Master Model Research Articles

Effect of a Novel ‘Scan Body’ on the In Vitro Scanning Accuracy of Full-Arch Implant Impressions

ObjectiveThis in vitro study aimed to determine whether a newly designed arcuate scan body can improve intraoral scanning accuracy for implant rehabilitation of edentulous jaws. Material and methodsA master model containing 4 implant abutment replicas was fabricated and digitized with different scan bodies using an intraoral scanner. Four types of scan bodies were evaluated: original scan bodies (group OS), computer-aided design and computer-aided manufacturing (CAD/CAM) scan bodies without extension (group CS), CAD/CAM scan bodies with straight extension (group CSS), and CAD/CAM scan bodies with arcuate extension (group CSA). Conventional splinted open-tray impressions (group CI) were used as controls. The master model and the poured casts were digitized using a laboratory scanner. Impressions were repeated 10 times each in 5 groups. Scans in standard tessellation language format were exported to reverse engineering software and root mean square (RMS) values were used for trueness and precision assessments. In each group, 45 RMS values were acquired for precision evaluation and 10 RMS values were obtained for trueness assessment. Statistical evaluation was performed with the Kruskal–Wallis test and Dunn–Bonferroni test (α = 0.05). ResultsThe median trueness values were 41.40, 55.95, 39.80, 39.75, and 22.30 μm for group OS, CS, CSS, CSA, and CI, respectively. CI showed better trueness than OS (P = .020), CS (P < .001), and CSS (P = .035). The median precisions for group OS, CS, CSS, CSA, and CI were 47.40, 51.50, 43.90, 25.20, and 24.60 μm. respectively. The precision of CSA and CI were higher than OS (P < .001), CS (P < .001), and CSS (P < .001). Between CI and CSA, there was no significant difference (P = 1.000). ConclusionsFor full-arch implant rehabilitation, the scan body with arcuate extension could improve the intraoral scanning precision and showed similar 3-dimensional discrepancy compared to conventional splinted open-tray impressions.

Comparative Accuracy of Intraoral and Extraoral Digital Workflows for Short Span Implant Supported Fixed Partial Denture Fabrication: An In Vitro Study.

BACKGROUND The advent of digital impressions using computer-aided design and manufacturing technology (CAD/CAM) has simplified and improved the fabrication of implant prostheses in dentistry. The conventional impression has several drawbacks, including tray selection, material type, impression technique, impression disinfection, and cast model storage. The inaccuracies caused by distortion and contraction of impression material can be minimized with digital impressions. This study aimed to compare digital dental impressions of 10 working casts made using the Pindex laser removable die system to fabricate parallel drill channels vs 10 working casts made using the Di-Lok plastic tray removable die system. MATERIAL AND METHODS An implant master die with 2 dental implant analogs was fabricated. Ten working casts using the Pindex laser removable die system with parallel drill channels and 10 working casts using the Di-Lok plastic tray removable die system were fabricated. The working casts were scanned using an extra-oral laboratory scanner and the implant master model was scanned with an intra-oral scanner. RESULTS The properties of the casts made using the 2 systems were evaluated and analyzed with ANOVA and post hoc Tukey test. The mean horizontal linear distances between A1B1 (P<0.021), A2B2 (P<0.018), C1D1 (P<0.026), C2D2 (P<0.03), B1C1 (P<0.01), and mean vertical distances between B1A2 (P<0.015), C1D2 (P<0.001), B1B2 (P<0.028), and C1C2 (P<0.001) were significantly different between the Pindex system and Di-Lok tray system as compared to intra-oral scans. CONCLUSIONS Complete digital workflow with intra-oral scans were more than the partial digital workflow with extra-oral scans for the Pindex system and Di-Lok tray systems.

Accuracy of Silicone Impressions and Stone Models Using Two Laboratory Scanners: A 3D Evaluation.

