and degree of conversion (DC), respectively. A control group (for each examined RBC) underwent conventional photo-activation. ResultsThe experimental protocol significantly reduced model deformation by 15 – 35 %, accompanied by an 18 – 54 % reduction in RBC temperature change, emphasizing the impact of thermal shrinkage on PSS. Real-time measurements of deformation and temperature provided indirect insights into reaction dynamics and illuminated potential mechanisms underlying PSS reduction. After a 24-hour dark-storage period, DC outcomes comparable to conventional curing were observed, affirming the clinical applicability of the method. ConclusionsProtocol involving the use of two 1.5 mm fibers in the first step (300 mW/cm2 x 10 s), followed by a second conventional curing step (1000 mW/cm2 x 10 s), is recommended to achieve the desired PSS reduction, while maintaining adequate DC and ensuring efficient clinical application. Clinical SignificanceObtained PSS reduction offers promise in potentially improving the performance of composite restorations. Additionally, leveraging the flexibility of optical fibers improves light guide approach for restorations on posterior teeth. Meanwhile, implementation in clinical practice is easily achievable by coupling the fibers with commercial dental LCUs using the provided plastic adapter.

Chairside digital design and manufacturing method for children's band and loop space maintainers.

This study proposes a chairside digital design and manufacturing method for band and loop space maintainers and preliminarily validates its clinical feasibility. Clinical cases of 10 children requiring space maintenance caused by premature loss of primary teeth were collected. Intraoral scan data of the affected children were also collected to establish digital models of the missing teeth. Using a pediatric band and loop space maintainer design software developed by our research team, a rapid personalized design of band and loop structures was achieved, and a digital model of an integrated band and loop space maintainer was ultimately generated. A chairside space maintainer was manufactured through metal computer numerical control machining for the experimental group, whereas metal 3D printing in the dental laboratory was used for the control group. A model fitting assessment was conducted for the space maintainers of both groups, and senior pediatric dental experts were invited to evaluate the clinical feasibility of the space maintainers with regard to fit and stability using the visual analogue scale scoring system. Statistical analysis was also performed. The time spent in designing and manufacturing the 10 space maintainers of the experimental group was all less than 1 h. Statistical analysis of expert ratings showed that the experimental group outperformed the control group with regard to fit and stability. Both types of space maintainers met clinical requirements. The chairside digital design and manufacturing method for pediatric band and loop space maintainers proposed in this study can achieve same-day fitting of space maintainers at the first appointment, demonstrating good clinical feasibility and significant potential for clinical application.

Theoretical and experimental investigation of contact wear of three crowned teeth with angular misalignment

Gear couplings are usually used under misalignment conditions, and the load-carrying capacity decreases as the misalignment angle increases. In order to improve the contact and wear performance of crowned tooth at high misalignment angle, this study investigates the forming mechanism of crowned tooth, and based on the circular hobbing method, proposes two forming methods, namely, elliptical hobbing and surface modification, and the mathematical models of tooth with high precision are established respectively. The contact characteristics and wear mechanism of three crowned teeth are studied by experiment and theory. The results show that the wear performance and operation stability of crowned teeth with elliptical hobbing and modification are far better too circular, and the performance after modification is the best.

Effects of fissure length and angle on the fracture modes of 3D printed teeth model: Insights from DIC-based fracture tests and meshless numerical simulations

To investigate the influences of teeth fissure properties on their failure modes, 3D Printing technology is used to prepare the teeth models. The strain distributions of the teeth model surfaces at each moment of the loading processes are obtained by the DIC technique. And the progressive failure processes as well as the stress distributions of the teeth models are simulated by the improved Smoothed Particle Hydrodynamics (SPH) Method. Experimental results show that under the action of the steel ball, the teeth models mainly produce two types of cracks: The tensile cracks along the pre-existing fissures and the shear cracks along both sides of the teeth model. The existence of prefabricated fissures greatly reduces the peak strength of the teeth models. Compared with the circumstances containing no pre-existing fissures, the peak strength of d = 1 cm, d = 2 cm and d = 3 cm decreases by 22.33%, 31.79% and 18.94%, respectively, and the peak strength of θ = 30°, θ = 45°, θ = 60° decreases by 10.78%, 44.01% and 34.3%, respectively. Numerical results show that the initiations of tensile cracks are induced by the high tensile stress concentrations at the pre-existing fissure tips, while the shear cracks are caused by the high tensile stress concentrations in the low tensile stress concentration areas after the initiation of tensile cracks. The research results can provide some references for the understandings of teeth failure mechanisms as well as the applications of SPH method into teeth crack propagation simulations.

