Internal Discrepancies Research Articles

Verification report: A critical reanalysis of Vahey et al. (2015) "A meta-analysis of criterion effects for the Implicit Relational Assessment Procedure (IRAP) in the clinical domain".

The meta-analysis reported in Vahey et al. (2015) concluded that the Implicit Relational Assessment Procedure (IRAP) has high clinical criterion validity (meta-analytic r‾=.45) and therefore "the potential of the IRAP as a tool for clinical assessment" (p. 64). Vahey et al. (2015) also reported power analyses, and the article is frequently cited for sample size determination in IRAP studies, especially their heuristic of N>37. This article attempts to verify those results. Results were found to have very poor reproducibility at almost every stage of the data extraction and analysis with errors generally biased towards inflating the effect size. The reported meta-analysis results were found to be mathematically implausible and could not be reproduced despite numerous attempts. Multiple internal discrepancies were found in the effect sizes such as between the forest plot and funnel plot, and between the forest plot and the supplementary data. 23 of the 56 (41.1%) individual effect sizes were not actually criterion effects and did not meet the original inclusion criteria. The original results were also undermined by combining effect sizes with different estimands. Reextraction of effect sizes from the original articles revealed 360 additional effect sizes that met inclusion criteria that should have been included in the original analysis. Examples of selection bias in the inclusion of larger effect sizes were observed. A new meta-analysis was calculated to understand the compound impact of these errors (i.e., without endorsing its results as a valid estimate of the IRAP's criterion validity). The effect size was half the size of the original (r‾=.22), and the power analyses recommended sample sizes nearly 10 times larger than the original (N>346), which no published original study using the IRAP has met. In aggregate, this seriously undermines the credibility and utility of the original article's conclusions and recommendations. Vahey et al. (2015) appears to need substantial correction at minimum. In particular, researchers should not rely on its results for sample size justification. A list of suggestions for error detection in meta-analyses is provided.

Accuracy of Intraoral Scanner Systems for Fabricating Inlay, Onlay, and Veneer Restorations: A Systematic Review and Meta-Analysis.

To evaluate the accuracy of intraoral scanners (IOSs) for fabricating inlay, onlay, and veneer restorations. A literature search was completed in five databases: PubMed/Medline, Scopus, Embase, Web of Science, and Cochrane. A manual search was also conducted. Two methods have been used to assess the accuracy of IOSs for fabricating inlay, onlay, and veneer restorations: accuracy of the definitive virtual casts and the marginal and internal discrepancies of inlay, onlay, and veneer restorations fabricated by using IOSs. Included articles were classified into two groups: definitive virtual casts accuracy and restoration fit. Two investigators evaluated the studies independently by applying the Joanna Briggs Institute critical appraisal. A third examiner was consulted to resolve any lack of consensus. Thirty four articles were included: 17 analyzed the accuracy of definitive virtual casts and 17 assessed the marginal and internal discrepancies. Regarding the accuracy of definitive virtual casts, a trueness of 27.47 μm (p < 0.001) in the inlay subgroup and 64.15 μm (p < 0.001) in the onlay subgroup were found among the IOSs tested. For digitizing inlay preparations, a trueness of 12.29 μm (p < 0.001) in the Primescan, 69.34 μm (p < 0.001) in the Omnicam, 38.39 μm (p < 0.001) in the Trios 3, 52.96 μm (p < 0.001) in the Trios, and 28.90 μm (p < 0.001) in the CS3500 were found. A trueness of 53.00 μm (I2 = 99%, p < 0.001) in the Omnicam. Also, a precision of 19.88 μm (p < 0.001) in the inlay subgroup and 19.69 μm (p < 0.001) in the onlay subgroup was obtained. Furthermore, a nonsignificant test result for subgroup differences (p = 0.06) in the marginal discrepancy between conventional and IOS methods was found with a significant heterogeneity (I2 = 99%, p < 0.001). However, a significant test result for subgroup differences (p < 0.001) in the internal discrepancy values was found with a significant heterogeneity (I2 = 72%, p < 0.001). IOSs and restoration type influenced the accuracy of the definitive virtual casts. A Better trueness and worse precision was found on the definitive virtual cast of inlay restorations when compared with those of onlay restorations. The impression method used did not impact the marginal discrepancy of inlay and onlay restorations. However, a higher internal discrepancy was found in the inlay and onlay restorations fabricated by using conventional methods, but the discrepancy was not significant. Studies are needed to assess the accuracy of definitive virtual casts for fabricating veneer restorations captured by using IOSs and to measure the fit of the veneer restorations fabricated by using IOSs. Intraoral scanners provide a reliable method for fabricating inlay and onlay restorations. The accuracy of IOSs for fabricating veneer restorations remains uncertain.