To evaluate the in vitro accuracy of impressions obtained with two silicone and corresponding stone models using two laboratory scanners. A master model with synthetic resin teeth with two single-unit crown preparations was created and scanned using a 12-megapixel scanner. Five conventional impressions of the physical model were prepared with different silicone impression systems (Zhermack and Coltene) using the double-mix technique and poured with gypsum. The impressions and stone models obtained were scanned using two extraoral scanning systems (Identica T500, Medit; S600 ARTI, Zirkonzahn). All best-fit superimpositions of the teeth areas were conducted between the master model and the scans of the impressions and models obtained with the two scanners. A P < .05 level was considered significant. The Identica T500 Medit scanner showed an accuracy of 102.34 (89.67, 115.01) μm for Coltene silicone and 79.51 (67.82, 91.21) μm for Zhermack silicone, while the S600 ARTI Zirkonzhan scanner presented 110.79 (98.24, 123.33) μm and 91.91 (81.29, 102.54) μm, respectively, with significant differences between scanners for Zhermack silicone (P = .008) and for the corresponding stone models (P = .002). Zhermack silicone presented overall discrepancies lower than Coltene silicone, with statistically significant differences in both scanners analyzed (P < .001; P = .017). However, the discrepancies found were within clinically acceptable values. With the Zirkonzahn scanner, discrepancies found in the Zhermack impressions were lower than in the corresponding stone models (P < .001). The direct digitization of silicone impressions with laboratory scanners presented comparable results to conventional techniques with stone models.

Comparison of Some Properties between Commercially Available Gypsum Products

Gypsum models are often used in dental healthcare, and there is an increased need for manipulation of master casts in extensive reconstructions requi ring a material that is not easily abraded or damaged with dimensional accuracy, accurate reproduction of details, and the use of a voids free surface master model. This study was conducted to compare between commercially available type III and type IV dental stones in some of their properties. Four groups were compared: Zhermack and Geastone of Type III dental stone, and Zhermack and Bluejey of Type IV improved dental stone. Ten specimens were fabricated for each material from a rubber ring w ith dimensions of 20mm height and 30mm diameter. Dimensional stability, reproduction of details, surface porosity, and surface hardness were evaluated for the different gypsum products. Results of this study show that for the dimensional stability there was an increase in dimension more than that of the test block and was only highly significant for groups Z3 and Z4. The surface hardness for groups Z3 and Z4 was significant higher than groups G3 and B4 in all of time intervals except after 24h for groups Z4 and B4 this was insignificant. Surface porosity test and reproduction of details test, both revealed no significant difference between the test groups. As conclusion the Zhermack dental stone products, type III &amp; IV, showed higher surface hardness than Zeus dental stone products, type III &amp; IV (Geastone and Bluejey). On the other hand we found that Zeus dental stone products showed good dimensional stability than the Zhermack dental stone products. All stone products provided similar scores for details reproduction, and were similar in relation to surface porosity.

Machine learning assisted design of high-entropy alloys with ultra-high microhardness and unexpected low density

High-entropy alloys (HEAs) have attracted considerable attention for their exceptional microstructures and properties. Discovering new HEAs with desirable properties is crucial, but traditional design methods are laborious and time-consuming. Fortunately, the emerging Machine Learning (ML) offers an efficient solution. In this study, composition-microhardness data pairs from various alloy systems were collected and expanded using a Generative Adversarial Network (GAN). These data pairs were converted into empirical parameter-microhardness pairs. Then Active Learning (AL) was employed to screen the Al-Co-Cr-Cu-Fe-Ni system and identify the eXtreme Gradient Boosting (XGBoost) as the optimal ML master model. Millions of data training iterations employing the XGBoost sub-model and accuracy evaluations using the Expected Improvement (EI) algorithm establish the relationship between HEA compositions and microhardness. The proposed sub-model aligns well with experimental data, wherein four Al-rich compositions exhibit ultra-high microhardness (>740 HV, with a maximum of ∼780.3 HV) and low density (<5.9 g/cm3) in the as-cast bulk state. The hardening increment originates from the precipitation of disordered BCC nanoparticles in the ordered AlCo-rich B2 matrix compared to the dilute B2 AlCo intermetallics. This lightweight, high-performance alloy shows potential for engineering applications as thin films or coatings.

The effect of different scanning protocols on precision and trueness of intraoral scanning: A pilot trial.

