Planar Space Research Articles

Precision-brace positioner (A modified bracket holding tweezer)

The process of orthodontic bonding should be accurate for excellent clinical outcome. For clinicians and postgraduate residents, accurately determining the center of the clinical crown—where the bracket should ideally be placed to express the built-in prescription—poses a challenge. Typically, gauges are used to place the bracket accurately both in horizontal and vertical plane of space. In an effort to streamline the bonding procedure and eliminate the need for drawing lines on the teeth, we have enhanced the bracket-holding tweezer. This modification involves incorporating a diode laser, aiming to simplify the assessment of the clinical crown's center for clinicians, ultimately contributing to a more precise bonding procedure.

Clustering in point processes on linear networks using nearest neighbour volumes

This study introduces a novel method specifically designed to detect clusters of points within linear networks. This method extends a classification approach used for point processes in spatial contexts. Unlike traditional methods that operate on planar spaces, our approach adapts to the unique geometric challenges of linear networks, where classical properties of point processes are altered, and intuitive data visualisation becomes more complex. Our method utilises the distribution of the Kth nearest neighbour volumes, extending planar-based clustering techniques to identify regions of increased point density within a network. This approach is particularly effective for distinguishing overlapping Poisson processes within the same linear network. We demonstrate the practical utility of our method through applications to road traffic accident data from two Colombian cities, Bogota and Medellin. Our results reveal distinct clusters of high-density points in road segments where severe traffic accidents (resulting in injuries or fatalities) are most likely to occur, highlighting areas of increased risk. These clusters were primarily located on major arterial roads with high traffic volumes. In contrast, low-density points corresponded to areas with fewer accidents, likely due to lower traffic flow or other mitigating factors. Our findings provide valuable insights for urban planning and road safety management.

THE BEREZIN TRANSFORMATION ON L 2 (U+)

Let L 2 a (U+) be the Bergman space of the upper half plane U+. In this paper, we consider the integral operator H from L 2 (U+) into L 2 (U+) defined by (Hf)(w) = fe(w) = Z U+ f(s)|dw(s)| 2 dAe(s), w ∈ U+, where dw(s) = 1 √ π w + i w − i (−2i)Im w (s + w) 2 and dAe is the area measure on U+. We refer the map H as the Berezin transformation defined on L 2 (U+). We have derived various algebraic properties of the operator and showed that ||H|| ≤ 3π 4 considered as an operator on L 2 a (U+).

Analytical solutions of ray-tracing equations in generalized elliptical anisotropy

Ray-tracing in anisotropic media is pivotal for interpreting observed seismic data and creating high-resolution images of subsurface structures, which are crucial in exploration geophysics. Elliptical anisotropy, a simplified model that approximates a transversely isotropic medium, is particularly relevant for geologic settings such as shale formations or stressed sedimentary layers where directional dependencies of seismic velocities are pronounced. We develop an analytical solution of the ray-tracing equations for a 2D inhomogeneous and anisotropic medium, where velocities depend elliptically on direction and increase linearly with depth — a scenario frequently encountered in stratified geologic formations. Unlike previous studies that assume constant ellipticity throughout the medium, our approach allows for variations in ellipticity, providing a more flexible and realistic representation of subsurface anisotropy. The phase velocities along the x- and z-axes are not necessarily multiples of each other at every point, offering a generalized version of the elliptical anisotropy. This enhancement may enable more accurate predictions and interpretations of observed seismic data, particularly in complex exploration scenarios. The analytical solution yields expressions for the ray paths and the wavefront normals. By setting the normals of the wavefront at the seismic source point and the location of the seismic source as the initial conditions in phase space, we explore the evolution of these wavefront normal curves across different types of the elliptical anisotropy. Our innovative approach includes plotting the evolution of wavefront normal curves on the generalized momentum coordinate plane of the phase space — that commonly overlooked in traditional models focused only on position coordinates.

Defect detection using spatial spectral entropy for noncontact acoustic inspection method

Inspection of concrete structures is important for maintaining social infrastructure such as tunnels and viaducts. Therefore, noncontact acoustic inspection method using acoustic irradiation induced vibration and a scanning laser Doppler vibrometer (SLDV) has been devised. Since this method uses flexural resonance, it can be said to be an alternative method for a hammering test. Using our method, internal defects of concrete can be detected up to a depth of about 10 cm from the surface of concrete, even at a distance of about 30 m. However, in a closed space such as an underground cavity, the signal-to-noise (S/N) ratio decreases due to reverberation from the surroundings, making it difficult to detect defects compared to open spaces such as viaducts. This problem can be solved by using spatial spectral entropy (SSE), which extends the concept of spectral entropy to the two-dimensional space of the measurement plane. In other words, by SSE analysis, the resonance frequency of both the defect and the SLDV can be detected and separated because of the difference in the spatial distribution characteristics of the vibration velocity spectrum for each the frequency. Therefore, it is possible to detect a defective part even in a place where the S/N ratio is not sufficient.