Versatility of copper-iron bimetallic nanoparticles fabricated using Hibiscus rosa-sinensis flower phytochemicals: various enzymes inhibition, antibiofilm effect, chromium reduction and dyes removal.

Bimetallic nanoparticles (NPs) are considered superior in terms of stability and function with respect to its monometallic counterparts. Hence, in the present study Hibiscus rosa-sinensis flower extract was used to synthesis copper-iron bimetallic nanoparticles (HF-FCNPs). HF-FCNPs was characterized and its applications (biological and environmental) were determined. HF-FCNPs were spherical in shape with high percentage of copper inducted into the NPs. HF-FCNPs inhibited mammalian glucosidases [maltase (IC50: 548.71 ± 61.01µg/mL), sucrase (IC50: 441.34 ± 36.03µg/mL), isomaltase (IC50: 466.37 ± 27.09µg/mL) and glucoamylase (IC50: 403.12 ± 14.03µg/mL)], alpha-amylase (IC50: 16.27 ± 1.73µg/mL) and acetylcholinesterase [AChE (IC50: 0.032 ± 0.004µg/mL)] activities. HF-FCNPs showed competitive inhibition against AChE, maltase and sucrase activities; mixed inhibition against isomaltase and glucoamylase activities; whereas non-competitive inhibition against α-amylase activity. HF-FCNPs showed zone of inhibition of 16 ± 2mm against S. mutans at 100µg/mL concentration. HF-FCNPs inhibited biofilm formation of dental pathogen, S. mutans. SEM and confocal microscopy analysis revealed the disruption of network formation and bacterial cell death induced by HF-FCNPs treatment on tooth model of S. mutans biofilm. HF-FCNPs efficiently removed hexavalent chromium in pH-independent manner and followed first order kinetics. Through Langmuir isotherm fit the qmax (maximum adsorption capacity) was determined to be 62.5mg/g. Further, HF-FCNPs removed both anionic and cationic dyes. Altogether, facile synthesis of HF-FCNPs was accomplished and its biological (enzyme inhibition and antibiofilm activity) and environmental (catalyst to remove pollutants) applications have been understood.

Study on the mechanism of multidimensional cutting teeth and the influencing factors of rock breaking efficiency.

The innovative cutting mechanism of multi-dimensional teeth presents a groundbreaking approach to drill bit design, particularly optimizing drilling efficiency in challenging geological formations such as interlayers and gravel-rich layers within the Changqing Oilfield. Nevertheless, compared to conventional flat-tooth PDC drill bits, several aspects of the cutting mechanism and design parameters for multi-dimensional teeth require further elucidation. This article employs a linear cutting finite element model to establish cutting models for traditional flat teeth and two distinct types of multi-dimensional teeth, designated as Ridge and Benz. It systematically investigates the influence of varying cutting parameters on the effectiveness of rock-crushing within the multi-dimensional tooth-cutting mechanism. This study conducts laboratory-based single-tooth rock-crushing experiments to validate the numerical simulation results. Furthermore, applying principles derived from soil plastic mechanics contrasts the stress states experienced by rocks during the rock-crushing process between multi-dimensional teeth and conventional flat teeth, shedding light on the rock-crushing mechanism employed by multi-dimensional teeth. This research categorizes PDC cutting teeth on the drill bit into two groups: those near the center and those near the outer shoulder. A linear cutting model for teeth positioned near the outer shoulder is developed to analyze the impacts of different rake angles, side clearance angles, and welding errors on the tooth helix angle and the rock-crushing efficiency of the Benz tooth. This comprehensive study is a valuable reference for tailored drill bit design and holds potential for publication in a prestigious scientific journal.

IOTeeth

While occlusal diseases - the main cause of tooth loss -- significantly impact patients' teeth and well-being, they are the most underdiagnosed dental diseases nowadays. Experiencing occlusal diseases could result in difficulties in eating, speaking, and chronicle headaches, ultimately impacting patients' quality of life. Although attempts have been made to develop sensing systems for teeth activity monitoring, solutions that support sufficient sensing resolution for occlusal monitoring are missing. To fill that gap, this paper presents IOTeeth, a cost-effective and automated intra-oral sensing system for continuous and fine-grained monitoring of occlusal diseases. The IOTeeth system includes an intra-oral piezoelectric-based sensing array integrated into a dental retainer platform to support reliable occlusal disease recognition. IOTeeth focuses on biting and grinding activities from the canines and front teeth, which contain essential information of occlusion. IOTeeth's intra-oral wearable collects signals from the sensors and fetches them into a lightweight and robust deep learning model called Physioaware Attention Network (PAN Net) for occlusal disease recognition. We evaluate IOTeeth with 12 articulator teeth models from dental clinic patients. Evaluation results show an F1 score of 0.97 for activity recognition with leave-one-out validation and an average F1 score of 0.92 for dental disease recognition for different activities with leave-one-out validation.