The aim of this study was to investigate how different scanning protocols affect the accuracy (trueness and precision) of intraoral scanning of complete arches with implant cylinders. A master model was designed with five cylinders. One scanner, TRIOS2 (3shape), was used to scan the model with four different scan protocols: ROCK (wavelike scanning in a pendulum movement), ZIGZAG (wavelike scanning technique), OBP (occlusal, buccal, and palatal), and OWBP (occlusal, wiggling, buccal, and palatal). A total of 30 scans were performed using each of the four protocols. The master model was digitized with an industrial ISO-certified ATOS scanner. GOM inspect software was used to compare the scans to the master model and evaluate any deviation between the scan protocols and the master model. The data was analyzed using the One Sample t-test (p=0,05). The precision (standard deviation) ranged from 23-83μm for protocol ROCK, 22-147μm for ZIGZAG, 21-170μm for OBP, and 23-116μm for OWBP. The trueness (mean deviation from master model) was 5-41μm for ROCK, 7-97μm for ZIGZAG, -21-29μm for OBP, and 1-24μm for OWBP. All protocols showed statistically significant differences to the master model in multiple distances, except OWBP, which had a single significant difference in comparison to the master model. Protocol OWBP has a higher trueness than other tested protocols. All tested protocols have higher trueness and precision when scanning smaller distances than inter-arch measurement. Clinical significance;The trueness and precision of intraoral scanning is generally better in smaller spans due to less deviation. The protocol OWBP, that is recommended by the manufacturer, has the least deviating trueness in comparison to the master model. Key words:Accuracy, trueness, precision, intraoral scanner, digital impression, scanning protocol.

Digital Evaluation of the Trueness and Fitting Accuracy of a Three-Unit Fixed Zirconium Bridge Fabricated from Different Types of Zirconia and Different Marginal Cement Space Thickness

Abstract Objective The aim of this study was to measure the internal, marginal fitness, and trueness of a three-unit fixed zirconium bridge fabricated using two types of zirconia and different marginal cement space thicknesses. Methods and Materials Thirty-two aluminum master models, constructed by computer numerical control (CNC) milling machines using aluminum rod, representing two prepared aluminum abutments (the upper first premolar and the first molar) were chosen due to differences in shape and dimensions, which may affect adaptation. It may also be considered one of the most common cases in clinical practice and a missing second premolars were used to fabricate a three-unit fixed partial zirconium bridge. A master model was scanned with an intraoral scanner. Fixed dental prostheses (FDPs) were fabricated with two designs (single-layer high-translucent [HT] Katana and ultra-translucent multilayer (UTML] zirconia Katana) and two marginal cement space thicknesses (0 and 25μm for HT and ML). These specimens are divided according to marginal cement space and type of zirconia into four groups, each containing eight samples. Group A: 25-μm marginal cement space with single-layer HT zirconia. Group B: 25-μm marginal gap with UTML zirconia. Group C: 0 μm marginal gap single-layer HT zirconia. Group D: 0 μm marginal gap with UTML zirconia. Fitness and trueness of the fabricated three-unit FDPs were evaluated by scanning the silicone replica of the cement space and analyzing the thickness of the silicone replica in the three-dimensional inspection software (Geomagic Control X, Morrisville, North Carolina, USA). Results Highest mean value of internal gap was recorded at the molar abutment of group D (95.05, ± 3.42 μm), while the lowest was recorded at the premolar abutment of group A (57.12, ± 2.43μm). For marginal gap, the lowest marginal gap was also recorded at the premolar abutment of group A (36.14, ± 3.94μm), and the highest was at the molar abutment of group D (84.74, ± 2.98 μm).For trueness, group A showed the lowest root mean square (RMS) of mean with both abutments compared with group D, which recorded the highest RMS of mean for trueness. Conclusion The marginal cement space thickness affects the FPD internal, marginal fitness, and trueness; single-layer HT (Katana) zirconia shows better fitness and trueness than UTML (Katana).