Inhibition of return in a 3D scene depends on the direction of depth switch between cue and target.

Inhibition of return (IOR) is a phenomenon that reflects slower target detection when the target appears at a previously cued rather than uncued location. In the present study, we investigated the extent to which IOR occurs in three-dimensional (3D) scenes comprising pictorial depth information. Peripheral cues and targets appeared on top of 3D rectangular boxes placed on the surface of a textured ground plane in virtual space. When the target appeared at a farther location than the cue, the magnitude of the IOR effect in the 3D condition remained similar to the values found in the two-dimensional (2D) control condition (IOR was depth-blind). When the target appeared at a nearer location than the cue, the magnitude of the IOR effect was significantly attenuated (IOR was depth-specific). The present findings address inconsistencies in the literature on the effect of depth on IOR and support the notion that visuospatial attention exhibits a near-space advantage even in 3D scenes consisting entirely of pictorial depth information.

A modified protocol merging two published techniques for computer guided zygomatic implants surgery: a technical note

ObjectivesZygomatic implant surgery can be difficult due to the limited intraoperative visibility of the surgical field and the complex anatomy of the zygomatic bone, which could lead to serious complications. This study aims to assess the accuracy of zygomatic implants placement using computer-guided surgical templates.Materials and methodsA total of 13 zygomatic implants were placed in four participants. Double-sleeve drill guides were used with the help of computer-guided surgical templates designed with a lateral window. The accuracy was evaluated by measuring the linear deviations regarding the implants’ platforms and apices’ positions in addition to the angular deviations. Moreover, deviations of both implants from three fixed planes of space were measured.ResultsThe mean linear deviation at platforms was 2.44 mm ± 1.57 and at the apices 2.32 mm ± 1 while the mean angular deviation was 3.6˚ ± 1.92. Differences at the entry points were 0.43 ± 1.79 mm, 0.39 ± 1.12 mm, and − 0.54 ± 2.00 mm from the mid-sagittal, horizontal, and coronal planes respectively. Differences at the exit points were − 0.75 ± 1.25 mm, -0.06 ± 1.09 mm, and 0.63 ± 1.24 mm from the same planes respectively. Within all planes, there was no statistically significant difference.ConclusionGiven the limitations of this study, the use of the computer-guided surgical templates augmented by the double sleeve drill guides allowed favorable control over the tip of the long surgical drill away from vital structures during the zygomatic implant osteotomy. It also allowed control over alveolar crest osteotomy and its placement in a favorable prosthetic position. Overall, this protocol should be considered for further research and improvement to allow more predictable surgical outcomes while preventing the occurrence of complications. Before conducting this study, the protocol was reviewed and approved by the Research Ethical Committee of Faculty of Dentistry, Ain Shams University in meeting no. (105), on 15th of July 2020 with the application no.: (FDASU-RecD072029).

A concurrent learning approach to monocular vision range regulation of leader/follower systems

This paper explores range and bearing angle regulation of a leader–follower using monocular vision. The main challenge is that monocular vision does not directly provide a range measurement. The contribution is a novel concurrent learning (CL) approach, called CL Subtended Angle and Bearing Estimator for Relative pose (CL-SABER), which achieves range regulation without communication, persistency of excitation or known geometry and is demonstrated on a physical, robot platform. A history stack estimates target size which augments the Kalman filter (KF) with a range pseudomeasurement. The target is followed to scale without drift, persistency of excitation requirements, prior knowledge, or additional measurements. Finite excitation is required to achieve parameter convergence and perform steady-state regulation using CL-SABER. Evaluation using simulation and mobile robot experiments in special Euclidean planar space (SE(2)) show that the new method provides stable and consistent range regulation, as demonstrated by the inter-rater reliability, including in noisy and high leader acceleration environments.

Impact of Stabilization Splint Therapy on Orthodontic Diagnosis in Patients with Signs and Symptoms of Temporomandibular Disorder.