Comparing the accuracy of crown fitting between milling and 3D printing techniques using CAD/CAM technologies.

The accuracy of dental crowns is crucial for their longevity and effectiveness. This study aims to investigate how the precision of crowns is affected by two different fabrication methods, either subtractive (milling) or additive (3D printing), within computer-aided design/computer-aided manufacture (CAD/CAM) technology. A standardised digital scan of a maxillary first molar with a shoulder margin (.stl file) was used to design and fabricate crowns through both subtractive (milling) and additive (3D printing) processes. The crowns' marginal and internal fits were assessed comprehensively. Statistical analysis, including two-way ANOVA and independent t-tests, revealed significant differences in fitting accuracy between the two methods. Crowns produced via 3D printing demonstrated superior fitting with minimal marginal (14 ± 5 μm) and internal discrepancies (22 ± 5 μm) compared to milling (marginal: 22 ± 4 μm, internal: 23 ± 3 μm), indicating a statistically significant advantage in precision (p⁢s⩽ 0.022 for marginal fit). The findings suggest that 3D printing may offer a more accurate alternative to milling in the fabrication of digital dental prostheses, potentially revolutionising the field with its enhanced precision capabilities.

Accuracy of Mandibular Removable Partial Denture Frameworks Fabricated by 3D Printing and Conventional Techniques.

Herein, we used digital superimposition to evaluate the accuracy of metal frameworks for mandibular removable partial dentures fabricated using three techniques. Thirty master casts of a mandibular dentiform were categorized into three groups (n = 10) based on the framework manufacturing method: selective laser melting-based metal three-dimensional (3D) printing (SLM), digital light projection-based resin 3D printing and subsequent casting (RPC), and conventional casting (CON). The master casts were scanned twice, initially after preparation and subsequently after attaching silicone using the frameworks. These scan files were digitally superimposed to measure the silicone thickness. Statistical analysis was conducted using SPSS Statistics (Version 23.0, IBM Corp., Somers, NY, USA). One-way ANOVA and a post hoc Tukey's multiple comparison tests were performed to determine differences among the three groups (α = 0.05). The RPC group exhibited significantly higher overall and mean internal discrepancies at rest and tissue stops than the SLM and CON groups, which exhibited statistically insignificant differences. Thus, SLM fabrication resulted in comparable accuracy to that achieved by CON, whereas sequentially performing resin 3D printing and casting induced inferior accuracy. However, all frameworks across the three groups were clinically acceptable.

Influence of the Manufacturing Trinomial (Technology, Printer, and Material) on the Marginal and Internal Discrepancies of Printed Metal Frameworks for the Fabrication of Tooth-Supported Prostheses: A Systematic Review and Meta-analysis.

The purpose of this systematic review and meta-analysis was to compare the influence of fabrication method (conventional, subtractive, and additive procedures) and manufacturing trinomial (technology, printer, and material combination) on the marginal and internal fit of cobaltchromium (Co-Cr) tooth-supported frameworks. An electronic systematic review was performed in five data bases: MEDLINE/PubMed, Embase, World of Science, Cochrane, and Scopus. Studies that reported the marginal and internal discrepancies of tooth-supported Co-Cr additive manufacturing (AM) frameworks were included. Two authors independently completed the quality assessment of the studies by applying the Joanna Briggs Institute Critical Appraisal Checklist for Quasi-Experimental Studies. A third examiner was consulted to resolve lack of consensus. A total of 31 articles were included and classified based on the evaluation method: manufacturing accuracy, the dual- or triple-scan method, stereomicroscope, optical coordinate measurement machine, microCT, profilometer, and silicone replica. Six subgroups were created: 3D Systems, Bego, Concept Laser, EOS, Kulzer, and Sisma. Due to the heterogeneity and limited data available, only the silicone replica group was considered for meta-analysis. The metaanalysis showed a mean marginal discrepancy of 91.09 μm (I2 = 95%, P < .001) in the conventional group, 77.48 μm (I2 = 99%, P < .001) in the milling group, and 82.92 μm (I2 = 98%, P < .001) in the printing group. Additionally, a mean internal discrepancy of 111.29 μm (I2 = 94%, P < .001) was obtained in the conventional casting group, 121.96 μm (I2 = 100%, P < .001) in the milling group, and 121.25 μm (I2 = 99%, P < .001) in the printing group. Manufacturing method and selective laser melting (SLM) metal manufacturing trinomial did not impact the marginal and internal discrepancies of Co-Cr frameworks for the fabrication of tooth-supported restorations.