Training Model of Electronic Information Professional Master with Double Tutor System in Collaboration between Universities and Enterprises

Training Model of Electronic Information Professional Master with Double Tutor System in Collaboration between Universities and Enterprises

Teacher’s Professional Qualifications in Terms of Competency Model Pedagogical Growth

The paper considers the system of professional qualifications for teachers of subject education and defines the most important criterion for obtaining a higher pedagogical education. As part of the implementation of the structural model of teacher education, bachelor's and master's programs are distinguished. Each level is an independent system, but in unity, they form a model of a complete higher pedagogical education. This study established the pedagogical model of professional growth of a bachelor's graduate at the formal and non-formal levels of education, and the pedagogical trajectory of a graduate of a master's program determined the deepening of qualifications and work in higher education. The results of this study indicate a clear system of qualification levels, however, at the level of its content – professional competence – there is no single description of its constituent competencies. In the context of the competence-based approach to teaching implemented in higher education, pedagogical and methodological competence for a teacher of any qualification, as well as research competence for a master's degree graduate, are defined as a key component of pedagogical qualification. Based on the analysis of previous studies of teacher training under the conditions of a competency-based model, regulations and standards, the previously defined competencies were identified as basic ones. The development of the basic competencies of a teacher is determined by the system of professional growth and, within the framework of the “lifelong learning” model, forms a system of continuous teacher education. The system of professional growth in this study is determined by the qualifications achieved and depends on the education system: for a teacher of secondary education, the model for improving pedagogical skills through obtaining qualification categories is determined as the basis, and for a teacher of higher education, obtaining an academic degree, title and professional growth by position is available. Lifelong education for a teacher in this study also depends on the level: in secondary education – an increase in the level of pedagogical and methodological activities, and in higher education – an increase in the level of scientific and pedagogical activity throughout the entire period of professional activity.

Chairside 3-D printed impression trays: a new approach to increase the accuracy of conventional implant impression taking? An in vitro study

PurposeA high transfer accuracy of the intraoral implant position to a model is required, to manufacture implant-supported restorations. However, clinically relevant deviations persist between the intraoral implant position and the model obtained, even for the benchmark conventional custom implant impressions with polyether. Thus, new approaches using 3-D printed impression trays may increase the transfer accuracy of implant impressions. The ability to adjust parameters such as the thickness of the layers and the influence of the openings in the impression tray could potentially affect accuracy.MethodsFour different types of impression trays (n = 10 for each group) for the conventional impression technique were investigated: conventional custom impression tray, customized foil tray, chairside 3-D printed impression tray with the SHERA system, and the Primeprint system using an implant master model with four implants in the posterior region and a reference cube. After plaster model casting, all models were measured using a coordinate measuring machine, and the deviation from the reference dataset was determined. A statistical ANOVA analysis was performed (p < 0.05).ResultsChairside 3-D printed impression trays showed the best results, followed by conventional custom impression trays. Implant impressions obtained using a customized foil tray exhibited the lowest accuracy. Statistically significant differences were observed between 3-D printed impression trays and conventional custom impression and customized foil trays (p < 0.05). Whereas, the implant position did not have any significant influence on accuracy (p > 0.05).ConclusionsChairside 3-D printed impression trays significantly increase the transfer accuracy for implant impression taking.Graphical

Comparative analysis of the retention force and deformation of PEEK and PEKK removable partial denture clasps with different thicknesses and undercut depths

Statement of problemThe retentive force and deformation of milled polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) removable partial denture (RPD) frameworks are not well understood. PurposeThe purpose of this in vitro study was to assess the retentive force and deformation of PEEK and PEKK Akers clasps with different designs and undercut depths. Material and methodsA master model containing the first and second molar abutments was used to design Akers clasps of different cross-sectional dimensions, undercut depths (0.5 and 0.75 mm), and materials. The components of the removable partial denture framework also included an occlusal rest and were manufactured using a milling machine (n=5). The fatigue resistance of the Akers clasps was measured before and after deformation regarding the retentive forces. ResultsThe PEEK2-U50 clasp had the largest retentive force with no significant difference among all groups before and after the insertion and removal cycle. In addition, the increased cross-sectional dimensions of the design resulted in significant differences in retentive forces between the PEEK1 and PEEK2 groups and between the PEEK and PEKK materials. ConclusionsIncreasing the clasp's cross-sectional dimensions significantly impacted retentive forces, especially between different PEEK groups and between PEEK and PEKK materials.