The relation between the orthopedic temporomandibular joint (TMJ) instability and temporomandibular disorder (TMD) most commonly remain unrecognized by orthodontists. In this study we aimed to evaluate the dentofacial characteristics and temporomandibular disorder symptomatology of patients with orthopedic instability before and after deprogramming with a stabilization splint. Sixty patients with the signs and symptoms of TMD were assessed using the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and underwent stabilization splint therapy to place the condyles in a more stable musculoskeletal position. The extent of condylar displacement was evaluated using the condylar position indicator (CPI). Sixteen angular and linear hard tissue landmarks were traced and compared from lateral cephalograms taken in the maximum intercuspation (MI) position before, and in the centric relation (CR) position after, the splint therapy. Following the splint therapy, the signs and symptoms of TMD were significantly reduced or completely eliminated in more than 90% of patients. Compared with the values registered before the splint therapy, a significant reduction in the mean values of condylar displacement was observed on both sides of the vertical (p < 0.001), horizontal (p < 0.05), and transverse (p < 0.001) planes of space after the splint therapy. A comparison of pre- and post-splint lateral cephalograms revealed that, following the splint therapy, the mandible moved more posteriorly and rotated in a more clockwise direction. In patients with orthopedic instability and the signs and symptoms of TMD, muscle deprogramming with a stabilization splint therapy is highly recommended to improve the health of the temporomandibular joint and masticatory structures and contribute to a more correct orthodontic diagnosis.

Effect of austenitizing temperature on variant selection of martensite transformation in a 2 GPa grade steel

The correlation of prior austenite grain (PAG) size, mechanical properties, and the variant selection in martensite transformation of a 2 GPa grade automobile steel has been systematically investigated by using a combination of scaning electron microscopy (SEM), electron backscatter diffraction (EBSD), and uniaxial tesile tests. As the austenitizing temperature decreases from 970 °C to 870 °C, the as-quenched microstructure of the studied steel is fully lath martensite. Meanwhile, the average size of PAG is refined from 7.2 ± 3.9 μm to 2.1 ± 1.2 μm, and the volume fraction of high angle grain boundaries (HAGB) is increased from 59.8% to 72.3%, accompanied with an increased number fraction of grains belonging to closely spaced planes (CP) group. With the refinement of the PAGs, the martensitic variant selectivity becomes strong, and the Bain group variant selection discretely transites to the CP group, resulting in a dominate CP group. Consequently, a tensile strength of 2014 ± 33 MPa, a tensile elongtation of 12.9 ± 0.5% and a maximum strength × ductility production of 26.0 ± 1.4 GPa·%, are obtained when the austenitization temperature is at 920 °C.

Gating-Enhanced Hierarchical Structure Learning in Hyperbolic Space and Multi-scale Neighbor Topology Learning in Euclidean Space for Prediction of Microbe-Drug Associations.

Identifying drug-related microbes may help us explore how the microbes affect the functions of drugs by promoting or inhibiting their effects. Most previous methods for the prediction of microbe-drug associations focused on integrating the attributes and topologies of microbe and drug nodes in Euclidean space. The heterogeneous network composed of microbes and drugs has a hierarchical structure, and the hyperbolic space is helpful for reflecting the structure. However, the previous methods did not fully exploit the structure. We propose a multi-space feature learning enhanced microbe-drug association prediction method, MFLP, to fuse the hierarchical structure of microbe and drug nodes in hyperbolic space and the multiscale neighbor topologies in Euclidean space. First, we project the nodes of the microbe-drug heterogeneous network on the sphere in hyperbolic space and then construct a topology which implies hierarchical structure and forms a hierarchical attribute embedding. The node information from multiple types of neighbor nodes with the new topological structure in the tangent plane space of a sphere is aggregated by the designed gating-enhanced hyperbolic graph neural network. Second, the gate at the node feature level is constructed to adaptively fuse the hierarchical features of microbe and drug nodes from two adjacent graph neural encoding layers. Third, multiple neighbor topological embeddings for each microbe and drug node are formed by neighborhood random walks on the microbe-drug heterogeneous network, and they cover neighborhood topologies with multiple scales, respectively. Finally, as each scale of topological embedding contains its specific neighborhood topology, we establish an independent graph convolutional neural network for the topology and form the topological representations of microbe and drug nodes in Euclidean space. The comparison experiments based on cross validation showed that MFLP outperformed several advanced prediction methods, and the ablation experiments verified the effectiveness of MFLP's major innovations. The case studies on three drugs further demonstrated MFLP's ability in being applied to discover potential candidate microbes for the given drugs.

