1,721,076 research outputs found
TUTE PULITE PER UN LAVORO SPORCO. CULTURE DELLA CORPORATE SOCIAL SUSTAINABILITY NELLE FONDERIE ITALIANE
No full textLo scritto approfondisce i costrutti di cultura della c.d. Corporate Social Sustainability (“CSS”) e sostenibilità della vita organizzativa nelle fonderie italiane, inquadrate nella letteratura di settore come organizzazioni ad alto rischio. Le fonderie sono comunemente percepite come “Industrie 3D: Dirty, Dusty and Dangerous”, poco attente alla sostenibilità ambientale, sociale ed economica. La nostra ipotesi è che in questi contesti sia possibile identificare elementi culturali in grado di “rendere pulito” un lavoro “sporco”, così da migliorare la sostenibilità della vita lavorativa e contribuire alla transizione da “Industrie 3D” a “Industrie 3P: Profit, Planet and People”. Gli obiettivi conoscitivi riguardano (i) la descrizione degli elementi culturali in cui si esprime la CSS, e (ii) lo studio delle relazioni esistenti tra la CSS e altri oggetti teorici, (iii) la ricognizione di conoscenze empiriche a sostegno di processi di trasformazione di contesti lavorativi in un’ottica di sostenibilità organizzativa. A tale proposito abbiamo articolato un progetto di ricerca etnografico in tre fasi, giungendo ai risultati di cui in seguito.
In particolare, la prima fase si è sostanziata in numerose osservazioni etnografiche su un campione di sei fonderie per descrivere la CSS, mostrando la sua espressione in diversi elementi culturali (pratiche, norme, valori, credenze, rituali, ruoli) legati ai seguenti oggetti teorici: pianificazione, comunicazione, team, sicurezza, contesto/contenuto, riconoscimento, identificazione, giustizia, management e conoscenza. Nella seconda fase, attraverso quattro focus group, sono state verificate le conoscenze sviluppate precedentemente e introdotto l’oggetto “tecnologia”. La relazione dell’oggetto “tecnologia” con la CSS è stata approfondita nella terza fase, mediante le c.d. “Visual Methodologies” e concludendo che le nuove tecnologie sono fondamentali per lo sviluppo di culture della CSS poiché agevolano la gestione di spazi e movimentazioni, di contesto e contenuto lavorativo, sicurezza, riconoscimento e identificazione, conoscenze, organizzazione del lavoro, impegno e innovazione.This dissertation explores the constructs of Corporate Social Sustainability (“CSS”) culture and sustainability of organizational life in Italian foundries, considered as high- risk organizations in the industry literature. Foundries are commonly perceived as “3D Industries: Dirty, Dusty and Dangerous”, with little attention to environmental, social and
economic sustainability. We deem that in these contexts it is possible to identify cultural elements that can “make clean” a “dirty” job, so as to improve the quality of working life and contribute to the transition from “3D Industries” to “3P Industries: Profit, Planet and People”. The research goals concern (i) the description of cultural elements in which CSS is expressed, and (ii) the study of relations between CSS and other theoretical objects, and (iii) the recognition of empirical knowledge to support transformative processes of work contexts in an organizational sustainability perspective. We have developed a three- phase ethnographic research project, achieving the outcomes set out below.
The first phase focused on ethnographic observations in a sample of six foundries to describe CSS, showing its expression in several cultural elements (practices, norms, values, beliefs, rituals, roles) related to the following theoretical objects: planning, communication, team, safety, context/content, rewarding, identification, justice, management and knowledge. During the second phase, through four focus groups, the previously developed knowledge was assessed and the object “Technologies” was introduced. The relation of the latter with CSS was studied in the third phase, through the so-called “Visual Methodologies” and it was concluded that new technologies are fundamental to the development of CSS cultures as they facilitate the management of space and movement, work context and content, safety, recognition and identification, knowledge, work organization commitment and innovation
Bond Strength to Cubic Zirconia and Lithium-disilicate. A Preliminary Study
No full textObjectives: Bonding to polycrystalline ceramics is a concern in fixed prosthodontics. Aim of this study was to determine the micro-SBS of two MDP-based cements to cubic-zirconia (ZIR) and lithium-disilicate (L-DIS).