Grey Wolf Optimizer with Behavior Considerations and Dimensional Learning in Three-Dimensional Tooth Model Reconstruction.

Three-dimensional registration with the affine transform is one of the most important steps in 3D reconstruction. In this paper, the modified grey wolf optimizer with behavior considerations and dimensional learning (BCDL-GWO) algorithm as a registration method is introduced. To refine the 3D registration result, we incorporate the iterative closet point (ICP). The BCDL-GWO with ICP method is implemented on the scanned commercial orthodontic tooth and regular tooth models. Since this is a registration from multi-views of optical images, the hierarchical structure is implemented. According to the results for both models, the proposed algorithm produces high-quality 3D visualization images with the smallest mean squared error of about 7.2186 and 7.3999 μm2, respectively. Our results are compared with the statistical randomization-based particle swarm optimization (SR-PSO). The results show that the BCDL-GWO with ICP is better than those from the SR-PSO. However, the computational complexities of both methods are similar.

Stress Distribution on Prepared Tooth With Shoulder and Radial Shoulder Margin to Receive Crowns of Three Different Materials: A Finite Element Analysis.

Aim and background This study aims to determine the stress distribution on the prepared tooth at the margins with shoulder and radial shoulder finish lines when an occlusal load of 300N was applied to ceramic, zirconia, and polyether ether ketone (PEEK) crowns. Materials and methods Six models of mandibular first molar teeth were fabricated. The tooth models were subdivided into two groups with shoulder and radial shoulder margins, respectively (n = 18). The teeth were restored with three different prosthetic crown materials (ceramic, zirconia, and PEEK). To simulate the typical forces experienced by a prosthetic crown material in a lower posterior tooth during chewing and biting, an occlusal load of 300N was applied to each of the samples, and the maximum principal stress (Pmax) and von Mises stress were calculated, respectively. These samples were then compared and evaluated to determine the material best suited as a prosthetic crown material of choice for a lower posterior tooth. Results Among the materials used, the maximum principal stress value was the least in PEEK crowns. The von Mises stress value was highest for the zirconia crown with shoulder margin and was least for the PEEK crown with a similar margin. Conclusion PEEK as a crown material was found to be a better choice for lower posterior teeth as there was the least maximum principal stress at the margin, irrespective of either shoulder or radial shoulder finish line used.

Accuracy of maxillary full-arch digital impressions of tooth and implant models made by two intraoral scanners.

Limited studies are available on the accuracy of intraoral scanners (IOSs) for full-arch implant and tooth models. This study aimed to assess the accuracy of maxillary full-arch digital impressions of tooth and implant models made by two IOSs. This in vitro, experimental study was conducted on two maxillary dentiform models: one with six prepared natural teethand the other with six implants at the site of canine, first premolar, and first molar teeth, bilaterally. A highly accurate industrial scanner was used for actual measurements on the models that served as the reference scan. TS (Trios3) and CO (CEREC Omnicam) IOSs were then used to scan each model 10 times according to the manufacturer's instructions. All scans were saved in STL format. The GOM Inspect software was used according to the best-fit algorithm to compare the accuracy of measurements in the groups with the reference scan. The trueness and precision were calculated. Statistical analyses were carried out using SPSS by one-way analysis of varianceand t-test (α = .05). TS showed a significantly higher trueness than CO for both tooth and implant models (p < .05). TS also revealed significantly higher precision than CO for the tooth model; however, the difference in precision for the implant model was not significant between the two IOSs (p > .05). TS showed higher accuracy than CO in both tooth and implant models.

Composite Restoration Design Effect During Curing and Chewing.

