Internal Adaptation Research Articles

Innovation and competitiveness in the industry 4.0 era: the SYNCHRO framework for digital servitization

PurposeThis study aims to develop a theoretical and practical framework to guide manufacturing companies in their transition towards digital servitization (DS), identifying relevant elements in implementing a digital servitization (DS) strategy.Design/methodology/approachWe use a mixed-methods approach combining qualitative interviews and quantitative surveys. Data were collected from 98 manufacturing companies in Spain to understand their DS strategies and outcomes.FindingsThe SYNCHRO framework, encompassing seven components: Stakeholder environment, Yield through co-creation, New capabilities, Connectivity through Industry 4.0, Handling challenges, Restructuring internally and Organizational adaptation, is presented. The results indicate that companies can advance towards DS autonomously, without necessarily relying on co-creation with customers. However, the implementation of Industry 4.0 technologies and internal adaptation are critical for success.Research limitations/implicationsFuture research should expand the sample size and explore the implementation of the SYNCHRO framework in different industrial and geographical contexts to validate its effectiveness.Practical implicationsThe framework provides a structured approach for companies to integrate digital technologies and reconfigure their business models, ensuring improved competitiveness and adaptability in the Industry 4.0 landscape.Social implicationsBy promoting sustainable business practices and enhancing competitiveness, the SYNCHRO framework can contribute to economic growth and stability within manufacturing sectors.Originality/valueThe SYNCHRO framework offers a comprehensive guide for DS, highlighting the importance of internal innovation and organizational flexibility. This framework contributes to the existing literature and provides a tool for companies to enhance business competitiveness and sustainability.

Adaptation and Biomechanical Performance of Custom-Fit Mouthguards Produced Using Conventional and Digital Workflows: A Comparative InVitro Strain Analysis.

The use of different models for the fabrication of custom-fit mouthguards (MTGs) can affect their final thickness, adaptation, and shock-absorption properties. This study aimed to evaluate the adaptation, thickness, and shock absorption of ethylene-vinyl acetate (EVA) thermoplastic MTGs produced using conventional plaster or three-dimensional (3D) printed models. A typical model with simulated soft gum tissue was used as the reference model to produce MTGs with the following two different protocols: plast-MTG using a conventional impression and plaster model (n = 10) and 3DPr-MTG using a digital scanning and 3D printed model (n = 10). A custom-fit MTG was fabricated using EVA sheets (Bioart) plasticized over different models. The MTG thickness (mm), internal adaptation (mm) to the typodontic model, and voids in the area (mm2) between the two EVA layers were measured using cone-beam computed tomography images and Mimics software (Materialize). The shock absorption of the MTG was measured using a strain-gauge test with a pendulum impact at 30° with a steel ball over the typodont model with and without MTGs. Data were analyzed using one-way analysis of variance with repeated measurements, followed by Tukey's post hoc tests. The 3DPr-MTG showed better adaptation than that of the Plast-MTG at the incisal/occlusal and lingual tooth surfaces (p < 0.001). The 3DPr-MTG showed a thickness similar to that of the Plast-MTG, irrespective of the measured location. MTGs produced using both model types significantly reduced the strain values during horizontal impact (3DPr-MTG 86.2% and Plast-MTG 87.0%) compared with the control group without MTG (p < 0.001). The MTGs showed the required standards regarding thickness, adaptation, and biomechanical performance, suggesting that the number and volume of voids had no significant impact on their functionality. Three-dimensional printed models are a viable alternative for MTG production, providing better adaptation than the Plast-MTG at the incisal/occlusal and lingual tooth surfaces and similar performance as the MTG produced with the conventional protocol.

Comparison of Class II Bulk-Fill, Self-Adhesive Composites, Alkasite, and High-Viscosity Glass Ionomer Restorations in Terms of Marginal and Internal Adaptation.