The null hypothesis was that mean micro-SBS did not vary among tested groups.
Methods: Twenty plates 12x12x2mm of Katana-UTML, (Kuraray-Noritake), and 20 of IPS e.max CAD LT, (Ivoclar-Vivadent) were used as substrates. They were assigned to 4 groups (n=40) according to the combination with two resin-cements: PanaviaV5 (PV5) + Clearfil-Ceramic-Primer-Plus, (groups PV5/ZIR and PV5/L-DIS); PanaviaSA (PSA) self-adhesive cement, (groups PSA/ZIR and PSA/L-DIS).
The ceramics were pre-treated following the cements manufacturer instructions: ZIR-tablets were sandblusted (Al2O3 powder, 50mm); L-DIS-tablets were conditioned (35% H3PO4, K-Etchant Syringe).
Four cylinders (1.7mm diameter, 2mm height) of resin-cement were applied on each plate with vertical load (1Kg) and light-cured (20sec).
All samples were stored in water (37°C, 24h) and tested for micro-SBS (Instron-machine). Failed surfaces were analyzed under optical-microscope and failure pattern was determined (adhesive, cohesive or mixed). Percentage of actual-failed/total adhesive surface was calculated with dedicated software (Zeiss ZEN). Mean micro-SBS values were measured (MPa) and statistically analyzed (Kruskall-Wallis-test, Dunn’s test, a=0.05).
Results: The null hypothesis that micro-SBS did not vary among the groups was rejected, (p<0.05). Mean values varied from 7.7±1.9MPa (PSA/L-DIS) to 19.6±1.7MPa (PV5/ZIR). All groups were statistically different, except PSA/ZIR vs PV5/L-DIS, (p>0.05). Both cements presented significantly higher bond strength to ZIR than L-DIS substrate. For each substrate, PV5 showed higher bond strength than PSA. Adhesive failures were mostly observed in all groups. Mean percentage of actual-failed adhesive surface varied from 69.5% (PSA/ZIR) to 85.1% (PV5/L-DIS).
Conclusions: ZIR treatment with MDP-based primer helped obtaining improved adhesion. L-DIS treatment with H3PO4 should be further investigated and compared with the conventional HF treatment. Micro-SBS measurements after longer aging conditions are needed to evaluate the bonding stability
Prosthetic digital solutions for the reconstructed mandible after cancer surgery: preliminary results of ongoing research.
No full textBackground
After cancer ablative surgery of the mandible, the fibula results not thick enough to reach the original height of the native alveolar bone of the mandible. As a consequence, positioning of dental implants is often deeper then the mouth floor, and unaesthetic and inappropriate hygienic maintenance may outcome with the final prosthetic restoration. Aim of this study is to discuss a novel approach to the positioning of the Fibula Free Flap (FFF) as a function of the restoration of the vertical height of the mandible, for improving the natural gingival/crown ratio and consequently the oral hygiene maintenance of the prosthetic rehabilitation. Moreover, the secondary aim is to present the hybrid (fixed and removable) approach to the prosthetic restoration.
Methods and Materials
In this novel protocol the design of the bone plate was modified to allow reproducing a double-level anatomy: the more lateral/basal bone inferior margin of the mandible and the more medial alveolar bone position. The customized plate is projected to support the FFF at the higher position of the alveolar bone level, so that no pink resin body of the prosthesis is projected to fill the discrepancy between teeth crowns and the gingiva. The cobalt/chrome framework is then prototyped using a hybrid manufacturing machine, and a new concept of connection to implants is used to fix the prosthesis in place: a double-option attachment allowed using the prosthesis both as a removable or fixed restoration.
Results
This new methodology allows giving a physiologic gingival appearance to the prosthetic rehabilitation without any additive pink resin to recover the missing alveolar bone and mucosa. The digital workflow permits the transfer of occlusal, aesthetic, and functional data from the pre-operative status of the patient to the final design of the rehabilitation. Moreover, the double-option attachments used for the prosthetic connection to implants permitted to use the restoration as a removable or fixed prosthesis, depending on the home care maintenance results of each patient, avoiding the risk of reactive gingival hyperplasia.