The purpose of this work is to observe the effect of the cavity design of the direct composite restoration on a real case of the patient's tooth structures after applying his mandibular kinematics with finite element analysis. Four complex maxillomandibular models of teeth 17 and 47 were constructed from the patient's cone-beam acquisition and the patient's kinematic data recorded with Modjaw® were added. Different shapes and sizes of mesio-occluso-distal (M.O.D.) composite restorations were simulated, including the polymerization shrinkage of this material. Finite element analyses were used to observe the Von Mises stresses occurring during polymerization and mastication. The stresses were observed at the cavity margin and the amplitude of the stresses was higher when the enamel volume was lower. The reduction in occlusal enamel volume with the open-angle vestibular and palatal walls resulted in a greater increase in stresses observed on the structures. The occlusal enamel is the area that bears the maximum masticatory stress, the loss of this enamel volume generates a much greater concentration of stress on the underlying structures. It is important to preserve as much enamel tissue as possible when designing a cavity for a direct composite restoration.

Calculation of Magnetic Losses with Non-Uniform Distribution of Magnetic Induction in the Stator Tooth of a Switched Reluctance Motor

The aim of this study is to investigate and determine the effect of accounting for the non-uniform distribution of magnetic induction (by detailing the stator tooth model) on the calculation results of magnetic losses in the stator teeth of a switched reluctance motor in quasi-steady-state modes. To achieve this goal, dependencies of phase flux linkage, electromagnetic torque of the motor, and additionally, dependencies of the root mean square values of magnetic inductions in stator tooth elements on the rotor angle and current have been determined using the finite element method. An investigation of dynamic modes of the switched reluctance motor based on an improved simulation model has been conducted at various values of constant load torque. Dependencies of magnetic inductions over time for each stator tooth element for the studied quasi-steady-state operating modes have been obtained. Magnetic losses have been calculated, taking into account the maxima of the temporal dependencies of root mean square values of magnetic induction in stator tooth elements. The most important outcome is a quantitative assessment of the influence of the non-uniform distribution of magnetic induction on the calculated value of magnetic losses based on the detailing of the stator tooth model in the operational modes of the switched reluctance motor compared to the traditional approach. The significance of the work lies in developing an approach to refining the calculation of magnetic losses by considering local saturation in the magnetic circuit during the operation of the switched reluctance motor.

The impact of administration of Annona muricata leaf on estrogen and progesterone functions following mercury-induced toxicity in adult female Wistar rats

Environmental toxicants have been linked to female reproductive dysfunction resulting from oxidative stress. The study assesses the impact of ethanolic leaf extract of Annona muricata (EAM) on ovarian and uterine function following mercury-induced toxicity in female Wistar rats. The study involved 40 female Wistar rats, each weighing 114–156g, divided into eight groups of five animals each. Group A received feed and water only; group B received 500 mg/kg of EAM only; and group C received 25 mg/kg of mercury chloride (HgCl2). Groups D and E received 100 mg/kg and 500 mg/kg of EAM for 4 weeks and were treated with 25 mg/kg of HgCl2, respectively. Group F received 500 mg/kg of EAM for 4 weeks and treated immediately with co-administrstion of 25 mg/kg of HgCl2 and 500 mg/kg of EAM for 4 weeks. Groups G and H received 25 mg/kg of HgCl2 and received 100 mg/kg and 500 mg/kg of EAM for 4 weeks, respectively. Progesterone amd Estrogen levels were measured at the end of the administration. The data was analysed using SPSS version 25, with inferential statistics performed, and significant values were set at p≤0.05. Administration of mercury resulted in a decreased level of oestrogen, and progesterone. EAM treatments resulted in statistically significant increased levels of progesteron in groups E, F, G and H; group D also showed an increase, though not statistically significant. Estrogen levels were increased in groups F, G and H, but groups D and E showed a decrease in estrogen levels, though not statistically significant. The study reveals that EAM enhances female reproductive hormonal levels and may turn out into a potential capable of reversing or preventing female infertility linked to mercury chloride toxicity.

The stress distribution of a primary molar tooth restored with stainless steel crown using different luting cements

BackgroundThe aim of this study is to evaluate the stress distributions of a primary molar tooth restored with a stainless steel crown (SSC) using resin and glass ionomer luting cements by Finite Element Analysis (FEA).MethodsOriginal DICOM data of a primary molar was used to create a 3D model. One model was prepared as a tooth model with SSC. A 30 μm cement layer was used in model. Two different luting cements were tested in the study: self-cure adhesive resin cement, and glass ionomer cement. Vertical and oblique loads of 330 N were applied to simulate maximum bite force and lateral forces in the occlusal contact areas of the models. Maximum von Mises stress values in the models were evaluated as MPa.ResultsThe maximum von Mises stress value was observed in the force application and general occlusal contact areas for all models. The maximum von Mises stress values were higher in the tooth model with SSC using self-cure adhesive resin cement (478.09 MPa and 214.62 MPa) than in the tooth model with SSC using glass ionomer cement (220.06 MPa and 198.72 MPa) in both vertical and oblique loading, respectively.ConclusionsDepending on the magnitude of the bite force on the SSC, fracture of the luting cement materials could occur if the stress exceeds the endurance limit of the luting cement. Cementation with glass ionomer cement may help to reduce stress levels in SSC restorations of primary molars in children.

