Negative Replica Research Articles

New Data-Driven Constraints on the Sign of Gluon Polarization in the Proton

Recently, the possible existence of negative gluon helicity Δg has been observed to be compatible with existing empirical constraints, including from jet production in polarized proton-proton collisions at the Relativistic Heavy Ion Collider, and lattice QCD data on polarized gluon Ioffe time distributions. We perform a new global analysis of polarized parton distributions in the proton with new constraints from the high-x region of deep-inelastic scattering (DIS). A dramatic reduction in the quality of the fit for the negative Δg replicas compared to those with positive Δg suggests that the negative Δg solution cannot simultaneously account for high-x polarized DIS data along with lattice and polarized jet data. Published by the American Physical Society 2024

Polarization‐Controlled Diffractions of Submicron Pillar Arrays of Azo Molecular Glass for Image Recording and Reconstruction

Recording and manipulating optical waves with functional structures are crucially important for many applications. Herein, the submicron pillar arrays of an azo molecular glass (IA‐Chol) are explored to show functional synergy of a recording medium and a diffractive optical element. The image recording is achieved through the pillar deformation along the electric‐field oscillation direction of incident light. When illuminated with a polarized beam, the reconstructed images appear in the first‐order diffraction spots of the pillar array with the tailored intensity distributions depending on the states of polarization of the recording beam and the image reconstruction beam. This approach enables several images to be recorded in the adjacent zones of the same pillar array using lights with different polarization directions, and then the images are reconstructed separately or simultaneously upon the polarization directions of the illumination light. Furthermore, the topographic features of the pillar array after the recording are replicated by replica‐molding to the surfaces of polydimethylsiloxane (PDMS) slices as negative replicas and transformed to surfaces of poly(methylmethacrylate) (PMMA) films through hot‐embossing. The PDMS and PMMA replicas are highly transparent in the visible light range and able to produce the reconstructed images with light in a wide‐wavelength extent.

Concave/Convex Curvature of Anisotropic Grooves Differentially Alters Cellular Morphology, Adhesion, and Proliferation.

Curvature is an integral part of the complex in vivo tissue architecture across various length scales. Therefore, several in vitro models with a patterned curvature in different length scales have been developed to understand the role of this in cellular behavior. At the subcellular scale, wavy patterns have been reported wherein concave and convex grooves are adjacently present. However, the independent effect of continuous subcellular concave and convex shapes has not been reported, mainly owing to the limitations in fabricating such patterns. In this study, we developed continuous concave and convex grooves on polydimethylsiloxane (PDMS) using a Dracaena sanderiana (bamboo) leaf as a template. The first (negative) replica from the abaxial side of the bamboo leaf, which imparted concave grooves on PDMS, was subsequently used as a template to fabricate a positive replica of the leaf, resulting in convex grooves of the same size and arrangement as the concave grooves. We examined the influence of the groove curvature on the morphology of bone marrow-derived human mesenchymal stem cells (BM-hMSCs) and skeletal muscle cells (C2C12). BM-hMSCs and C2C12 cells aligned on both concave and convex grooves as compared to the random orientation on a flat substrate. The significant difference was observed in the morphology of both cells, in terms of area, aspect ratio, number, and length of protrusions on concave and convex patterns. We found that the number of protrusions was also dependent on the ratio of cell to pattern length scale for convex-shaped grooves but independent of length scale for concave-shaped grooves. The proliferation of BM-hMSCs was also found to be different on concave and convex shapes. Therefore, this study shows the importance of (1) convex and concave curvatures of the subcellular length scale in cellular response, (2) dependence on the ratio of cell and curvature length scale, and (3) use of natural templates for overcoming fabrication challenges.

Understanding the petal effect: Wetting properties and surface structure of natural rose petals and rose petal-derived surfaces

The petal effect is identified as a non-wetting state with high drop adhesion. The wetting behavior of petal surfaces is attributed to the papillose structure of their epidermis, which leads to a Cassie-Baxter regime combined with strong pinning sites. Under this scenario, sessile drops are pearl shaped and, unlike lotus-like surfaces, firmly attached to the surface. Petal surfaces are used as inspiration for the fabrication of functional parahydrophobic surfaces such as antibacterial or water-harvesting surfaces. In this work, two types of rose petals were replicated by using a templating technique based in Polydimethylsiloxane (PDMS) nanocasting. The topographic structure, the condensation mechanism under saturated environments and the wetting properties of the natural rose petal and their negative and positive replicas were analyzed. Finally, we performed prospective ice adhesion studies to elucidate whether petal-like surfaces may be used as deicing solutions.