Conclusion
This novel protocol, due to the new design of the customized bone plate, allowed maintaining the face profile and a correct alveolar bone volume of the mandible, restoring the occlusion without artificial crossbite and excessive crown/implant ratio with consequent usage of large volume of pink resin prosthetic body. Moreover reactive gingival hyperplasia may be avoided using the double option abutment on implants that allow using the prosthesis both as removable or fixed restoration, depending on the oral hygienic maintenance ability of the patient
The prototype concept in a full digital implant workflow
No full textBackground: The aim of this case report is to describe the innovative concept of a prototype use in a digital implant workflow. A prototype is required for simultaneous evaluation of the accuracy of a dental impression and esthetic and functional parameters before final framework realization. Case Description: Three digital impressions were obtained to create a master file, which contained information on the 3-dimensional (3D) position of the implant, the gingival architecture, and the esthetic and functional features of the provisional restoration. A stereolithographic master model (SMM) featuring implant analogs was 3D printed. Two prototypes were realized with the use of 2 different modalities. The first resin prototype (A), which lacked implant connections, was produced with the use of a certified digital workflow process. The titanium connections were luted onto the SMM. The second resin prototype (B), considered experimental, was a single piece with milled implant connections. Both prototypes were tested in the patient by means of visual inspection, finger pressure testing, screw resistance testing, and periapical radiography. In the case of accurate fit of prototype A or B on the SMM and misfit in the patient, the impression should be invalidated. For prototype B, in the case of proper fit in the patient and misfit on the SMM (because of the occurrence of an error during 3D printing, incorrect analog position, or both), the impression should be validated, but the model should be adapted. Conclusions and Practical Implications: The use of a prototype allows the clinician to simultaneously test implant position and esthetic and functional parameters. However, a single-structure prototype could be preferable for the identification of impression inaccuracy
Fatigue Resistance of Monolithic Ceramic Crowns: In Vitro Comparison with Teeth.
No full textPurpose: To compare the tooth fatigue resistance to lithium disilicate, UTML (ultra-translucent-multi-layered zirconia), and Y-TZP (yttrium-stabilized tetragonal zirconia) monolithic crowns, tested using a new, simplified fatigue testing machine (Ball-mill) and digital wear analysis. Materials and Methods: Twenty extracted human molars were used. In addition, 60 monolithic crowns were produced and subdivided into 3 groups (n = 20) according to material (lithium disilicate 1.5 mm, IPS e-max CAD LT, IvoclarVivadent; UTML 1.5 mm, Katana STML, Kuraray Noritake; Y-TZP 1.0 mm, Katana, Kuraray Noritake). Teeth were subjected to three 10-min cycles of Ball-mill and to one 30-min cycle. For monolithic crowns, twelve 60-min cycles were performed (since in a preliminary pilot study no significant volumetric losses were observed before 60 min). At T0 and after each cycle, an analysis was carried out using a stereomicroscope (Wild M3C, Heerbrugg) to evaluate the wear morphology, an intraoral scanner (CS 3500, Carestream Dental), and software (Rhinoceros, McNeel) to calculate the volumetric loss of the samples caused by the wear. Results: The lithium disilicate and Y-TZP crowns showed a 100% survival rate and high wear resistance; UTML had 95% survival. Lithium disilicate and UTML showed many parting-cleavage fractures (>90%). The wear generated on teeth at T60 was statistically greater (p < 0.05) than the one of crowns, Y-TZP in particular (p < 0.0001); all couples of compared materials differed significantly (p = 0.0008), except for lithium disilicate and UTML crowns. From comparison with the anthropometric classification of Miles, it was estimated that 60 min of Ball-mill testing correspond approximately to an average clinical wear time of 18 years. Conclusion: The Y-TZP crowns showed the best results in terms of wear resistance. The lithium disilicate presented excellent resistance, but with uniform 1.5-mm thickness over the entire crown (marginal and occlusal area). The Ball-mill testing machine provided good results in reproducing the clinical conditions: its in vitro outcomes demonstrated the same mechanical characteristics of the 3 ceramics as shown by other fatigue testing machines. The investigation methodology was effective when using digital technology to compare materials and calculate the volumetric dental loss over time
Morphological results of customized microvascular mandibular reconstruction: A comparative study