Effect of different intraoral scanning strategies on the marginal and internal fit of CAD-CAM inlay restorations: An in vitro study

Whether the scanning strategy of intraoral scanners (IOSs) affects the accuracy of the digital recording for an indirect ceramic inlay restoration is unclear. Furthermore, which strategy would be optimal and most effective is uncertain. The purpose of this in vitro study was to evaluate the impact of 3 different scanning strategies using the Carestream CS 3700 IOS on the marginal and internal fit of a mesio-occluso-distal (MOD) ceramic inlay restoration. A typodont master model (ANA-4 VCER; Frasaco) was used with a standardized preprepared MOD inlay maxillary first molar typodont tooth (ANA-4 ZP16 CER99-008; Frasaco) (N=30). These inlay preparations were scanned with the CS 3700 IOS using 3 different scanning strategies: linear, wave, and S-figure scanning strategies. Each scan strategy group was scanned 10 times for all groups to obtain 30 standard tessellation language (STL) files. Thirty restorations were milled from lithium disilicate CAD blocks (IPS e.max; Ivoclar AG) and cemented into their typodont-prepared inlay cavities. A single examiner used a stereomicroscope to measure the marginal and internal gaps at the predetermined points. A 1-way ANOVA was used for the statistical analysis, followed by the Tukey post hoc test with Bonferroni adjustment. All tests were 2-tailed (α=.05). All scanning strategy groups demonstrated statistically significant differences for the marginal and internal fit of the inlay restorations (P<.001). Overall, the linear scanning strategy showed the lowest mean marginal and internal gap values (29.2 ±3.6µm and 39.0 ±6.4µm), followed by the wave scanning strategy, which had comparable mean marginal and internal gap values: 49.1 ±3.6µm and 48.2 ±6.0µm, respectively. The S-figure scan strategy had the highest mean marginal and internal gap values: 50.2 ±12.6µm and 71.3 ±7.7µm, respectively. Inlay restorations scanned by the linear scan strategy had the best marginal and internal fit when scanned with the CS 3700 IOS.

Comparative evaluation of open tray impression technique: investigating the precision of four splinting materials in multiple implants

BackgroundThis study aimed to determine the relative positioning accuracy of multiple implants utilizing four distinct types of splinting materials.MethodsThe purpose of this in-vitro study was to compare the precision of four splinting materials in an open tray impression technique in multiple implant situations. Based on the material used for splinting, four groups were made (n = 40)- Group A: Conventional Method, Group B: Prefabricated Pattern Resin Framework, Group C: Prefabricated Metal Framework, Group D: Light Cured Pattern Resin, these groups were compared with the master model. A heat-cured clear acrylic resin and a master model were constructed. A pilot milling machine drill was used to drill four parallel holes in the anterior and premolar regions, which were later labeled as A, B, C, and D positions from right to left. Then, sequential drilling was carried out, and four 3.75‑mm diameter and 13-mm long ADIN implant analogs with internal hex were placed in the acrylic model using a surveyor for proper orientation. The impression posts were then manually screwed to the implant analogs using an open tray, and they were secured to the implants using 10 mm flat head guide pins with a 15 N.cm torque. 10 Open tray polyether impressions were made, and casts were poured. Each splinting method’s distortion values were measured using a coordinate measuring machine capable of recordings in the X-, Y-, and Z-axes. Comparison of mean distances for X1, X2, and X3 was made using the Kruskal-Wallis test, and Pairwise comparison was done using Post Hoc Tukey’s Test.ResultsThe differences between the groups were significant when assessing the distances X1, X2, and X3 (p < 0.05). The comparison of deviations between the groups revealed a statistically significant difference (p < 0.05) for the deviation distance X3 but not for the deviation distances X1 and X2. For distance Y1, the difference between the groups was statistically significant (p0.05), but it was not significant for distances Y2 and Y3. A statistically significant difference was seen in the comparison between the groups (p < 0.05) for the deviation distances Y1, Y2, and Y3. The results were statistically significant for the distance Z1 comparisons, namely, control vs. Group A (p = 0.012), control vs. Group B (p = 0.049), control vs. Group C (p = 0.048), and control vs. Group D (p = 0.021), and for distance Z3 comparison for control vs. Group A (p = 0.033). The results were statistically insignificant for the distance Z2 comparisons (p > 0.05).ConclusionsAll splinting materials produced master casts with measurements in close proximity to the reference model. However, prefabricated pattern resin bars splinting showed the highest accuracy among the studied techniques. The most recent splinting techniques using prefabricated metal framework and light-cure pattern resin showed similar accuracy.