A prospective study comparing intra-operative and postoperative complications in totally extra peritoneal repair vs extended totally extra peritoneal for inguinal hernia

Introduction: Inguinal hernia repair is one of the most common surgical procedures worldwide. Total extra peritoneal repair (TEP) and Extended-TEP (eTEP) are widely used minimally invasive methods. TEP involves creating a space in the preperitoneal plane without entering the abdominal cavity, whereas eTEP extends this approach, allowing for a broader operative field.This study compares the intra-operative and postoperative complications of TEP and eTEP, contributing to the optimisation of inguinal hernia management. Methods: It is a prospective study. A total of 60 patients who underwent TEP and e-TEP for inguinal hernia, who fulfilled the inclusion criteria. Patients were randomised by simple random sampling technique and were divided into two groups of 30 each (group A-TEP and group B-eTEP). Data of both groups were compared and analysed for statistical significance using Chi square test and Student ‘t’ test. Result: The comparative analysis between TEP and eTEP procedures shows no significant differences in demographic parameters. However, eTEP demonstrates significantly shorter operative time and hospital stay, quicker return to work. Both procedures have similar rates of low intra-operative and postoperative complications, indicating comparable safety profiles. Conclusion: Our study suggest that both techniques are associated with low complication rates and good patient outcomes, with eTEP showing potential advantages in terms of pain, recovery and wider access. These findings help to take better surgical decision, to make and helped optimize patient care in inguinal hernia management.

The role of subcutaneous drain in laparotomy patients

Background: In surgical incision wounds, hematoma, serous fluid, and dead space increase the risk of infection because they provide a surface for microbial growth. Subcutaneous drain reduces dead space in the subcutaneous tissue plane, which prevents fluid from accumulating and seroma from forming by removing infectious content, residual effusion, and blood from the wound. This study attempts to determine the efficacy of subcutaneous drain in laparotomy in the management of surgical site infection (SSI). Methods: This prospective study was conducted at the Department of Surgery in various hospitals in Cumilla, Bangladesh. This study includes 150 adult patients aged between 18 to 70 years. A closed subcutaneous suction drain was inserted before the skin was closed in 75 patients at random (drain group), whereas the rest of the 75 patients' subcutaneous suction drains were not kept (no-drain group). Results: The association between comorbidities and SSI in both the drain and no-drain groups were significant, p value &lt;0.001 respectively. SSI was mainly in the group with fewer surgery hours (72.4%). Patients with SSI also have longer hospital stays on average. Conclusions: Patients with SSI have increased morbidity, and those undergoing major procedures are more likely to experience SSI afterwards. The presence of a subcutaneous closed suction drain contributes to reducing SSI.

Augmented Reality as a Tool to Support the Connection Between Reality and Mathematical Knowledge: A Case for Teaching Parallel Relations of Planes in Space

In the 11th−grade Vietnamese Mathematics Curriculum, students learn about parallel relations between planes in space. This is cognitively challenging for many students. Studies have shown difficulties relating to limited spatial imagination and drawing representations. The teacher’s approach also causes difficulties for some students; for example, some teachers do not approach new knowledge from practice. These approaches lead students to learn math only in that class rather than to relate math knowledge to real life, whereas real-life objects can be good tools for illustrating knowledge of spatial geometry. This study uses an action research method using GeoGebra 3D Calculator software to design teaching situations about parallel relations of lines and planes in space. This study was conducted with 40 students in 11th grade in Long An Province, Vietnam. It was found that learning tasks can be designed to help students construct knowledge effectively and overcome difficulties. The results of this research show that AR software for 3D Geometry, in particular GeoGebra, creates a connection between reality and abstract knowledge about the parallel relations of lines and surfaces in space. The research also shows that the application of augmented reality in teaching helps students understand and test hypotheses, eliminate false hypotheses, and build new knowledge about parallel relations effectively.

Total laparoscopic hysterectomy with posterior cul-de-sac obliteration: step-by-step procedures based on precise anatomical landmarks.

Dense adhesion due to severe endometriosis between the posterior cervical peritoneum and the anterior sigmoid or rectum obliterates the cul-de-sac and distorts normal anatomic landmarks. Surgery for endometriosis is associated with severe complications, including ureteral and rectal injuries, as well as voiding dysfunction. It is important to develop the retroperitoneal avascular space based on precise anatomical landmarks to minimize the risk of ureteral, rectal, and hypogastric nerve injuries. We herein report the anatomical highlights and standardized and reproducible surgical steps of total laparoscopic hysterectomy for posterior cul-de-sac obliteration. We approach the patient with posterior cul-de-sac obliteration using the following five steps. Step 1: Preparation (Mobilization of the sigmoid colon and bladder separation from the uterus). Step 2: Development of the lateral pararectal space and identification of the ureter. Step 3: Isolation of the ureter. Step 4: Development of the medial pararectal space and separation of the hypogastric nerve plane. Step 5: Reopening of the pouch of Douglas. Surgeons should recognize the importance of developing the retroperitoneal avascular space based on precise anatomical landmarks, and each surgical step must be reproducible.