Impact of different CAD software programs on marginal and internal fit of provisional crowns: An in vitro study

Statement of the problemDifferent CAD software programs used for designing crowns show variations in marginal and internal fit. Marginal and internal discrepancies may cause poorly fitting crowns. PurposeThe aim of this study was to compare the marginal and internal fit of single crown temporary restorations designed using three different CAD software programs. Materials and methodsDentbird, Exocad and Inlab 20 were used to design temporary single crowns using the same cement gap. Three experimental groups (n = 10/group) were formed based on the CAD software used. Geomagic Control X three-dimensional analysis software was used to compare the marginal and internal fit among the groups. Measurements were obtained at nine different thickness points. IBM SPSS Statistics, version 22 was used for all statistical analyses. ResultsAmong the CAD software programs tested, Dentbird produced the best internal fit on the buccal surface and the best marginal fit on both buccal and mesial surfaces. Exocad achieved the best values on the distal surface for both internal and marginal fit, while Inlab showed the best values on the mesial surface for internal fit and on the palatal surface for marginal fit. ConclusionsThe Dentbird CAD software program provided the most accurate fit values that closely matched the design. The marginal and internal fit oftemporary crowns may vary depending on the CAD software used.

Marginal and internal discrepancies associated with carbon digital light synthesis additively manufactured interim crowns

Statement of problemThe carbon digital light synthesis (DLS) or continuous liquid interface production (CLIP) technology is an innovative additive manufacturing technology using oxygen-inhibited photopolymerization to create a continuous liquid interface of unpolymerized resin between the growing component and the exposure window. This interface eliminates the need for an incremental layer-by-layer approach, allowing for continuous creation and increased printing speed. However, the internal and marginal discrepancies associated with this new technology remain unclear. PurposeThe purpose of this in vitro study was to evaluate the marginal and internal discrepancies by using the silicone replica technique of interim crowns fabricated by 3 different manufacturing technologies: direct light processing (DLP), DLS, and milling. Material and methodsA mandibular first molar was prepared, and a crown was designed with a computer-aided design (CAD) software program. The standard tessellation language (STL) file was used to create 30 crowns from the DLP, DLS, milling technologies (n=10). The gap discrepancy was determined using the silicone replica approach, with 50 measurements made with a ×70 microscope for each specimen for the marginal and internal gaps. The data were analyzed using 1-way ANOVA, followed by the Tukey HSD post hoc test (α=.05). ResultsThe DLS group had the least marginal discrepancy compared with the DLP and milling groups (P<.001). The DLP group showed the highest internal discrepancy followed by the DLS and milling groups (P=.038). No significant difference was found between DLS and milling in terms of internal discrepancy (P>.05). ConclusionsThe manufacturing technique had a significant effect on both internal and marginal discrepancies. The DLS technology showed the smallest marginal discrepancies.

Evaluation of marginal and internal fit of single crowns manufactured with an analog workflow and three CAD-CAM systems: A prospective clinical study.