Integrated train timetabling and rolling stock rescheduling for a disturbed metro system: A hybrid deep reinforcement learning and adaptive large neighborhood search approach

For a metro line with high density and short trip time, the original train timetable and rolling stock circulation face infeasible risks under unexpected disturbances. This paper focuses on integrated train timetabling and rolling stock rescheduling for a disturbed metro system to reduce the negative impact. The problem is formulated as a multi-objective master model, in which required operational constraints and dispatching strategies are taken into account. To satisfy the real-time requirement, an innovative solution framework consisting of an independent rescheduling process and a cooperative rescheduling process is proposed. In the independent rescheduling process, the master model is decomposed into a series of submodels in the unit of train service. The submodel can be transformed into a Markov Decision Process (MDP) with well-defined fundamental elements (i.e., state, action, and reward function). Based on the MDP, a hierarchical policy is developed by introducing deep reinforcement learning to generate the initial solution, including the lower-level policy for train timetable and the higher-level policy for flexible rolling stock circulation. In the cooperative rescheduling process, the selfishness of agents that appears after the model decomposition is overcome by an adaptive large neighborhood search algorithm, which can improve the solution quality. Finally, two sets of numerical experiments are conducted to demonstrate the performance of the proposed solution framework. The experimental results show that a near-optimal solution can be obtained in a short time, which is better than the currently used practical rules in the automatic train supervision system, especially during peak hours. Furthermore, the effects of different parameter settings are analyzed.

Application of SWSRA-DS algorithm in improving the model transfer for near infrared analysis of pulpwood holocellulose

The SWSRA-DS combined algorithm is proposed with the goal of sharing the near infrared analysis model of the holocellulose content of pulpwood on three different types of spectroscopic instruments. That is, the screening wavelengths based on spectrum ratio analysis (SWSRA) algorithm is used to select the wavelengths with good stability and consistency. These important wavelength variables, which are insensitive to the measured sample parameters, can reduce the differences in sample information response by different instruments or measurement conditions. Then the systematic errors that still existed after the SWSRA method calibration are further calibrated using the Direct Standardization (DS) method on the basis of these wavelengths. This combined algorithm can improve the generalizability of the master model, reduce the spectrum matrix dimension, and make the model transfer more stabilized and simple. The results show that the SWSRA-DS combined algorithm is able to reduce the RMSEP of the master model to predict the holocellulose content of samples measured on the target 1 and target 2 instruments from 2.01% and 9.45% to 0.96% and 1.08%, respectively. The SWSRA-DS algorithm result is compared with the calibration results of SWSRA and DS alone and the commonly used PDS and S/B model transfer algorithms to transfer performance is significantly improved, which provides a new idea for the sharing of NIR analysis models among different types of spectroscopic instruments.

A Y-Shaped Tilting Wing UAV for Vertical Take-off and Landing Cargo

To address the growing demand for express cargo transportation within and between cities, this study presents a conceptual design of a Y-shaped tilting wing unmanned aerial vehicle (UAV) capable of vertical take-off and landing (VTOL). The design aims to overcome the limitations of existing UAV designs and combine the advantages of multi-rotor and fixed-wing aircraft. By incorporating fixed-wing features, the UAV offers an extended battery life and range, making it an ideal choice for urban express cargo transportation. Firstly, a master geometry model of the UAV is established. Subsequently, dynamic simulations are conducted to evaluate the UAV’s performance under different trajectories. The analysis of the research results verifies that the UAV can successfully complete its flight missions along predetermined paths.