(1) Background: Restoring decayed teeth in young patients can be challenging. This calls for a simplification of the protocols through new biomaterials. Therefore, the aim of this study was to compare the marginal adaptation delivered by restorative materials applied on class II cavities by using a simplified protocol, before and after fatigue test, followed by the assessment of the internal adaptation. (2) Methods: Forty-eight human teeth were divided into six groups (n = 8). Dentinal fluid simulation was performed before restoring the class II cavities: Gr 1-adhesive (Clearfil Universal Bond Quick) and nanohybrid flowable composite (Clearfil Majesty ES Super Low Flow), Gr 2-adhesive (Clearfil Universal Bond Quick) and nanohybrid composite (Clearfil Majesty ES standard), Gr 3-bulk fill self-adhesive composite (Surefil One), Gr 4-bioactive powder-liquid filling material (Cention Forte), Gr 5-universal adhesive (Adhese Universal) and nanohybrid composite resin (Tetric Powerfill); and control group (CT)-high-viscosity glass ionomer (Equia Forte). Marginal adaptation was observed with scanning electron microscopy (SEM) and compared before and after a fatigue test consisting of repeated thermal and mechanical cycles. The specimens were then cut mesio-distally, and internal adaptation was undertaken using SEM again. Repeated measures and one way ANOVA followed by a Fisher's LSD test and Fisher's LSD post hoc test were used in order to compare the statistically significant differences among groups. (3) Results: As for the marginal adaptation after loading, Cention Forte (58%) and Equia Forte HT (53%) were statistically equivalent and presented the highest results, followed by Clearfil Majesty ES Standard (32%) and Tetric Powerfill (27%), with Surefil One (8%) and Clearfil Majesty ES Flow Super Low (7%) showing the worst results. In terms of internal adaptation, Cention Forte (85%) and Clearfil Majesty ES Standard (74%) had the highest percentages of continuous margins. Tetric powerfill (56%) and Equia Forte HT (44%) showed statistically significantly lower results, followed by Clearfil Majesty ES Flow Super Low (33%) and eventually Surefil One (17%). (4) Conclusions: This in vitro study showed promising results for the marginal and internal adaptation of alkasite dual cured Cention Forte in the restoration of class II cavities. This material could be considered an interesting restorative alternative for the restoration of deciduous teeth.

Fracture resistance, marginal and internal adaptation of innovative 3D-printed graded structure crown using a 3D jet printing technology.

This in vitro study aimed to create a graded structured dental crown using 3D printing technology and investigate the fracture resistance and the adaptation of this new design. A dental crown with a uniform thickness of 1.5mm was designed, and the exported stereolithography file (STL) was used to manufacture 30 crowns in three groups (n = 10), solid (SC), bilayer (BL), and multilayer (ML) crowns using 3D jet printing technology. Marginal and internal gaps were measured using the silicone replica technique. Crowns were then luted to a resin die using a temporary luting agent and the fracture resistance was measured using a universal testing machine. One-way ANOVA and Tukey post hoc tests were used to compare the fracture resistance and the adaptation of crowns at a significance level of 0.05. Mean marginal and internal gap of the ML group were 80 and 82mm, respectively; which were significantly (p<0.05) smaller than BL (203 and 183mm) and SC (318 and 221mm) groups. The SC group showed the highest mean load at fracture (2330 N) which was significantly (p<0.05) higher than the BL (1716 N) and ML (1516 N) groups. 3D jet printing technology provides an opportunity to manufacture crowns in a graded structure with various mechanical properties. This study provided an example of graded structured crowns and presented their fracture resistance. SC group had the highest fracture resistance; however, ML had the best marginal and internal adaptation.

Comparative Evaluation of the Marginal Fit and Internal Adaptation of Polymethyl Methacrylate Interim Crowns Fabricated using two different techniques- “Conventional” and “CAD-CAM Milling”: An In Vitro Study