This prospective clinical study evaluated and compared the marginal and internal fit of crowns fabricated with an analog workflow and three different computer-aided design and computer-aided manufacturing (CAD-CAM) systems. Twenty-five participants in need of a single complete-coverage molar or premolar crown were recruited in the study. Twenty-two completed the study, and three participants dropped out. Teeth were prepared according to a standardized protocol by one operator. For each participant, one final impression was made with polyether material (PP) and three intraoral scanners: CEREC Omnicam (C), Planmeca Planscan (PM), and True Definition (TR). For the PP group, crowns were fabricated with a pressable lithium disilicate ceramic, whereas for the other three groups (C, PM, and TR), crowns were designed and milled with dedicated CAD-CAM systems and materials. Marginal (vertical and horizontal) and internal discrepancies between the crowns and tooth preparation were measured at various locations with digital superimposition software. Data was analyzed for normality with Kolmogorov-Smirnov and Shapiro-Wilk tests and then compared with one-way ANOVA and Kruskal-Wallis tests. Mean vertical marginal gap values were 92.18±141.41μm (PP), 150.12±138.06μm (C), 129.07±109.96μm (PM), and 135.09±112.03μm (TR). PP group had statistically significantly smaller vertical marginal discrepancy (p=0.001) than all other groups, whereas no significant difference was detected among the three CAD-CAM systems (C, PM, and TR). Horizontal marginal discrepancies were 104.93±111.96μm (PP), 89.49±119.66μm (C), 113.36±128.49μm (PM), and 136.39±142.52μm (TR). A significant difference was detected only between C and TR (p<0.0001). Values for the internal fit were 128.40±49.31μm (PP), 190.70±69.79μm (C), 146.30±57.70μm (PM), and 168.20±86.67μm (TR). The PP group had a statistically significant smaller internal discrepancy than C (p<0.0001) and TR groups (p=0.001), whereas no significant difference was found compared to the PM group. Posterior crowns fabricated with CAD-CAM systems showed vertical margin discrepancy greater than 120μm. Only crowns fabricated with the conventional methodology had vertical margins below 100μm. Horizontal marginal discrepancy was different among all groups, and only CEREC CAD-CAM was below 100μm. Internal discrepancy was less for crowns fabricated with an analog workflow.

Effect of a new support design on the marginal and internal gap of additively manufactured interim crowns using direct light deposition technology.

To investigate the design and location of supporting structures on the marginal and internal gap of interim restorations. A mandibular right first molar resin tooth was prepared for a full coverage crown and scanned using a laboratory scanner (3Shape D900). The scanned data were converted into standard tessellation language (STL) format and an indirect prosthesis was designed using computer-aided design (CAD) software (exocad DentalCAD). The STL file was used to fabricate a total of 60 crowns with a 3D printer (EnvisionTEC Vida HD). The crowns were printed using E-Dent C&B MH resin and divided into 4 groups based on four different support structure designs, including supports on the occlusal (0° group), buccal and occlusal (45° group), buccal (90° group), and a new design consisting of horizontal bars placed on all surfaces and line angles (Bar) (n=15). The silicone replica technique was used to determine the gap discrepancy. Fifty measurements were obtained for each specimen to examine the marginal and internal gaps by using a digital microscope (Olympus SZX16) at ×70 magnification. Additionally, the marginal discrepancy at different locations of the tested crowns, including buccal (B), lingual (L), mesial (M), and distal (D), as well as the maximum and minimum marginal gap intervals among groups, were analyzed. The collected data were analyzed using factorial ANOVA, followed by the Tukey HSD test for multiple comparisons (a=0.05). There was a significant difference in marginal and internal gaps among the groups (p<0.001). The buccal placement supports (90° group) had the least marginal and internal discrepancies (p<0.001). The new design group showed the highest marginal and internal gap. The marginal discrepancy in different locations of the tested crowns (B, L, M, D) was found to be significantly different among the groups (p<0.001). The mesial margin of the Bar group had the largest marginal gap, whereas the buccal margin of the 90° group had the lowest marginal gap. The new design had a significantly smaller difference between the maximum and minimum marginal gap intervals than other groups (p<0.001). The location and design of the supporting structures affected the marginal and internal gaps of an interim crown. The buccal placement of supporting bars (90° printing orientation) showed the smallest mean internal and marginal discrepancies.

Trueness of stereolithography ZrO2 crowns with different build directions.

This study aims to measure the trueness of zirconia crowns with different build directions of materials fabricated using the stereolithography (SLA) method. The anatomic contour crown of prepped maxillary right first molar was designed using CAD software to obtain the standard tessellation language (STL) file. Two different build directions were set for the crowns using Materialize Magics software. One group was built with a margin base platform, while the other group was built in the direction opposite to the occlusal surface base platform. The 20 crown-shaped parts were printed. The STL files of scanned printing zirconia crowns were superimposed each segment by the 3D analysis software. The two groups were statistically analyzed using t-tests. Significant differences were found in the marginal and internal discrepancies between the groups. The build direction had a significant influence on the accuracy of the zirconia crown. The results indicate the most effective build direction for manufacturing SLA 3D-printed crowns.