Roll‐to‐Roll Compatible Topochemical Wetting Control for Metamaterial Printing

AbstractThe widespread utilization of metamaterials, despite their immense transformative potential, faces challenges regarding scalability in mass production. To address these limitations, an additive method that leverages liquid inks and selective wetting to produce scalable and cost‐effective metamaterials is presented. UV‐based imprinting lithography is utilized to fabricate surface energy‐modulated patterns, enabling precise solution patterning. This approach, unlike conventional UV‐based imprinting lithography, not only accurately produces the negative replica of the stamp topography during UV‐induced crosslinking but also transfers a hydrophobic layer onto the raised surfaces of the imprinted hydrophilic layer, resulting in 3D shapes with spatially modulated surface energy. In the second process step, a functional ink is dragged over the patterned substrate where it dewets to fill the hydrophilic recesses. This innovative process enables high‐speed metamaterial production, with ink deposition speeds up to 12 m min−1. The method accommodates a wide range of inks, including metals, dielectrics, and semiconductors, providing meticulous control over vertical structures such as pattern thickness and hetero‐multilayer formation. Additionally, it offers flexibility in creating metamaterials on free‐standing ultra‐thin sheets, introducing desirable attributes like foldability and disposability. The effectiveness of this approach is validated through the fabrication and characterization of metallic metamaterials.

CBCT Imaging for Bracket Positioning with Consideration to Root Axes

Cone-beam computed tomography (CBCT) imaging and computer-aided manufacturing were used to produce stereolithographic trays for indirect-direct bonding. The ability to align teeth considering both the crown and the root decreases the chances for post treatment relapse. Three-dimensional (3D) images for separate brackets in a bracket kit were obtained from CBCT scanning in DICOM format and then converted to stereolithography format using Mimics software. Another CBCT image was obtained for the patients’ dentition. The images were saved in DICOM format and then placed into the Mimics image processing software. The images were enhanced, and the teeth were isolated to gain a clear view of their roots. With both images in the Mimics image-processing software, each bracket was placed on its designated tooth and positioned accurately. After the brackets were placed, a 3D image of a U-shaped stent was added to the project. Then, the image of the stent was placed over the teeth and half of the brackets. In the Mimics software, the teeth and brackets were then subtracted from the image of the tray to have a negative replica. The subtracted image of the tray in stereolithography format was printed with a 3D printer to obtain a 3D printed bracket positioning tray with indentations for bracket seating. This allowed brackets to be seated on the tray and bonded using conventional bonding steps.

Comparison of the Anatomy and Adaptability of Reconstructed Teeth with Natural Teeth: An Innovative Approach in Forensic Dentistry

Abstract Background: Forensic tooth reconstruction is the technique of reconstructing the morphology of a missing tooth from the intra-alveolar morphology of dental sockets from skeletal remains. Aims and Objectives: The aim and objective of the study are to compare and investigate whether the anatomy and adaptability of reconstructed teeth simulate with the natural tooth and to investigate whether the dental materials have potential in reconstruction of teeth. Materials and Methods: An in vitro experimental study was undertaken on a human mandible. According to the Fédération Dentaire Internationale, charting will be done based on the number of teeth present. The entire study will be conducted in three phases using dental materials. Phase 1 comprised preparation for negative replica, where an impression will be taken, Phase 2 comprised preparation of a positive replica or cast, and Phase 3 comprised tooth reconstruction using the flowable composite. Results: The specimen tooth (which had been taken from its socket) and the newly constructed tooth were compared, and when the length of the newly constructed root was measured using digital vernier calipers, there was a disparity of 0.5–1 mm. The cone-beam computed tomography radiographs demonstrated the necessary flexibility. Conclusion: The present study demonstrated that dental information can be obtained even when teeth are absent postmortem by making an attempt to recreate the teeth using dental materials while documenting the intra-alveolar anatomy of the dental root socket.