Introduction Interim crowns provide valuable functional and esthetic information of the final outcome during the evaluation period and act as the blueprint for the design of definitive prostheses. The fabrication technique and material used are the key factors involved in the success of the prosthesis. However, marginal fit and internal adaptation of Polymethyl Methacrylate (PMMA) interim crowns fabricated using conventional and computer aided designing-computer aided machining (CAD-CAM) PMMA milling have not been well investigated. The inter-group statistical comparison of means of normally distributed continuous variables is done using independent sample t test. Material and Methods Typodont (Nissin, Japan) of the maxillary central incisor was scanned (Ceramill Map 600+, Amann Girrbach AG) and 3D printed (Form 4, Formlabs) to create the master die used in the study, while a Typodont of a prepared maxillary central incisor was scanned using a digital scanner (Ceramill Map 600+, Amann Girrbach AG) and a .STL file obtained was modified using Exocad software for designing the study models. Three equidistant points A, B and C passing from the center of the incisal edge to the root of the typodont were indented labially and A` B` and C` were indented palatally in the same plane using Exocad software for symmetrical sectioning while checking for marginal fit and internal adaptation. 50 3D printed (Form 4, Formlabs India) models of the prepared tooth were printed and 25 interim crowns were fabricated using Polymethyl Methacrylate (DPI Tooth moulding material, DPI India) by conventional and 25 interim crowns were fabricated using CAD-CAM PMMA (Ceramill a-temp, Amann Girrbach AG). They were then luted (Han Temp Cement eugenol free, NE Korea) to respective models and viewed under a stereomicroscope (Ziess) for marginal fit at 2 specific points and internal adaptation at 4 specific points. Results The mean SD of marginal fit measurements at buccal and site in Group A (conventional technique) and Group B (CAD-CAM milling) was 95.32 ± 7.78 µm and 66.92 ± 14.59 µm respectively. At lingual site in Group A and Group B was 94.84 ± 7.97 µm and 66.80 ± 10.93 µm respectively. The mean marginal fit measurement at lingual site is significantly higher in Group A compared to Group B (P-value%3C0.05). The mean SD of internal fit measurements at upper 1 site in Group A and Group B was 335.19 ± 94.70 µm and 226.76 ± 89.68 µm respectively. At upper 2 site in Group A and Group B was 368.88 ± 120.25 µm and 240.85 ± 93.72 µm respectively. At lower 1 site in Group A and Group B was 313.52 ± 99.92 µm and 262.49 ± 94.33 µm respectively. At lower 2 site in Group A and Group B was 367.93 ± 107.36 µm and 264.52 ± 86.97 µm respectively. The mean internal fit measurement is significantly higher in Group A compared to Group B (P-value%3C0.05). Conclusion The interim crowns fabricated using the conventional technique displayed a less favourable marginal fit and internal adaptation when compared to CAD-CAM fabricated interim crowns. Key Words CAD-CAM, Interim crowns, Marginal fit and internal adaptation

In Vitro Investigation of Marginal &amp; Internal Adaptation of Two Screw-Retained Implant Supported Crowns: A Comparative Analysis of Direct Optical &amp; Subtractive Reverse Engineering Techniques.

In Vitro Investigation of Marginal &amp; Internal Adaptation of Two Screw-Retained Implant Supported Crowns: A Comparative Analysis of Direct Optical &amp; Subtractive Reverse Engineering Techniques.

Accuracy, adaptation and margin quality of monolithic zirconia crowns fabricated by 3D printing versus subtractive manufacturing technique: A systematic review and meta-analysis of in vitro studies

ObjectiveThe purpose of this systematic review and meta-analysis was to evaluate the accuracy (trueness and precision), marginal and internal adaptation, and margin quality of zirconia crowns made by additive manufacturing compared to subtractive manufacturing technology. MethodsThe investigation adhered to the PRISMA-ScR guidelines for systematic reviews and was registered at the Prospero database (n°CRD42023452927). Four electronic databases, including PubMed, Scopus, Embase, and Web of Science and manual search was conducted to find relevant studies published until September 2023. In vitro studies that assessed the trueness and precision, marginal and internal adaptation, and margin quality of printed crowns compared to milled ones were included. Studies on crowns over implants, pontics, temporary restorations, laminates, or exclusively experimental materials were excluded. ResultsA total of 9 studies were included in the descriptive reporting and 7 for meta-analysis. The global meta-analysis of the trueness (P<0.74,I2=90 %) and the margin quality (P<0.61,I2=0 %) indicated no significant difference between the root mean square of printed and milled zirconia crowns. The subgroup analysis for the printing system showed a significant effect (P<0.01). The meta-analysis of the crown areas indicated no significant difference in most of the areas, except for the marginal (favoring milled crowns) and axial (favoring printed crowns) areas. For precision and adaptation, both methods showed a clinically acceptable level. ConclusionsAdditive manufacturing technology produces crowns with trueness and margin quality comparable to subtractive manufacturing. Both techniques have demonstrated the ability to produce crowns with precision levels, internal discrepancy, and marginal fit within clinically acceptable limits. Clinical significance3D printing emerges as a promising and potentially applicable alternative method for manufacturing zirconia crowns, as it shows trueness and margin quality comparable to restorations produced by the subtractive method.