No full textIntroduction Virtual planning and guided surgery with customized reconstructive plates are becoming more and more common for mandibular reconstruction with fibular free flaps. Although the literature describes many potential applications, no systematic analyses have been made about morphological results regarding computer-aided reconstruction compared to traditional freehand bent plate. Materials and methods In the present study, we propose a comparative study in this innovative field, analysing a case series of 30 CAD/CAM reconstructed mandibles, compared to traditional reconstructed mandibles, in terms of morphological results. All patients were evaluated by pre-operative and a post-operative CT scan. To evaluate the morphological results, several anatomical landmarks were measured on CT scan: 1) the midline deviation; 2) the amplitude variation, in grades, of the mandibular angle; 3) the bi-gonial diameter of the mandibular and 4) the chin protrusion. Results The mean differences registered between pre-operative and post-operative CT scan were significantly better for test group regarding mandibular angle (p = 0.034), bi-gonial diameter (p = 0.041), chin protrusion (p = 0.05). No significant differences were registered for midline deviation (p = 0.092). Conclusion CAD/CAM reconstructive technique appears to be a valid method to accurately restore the pre-operative morphological situation
A semi-automated tool for digital and mechanical articulators comparative analysis of condylar path elements
Full text linkDigital workflows have revolutionized dentistry, especially when it comes to fabrication of complete dentures through Computer-Aided Design and Computer-Aided Manufacturing (CAD-CAM) procedures. Digital articulators manage to simulate mandibular movements and are emerging as alternatives to mechanical articulators like the Gerber semi-adjustable model. Despite being a promising tool, digital articulators require refinement in order to grant consistent functionality and effective occlusal balance. The aim of this research is to present a semi-automated MATLAB tool designed to compare trajectories from different articulator types—digital versus analog—used in dental practice. Validation of the MATLAB tool compared to existing data demonstrates its reliability and effectiveness. Sensitivity analyses assess the tool's robustness under various settings. Results suggest optimal input parameters and settings ensuring precision. Future developments may include integrating anatomically-based reference systems and advanced metrics for rotational analysis of condylar path elements (CPEs), thereby enhancing digital dentistry potentialities. Ultimately, the semi-automated MATLAB tool represents a significant step towards improving dental occlusal analysis, bridging the gap between analog and digital methodologies and enabling comparison among these tools
Digital Jaw Relation Record of Edentulous Patients in the CAD-CAM Workflow of the Implant-Supported Full-Arch Prosthesis
No full textNo abstract is required for research letters
Metrological Protocol for Comparison of Digital and Analogic Articulators for Complete Dentures
Full text linkThis paper proposes a methodology to compare the trajectories from different articulators - both physical and digital - during lateral and protusive movements. In the case of digital articulators, the articulated models are digitally moved and exported in position; in the case of mechanical articulators, the models are locked into position and 3D scanned. The digital models in position, both digital and scanned, are aligned to a common reference system and a maxilla-based reference system is tracked. The trajectories are defined as interpolating splines through the maxilla-based reference system origins. A Gerber mechanical articulator and an “Artex CR adjustable” virtual articulator were compared. The repeatability of the mechanical trajectory is found to be less than 184 microns. The resting position of the two articulators is found significantly different meaning that a bias is introduced by the operator in the analogic protocol. The trajectories have significantly different shapes as expected coming from two different articulator models. The proposed methodology proved to be a valid means to compare different articulators
Updates on the Construction of an Eyeglass-Supported Nasal Prosthesis Using Computer-Aided Design and Rapid Prototyping Technology
No full textThis study was undertaken to design an updated connection system for an eyeglass-supported nasal prosthesis using rapid prototyping techniques. The substructure was developed with two main endpoints in mind: the connection to the silicone and the connection to the eyeglasses. The mold design was also updated; the mold was composed of various parts, each carefully designed to allow for easy release after silicone processing and to facilitate extraction of the prosthesis without any strain. The approach used in this study enabled perfect transfer of the reciprocal position of the prosthesis with respect to the eyeglasses, from the virtual to the clinical environment. Moreover, the reduction in thickness improved the flexibility of the prosthesis and promoted adaptation to the contours of the skin, even during functional movements. The method described here is a simplified and viable alternative to standard construction techniques for nasal prostheses and offers improved esthetic and functional results when no bone is available for implant-supported prostheses
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