58 Effects of Pellet Quality on Growth Performances of Pigs When Fed Diets During Varying Weight Ranges

Abstract The objective of these experiments was to determine if the importance of pellet quality was dependent on pig weight ranges. Therefore, a total of 350 grow-finish pigs (line 600 × 241; DNA) were used in 3 separate experiments. Each experiment was conducted as a randomized complete block design. Pigs were weighed before the onset of each experiment and split into 7 blocks based on average body weight, resulting in 7 replications per treatment. For Exp. 1, 2, and 3, pigs were fed treatments for 20 days from 43 to 68 kg, 21 days from 81 to 107 kg, and 20 days from 118 to 144 kg, respectively. Pelleted diets for Exp. 1, 2, and 3 were steam conditioned at approximately 83, 77, and 67°C, respectively and subsequently pelleted with a 30-horsepower pellet mill (1012-2 HD Master Model, California Pellet Mill, Crawfordsville, IN). For Exp. 1 and 2 diets were pelleted with a 4.8 × 31.8 mm (L:D 6.7) die while a 4.8 × 57.2 mm (L:D 12) die was used for Exp. 3. Treatments consisted of a mash diet and pellets with fines inclusion rates of 9-16, 41-47, 60-68, and 84-91%. For Exp.1, pigs fed pellets with 12.5% fines had improved (P &amp;lt; 0.05) G:F when compared with those fed the mash diet. Pig ADFI increased (linear, P = 0.006) as percent fines at the feeder increased. Pig G:F decreased (linear, P = 0.002) as percent fines increased at the feeder. For Exp. 2, pigs fed pellets with 15.5% fines had improved (P &amp;lt; 0.05) G:F compared with those fed the mash diet. Pig ADFI increased (linear, P = 0.016) when fed pellets with increasing percent fines at the feeder. Pig G:F decreased (linear, P = &amp;lt; 0.001) as fines percentage increased at the feeder. For Exp. 3, pigs fed pellets with 9.6 and 41.8% fines had increased (P &amp;lt; 0.05) G:F when compared with those fed mash diets. Pig G:F decreased (linear, P = 0.005) as pellet fines percentage increased at the feeder. In conclusion, feeding pigs 12.5, 15.5, and 9.6% fines in Exp. 1, 2, and 3 improved G:F by 3.9, 5.4, and 9.1%, respectively, compared with pigs fed mashed diets. Increasing the percent fines from 12.5 to 90.4%, 15.5 to 86.0%, and 9.6 to 83.6% reduced G:F of pigs by 5.7, 7.7, and 5.6% for Exp. 1, 2, and 3, respectively.

Trueness and precision of complete arch dentate digital models produced by intraoral and desktop scanners: An ex-vivo study

ObjectivesThe study aimed to compare the trueness and precision of five intraoral scanners (Emerald S, iTero Element 5D, Medit i700, Primescan, and Trios 4) and two indirect digitization techniques for both teeth and soft tissues on fresh mandibular and maxillary cadaver jaws. MethodsThe maxilla and mandible of a fully dentate cadaver were scanned by the ATOS industrial scanner to create a master model. Then, the specimens were scanned eight times by each intraoral scanner (IOS). In addition, 8 polyvinylsiloxane (PVS) impressions were made and digitized with a Medit T710 desktop scanner. Stone models were then poured and again scanned with the desktop scanner. All IOS, PVS, and stone models were compared to the master model to calculate the mean absolute surface deviation for mandibular teeth, maxillary teeth, and palate. ResultsFor mandibular teeth, the PVS trueness was only significantly better than the Medit i700 (p < 0.001) and Primescan (p < 0.05). In maxillary teeth, the PVS trueness was significantly better than all IOSs (p < 0.05–0.001); the stone trueness was significantly better than Emerald S (p < 0.01), Medit i700 (p < 0.001) and Primescan (p < 0.01). In the palate, PVS and stone trueness were significantly lower than the iTero Element 5D (p < 0.01) and Trios 4 (p < p < 0.01). Stone trueness was significantly lower than the Medit i700 (p < 0.05). The precision in the palate was significantly lower for PVS and stone than for Emerald S (p < 0.01, p < 0.05), iTero Element 5D (p < 0.01, p < 0.01), Primescan (p < 0.001, p < 0.001), and Trios 4 (p < 0.001, p < 0.01). Significant differences in trueness between the IOSs were observed only in the mandibular teeth. The Medit i700 performed worse than Emerald S (p < 0.01) and iTero Element 5D (p < 0.01). For mandibular teeth, the Medit i700 was significantly more precise than Primescan (p < 0.01) and the Emerald S (p < 0.05). The Trios 4 was significantly less precise than Emerald S (p < 0.05). The precision of Medit i700 was significantly worse than iTero Element 5D (p < 0.01) for maxillary teeth, as well as the Primescan (p < 0.01) and Trios 4 (p < 0.05) for the palate. ConclusionsIn general, indirectly digitized models from PVS impressions had higher trueness than IOS for maxillary teeth; precision between the two methods was similar. IOS was more accurate for palatal tissues. The differences in trueness and precision for mandibular teeth between the various techniques were negligible. Clinical significanceAll investigated IOSs and indirect digitization could be used for complete arch scanning in mandibular and maxillary dentate arches. However, direct optical digitization is preferable for the palate due to the low accuracy of physical impression techniques for soft tissues.