Engineering Mn Vacancies to Enhance Ion Kinetics in Layered Manganese Silicate for High-Energy and Durable Intercalation Pseudocapacitance.

Transition metal silicates (TMSs) are potential electrodes for aqueous metal-ion intercalation pseudocapacitors owing to their superior theoretical capacity and high structural stability. However, the narrow interlayer spacing and intrinsic inert basal plane of TMSs lead to sluggish ions and charge transfer, causing an undesirable energy storage performance. Herein, rich Mn vacancies are introduced in layered manganous silicates (M2-xS@FA) to expedite K+ diffusion, while enhancing charge storage capacity and prolonging lifespan. In situ characterizations validate the K+ intercalation pseudocapacitance mechanism with evident crystal structure and valence state variations in M2-xS@FA. Both theoretical calculations and electrochemical experimental evaluations elucidate the imperative role of Mn vacancies in enhancing K+ diffusion kinetics and electron transfer through increased interlayer spacing and activated basal plane. Mn vacancies further boost the charge storage capacity by providing additional K+ storage sites, while simultaneously reinforcing local atomic bonding within M2-xS@FA, thereby augmenting structural stability. The assembled aqueous asymmetric solid-state cell, featuring a M2-xS@FA cathode, demonstrates exceptional power and energy densities (144.08 W h kg-1 at 375.80 W kg-1) and ultralong lifespan (100% capacity retention after 10,000 cycles). This work heralds a paradigm whereby modulating cation vacancies in layered TMSs significantly enhances K+ storage and stability for high-energy intercalation pseudocapacitance.

Three-dimensional analysis of posttreatment tooth movements despite bonded retainers: partI-upper jaw.

Adverse side effects of fixed retainers in terms of unwanted tooth movements have been described for both the upper and lower jaw, but data about the extent and movement patterns for the maxilla are scarce. The purpose of the present retrospective case-control study was to analyze the amount and direction of unwanted tooth movements despite upper bonded retainers as well as to analyze possible predisposing pretreatment- and treatment-related factors. Plaster casts of 1026 patients who completed orthodontic treatment and asubsequent retention phase of 2years were screened for unintentional tooth movements. The study group comprised 57patients with visually obvious tooth movements in the upper jaw, while 57randomly selected patients without visible tooth movements served as control group. For all patients, plaster casts after debonding of multibracket appliance (T1) and after supervised retention (T2) were digitized, and superimposed digitally using astable palatal reference area. Thereafter, translational and rotational movements were measured in all three planes of space. Pretreatment- and treatment-related factors of the study and control groups were compared by χ2 test, exact Fisher test, Mann-Whitney U test, and the T‑test for independent samples. The mean translational movements ranged between 0 and 0.6 mm and the average rotational movements between 0 and 1.3°. Large individual movements up to 2.7 mm translation and 15.9° rotation were seen. Amovement pattern around the Y‑ and Z‑axis with an opposite rotational peak at the canines ("upper twist effect") was identified. Compared to the control group, patients of the study group showed asignificantly smaller intercanine width pretreatment. Also, study group patients presented alarger intercanine expansion and aslightly larger overjet reduction during treatment, and were more often affected by retainer bonding site detachments and wire fractures, but without reaching statistically significance. Upper bonded retainers show asimilar unwanted movement pattern ("twist effect") like the one described for mandibular retainers.