Assessment of crown dimensions of primary teeth in a selected sample of Indian children - An odontometric study

Abstract Introduction: The size and shape of the tooth are important sources of information for anthropology, forensic odontology, and clinical dentistry. Different populations, and even individuals within the same population, may have variations in the odontometric characteristics of their teeth, which limits the applicability of the data across groups. Aim: To establish the normal odontometric data of primary teeth and examine the sexual dimorphism and its usefulness as a tool to identify the sex among young children. Materials and Methods: This cross-sectional study involved 150 children aged 3–5 years. The parents of the selected children were informed about the procedure protocol of the study and their written consent was obtained. The negative replica of the maxillary and mandibular teeth was obtained and dental casts were prepared. The mesiodistal, buccolingual, and crown height dimensions of each tooth were measured with a digital Vernier caliper. Two independent examiners measured each tooth’s dimensions three times, and the mean was analyzed. Results and Discussion: There was no significant difference between the teeth in the right and left quadrants. Males had larger odontometric dimensions than females. The sex of children based on odontometrics of primary teeth crowns could be determined with an accuracy of 98%, 72%, and 86% using mesiodistal, buccolingual, and crown height dimensions, respectively. Conclusions: There was a clear sexual dimorphism of the primary teeth. The odontometrics can be used as a low-cost and alternative tool for sex identification among children.

Ordered non-close packed colloidal array with morphology control.

Non-close packed (NCP) colloidal arrays find wide applications in the fields of photonics, optical chip fabrication, nano sphere lithography and so on. However, unlike their close packed counterparts, such arrays cannot be obtained by direct self-organization of colloidal particles and require specialized techniques involving plasma/reactive ion etching, electric field driven assembly, substrate stretching or precise positioning of the particles. In this article, we present a facile template guided approach for fabricating ordered NCP arrays of colloidal particles. First, we employ soft lithography to replicate self-assembled hexagonal close packed (HCP) arrays of 'larger colloidal particles' (LPs) to obtain a topographically patterned positive and/or negative replica of the initial array. These replicas are then used as templates to spin coat 'smaller colloidal particles' (SPs), which may even have some degree of poly-dispersity, to obtain ordered NCP arrays. We further show that pattern morphology can be modulated based on whether a single or a double replicated template is used to confine the SPs, the concentration (Cn) of the SPs in the casting solution as well as the relative commensuration of the diameter of the SPs (ds) with that of the LPs (dL). Finally, we show that such NCP arrays can be transferred onto any flat surface by UVO mediated colloidal transfer printing.

Biomimetic Rose Petal Structures Obtained Using UV-Nanoimprint Lithography.

This study aims to produce a hydrophobic polymer film by mimicking the hierarchical micro/nanostructures found on the surface of rose petals. A simple and two-step UV-based nanoimprint lithography was used to copy rose petal structures on the surface of a polyurethane acrylate (PUA) film. In the first step, the rose petal was used as a template, and its negative replica was fabricated on a commercial UV-curable polymer film. Following this, the negative replica was used as a stamp to produce rose petal mimetic structures on UV curable PUA film. The presence of these structures on PUA influenced the wettability behavior of PUA. Introducing the rose petal mimetic structures led the inherently hydrophilic material to display highly hydrophobic behavior. The neat PUA film showed a contact angle of 65°, while the PUA film with rose petal mimetic structures showed a contact angle of 138°. Similar to natural materials, PUA with rose petal mimetic structures also displayed the water pinning effect. The water droplet was shown to have adhered to the surface of PUA even when the surface was turned upside down.

Quantification of methods used in field metallography using the example of quality assurance measures for a circular economy for high-alloy steels

Abstract This study aims to develop a method for on-site metallography, enabling the characterization of carbide banding in cold-work steels via cellulose acetate film replication. It will be demonstrated that for this purpose, it is sufficient to grind the sample surface using P1500 mesh SiC abrasive paper and etch it with V2A etchant or nitric acid for 7 minutes. By sample preparation and etching, the matrix of the parent material is sufficiently removed for the carbides to leave a “negative” impression on the film. This negative replica can then be studied under reflected light microscope, enabling the characterization of carbide banding.

Performance of Luminescent Solar Concentrators Integrated with Negative Replica Layers of Leaf Surface Microstructures.