Dimensional Stability and Retention Strength of Impressions to Custom Impression Trays Fabricated Using Conventional Method and Additive Technology - An In-vitro Study.

3D printing technology is replacing manual fabrication in all fields. 3D-printed impression trays should be assessed as they could replace conventional impression trays in the future. In-vitro comparison and evaluation of the dimensional stability and retention strength of impressions to custom impression trays fabricated using conventional method and additive technology. A maxillary edentulous auto-polymerizing acrylic resin model served as the master model. Two moulds were prepared from the master model in order to obtain 12 casts. One cast was scanned for 3D printing digital light processing (DLP) and fused deposition modelling (FDM) 24 impression trays using polylactic acid (PLA). Twelve casts were used to fabricate light cure impression trays. Polyvinyl-siloxane impressions were made on the master model using 36 impression trays and 18 trays each were used to assess dimensional stability and retention strength. In dimensional stability analysis, one sample t-test revealed a statistically significant difference between each group and the master model followed by a one-way ANOVA. There were significant differences, but the difference was less with FDM trays (P < 0.05). In retention strength analysis, one-way Analysis of variance (ANOVA) revealed statistically significant difference between each group and post-hoc test revealed specific difference, the highest with FDM trays (P < 0.05). Dimensional changes were observed at 30 minutes and 72 hours. Lesser dimensional changes were observed when impressions were made using FDM trays followed by DLP and light cure trays. The mean retention strength seen in descending order was FDM, followed by DLP and light cure trays. The best retention strength was noticed when impressions were made using FDM trays.

Accelerating artificial intelligence: How federated learning can protect privacy, facilitate collaboration, and improve outcomes.

Cross-institution collaborations are constrained by data-sharing challenges. These challenges hamper innovation, particularly in artificial intelligence, where models require diverse data to ensure strong performance. Federated learning (FL) solves data-sharing challenges. In typical collaborations, data is sent to a central repository where models are trained. With FL, models are sent to participating sites, trained locally, and model weights aggregated to create a master model with improved performance. At the 2021 Radiology Society of North America's (RSNA) conference, a panel was conducted titled "Accelerating AI: How Federated Learning Can Protect Privacy, Facilitate Collaboration and Improve Outcomes." Two groups shared insights: researchers from the EXAM study (EMC CXR AI Model) and members of the National Cancer Institute's Early Detection Research Network's (EDRN) pancreatic cancer working group. EXAM brought together 20 institutions to create a model to predict oxygen requirements of patients seen in the emergency department with COVID-19 symptoms. The EDRN collaboration is focused on improving outcomes for pancreatic cancer patients through earlier detection. This paper describes major insights from the panel, including direct quotes. The panelists described the impetus for FL, the long-term potential vision of FL, challenges faced in FL, and the immediate path forward for FL.