Scarcity, corruption, disloyalty, and discrepancies: Containment and defense preparation against the French Intervention in Michoacán, 1861–1863

This article explains the conditions, circumstances, and means in which the liberal-republican faction – identified with the Benito Juárez government – became involved in the containment and defense strategy against the Franco-Mexican troops in state of Michoacán. The period studied extends from the end of the Reform War to the beginning of the French Intervention – i.e., the Franco-Mexican War. As a hypothesis, I assume that the liberal-republican faction was conditioned in its performance by the scarcity of material resources, widespread corruption, disloyalty to institutions and internal discrepancies, which limited its room for maneuver and action. This research is based on documentary interpretation from the perspective of political history and war. I conclude that the Army, the National Guard, and civil society privileged their interests and expectations over the priority represented by the effective organization and defense of the country against the foreign invasion.

MicroCT evaluation for CAD/CAM occlusal veneer fit using two materials and three cement space settings.

This study was aimed to evaluate the fit of occlusal veneer restoration for two CAD/CAM materials with different cement space settings, using microCT scans. Sixty resin dies were made and divided into two groups (n=30) according to the materials, (I): Hybrid all-ceramic, and (II): zirconia-reinforced lithium silicate glass-ceramic. Each group was subdivided into three subgroups (n=10) according to the cement space parameters (30, 40, and 50 µm). Occlusal veneers for the six subgroups were milled. A circle with 20 different sections was placed at the center of every scanned specimen to measure four different locations (Occlusal, Axial, Marginal, and Absolute marginal discrepancy). Data were analyzed using two-way ANOVA at a 0.05 level of significance. There was no statistically significant effect of material type on the mean values of internal and marginal gaps for the three cement space parameters (P>0.05). There were no statistically significant differences in the occlusal and axial gap between the cement space parameters, furthermore, there were statistically significant differences in marginal gap distances and absolute marginal discrepancies (P>0.05). Hybrid all-ceramic showed smaller marginal and internal discrepancies than zirconia-reinforced lithium silicate glass-ceramic without statistically significant differences, and, for both materials, 50 µm cement space significantly improved the marginal fit and absolute marginal discrepancy.

Evaluation of the flexural strength of metal frameworks fabricated by sintering-based computer-aided manufacturing methods

Statement of problemSintering-based computer-aided metal manufacturing strategies have been proposed as an alternative to hard metal milling. While these fabrication methods have been evaluated in terms of marginal and internal discrepancies and bond strength to porcelain, limited information on metal frameworks is available regarding their flexural yield strength. PurposeThe purpose of this in vitro study was to evaluate the flexural yield strength of 3-unit cobalt-chromium (Co-Cr) metal frameworks fabricated by hard metal milling (HMM), presintered soft metal milling (PSMM), and direct metal laser melting (DMLM) with 25-μm and 50-μm layer thicknesses. Material and methodsThree-unit master metal die models were prepared. A total of 40 metal frameworks (n=10) were fabricated by using HMM (group HM), PSMM (group PSM), and DMLM with 25-μm (group LM25) and 50-μm layer thicknesses (group LM50). Metal frameworks were cemented to the master die and then subjected to a 3-point bend test. The flexural yield force was used to calculate the flexural yield strength. The data were statistically analyzed (α=.05). One metal framework from each group was evaluated with scanning electron microscopy for microstructural analysis. ResultsThe group LM50 exhibited the lowest significant (P<.001) flexural yield strength values. The group HM exhibited higher flexural yield strength values than the other groups. No significant difference was found between the groups LM25 and PSM (P=.954) or between the groups PSM and HM (P=.111). ConclusionsThe fabrication method significantly affected the flexural yield strength of metal frameworks. Metal frameworks fabricated by DMLM with a 50-μm layer thickness exhibited considerably lower flexural yield strength values.

Internal and Marginal Fit Accuracy of Pre-sintered CAD/CAM Implant-Supported Frameworks Before and After Porcelain Layering.