Stereomicroscope-Based in Vitro Study Evaluating the Marginal and Internal Fit of PEEK and PEKK Crowns.

The aim of the in vitro study was to compare the internal merge and marginal perfection of polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) crowns under a stereomicroscope. All-ceramic preparation is done on the maxillary first premolar which is mounted on the wax block which was scanned using 3Shape scanner and duplicated into 30 acrylic CAD/CAM dies (n = 15) for the placement of PEEK and PEKK crowns. The YENADENT milling system was used to fabricate 15 samples from Group A PEEK crowns and to fabricate 15 samples from Group B PEKK crowns. According to the manufacturer's instructions, an equal amount of the dual-cure resin luting agent (Rely X U200 Self-Adhesive resin, 3M, Germany) was dispensed on the mixing pad before being mixed with cement and painted on the internal surfaces of the copings with the finger pressure crowns which were luted. The values were then analyzed using one-way ANOVA (post hoc) followed by Dunnett's t-test. Among those two groups, PEEK group materials showed the lowest mean value of (28.73.3 ± 4.01) for marginal fit and (26.72 ± 2.53) for internal gap, whereas PEKK group showed a mean value of (32.85 ± 4.63) and (33.06 ± 4.14), respectively. Among these two groups, comparatively less marginal fit and internal adaptation is seen in PEKK when compared to the PEEK crowns. While the marginal fit and internal adaptation of both PEEK and PEKK copings were in acceptable clinical range.

Comparative study of the adaptation of alkasite versus self-adhesive flowable restorations

Aim To compare the adaptation of self-adhesive flowable composite versus alkasite restorations with or without the use of an adhesive system. Materials and Methods A total of 30 noncarious maxillary premolars were selected and mounted 2 mm below the cemento–enamel junction in acrylic blocks. Trapezoidal class V cavities were prepared on the buccal surface of each tooth. The gingival margins of the prepared cavities were located 1 mm above cemento–enamel junction. All cavity margins were not bevelled. During the experiment time, all samples were kept in artificial saliva renewed daily at 37°C in an incubator to prevent dehydration. These were randomly divided into three groups (n = 10). Alkasite restorative material was applied in a bulk fill technique using a universal adhesive in samples of group I, while those of group II did not have any adhesive using the same restorative material and those of group III were restored using self-adhesive flowable composite (vertise flow). Specimens of the three tested groups were subjected to 500 thermal cycles from 5 to 55°C with 30 s. Dwell time and 15 s transfer time. They were all immersed in methylene blue dye 2% for 24 h in an incubator. Then all samples were examined under stereomicroscopy at ×40 to determine the percentage of gap free length along the entire margins. All specimens were then sectioned buccolingually to detect the percentage of internal gap length along the restoration/tooth interface. Results Regarding the marginal adaptation, the highest % of marginal free gap was recorded for group I, while the lowest was recorded for group II. Concerning the internal adaptation, it was found that the highest % of free gap was related to group I and III while the lowest was related to group II. Comparing the marginal versus internal % of gap free margins it was found that group I versus II showed a statistically significant difference. Also, group III versus II showed a significant difference. While group I versus III recorded no statistically significant difference. This was true at both marginal and internal % of free gaps. These findings indicated the responsibility of group II for the recorded differences since group II showed the least % of free gap margins and the highest percentage of total dye penetration values. Conclusions Within the limitations of this in vitro study, the adhesive system was effective in increasing the percentage of free gaps of tested groups whether marginal or internal. Recommendations The use of any composite material is not recommended without an adhesive system. Further in vitro studies providing more precise gap measurement are required.

