1,720,957 research outputs found
Impact of digital dentistry in daily prosthodontics
Get PDFThe goal of this Ph D thesis was to evaluate the impact of new digital technologies in the field of prosthodontics and to assess the advantages and disadvantages of them through in vivo and in vitro studies to implement their use in everyday practice.
Firstly, in vitro studies for fixed and removable prosthodontics were conducted to test the devices and materials in laboratory without variables and potential confounding factors present in whole organisms and to evaluate parameters before testing them in vivo.
Different intraoral scanners have been tested to assess the accuracy in terms of trueness and precision in different possible clinical scenarios: vertical or horizontal finish line designs, supra or subgingival margins, implant scanbodies.
Additionally in vitro studies assessed also the outcomes of a completely digital workflow: from digital intraoral impression of abutments with two different intraoral scanners to the final milled lithium disilicate complete crowns that have been evaluated in terms of accuracy of marginal and internal fit.
From these studies emerged a high accuracy of intraoral scanners when used for detecting vertical iuxta or supragingival margins and good fit of the milled restorations.
Since the positive outcomes of in vitro studies, in this thesis in vivo protocols have been performed thorough three different Randomized Controlled clinical trials. Clinical research lays the groundwork for progress in medicine and is an indispensable prerequisite for evidence-based medicine. Randomized controlled clinical trials (RCTs) are the gold standard for ascertaining the efficacy and safety of a treatment or device. As reported in the present thesis , it emerged that there aren9t any statistically significative differences between traditional, hybrid or digital workflows for the realization of partial restorations or veneers. Additionally traditional pressed lithium disilicate partial restoration have been compared with UHPHS evaluation criteria to milled ones and to 3D printed PMMA restorations and no statistically significative difference was found.
This RCT studies have reported encouraging results regarding the new materials tested and digital workflow but longer periods of follow up and larger sample are needed to confirm the present data. Regarding removable prosthodontics, interesting flexural strength values of printable resins emerged when compared to milled and traditional ones. Additionally, two different case reports have been conducted to report the clinical performances of cad-cam milled complete dentures realized with a completely digital workflow that highlighted once again the advantages of using intraoral scanners and new prosthodontics material in a completely digital workflow
Analog and digital complete denture bases accuracy and dimensional stability: an in-vitro evaluation at 24 hours and 6 months
Get PDFObjectives: The study aimed to evaluate the accuracy of 3D printed complete denture bases compared to analog and milling manufacturing. Methods: Denture bases (n = 60) were created using three methods: milling (n = 10), analog (flasking) (n = 10), and 3D printing (n = 40). The 3D printing group was further divided into subgroups and each of the material groups. All samples were scanned, and their surfaces were analyzed using 3D software (Geomagic Control X software, 3D Systems) to compare them to the reference model. The accuracy was assessed using root mean square (RMS) values, reflecting the average deviation between the denture bases and the reference model. Results: At 24 h, the "Temp Print", from 3D printing group had the lowest RMS values (54.20±9.44 μm), indicating higher accuracy, while the "ProBase Hot" from the anlog group showed the highest discrepancies, particularly in the border areas. Over six months, all groups experienced increased RMS values, with the 3d pronted "Denture 3d+" group showing the most significant variations (194.1 ± 49.63 μm). The "Temp Print" group maintained the lowest RMS values, indicating better stability at 6 months. Conclusions: Despite some discrepancies, all denture bases remained within clinically acceptable limits (300 μm). Milled bases were the most stable between 24 h and six months. In terms of accuracy and stability, 3D printed resins are suitable for both prototypes and definitive dentures. Further research is required to confirm the clinical acceptability of these materials. Clinical significance: Accuracy in the fabrication of denture bases is paramount for ensuring proper fit, function, and comfort for patients. Analog, addictive and subtractive manufacturing methods of production obtained good dentures accuracy
Digital vs. conventional removable complete dentures: A retrospective study on clinical effectiveness and cost-efficiency in edentulous patients
Get PDFObjectives: This study aimed to compare the clinical effectiveness and cost-efficiency of conventional and digital prosthodontic protocols, with a specific focus on milled and 3D-printed digital removable complete dentures. Methods: This retrospective clinical study was conducted at the Removable Prosthodontics Department of the University of Siena. 60 patients were divided into two groups: 30 received conventional complete dentures, while the remaining 30 received digital complete dentures (15 milled and 15 3D-printed). Clinical outcomes were assessed using OHIP-14, bite force measurements, and masticatory performance tests before and six months after treatment. Treatment-related metrics, including chairside time, follow-up time, and laboratory costs, were recorded and compared across the groups. Statistical analysis was performed to determine the significance of differences between conventional and digital complete dentures, as well as between milled and 3D-printed digital complete dentures. Results: The study revealed that digital complete dentures significantly reduced chairside time compared to conventional dentures, with average times of 154.31 ± 13.19 min for digital dentures and 218.00 ± 20.75 min for conventional dentures (p < 0.0001). Laboratory costs were found to be statistically lower for digital dentures, (€378.79 ± 137.46 vs. €459.15 ± 63.72, p = 0.0059) compared to conventional dentures. No statistically significant differences were observed in bite force or masticatory performance between the groups. OHIP-14 scores indicated slightly lower patient satisfaction with digital dentures, but the difference was not clinically significant. Conclusion: Digital removable dentures, including both milled and 3D-printed models, offer a practical and efficient alternative to conventional dentures, particularly in terms of reducing chairside time and laboratory costs. Clinical significance: Digital removable dentures offer a practical and efficient alternative to conventional dentures, particularly in terms of reducing chairside time and costs. These simplified digital protocols could be applied in residential facilities or within national healthcare programs, improving access to prosthetic care for a larger number of patients
A randomized controlled clinical trial on press and block lithium disilicate partial crowns: A 4-year recall
Get PDFPurpose: To evaluate clinical performances of two lithium disilicate systems (Initial LiSi press vs Initial LiSi Block, GC Co.) using modified United States Public Health Service (USPHS) evaluation criteria and survival rates after 4 years of clinical service. Methods: Partial adhesive crowns on natural abutment posterior teeth were made on 60 subjects who were randomly divided into two groups: Group 1: Initial LiSi press and Group 2: Initial LiSi Block. Fabrication of partial crowns was made with full analog and digital procedure in Groups 1 and 2 respectively. The restorations were followed-up for 1 and 4 years, and the modified USPHS evaluation was performed at baseline and each recall together with periodontal evaluation. Contingency tables to assess for significant differences of success over time in each group and time-dependent Cox regression to test for differences between the two groups were used and the level of significance was set at P 0.05). No statistically significant difference between scores recorded at the baseline and each recall. All modified USPHS scores were compatible with the outcome of clinical success and no one restoration was replaced or repaired, and the survival rate was 100% after 4 years of clinical service. No difference was found between traditional and digital procedure to fabricate the crowns. The two lithium disilicate materials showed similar results after 4 years of clinical service. Clinical significance: The crowns made with the two tested lithium disilicate materials with analog and digital procedures showed 100% survival after 4 years of clinical service with no statistically significant difference using the modified USPHS scores
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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