In this study, a negative replica layer of leaf surface microstructures was used to cover the top surfaces of semitransparent thin-film luminescent solar concentrators (LSCs) to enhance the concentrators’ performance. With low reflection on the air–glass interface of the glass plate in a thin-film LSC, a negative replica layer enables the scattering of incident sunlight and increases the path of light transmitted into the LSC and the thin phosphor layer at the bottom surface of the LSC. The incident sunlight is therefore more likely to interact with the phosphor particles in the thin-film phosphor layer, thereby enhancing the performance of the LSC. In this study, semitransparent thin-film LSCs with different inorganic phosphors were examined. The experimental results revealed that the optical collection efficiency of semitransparent thin-film LSCs covered with negative replica layers of leaf surface microstructures was higher than that of the semitransparent thin-film LSCs without negative replica layers. Furthermore, the LSCs with negative replica layers with high haze ratios exhibited high optical collection efficiency. Integrating negative replica layers of leaf surface microstructures as semitransparent layers in thin-film LSCs may optimize the application of LSCs in building-integrated photovoltaics (BIPVs).

Solution-Driven Imprinting Lithography of Sol-Gel ZnO Thin Films for Liquid Crystal Display.

We present a simple and economically convenient method to fabricate nanopatterned ZnO films by imprinting lithography and use them for the layer alignment of liquid crystal (LC) displays. First, a one-dimensional nanopattern was obtained by laser interference lithography on a silicon wafer, and the silicon mold replica was transferred onto a flexible polydimethylsiloxane (PDMS) sheet for conformal patterning. The so-obtained PDMS mold was then applied on a ZnO film spin-coated on a glass substrate. During the imprinting process, the temperature was controlled from 100 to 250 °C to observe the transferring morphologies of the ZnO film; the nanopattern was successfully transferred at annealing temperatures of 200 and 250 °C because the ZnO film at the sol state filled the cavities of the PDMS nanopattern and solidified, forming a negative replica of the nanopattern. The direction of the nanopatterned ZnO film served as a guide for aligning the LC molecules on the LC surface at the centimeter scale and, due to their elastic characteristics and group behavior, propagating their directional states in the LC bulk. The resulting LC cell exhibited an enhanced electro-optical performance and high thermal endurance above 180 °C. The geometry of the alignment layer increased the electric field on the ZnO film and showed reduced threshold voltage. In addition, since flexible devices are generally based on polyimide, which imidized at around 200 °C, the relatively low annealing temperatures of our fabricated nanopatterned ZnO film allow it to be mounted on such devices without any deterioration of the underlying thermoplastic substrate. Therefore, nanopatterned ZnO has a considerable potential for advanced LC displays.

Controlling synchrony in an array of the globally coupled FitzHugh–Nagumo type oscillators

A feedback method of controlling synchrony in globally coupled oscillators is described. The technique is based on injecting a negative replica of the mean field into the array. The feedback force either desynchronizes the oscillators via compensation of the attractive coupling or causes the repulsive coupling of the oscillators. Both mechanisms result in low level of the mean field. Clustering of the oscillators is observed in the region of repulsive coupling. Numerical and analytical investigations have been carried with an array of the mean-field coupled FitzHugh–Nagumo type oscillators.

Biomimetic Mineralization Approach of Dentin Hypersensitivity in Patients with Early Non-Carious Cervical Lesions.

Objective: to evaluate the efficacy of non-invasive procedures through biomimetic mineralization of a fluoride gel, bioactive glass materials with and without fluoride and self-organizing biomimetic peptides in the treatment of dentinal hypersensitivity due to early non-carious cervical lesions. Materials and methods: Twenty-eight patients with self-reported history of dentin hypersensitivity were evaluated sequentially for evidence of erosion, abrasion or gingival recession at facial cervical region. Patients were randomly distributed into four treatment groups of seven patients each according to the type of the treatment (group I: Elmex Gele'e, group II: BioMin™ F, group III: BioMin™ C group IV: CurodontTM D’senz). The teeth were subjected to five follow up periods (baseline, after 3,6,9 and 12 weeks) and assessed in response to evaporative air-blast stimulus utilizing Schiff Sensitivity and Visual Analogue Scales. Electrical test was performed utilizing electrical pulp tester. The extent of tubule occlusion was examined under scanning electron microscope using negative replica of randomly selected patients. Results: All the tested groups showed different degrees of relieving dentinal hypersensitivity symptoms. The difference between the studied groups was statistically significant. Under SEM, group II, III and IV showed complete tubule occlusion. However, group I showed partial tubule occlusion. Conclusions: Elmex® gelee, BioMin™ F, BioMin™ C and Curodont™ D’senz were effective to manage dentin hypersensitivity related to early non-carious cervical lesions based on the biomimetic mineralization concept that has focused on permanent management of dentin hypersensitivity. Keywords: Fluoride, Bioactive glass, self-organizing biomimetic peptides, non-carious cervical lesions, dentin hypersensitivity.