The Influence of Ferrule Design and Pulpal Extensions on the Accuracy of Fit and the Fracture Resistance of Zirconia-Reinforced Lithium Silicate Endocrowns.

The study aimed to assess the marginal, axial, and internal adaptation, as well as the fracture resistance of zirconia-reinforced lithium silicate (ZLS) endocrowns with varying pulpal inlay extensions and marginal geometry. Sixty extracted maxillary first molar teeth were divided into six groups (n = 10) according to pulpal inlay extension and marginal configuration. The first three groups (J2, J3, and J4) utilized prepared teeth for endocrowns without ferrule design and 2 mm, 3 mm, and 4 mm pulpal extensions, respectively. The second three groups (F2, F3, and F4) utilized prepared teeth with 1 mm shoulder margins and 2 mm, 3 mm, and 4 mm pulpal extensions. The endocrowns were fabricated from ZLS blocks using CAD/CAM milling technology. After cementation, the specimens underwent thermal aging for 5000 cycles and were evaluated for marginal adaptation. Using a universal testing machine, the fracture resistance was tested under quasistatic loading (1 mm/min). Two-way ANOVA and the Tukey's post hoc test were employed for data analysis (p ≤ 0.05). The results of this study revealed that endocrowns without ferrule exhibited superior fracture strength than a 1 mm ferrule design p < 0.05, irrespective of the inlay depth. All designs with and without ferrule and all inlay depths showed clinically acceptable marginal and internal fit. The conventional endocrown design without ferrule and 2 mm inlay depth showed the lowest surface gap. The pulpal surface showed the highest discrepancy among all groups compared to the other surfaces. Endocrowns without ferrule are more conservative and have higher fracture strength than 1 mm ferrule designs; extending the inlay depth showed a significant increase in fracture resistance of the 1 mm ferrule design, but not for the conventional design without ferrule and 2 mm inlay depth. All groups exhibited a high auspicious fracture strength value for molar endocrown restorations.

Формування культури безпеки майбутніх фахівців з цифрових технологій як наукова проблема

The article examines the current problem of forming a safety culture of future specialists in digital technologies studying in technical institutions of higher education. An analysis of the conceptual and categorical apparatus of the study was carried out, in particular the terms: computer literacy, cyber literacy, Internet literacy, electronic literacy, information literacy, digital literacy, cyber safety. The latter term has been used by Western scholars who consider it in the context of the use of digital technologies and computers. Therefore, they understand cyber security as the formation of safe behavior in the online environment, based on the responsible use of the Internet and mobile technologies, as well as implemented measures that counteract possible risks. The use of the concept of digital literacy is proposed, as it includes not only the ability to use computer technologies, but also the ability to analyze information in the online environment, taking into account social, cultural, political and educational aspects in one's professional activity.&#x0D; The results obtained as a result of the analysis of psychological-pedagogical and methodical literature on the problem of forming a culture of safety in professional activity indicate that, despite certain achievements, this direction has not received conceptual clarity. Currently, even the term "safety culture of professional activity" does not have a scientifically based definition. Theoretical searches indicate the need to clarify its content and structure. In particular, for digital professionals, understanding and implementing a security culture becomes an integral part of their professional development. This involves not only technical skills, but also a deep understanding and internal adaptation of values and approaches that contribute to ensuring cyber security in the modern digital environment on the one hand, and on the other hand - compliance with the requirements for the organization of work in the process of professional activity.