Three-dimensional assessment of low-level laser therapy on orthodontic miniscrew displacement using CBCT: a retrospective study

BackgroundThis study aimed to assess the effect of Low-Level Laser Therapy (LLLT) on sagittal, transverse and vertical Orthodontic miniscrew displacement.Materials and methodsThe study included CBCTs from the records of 12 adult patients who underwent upper first premolar extraction and canine retraction with orthodontic miniscrews for maximum anchorage. The miniscrews on one side received LLL, while the other side served as a control. The Low-Level Laser was applied to assess its effect on the displacement of the miniscrews. The used CBCTs have been taken at two-time points: immediately after miniscrew insertion (T0) and four months after the start of canine retraction (T1) with a total of 24 CBCTs. Miniscrew displacement was assessed by measuring head (HMS) and tail (TMS) displacement to the axial, coronal and mid-sagittal planes on the CBCT at the two time points. Miniscrews displacement (T1-T0) was compared between LLL side and control side. Comparisons were performed using paired samples t-test. The significance level was set at p-value < 0.05. The reproducibility of measurements was assessed by intraclass correlation coefficient (ICC).ResultsAfter four months of canine retraction, HMS and TMS from both laser and control sides showed significant three-dimensional displacement at p < 0.05. No significant difference in mean displacement in the vertical, sagittal, nor transverse planes between both sides was elicited.ConclusionLLL application in the used protocol does not affect the amount of miniscrew displacement in any of the three planes of space. Miniscrew displacement was significant in both groups.

Three-dimensional analysis of posttreatment tooth movements despite bonded retainers: partII-lower jaw.

Complications of bonded lingual retainers in terms of unexpected tooth movements have been reported with increasing frequency during the last decade, but the vast majority of the literature comprises case reports. The purpose of the present retrospective case-control study was to analyze the amount and direction of unwanted tooth movements despite lower bonded retainers, to analyze possible predisposing pretreatment- and treatment-related factors, and to seek for movement thresholds which could enhance the rapid and objective identification of critical cases. Plaster casts of 1026 patients who completed orthodontic treatment and asubsequent retention phase of 2years were screened for unintentional tooth movements. The study group comprised 39patients with tooth movements in the lower jaw, while 39randomly selected patients without visible tooth movements served as the control group. For all patients, plaster casts after debonding of multibracket appliances (T1) and after supervised retention (T2) were digitized, and athree-dimensional (3D) digital superimposition based on the best fit of premolars and molars was undertaken. Thereafter, translational as well as rotational movements were measured in all three planes of space. Pretreatment- and treatment-related factors of the study and control groups were compared. Aseverity classification based on rotational movement thresholds was applied to seek acritical amount of translational movements. The mean translational movements ranged between 0 and 0.4 mm and the average rotational movements between 0 and 1.6°. Large individual movements up to 1.9 mm translation and 16° rotation were seen. Atwist-effect with opposite movements of the canines along the Y‑axis could be confirmed. Compared to the control group, patients of the study group had asmaller intercanine distance at all timepoints. In addition, study group patients presented aslightly larger intercanine expansion during treatment and were more often affected by retainer bonding site detachments. Applying the severity classification based on rotational thresholds, translational movements of 0.5-1.0 mm along the X‑ and Y‑axis could serve as acritical threshold. It can be assumed that extrusive translational movements along the Z‑axis seem to be of specific nature and perhaps do not reflect aretainer complication in terms of unwanted tooth movements. Patients with alarger intercanine distance after active treatment and those with more frequent retainer bonding site detachments could be at higher risk for unwanted tooth movements during fixed retention. Sagittal and transverse movements of 0.5-1.0 mm should sensitize the practitioner for further measures.

Effect of print orientation on the dimensional accuracy and cost-effectiveness of rapid-prototyped dental models using a PolyJet photopolymerization printer: An in vitro study

The purpose of this study was to evaluate the accuracy and cost-effectiveness of the dental models 3D printed in vertical and horizontal orientation as compared to the conventional plaster and digital models. This study involved scanning 50 plaster models using Maestro 3D Desktop Scanner (AGE Solutions, Pisa, Italy). The STL file obtained from the scanner was processed and three-dimensionally (3D) printed in the horizontal and vertical orientation using a PolyJet 3D printer (Objet 30 prime, Stratasys Ltd., Eden Prairie, Minnesota, United States). The accuracy of the rapid-prototyped (3D printed) models was measured from the pre-determined landmarks and was compared among the groups. In addition, determining the cost-effectiveness of the 3D printed models in different orientations was based on the amount of material (resin) utilized during the 3D printing process. ANOVA was used to determine the accuracy of the models. There were statistically insignificant differences (P>0.05) among rapid-prototyped models (≤0.06mm) compared to plaster models and digital models for the linear measurements made in all three planes of space. The dental models printed in the horizontal orientation were found to be more cost-effective than those printed in a vertical orientation in terms of the amount of material (resin) utilized and printing time during the 3D printing process. The accuracy of rapid-prototyped models 3D printed in the horizontal and vertical orientations was comparable to the plaster models and digital models for clinical applications. Horizontally printed models were more cost-effective than vertically printed models.