Triple Scanning Research Articles

Marginal fit of monolithic versus layered zirconia crowns assessed with 2 marginal gap methods

Statement of problemZirconia can be used either monolithically or veneered with porcelain. However, whether veneering zirconia affects marginal fit is unclear. PurposeThe purpose of this in vitro study was to evaluate the marginal fit of the monolithic and layered zirconia prostheses using 2 different assessment methods. Material and methodsAn ideal complete crown with a chamfer finish line was prepared on an extracted maxillary central incisor. Two prosthesis designs, a framework and a monolithic design, and 2 marginal fit evaluation methods, the silicone replica and the triple scanning techniques, were used. In the first group, 10 crowns were fabricated with the framework design followed by porcelain veneering, and 10 crowns were fabricated monolithically in the second group. The marginal gap in each group was evaluated with both the silicone replica and triple scan methods. Data were statistically analyzed with a 2-way repeated measures ANOVA (α=.05). ResultsA significant difference was found in the mean marginal gap by design type (P=.003), with the monolithic prostheses having lower mean marginal gaps (31.0 and 84.0 µm). However, both groups showed clinically acceptable marginal fit. No significant difference was found between the assessment methods (P=.092). ConclusionsMonolithic zirconia crowns had a better marginal fit than veneered zirconia frameworks. Both the replica and triple scan techniques for marginal gap assessment yielded similar results.

Simultaneous Chemical Mapping of Live Biofilm Microenvironmental pH and Hydrogen Peroxide in Real Time with a Triple Scanning Electrochemical Microscopy Tip.

Dental plaque biofilm is a complex ecosystem. The distribution of microbial species in the biofilm is heavily influenced by local chemical interactions that result from diverse metabolic activities and the nature of the released molecules. As a relevant example, H2O2-producing bacteria can antagonize disease-associated bacteria, leading to the maintenance of a healthy oral microbiome. Herein, we report the development of a triple-sensor (redox, pH, and H2O2) scanning electrochemical microscopy (SECM) tip capable of simultaneously mapping the pH and H2O2 concentration produced by a dental plaque-derived multispecies biofilm grown on hydroxyapatite. The pH sensor of the triple SECM tip showed a near Nernstian slope of -71.1 ± 2 mV/pH (N = 3), whereas the H2O2 sensor showed a slope of -0.052 ± 0.002 nA/μM H2O2 at pH 7.2 and a detection limit of 1.0 ± 0.2 μM (N = 7). There is no significant difference in the sensitivities of H2O2 sensors at pH 6.2, 7.2, and 8.2 at 95% CI (N = 7). The pH and H2O2 sensors demonstrated excellent reversibility with response times of 3 and 5 s, respectively, along with reliable stability over 4 h at 37 °C. The sensors did not show any cross talk between pH and H2O2 concentration ([H2O2]) measurements, highlighting the accuracy and versatility of the SECM tip. Simultaneous chemical imaging of pH and [H2O2] across the biofilm revealed a clustered distribution of local H2O2 concentrations, ranging from 0 to 17 μM. Conversely, the local pH remained constant at 7.2. The relation of local chemical profiles and the distribution of bacterial species within the oral microbiome was experimentally investigated in the context of bacterial H2O2 antagonism. The benefit of clustered H2O2 production was that the total area of H2O2 produced by smaller clusters was 67% more than that of a single cluster with the same starting number of bacteria. Thus, this triple SECM tip can potentially be used to study local molecular mechanisms that result in dysbiosis of the oral microbiome.

Comparison of internal fit of metal-ceramic crowns in CAD/CAM and lost-wax techniques in all fabrication stages through replica weighting, triple scanning, and scanning electron microscope.

ObjectivesRestoration fit is one of the prerequisites of clinical durability. It is controversial as to whether computer‐assisted design/computer‐aided milling (CAD/CAM) or lost‐wax fabrication methods result in more fit metal‐ceramic crowns. This in‐vitro study was conducted to examine the internal fit of porcelain fused to metal crowns fabricated using CAD/CAM and lost‐wax techniques during fabrication stages (framework, porcelain, cementation) through digital triple scanning, replica weighting, and observation with electron microscopy.Material and methodsTwenty uniform resin dies of prepared first maxillary molars were randomly divided into two groups according to the fabrication technique: lost wax and CAD/CAM. The internal fit was measured in all steps of completing the crowns (framework, porcelain, and cementation) using different methods, including triple scanning, replica weighting, and scanning electron microscopy. The data were statistically analyzed using t test, Pearson, and repeated measures analysis of variance (α = .05).ResultsTriple scanning revealed no difference in the internal fit of CAD/CAM and lost‐wax groups in all the fabrication steps (p > .05). The replica weighting method showed no difference between groups in the framework step (p > .05), while the internal fit was significantly better in the CAD/CAM group after porcelain application (p < .05). After cementation, electron microscopy measurements showed no difference between CAD/CAM and lost wax groups (p > .05). The Pearson correlation test showed no significant correlation between electron microscopy, replica weighing, and triple scanning methods (p > .05).ConclusionAccording to scanning electron microscopy as the superior evaluation method, the internal fit of cobalt–chrome PFM crown of both CAD/CAM and lost wax groups was within the acceptable clinical range and there was no significant difference between them. Triple scanning revealed no difference in the internal fit of framework and porcelain steps but a better fit after cementation. According to replica weighting, the internal fit in the porcelain step was higher than the framework.