Using dynamic capabilities to cope with digital transformation and boost innovation in traditional banks

Financial institutions operate in a competitive, complex, and uncertain environment. A series of changes—many accelerated by the COVID-19 pandemic—demand innovative movements from the organizations that operate in the sector. The emergence of new business models (e.g., fintecs) requires a realignment of the capabilities of traditional organizations, such as banks. Indeed, internal adaptations and the formulation of market strategies focused on a digital user are part of the current narrative. But how can it be executed? This article explores the relationship between dynamic capabilities and digital transformation. In summary, we present insights about how dynamic capabilities can drive innovation in traditional financial institutions based on the challenges brought by digital transformation. Starting from a Brazilian case study, we identified that external and internal contextual factors—especially the political-legal environment and cultural and governance issues—are necessary for stimulating the dynamic capabilities that should be addressed for digital transformation. Finally, we propose a framework that summarizes how dynamic capabilities enable the guidance of traditional banks amid challenges caused by digital transformation.

Evaluation of marginal and internal adaptation of veneers generated by the guided prosthetic tooth preparation system.

This in vitro study aimed to assess and contrast the marginal and internal adaptation of all-ceramic prefabricated veneers manufactured via the FirstFit guided tooth preparation system against all-ceramic veneers produced using the chairside Computer-Aided Design/Computer Aided Manufacture (CAD/CAM) system following identical guided preparation protocols. Two main groups were included, with 16 lithium disilicate veneers per group. Four typodonts were used for the test (FirstFit) and control CAD/CAM groups. Intraoral scans created master casts and preparation guides. Guides performed preparations on typodont teeth (two central incisors and two lateral incisors). Prepared teeth were scanned (CEREC Omnicam) to design and mill CAD/CAM veneers. Marginal gap thickness and cement space thickness were measured using light microscopy at four locations: marginal, cervical internal, middle internal, and incisal internal. No significant difference existed between groups for marginal adaptation (p = 0.058) or incisal internal adaptation (p = 0.076). The control group had significantly lower values for middle internal adaptation (p = 0.023) and cervical internal adaptation (p = 0.019). Guided preparation evaluation showed no significant differences in marginal or incisal internal adaptation. The CAD/CAM group had significantly lower middle and cervical internal adaptation values.

Influence of polyether ether ketone coping crown on the adaptation of implant abutment.

To evaluate the influence of polyether ether ketone coping crown on the adaptation of implant abutment. The vitro study was conducted at the department of Prosthodontics, Hainan Stomatological Hospital, China, from October 2021 to March 2022, and comprised patients undergoing implant surgery on first molar. Patients were divided into two groups, with group A patients receiving polyether ether ketone coping crowns, and group B receiving zirconia crowns. Replica technique was used to replicate the gap between the crowns and the abutments. The thickness of the silicone film was measured under the stereomicroscope, and the gap between the groups was compared. Data was analysed using SPSS 22. In group A, mean marginal gap was 82.43±25.00μm, and mean overall gap was 85.45±33.75μm. In group B, the corresponding values were 65.09±11.69μm and 78.04±26.67μm. There was a significant difference in the adaptation between the groups at the marginal and overall measurement points (p<0.05). Marginal and internal adaptations of polyether ether ketone coping crown for abutment could be considered clinically acceptable.

Managing crises as if no one is watching? Governance dilemmas from a public perspective

AbstractIn the midst of ongoing crises, understanding how citizens perceive administrative crisis management is more relevant than ever. Combining organizational literature with insights from legitimacy research, this article scrutinizes how the public evaluates governance decisions concerning prominent crisis management dilemmas: flexibility versus stability, inclusion versus exclusion, and equity‐based versus needs‐based resource distribution. The paper argues that flexible, inclusive, and equity‐based governance decisions are generally perceived as more legitimate. However, governance decisions are also associated with adverse effects that can mitigate any initially positive effect on legitimacy. The argument is tested in a large‐scale randomized survey experiment in the context of a migration crisis, where governance decisions were manipulated. The findings support the expectations for inclusive crisis management and equity‐based resource distribution, which are perceived as the most legitimate governance alternatives. Internal adaptations of administrative practices toward more flexible and adaptive solutions, however, are perceived less legitimate than stable governmental action.

Assessment of Marginal and Internal Adaptation in Provisional Crowns Utilizing Three Distinct Materials.