Magnetorheological-finishing of miniature gear teeth profiles using uniform flow restrictor

ABSTRACT Miniature gears are used in the biomedical, automotive, and aerospace industries for advanced automatic transmission. Significantly few finishing processes can be utilized to finish miniature gears due to the narrow spacing between the miniature gear teeth profiles. In the present study, a novel uniform flow restrictor, an exact negative replica of the miniature gear teeth profiles, is designed and developed while using the rotational magnetorheological fluid-based finishing process. The effect of critical parameters on the process’s performance has been studied through response surface methodology (RSM). The surface roughness and surface texture of the finished gear profiles with different magnetorheological fluids with and without using flow restrictors are compared for consistent and precise finishing. After finishing, it is observed that all manufacturing defects in SS316L miniature spur gear are entirely removed. Also, the ultrafine surface roughness of 23.9 nm (Ra) is achieved using a uniform flow restrictor at miniature gear teeth profiles. The forces responsible for finishing gear profiles are also simulated using Comsol® Multiphysics for understanding the controlling mechanism correctly. A mathematical model for material removal using abrasive grains on gear profiles is carried out to anticipate material dislodgement mechanism during finishing.

Robust superhydrophobic fabrics by infusing structured polydimethylsiloxane films

AbstractSuperhydrophobic coatings have large application potential in self‐cleaning textiles. Low durability, high cost of fabrication, and environmental concerns over the usage of chemicals such as fluorocarbons limit the utilization of superhydrophobic coatings. This study reports a convenient and inexpensive approach to fabricate robust and fluorine‐free superhydrophobic fabrics based on the transfer of structured polymer films and hydrophobic nanoparticles. In this approach, polydimethylsiloxane (PDMS) is infused between sheets of fabric and paper, followed by curing and removal of the paper. This process results in a fabric infused with PDMS whose structure is a negative replica of the paper surface. Then, hydrophobic nanoparticles are sprayed onto the structured PDMS side of the fabric. The infusion of PDMS and subsequent deposition of the hydrophobic nanoparticles enables strong bonding, as shown by the excellent solvent stability of the superhydrophobic fabric under ultrasonication. The proposed approach is universal in that it can be applied to almost any textiles, which upon coating, exhibited superhydrophobicity with a water contact angle of 172° and a sliding angle of 3°. Furthermore, the superhydrophobic fabric showed robust durability against water spray impact and mechanical bending where it can keep superhydrophobicity for at least 200 cycles of each test.

In vitro validation of Digital Image Analysis Sequence (DIAS) for the assessment of the marginal fit of cement-retained implant-supported experimental crowns

BackgroundThe replica technique with its modifications (negative replica) has been used for the assessment of marginal fit (MF). However, identification of the boundaries between prosthesis, cement, and abutment is challenging. The recently developed Digital Image Analysis Sequence (DIAS) addresses this limitation. Although DIAS is applicable, its reliability has not yet been proven.The purpose of this study was to verify the DIAS as an acceptable method for the quantitative assessment of MF at cemented crowns, by conducting statistical tests of agreement between different examiners.MethodsOne hundred fifty-one implant-supported experimental crowns were cemented. Equal negative replicas were produced from the assemblies. Each replica was sectioned in six parts, which were photographed under an optical microscope. From the 906 standardized digital photomicrographs (0.65 μm/pixel), 130 were randomly selected for analysis. DIAS included tracing the profile of the crown and the abutment and marking the margin definition points before cementation. Next, the traced and marked outlines were superimposed on each digital image, highlighting the components’ boundaries and enabling MF measurements.One researcher ran the analysis twice and three others once, independently. Five groups of 130 measurements were formed. Intra- and interobserver reliability was evaluated with intraclass correlation coefficient (ICC). Agreement was estimated with the standard error of measurement (SEM), the smallest detectable change at the 95% confidence level (SDC95%), and the Bland and Altman method of limits of agreement (LoA).ResultsMeasured MF ranged between 22.83 and 286.58 pixels. Both the intra- and interobserver reliability were excellent, ICC = 1 at 95% confidence level. The intra- and interobserver SEM and SDC95% were less than 1 and 3 pixels, respectively. The Bland–Altman analysis presented graphically high level of agreement between the mean measurement of the first observer and each of the three other observers’ measurements. Differences between observers were normally distributed. In all three cases, the mean difference was less than 1 pixel and within ± 3 pixels LoA laid at least 95% of differences. T tests of the differences did not reveal any fixed bias (P > .05, not significant).ConclusionThe DIAS is an objective and reliable method able to detect and quantify MF at ranges observed in clinical practice.