Mo(Si,Al)2 by laser powder bed fusion of AlSi10Mg and combustion synthesized MoSi2

In this study, for the first time, hexagonal structured molybdenum aluminosilicide Mo(Si,Al)2 has been successfully in-situ produced with the help of laser powder bed fusion (LPBF) of a blended powder mixture of 90 wt% MoSi2-10 wt.%AlSi10Mg feedstock. Applying triple scanning for upskin changed the top surface morphology, suggesting that application of remelting or triple-melting strategies made it possible to play with microstructural features. Aluminium fractionally reacted with MoSi2 replacing the silicon atoms and gradually expanding the tetragonal lattice of MoSi2 into hexagonal, yielding at formation of Mo(Si,Al)2 based material.

Comparison of the marginal discrepancy of PFM crowns in the CAD/CAM and lost-wax fabrication techniques by triple scanning.

Computer-aided design/computer-aided manufacturing (CAD/CAM) systems are widely used for the fabrication of porcelain-fused-to-metal (PFM) crowns. This study was conducted to compare PFM crowns through triple scanning in terms of marginal discrepancy between the CAD/CAM and lost-wax fabrication techniques. Twenty uniform resin dies of a prepared maxillary first molar were randomly divided into 2 groups: conventional lost-wax; and milling. Marginal discrepancy was evaluated at the framework and porcelain steps through triple scanning and direct visualization under a stereomicroscope. Then, the crowns were cemented to the related die and the marginal gap was measured with triple scanning, direct visualization under a stereomicroscope and scanning electron microscopy (SEM). The data was analyzed using the independent t test and the one-way analysis of variance (ANOVA). The significance level was set at 0.05. Differences in the mean marginal gap were measured by the various evaluation methods. Triple scanning and stereomicroscopy identified increasing discrepancy during the fabrication process. According to the results of the independent t test, stereomicroscopy showed no difference after cementation between the CAD/CAM and lost-wax groups (p > 0.05), triple scanning showed higher fitness in the CAD/CAM group (p < 0.05), and SEM showed better adaptation in the lost-wax group (p < 0.05); however, there was a positive correlation between the findings of stereomicroscopy and SEM (p < 0.05). The cobalt-chromium crowns had clinically acceptable marginal fitness from both the CAD/CAM and lost-wax techniques; however, the lost-wax group showed lower marginal discrepancy after cementation according to SEM.

Reconstruction of Ultrasound Reflector Images from Incomplete Data Using the Compressive Sensing Method

The article investigates the possibility of reconstructing a reflector image using the compressive sensing (CS) method based on an incomplete set of echo signals measured by an antenna array in double or triple scanning mode. For comparison, we also considered reflector reconstruction methods used in ultrasonic testing (UT): the correlation, combined SAFT (C-SAFT), and maximum entropy (ME) methods. The last method allows reconstruction of superresolution images from an incomplete set of measured echo signals. Numerical and model experiments have demonstrated the possibility of reconstructing a reflector image with superresolution for a significant decrease in the amount of data used. Reconstructed CS images were compared with images reconstructed by other methods.

Inpatient Use of Insulin Pens—Eliminating Risk for Inappropriate Use of Pen on More than One Patient

Use of insulin pens for inpatient insulin administration is accurate and safe. However, if the pen is used on more than one patient, there is potential risk of infection with pathogens including hepatitis viruses and HIV. Rapid-acting insulin (RAI) is a time-critical medication, both for correctional and nutritional doses. Many hospitals using insulin pens choose to dispense them with a patient specific ID barcode from the pharmacy. This workflow ensures the correct patient ID for scanning, yet it may result in dispensing duplicates and may create time-critical delays. At UCSF, automated dispensing machines (ADM) on adult-units house time-critical medications, including RAI. In this workflow, the RN labels the insulin pen with the patient specific 3D barcode generated on the unit. Prior to insulin pen administration, 3 barcodes must be scanned: 1. Patient armband, 2. Patient label on insulin pen. (NEW) 3. Insulin pen manufacturer (confirms an active order for this type of insulin). The EMR will flash a screen size alert with a red stop sign and a warning if the patient’s armband ID and the pen label’s patient ID do not match. Implemented in 2/2017, this workflow and alert system, for the approximately 18,000 insulin pen SQ injections administered per month has triggered 10-25 alerts per month. As of 11/1/2017, all alerts have stopped the process and the correct patient’s insulin pen was retrieved and administered. Each alert is followed by an investigation. Significant factors contributing to the triggering of an alert involve RNs caring for &amp;gt;1 patient with RAI insulin orders, pens returned to the wrong patient specific cassette in centralized medication rooms, carrying &amp;gt; 1 patient’s insulin pen at a time and opening &amp;gt; 1 patient’s EMR in the patient’s room when scanning. We conclude that pen misuse can be avoided with compliance to our triple scanning system, in conjunction with best practices, while preserving the critical timing of rapid-acting insulin. Disclosure H.W. Macmaster: None. A. Maruoka: None. C. San Luis: None. S. Gonzalez: None. R.J. Rushakoff: None.