This study aimed to assess the marginal and internal adaptation of provisional crowns fabricated from polymethyl methacrylate (PMMA) blocks by the computer-aided design/computer-aided manufacturing (CAD/CAM) system, autopolymerizing PMMA, and acrylic base composite resin. In this in vitro experimental study, a brass die was obtained, and provisional crowns were fabricated in three groups using Teliocad PMMA blocks by the CAD/CAM system, Tempron GC auto-polymerizing PMMA, and Bisico acrylic base composite resin (n = 7 in each group). The provisional crowns were coded and randomly placed on the die. Their marginal adaptation was evaluated under a stereomicroscope at 40× magnification, while their internal adaptation was assessed by the replica technique. Data were analyzed by one-way analysis of variance (ANOVA) (α = 0.05). The mean marginal gap was the highest in autopolymerizing PMMA and the lowest in the CAD/CAM PMMA group (p < 0.05). The mean marginal gap in the autopolymerizing PMMA group was significantly higher than that in the resin material (p = 0.014) and CAD/CAM PMMA (p = 0.000) groups. The difference between the resin material and CAD/CAM PMMA groups was not significant (p = 0.13). The mean internal gap was the highest in autopolymerizing PMMA group and the lowest in CAD/CAM PMMA group (p < 0.05). The mean internal gap in autopolymerizing PMMA group was significantly higher than that in composite resin (p = 0.002) and CAD/CAM PMMA (p = 0.00) groups. The difference between the resin material and CAD/CAM PMMA groups was not significant (p = 0.322). Computer-aided design/Computer-aided manufacturing PMMA provisional crowns showed the highest marginal and internal adaptation followed by acrylic base resin material crowns. Computer-aided design/computer-aided manufacturing PMMA crowns demonstrate superior marginal and internal adaptation compared with autopolymerizing PMMA and acrylic base composite resin crowns, suggesting CAD/CAM technology's potential for enhancing clinical outcomes. How to cite this article: Jalalian E, Younesi F, Golalipour S, et al. Assessment of Marginal and Internal Adaptation in Provisional Crowns Utilizing Three Distinct Materials. J Contemp Dent Pract 2023;24(11):853-858.

Effects of design software program and manufacturing method on the marginal and internal adaptation of esthetic crowns for primary teeth: A microcomputed tomography evaluation

Statement of problemThe adaptation of digitally produced crowns is affected by the design software program and manufacturing method. The effect of artificial intelligence (AI) software program design on the adaptation of the crowns is unclear and comparative evaluations should be documented. PurposeThe purpose of this study was to assess the marginal and internal gaps, the absolute marginal discrepancies, and the 3-dimensional (3D) discrepancy volumes of the resin-based milled and 3D printed crowns for primary teeth designed with computer-aided design (CAD) and AI software programs by using microcomputed tomography (µCT). Material and methodsA total of 40 resin-based esthetic crowns were produced for a prepared typodont tooth (right mandibular primary second molar) according to the design software program (CAD and AI) and manufacturing method (milling and 3D printing) (n=10). Four experimental groups were generated as CAD-milled, CAD-3D printed, AI-milled, and AI-3D printed. The marginal, axial, and occlusal gap values, the absolute marginal discrepancies, and the 3D discrepancy volumes of the specimens were measured by using µCT. The data were analyzed by using 2-way ANOVA and the Tukey HSD tests (α=.05). ResultsThe lowest value for the marginal gap (54 ±43 µm) was observed in the CAD-milled group and the marginal gap value of the AI-3D printed group was significantly lower than the AI-milled group (P<.05). The lowest value for the axial gap (63 ±7 µm) was observed in the AI-3D printed group, and the highest value (145 ±58 µm) was observed in the CAD-milled group; the result for the occlusal gap value was opposite. The highest absolute marginal discrepancy value was observed in the CAD-milled group. The 3D discrepancy volumes increased in the order of the CAD-3D printed, AI-milled, CAD-milled, and AI-3D printed groups. ConclusionsThe marginal and internal gap values of the resin-based crowns were affected by the design software program and manufacturing method; however, tested groups showed clinically acceptable gap values.

Evaluation of Marginal and Internal Adaptation of Crowns Fabricated with Three Different Zirconia CAD/CAM Materials.