Internal and marginal fit accuracy of an implant-supported fixed partial denture (I-FPD) along with passive fit are required for long-term clinical success. This study compared the fit accuracy of three-unit CAD/CAM-fabricated cementretained I-FPDs milled from pre-sintered cobalt-chromium (Co-Cr) and zirconia (Zr) and evaluated the effect of applying porcelain. Two implant analogs were positioned parallel at first premolar and first molar sites in an acrylic model. Their corresponding abutments were tightened with 25-Ncm torque force. Four groups were designed: two groups of I-FPD frameworks with pre-sintered Zr (ZrF) and soft millable Co-Cr alloy (SF) blocks, and two groups by applying porcelain to the Co-Cr (SP) and Zr (ZrP) frameworks (n = 4 in each group). Absolute marginal gap (AMG), marginal gap (MG), and internal discrepancies were measured. Kolmogorov-Smirnov, Levene, one-way analysis of variance (ANOVA), and Scheffe tests were used for statistical analysis using SPSS software version 22 at a significance level of .05. All measured criteria were significantly different from each other (all P values < .001). The rankings from the lowest gap to the highest gap for the main criteria were as follows: MG: SF < SP < ZrF < ZrP; AMG and internal discrepancies: SF < SP < ZrP < ZrF. Comparing molars and premolars, molars had smaller MGs, larger internal discrepancies, and smaller AMG in ZrP but larger AMG in SP. All three-unit CAD/CAM-fabricated cement-retained I-FPDs were in the clinically acceptable range of fit accuracy. The lowest and highest misfit values were observed in the SF and ZrF groups, respectively.

Evaluation of internal fit of press ceramic and porous structured cobalt–chromium crown fabricated by additive manufacturing

The purpose of this in vitro study is to fabricate a novel metal-ceramic prosthesis with a porous structure, to compensate for the disadvantages associated with the design of existing prostheses, and to measure the internal fit of this prosthesis. In this in vitro study, the mandibular first molar was scanned from the dental computer-aided-design to design a 3 mm porous structure frame. The frame was produced using the lamination method and fired in a pressed ceramic. For comparison, pore-free specimens were fabricated by selective laser sintering (SLS) as described above, and porous specimens were fabricated by casting (total n = 30). The internal fit was then measured using a digital microscope (at 100× magnification), and the data were analyzed using one-way ANOVA (α = 0.05). The total mean internal discrepancies for each group were 42.32 ± 22.50 μm for the porous structure SLS group (PS-group), 107.54 ± 38.75 μm for no-porous casting group (group), and 121.36 ± 50.19 μm for the no-porous SLS group (group), with significant differences (P < 0.05) among all groups. The internal discrepancies of porous structure crown fabricated by SLS were smaller than that of no-porous crown fabricated by casting and SLS. Based on these laboratory findings, further studies should be conducted to evaluate the feasibility of the newly designed porous structure and press ceramic prosthesis to determine whether they can be applied in clinical practice.

ASSESSING THE PERFORMANCE OF A MASTER PLAN FOR URBAN DEVELOPMENT IN THE PRODUCTION OF SPACE IN ENVIRONMENTAL PRESERVATION AREAS

Decision-making in urban planning should be based on accurate information on the performance of the spaces produced related to socioeconomic and environmental aspects. However, despite the current pattern observed in the peri-urban areas of most Brazilian cities, the planning system implemented does not establish models for investigating conflicts arising from the production of urban space. To expand the forms of assessment and control of environmental impacts, a theoretical-methodological framework is presented for assessing the performance of the space produced in urban areas of environmental preservation. The indicators of that framework are important measures to identify internal discrepancies to the system, showing its heterogeneity. The present study aimed to assess the performance of the Master Plan for Urban Development of the city of Pelotas, RS, Brazil in the production of space in areas of Environmental Preservation. The investigation considered socio-spatial, socioenvironmental and socio-economic aspects. The proposed analysis uses multivariate statistical analysis to classify the space produced. The study is useful in the production of a framework for monitoring and managing the current and future panorama of development in urban environmental preservation areas.