Rheonomic phenomenon shrinkage of holes drilled in fibreglass and carbon fibre-reinforced polymer composites

BackgroundThe research is devoted to machining polymer composite materials and reflects a non-trivial, accuracy-affecting phenomenon that occurs while drilling polymer composite materials, i.e. reduction of holes diameter over time after processing.MethodsThe article contains experimental data obtained in the research of rheonomic shrinkage of holes after drilling various grades of polymer composite materials. The research involved using different types of tools (high-performance Ham solid carbide drill bits and diamond drill bits). The tests were carried out combining different parameters of drilling modes. We adopted the range of spindle speed change n = 10,000-20,000 rev/min and tool feed range Sm = 50-300 mm/min. Measurements of shrinkage were performed with the help of ATOS III Triple Scan XL scanning system immediately after treatment and in 48 h thereafter. Based on the scanned polygonal mesh of each hole, three-dimensional models of holes drilled in the samples were built. Then, these models were verified against nominal drillings using GOM Inspect software. In this way, the values of rheonomic shrinkage were obtained. Verification was carried out according to Gaussian method of measurements by coincidence using variation variables sigma (Gaussian best-fit 3 sigma).ResultsShrinkage of holes does not take place in structural materials. However, in polymer composite materials, shrinkage of the drilled hole of 10 mm nominal diameter may reach reduction in diameter of 0.02-0.03 mm during a period of 48 h and depends on the grade of the polymer composite material. Observations have shown that shrinkage also depends on machining mode parameters.ConclusionsWe have developed two hypotheses to explain the influence of processing mode parameters on rheonomic shrinkage: the first one relates to the rate of processing, the second – to the force factors.

Bending Properties of Locally Laser Heat Treated AA2024-T3 Aluminium Alloy

The bending properties of AA2024-T3 aluminium alloy after localized laser assisted softening have been studied and compared to untreated material. Single and multi-path laser scanning strategies are applied for achieving a predictable and minimized springback. Process parameters for softening have been chosen based on FE modeling. In order to investigate the softening, and to characterize the size of this softened region, hardness measurements were carried out. Using a triple scanning path strategy springback was reduced by about 43% without changing the bending radius.

Testing of weld patches in Дy800 pipelines with ultrasonic antenna arrays using the triple scanning method

A method for obtaining flaw images in weld patches of Дy800 pipelines using antenna arrays operating in a triple-scanning mode is proposed. The triple-scanning method involves the mechanical motion of an antenna array operated in a double-scanning mode over the surface of an object to be tested. A complex partial image of flaws is reconstructed for each position of the antenna array using the combined SAFT (C-SAFT) method. The final image is obtained immediately after coherent imaging of all partial images. Images of flaw models in the form of side-drilled holes 2 mm in diameter in patches of Дy800 pipelines that were reconstructed from echo signals obtained in the triple scanning mode using longitudinal waves are demonstrated. As compared to traditional images obtained in the mode of phased antenna arrays, the front resolution doubles and the level of the reverberation noise and the noise formed by false images due to a large step between the antenna array elements increases by more than 12 dB.

120. The value of triple bone scanning in paediatric practice

120. The value of triple bone scanning in paediatric practice

Search statistics of triple scanning

Explicit expressions are given for the maximum-likelihood estimates of the true number of events subject to triple scanning in work with visual detectors, of its expectation value, and of the three detection efficiencies, as well as of their approximate variances.

Some remarks on scanning efficiency

Several nuclear emulsion plates have been triple scanned for nuclear interaction stars. Triple scanning showed that stars of different types had nearly similar intrinsic probabilities of being detected applying the Tolstov test. However, the estimated number of stars using the double scanning method of Lim et al. and the average value from triple scanning suggested by Tolstov were below the total number of stars found by the three scannings n 1+2+3. A method was suggested to classify the stars into two groups each of different intrinsic probability. With this classification and with the consideration of the effect of the positions of stars in their fields of view on their efficiencies, the double scanning method was found to an estimated total number above n 1+2+3.