Marginal and internal adaptation are key factors that determine the clinical success of dental restorations. The aim of this study is to evaluate the marginal and internal fit of crowns fabricated with three different CAD-CAM zirconia materials; two monolithic zirconia materials and one veneered zirconia copings in comparison with conventional metal-ceramic crowns. Ninety-six extracted molars (n = 96) were selected. Teeth were randomly divided into four groups (n = 24), and the following restorations were fabricated: Metal-ceramic crowns (Control group) (Group CG); monolithic zirconia crowns (GC initial) (Group MZ1); monolithic zirconia crowns (InCoris TZI),(Group MZ2); bilayered zirconia crowns, cores (InCoris ZI) veneered with a low-fusing glass-ceramic (IPS Emax Ceram),(Group BZ). Internal and marginal adaptations were evaluated using the silicone replica technique. A total of 20 points were recorded for every tooth under the light microscope at 20x magnifications. Results were compared using one-way analysis of variance (ANOVA) and the posthoc Tukey's test at a significance level of 0.01. Marginal, marginal-internal, axial, and occlusal gaps between CG, MZ1, MZ2, and BZ crowns showed statistically significant differences (P < 0.01). Monolithic zirconia groups showed better marginal adaptation compared with the veneered zirconia crowns.

Influence of different convergence angles of abutment teeth and cement spaces on internal adaptation of anterior CAD-CAM fixed dental prostheses.

The aim of this study was to investigate the influence of different convergence angles of abutment teeth and different cement spaces on internal adaptation of anterior fixed dental prostheses (FDPs) fabricated with a computer-aided design-computer-aided manufacturing (CAD-CAM) system. Composite resin FDPs for 99 standardized maxillary central incisors were fabricated according to nine parameters: three total convergence angles (4 [DG4], 12 [DG12], and 20 degrees [DG20]) and three cement space settings (10 [CS10], 50 [CS50], and 90 µm [CS90]). Internal space values were measured with a cement space replica technique. The Kruskal-Wallis and Steel-Dwass tests were used to evaluate differences in the total convergence angles and luting agent spaces, respectively (α = 0.05). For all three cement spaces tested, the median marginal gap values between abutment teeth and FDPs decreased significantly as the total convergence angle increased (P < 0.05). For the CS10 and CS50 groups, the internal space values at the axial area increased significantly as the total convergence angles increased (P < 0.05). Total convergence angles of the abutment teeth and cement spaces affected the marginal and internal adaptation of anterior FDPs fabricated with a CAD-CAM system.

The effect of cement and impression methods on the marginal and internal adaptation of the current monolithic blocks - 3D scanning evaluation.

This research aimed to evaluate the marginal and internal gaps of crowns, which were produced using both digital and conventional impression techniques and cemented with various types of cement. For the full ceramic crown restoration, an anatomically prepared acrylic first molar phantom tooth (Frasaco GmbH, Germany) was scanned with Scanner S600 ARTI (Zirkonzahn). 160 PMMA analogues produced from the milling unit. Two impression methods were used: digital impressions by intraoral scanner (Aadva Intra Oral 3D Scanner, GC) and PVS impression. Cerasmart, Initial LRF Block, Zirconia Prettau and ICE Zircon monolithic blocks milled with M1 Milling Unit (Zirkonzahn). Restorations cemented with light-cured and dual-cured cements. (n = 10) Pre and post-cementation 3D images overlap was performed using Geomagic Control X (3D Systems, NC, USA). Data were analysed by using SPSS 25.0. p<0.05 difference was considered significant. Digital impressions were significantly higher than PVS impressions in all groups (p<0.05). A significant difference was found between the materials (p<0.05). Cerasmart showed a significantly more marginal gap than the other groups. Prettau and ICE Zircon crowns with the conventional impression group showed a significantly smaller marginal gap than the others. Monolithic crowns fabricated by CAD-CAM using the digital and conventional impression methods had clinically acceptable marginal and internal gaps. Crowns cemented with dual-cured cements showed significantly more marginal gap than light-cure groups. Key words:3D scanning, Marginal accuracy, Marginal fit, Monolithic crown.