The Surfaces of the Ceratonia siliqua L. (Carob) Leaflet: Insights from Physics and Chemistry.

The production of superhydrophobic coatings inspired by the surface of plant leaves is a challenging goal. Such coatings hold a bright technological future in niche markets of the aeronautical, space, naval, building, automobile, and biomedical sectors. This work is focused on the adaxial (top) and abaxial (bottom) surfaces of the leaflet of the Ceratonia silique L. (carob), a high-commercial-value Mediterranean tree cultivated in many regions of the world. The adaxial and abaxial surfaces feature hydrophobic and superhydrophobic behaviors, respectively. Their chemical composition is very simple: monopalmitin ester and palmitic acid are protuberant in the epicuticular and intracuticular wax layers of the adaxial surface, respectively, whereas 1-octacosanol dominates in the abaxial wax layers. In both surfaces, epicuticular wax is organized along a randomly oriented and intricate network of nanometer-thick and micrometer-long plates, whose density and degree of interconnection are significantly higher in the abaxial surface. The measured tilting angles for the abaxial surface (12-70°) reveal unusual variable density and water adhesion of the nanostructured plate-based texture. Optical measurements demonstrate that light reflectance/absorbance of the glaucous abaxial surface is significantly higher/lower than that of the nonglaucous adaxial surface. In both surfaces, diffuse reflectance is dominant, and the absorbance is weakly dependent on the light incidence angle. We show that the highly dense nanostructured platelike texture of the epicuticular abaxial layer of the C. siliqua leaflet works as a sophisticated light and water management system: it reflects solar radiation diffusely to lower the surface temperature, and it has superhydrophobic character to keep the surface dry. Such attributes enable efficient gas exchange (photosynthesis and respiration), transpiration, and evaporation. To mimic for the first time the abaxial surface, a templation approach was adopted using poly(dimethylsiloxane) (PDMS)/poly(methylphenylsiloxane) (PMPS) positive/negative replicas and a soft polymer/siloxane negative replica produced by the sol-gel process. Because high topographical variations of the biotemplate and wax adhesion to the biohybrid film affected the replication quality, the reproduction of the wax texture via the synthesis of 1-octacosanol-grafted siloxane-based hybrid materials is proposed as a suitable route to duplicate the abaxial surface with high fidelity. The natural chemical/physical strategy adopted by the C. siliqua leaflet to face the harsh Mediterranean climate is a powerful source of bioinspiration for the development of diffuse reflecting and superhydrophobic material systems with foreseen applications as dual-functional antiglare and water-repelling coatings.

Effect of digital workflow on the marginal fit of long-span implant-supported bars for kennedy ii class removable prostheses in vitro

Introduction The production procedures, including impressions, introduce errors affecting the passivity of fit. A completely digital workflow is possible nowadays because of the intraoral scanners (IOS). This study aimed to evaluate the effect of the impression technique (conventional versus digital) and the screw tightening sequence on the marginal discrepancy (MD) of implant-supported bars. Methodology This laboratory study was conducted on a simulated Kennedy class II edentulous maxilla with three parallel implants in the edentulous quartile. The closed tray technique with a-silicon (CTM) and the intraoral scanning with the I-Tero™ system (IOS) were compared and three bars were manufactured from each technique. Depending on the screw tightening sequence (A11 and A17) 4 groups were created with 6 samples each. The MD was examined implementing 24 negative replicas, which were sectioned and studied under a stereomicroscope. The Horizontal Discrepancy (BHD), Vertical Discrepancy (BVD) and Conical Discrepancy (BCD) of the bar were calculated on the means of the measurements of the horizontal, the vertical and the conical MD respectively. The descriptive statistics, normality tests, one-way ANOVA (a=.05) and post-hoc Tukey’s tests were run and the graphs were draw with SPSS. Results There was a significant effect (P<.05) of the impression technique combined with the screw tightening sequence on all variables. The post-hoc Tukey’s tests revealed significant differences between all groups except from those of the same impression technique only for the BHD (P<.05). Conclusion In this study all groups resulted in marginal discrepancies. The closed tray impression technique gave better results.