Accuracy of metal 3D printed frameworks for removable partial dentures evaluated by digital superimposition

ObjectivesTo evaluate the accuracy of metal 3D printed frameworks (MEP group) for removable partial dentures (RPDs) by digital superimposition, in comparison to that of frameworks produced by the conventional (CON group) and resin printing/casting (RPC group) workflows. MethodsA partially edentulous maxillary dentiform was prepared with rest seats and guiding planes on the right canine, left first premolar, and left second molar. Thirty master casts were prepared via repeated impressions of the dentiform. Frameworks were fabricated by three different workflows (n = 10 for each group). The internal discrepancies of the frameworks were assessed at 12 points by digital scanning with an optical triangulation principle-based tabletop scanner and superimposition using a reference best-fit alignment method. First, the master cast was scanned alone. Subsequently, a thin silicone material was applied to the framework and fitted onto the master cast, after which the framework was removed. Finally, the master cast with the silicone material attached was rescanned. The data from the two scans were matched, with the reference being the area not occupied by the silicone. ResultsFor the CON, MEP, and RPC groups, respectively, the mean overall internal discrepancies (279.72 µm, 241.02 µm, and 331.70 µm), and the mean internal discrepancies on palate areas (292.92 µm, 250.72 µm, and 355.84 µm) and rest seat areas (240.12 µm, 211.91 µm, and 259.26 µm) did not significantly differ among the three fabrication methods (p = 0.558, 0.542, and 0.774). SignificanceThe reference best-fit alignment of scan datasets is a useful approach to evaluate the internal discrepancy of frameworks. Metal 3D printing produces RPD frameworks that are comparable to conventional frameworks and meet clinical standards.

The complicated connection between closeness and the quality of romantic relationships

Closeness is often considered synonymous with better quality romantic relationships. However, individual differences exist in the degree of closeness people desire in their relationships. This study examined the implications that discrepancies between actual and ideal closeness have for relationship quality in romantic couples. A questionnaire was administered to a sample of 103 cohabiting couples ( N = 206) in the United States, who were randomly selected from a nationally representative survey panel. Dyadic analysis using actor–partner interdependence models with latent outcomes revealed that internal discrepancies between actual and idealized closeness were associated with poorer relationship quality for both individuals and their partners. These associations persisted above and beyond the effects of actual closeness and dyad-level differences in actual and ideal closeness. The association between closeness and relationship quality may be more individual than dyadic in nature, warranting renewed attention to the idiographic experience of closeness and its association with relational well-being.

New Social Movements as Postmodern Challanges To Neoliberalism and Representative Democracy

In this article, the relationship between new social movements, representative democracy and neoliberalism is examined. Starting with student protests in Europe and the United State, the late 1960s have witnessed the emegence of new social movements. Ecological, anti-nuclear, feminist, student, anti-racist, and LGBTI+ protests all have been examined with the scope of the new social movements paradigm. The remarkable protest wave of the 1970s has been followed by contemporary movements in different forms like the Arab Spring and the Occupy movement. Although these movements differ in terms of issues they deal with and goals they seek, they have a lot in common. Unlike the old movements like labour protests, these new movements primarily focus on postmaterial issues. Postmaterial identity demands and rights of these movements conflict with material demands of neoliberal governments. Furthermore, modern democracies fail to address these issues. Representative democracy is seen as an obstacle to political participation. On the other hand, postmodernism is a suitable concept to explain internal discrepancies and dispersion of new social movements. It is argued that (a) the legitimacy crisis of representative democracy and neoliberal response of capitalism to its structural crisis have triggered new social conflicts and movements, (b) these movements differ from old movements in terms of their forms, goals, and demands, (c) new social movements are postmodern.

Two-layer additively manufactured crown: Proof of concept

ObjectivesTo assess the feasibility of additively manufacturing a crown with a 2-layer design. MethodsA mandibular first molar tooth preparation titanium die for a full coverage restoration was obtained. The die was used to design a monolayer (ML group) and 2-layer (2L group) anatomically contoured crown. In the ML group, the specimen was manufactured with a hard polymer (Rigur RGD450; Stratasys). In the 2L group, the crown was splinted into 2 parts: the intaglio that represented 25% of the total crown volume that was manufactured with a resilient polymer (Vero; Stratasys) and the exterior that represented the remaining crown volume that was manufactured with a hard polymer (Rigur RGD450; Stratasys). Specimens were manufactured using a material jetting printer (Connex3 Object260; Stratasys). The marginal and internal discrepancies of ML and 2L specimens were visually assessed. ResultsThe ML and 2L specimens were manufactured using a material jetting printer that obtained a visually acceptable marginal and internal discrepancy. ConclusionsThe 2-layer dental crown can be manufactured using a material jetting printer. Clinical significanceMaterial jetting technology has the capability to fabricate a 2-layer dental crown design which can be fabricated using materials with different properties.