Accuracy of Dental Restorations Fabricated Using Milling vs 3D-Printed Molds: A Pilot Study.

To compare the accuracy of 12 different dental restorations fabricated with milling or 3D-printed molds and robotically controlled casting. Twelve dental restorations (11 inlays and onlays and 1 crown) were made per restoration type, one per each of the 12 different teeth models (total of 24 restorations). On each tooth preparation, two restorations were manufactured using different CAD/ CAM techniques: (1) milling and (2) robotically controlled casting and 3D-printed molds. In addition, twolayer restorations were manufactured with 3D-printed molds. The marginal and internal gaps were evaluated at 120 points per restoration based on micro-CT 3D imaging. Internal gaps were evaluated using a replica technique with silicone. Median values (interquartile ranges) for marginal gaps, middle internal gaps, and central internal gaps were significantly lower for 3D-printed mold restorations (44.3 [65.4] μm, 95.4 [96.2] μm, and 104.6 [78.1] μm) compared to milled restorations (58.4 [93] μm, 145.9 [85.8] μm, and 138.6 [65.7] μm). Internal gaps in the 3D-printed mold group were 6% to 51% smaller than in the milled group. The accuracy of restorations fabricated with 3D-printed molds may be preferable compared to milled restorations, except in the case of crown restoration. However, additional studies with a larger number of samples and different types of restorations are needed to confirm the results.

Precise control of digital dental unit to reduce aerosol and splatter production: new challenges for future epidemics

BackgroundDuring dental procedures, critical parameters, such as cooling condition, speed of the rotary dental turbine (handpiece), and distance and angle from pollution sources, were evaluated for transmission risk of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), simulated by spiking in a plasmid encoding a modified viral spike protein, HexaPro (S6P), in droplets and aerosols.MethodsTo simulate routine operation in dental clinics, dental procedures were conducted on a dental manikin within a digital dental unit, incorporating different dental handpiece speeds and cooling conditions. The tooth model was immersed in Coomassie brilliant blue dye and was pre-coated with 100 μL water spiked-in with S6P-encoding plasmid. Furthermore, the manikin was surrounded by filter papers and Petri dishes positioned at different distances and angles. Subsequently, the filter papers and Petri dishes were collected to evaluate the aerosol splash points and the viral load of S6P-encoding plasmid in aerosols and splatters generated during the dental procedure.ResultsAerosol splashing generated a localized pollution area extended up to 60 cm, with heightened contamination risks concentrated within a 30 cm radius. Significant differences in aerosol splash points and viral load by different turbine handpiece speeds under any cooling condition (P < 0.05) were detected. The highest level of aerosol splash points and viral load were observed when the handpiece speed was set at 40,000 rpm. Conversely, the lowest level of aerosol splash point and viral load were found at a handpiece speed of 10,000 rpm. Moreover, the aerosol splash points with higher viral load were more prominent in the positions of the operator and assistant compared to other positions. Additionally, the position of the operator exhibited the highest viral load among all positions.ConclusionsTo minimize the spread of aerosol and virus in clinics, dentists are supposed to adopt the minimal viable speed of a dental handpiece with limited cooling water during dental procedures. In addition, comprehensive personal protective equipment is necessary for both dental providers and dental assistants.

Use of 3D printing models for donor tooth extraction in autotransplantation cases

ObjectiveTo clarify whether the 3D printing model has auxiliary functions in toto extraction of donor tooth in autotransplantation cases.MethodsTwo hundred and sixty patients who would have operation of ATT were divided into two groups. In group 1, determination of the tooth extraction in toto was predicted only according to the clinical and imaging examination. In group 2, the prediction was performed according to the clinical and imaging examination as well as the 3D model of donor tooth pre-extraction. A prespctive clinical study was designed on intra-group comparison between the predicted and actual donor teeth situation when extraction in cases of ATT. The consistent rate for the predicted results and the actual results were compared with the two groups.ResultsA remarkable difference was observed between the predicted results and the actual results of tooth positions and root numbers in group without model (p < 0,05). The consistency rate of the model group (94.62%) was significantly higher than that of non 3D model group (86.15%) (p = 0.034).ConclusionThe 3D printing model for the donor tooth is helpful for dentists to predict the accuracy of toto extraction of donor teeth in autotransplantation cases.

Research on the dynamic performance of double-helical planetary gear transmission under friction and wear

In this paper, the main research is to investigate the effects of mechanical, friction, temperature, and tooth wear on the dynamic performance of a double-helical planetary gear transmission system. To achieve this, a new lumped parameters model is presented, which combines dynamics and lubrication. The model allows for the study of excitation effects and considers various parameters such as material, lubricating oil, and working conditions. By proposing a multi-source excitation calculation method, the paper provides a novel approach that has not been reported in the existing literature. Additionally, the paper establishes a tooth wear model and a lubrication model for the double-helical gear pair. It shows that under constant torque, the displacement and acceleration amplitudes of the system initially decrease and then increase with increasing input speed. Under constant speed, the displacement and acceleration amplitudes increase with increasing torque. Amplitudes decrease during running-in wear, increase in stable wear, and rapidly increase in severe wear. Boundary lubrication minimizes vibration, while elastohydrodynamic lubrication maximizes it.

Evaluation of micromotion in multirooted root analogue implants embedded in synthetic bone blocks: an in vitro study

BackgroundWhile conventional threaded implants (TI) have proven to be effective for replacing missing teeth, they have certain limitations in terms of diameter, length, and emergence profile when compared to customised root analogue implants (RAI). To further investigate the potential benefits of RAIs, the aim of this study was to experimentally evaluate the micromotion of RAIs compared to TIs.MethodsA 3D model of tooth 47 (mandibular right second molar) was segmented from an existing cone beam computed tomography (CBCT), and a RAI was designed based on this model. Four RAI subgroups were fabricated as follows: 3D-printed titanium (PT), 3D-printed zirconia (PZ), milled titanium (MT), milled zirconia (MZ), each with a sample size of n = 5. Additionally, two TI subgroups (B11 and C11) were used as control, each with a sample size of n = 5. All samples were embedded in polyurethane foam artificial bone blocks and subjected to load application using a self-developed biomechanical Hexapod Measurement System. Micromotion was quantified by analysing the load/displacement curves.ResultsThere were no statistically significant differences in displacement in Z-axis (the loading direction) between the RAI group and the TI group. However, within the RAI subgroups, PZ exhibited significantly higher displacement values compared to the other subgroups (p < 0.05). In terms of the overall total displacement, the RAI group showed a statistically significant higher displacement than the TI group, with mean displacement values of 96.5 µm and 55.8 µm for the RAI and TI groups, respectively.ConclusionsThe RAI demonstrated promising biomechanical behaviour, with micromotion values falling within the physiological limits. However, their performance is less predictable due to varying anatomical designs.

Comparison of the removal of intracanal medicaments used in regenerative endodontics from root canal system using needle, ultrasonic, sonic, and laser-activated irrigation systems

This study aimed to compare the syringe-needle irrigation (SNI), passive ultrasonic irrigation (PUI), EDDY, and shock wave–enhanced emission photoacoustic streaming (SWEEPS) techniques regarding calcium hydroxide and double antibiotic paste removal from the root canal in regenerative endodontic treatments. Eighty single-rooted human teeth were decoronated and enlarged up to #100 to stimulate the immature tooth model. Root canals were irrigated with 1.5% sodium hypochlorite followed by saline solution according to the regenerative endodontic treatment protocol. Dressed teeth were divided into 2 main groups regarding the used intracanal medicaments. Calcium hydroxide and double antibiotic paste were introduced to the canals, and teeth were stored for 3 weeks. Each medicament group was divided into 4 subgroups according to the activation techniques. Medicaments were removed using a 17% EDTA solution. Teeth were split longitudinally into two parts. The remaining medicaments were evaluated under a stereo microscope with a scoring system. Data were analyzed with the Kruskal-Wallis and Mann-Whitney U tests. Regardless of the used irrigation activation systems, there was no statistically significant difference between the removal of the CH and DAP from the root canal (P>0.05). While SWEEPS had the highest ability regarding the removal of intracanal medicaments, syringe-needle irrigation had the lowest (P<0.05). There was no statistically significant difference between PUI and EDDY (P>0.05). Complete removal of intracanal medicaments could not be achieved with any techniques. SWEEPS technology was more effective in removing intracanal medicaments in regenerative endodontic treatments compared to the sonic and ultrasonic irrigation activation systems.