CAD) And Manufacturing Research Articles

Towards Sustainable Orthodontics: Environmental Implications and Strategies for Clear Aligner Therapy.

The increasing concern over environmental sustainability has prompted various industries to reassess their practices and explore greener alternatives. Dentistry, as a significant contributor to waste generation, is actively seeking methods to minimize its environmental footprint. This paper examines the environmental implications of clear aligner therapy (CAT) in orthodontics and explores strategies to prioritize sustainability in aligner manufacturing and usage. CAT has gained popularity as a viable alternative to traditional fixed appliances due to advancements in biomaterials and computer-aided design (CAD) and manufacturing (CAM) technologies. The global market for clear aligners is expanding rapidly, with significant growth projected in the coming years. To address these challenges, this paper proposes adopting the principles of reduce, reuse, recycle, and rethink (4Rs) in orthodontic practices. Strategies such as minimizing resource consumption, incorporating recycled materials, and promoting proper aligner disposal and recycling can significantly reduce environmental harm. This paper explores emerging technologies and materials to mitigate the environmental impacts of CAT. Additionally, initiatives promoting aligner recycling and repurposing offer promising avenues for reducing plastic waste and fostering a circular economy. In conclusion, while CAT offers numerous benefits in orthodontic treatment, its environmental impact cannot be overlooked. By implementing sustainable practices and embracing innovative solutions, the orthodontic community can contribute to a more environmentally conscious future while continuing to provide quality care to patients.

Advances in orthodontic clear aligner materials.

Rapid technological improvements in biomaterials, computer-aided design (CAD) and manufacturing (CAM) have endorsed clear aligner therapy (CAT) as a mainstay of orthodontic treatment, and the materials employed for aligner fabrication play an all-important role in determining the clinical performance of clear aligners. This narrative review has attempted to comprehensively encompass the entire gamut of materials currently used for the fabrication of clear aligners and elucidate their characteristics that are crucial in determining their performance in an oral environment. Historical developments and current protocols in aligner fabrication, features of contemporary bioactive materials, and emerging trends related to CAT are discussed. Advances in aligner material chemistry and engineering possess the potential to bring about radical transformations in the therapeutic applications of CAT; in the absence of which, clear aligners would continue to underperform clinically, due to their inherent biomechanical constraints. Finally, while innovations in aligner materials such as shape memory polymers, direct three-dimensional (3D) printed clear aligners and bioactive materials combined with clear aligner materials are essential to further advance the applications of CAT; increased awareness of environmental responsibilities among aligner manufacturers, aligner prescribing clinicians and aligner users is essential for better alignment of our climate change goals towards a sustainable planet.

Additive Manufacturing of Anatomical Poly(d,l-lactide) Scaffolds

Poly(lactide) (PLA) is one of the most investigated semicrystalline polymers for material extrusion (MEX) additive manufacturing (AM) techniques based on polymer melt processing. Research on its application for the development of customized devices tailored to specific anatomical parts of the human body can provide new personalized medicine strategies. This research activity was aimed at testing a new multifunctional AM system for the design and fabrication by MEX of anatomical and dog-bone-shaped PLA samples with different infill densities and deposition angles. In particular, a commercial PLA filament was employed to validate the computer-aided design (CAD) and manufacturing (CAM) process for the development of scaffold prototypes modeled on a human bone defect. Physical-chemical characterization of the obtained samples by 1H-NMR spectroscopy, size exclusion chromatography (SEC), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) demonstrated a small reduction of polymer molecular weight (~5%) due to thermal processing, as well as that the commercial polymer employed was a semicrystalline poly(d,l-lactide). Mechanical characterization highlighted the possibility of tuning elastic modulus and strength, as well as the elongation at break up to a 60% value by varying infill parameters.

P115. MAXILLO-MANDIBULAR RECONSTRUCTION WITH VASCULARIZED BONE FLAPS USING INSOURCED VIRTUAL SURGICAL PLANNING AND HOME-MADE CAD-CAM: A 5-YEAR SINGLE-CENTER EVOLUTION IN 75 PATIENTS

PURPOSE:Virtual surgical planning (VSP) and computer aided design (CAD) and manufacturing (CAM) of surgical guides and jigs turned craftmanship into precision and enables the surgeon to complement the donor bone osteotomies with the bony resection of the jaw. In recent years, immediate dental rehabilitation became an integral part of VSP. However, outsourced CAD-CAM is expensive and may be no option to many institutions worldwide. We developed an insourced facility for ‘in-house’ VSP and ‘home-made’ 3D printing. METHODS: We present a consecutive series of 150 cases (2010-2020). In 75 cases (2015 -2020) we used insourced VSP and CAD-CAM for the reconstruction of maxilla-mandibular defects with fibula, iliac crest and scapular angle flaps. Relevant parameters influencing the reconstructive outcome were determined. We compared data with 75 previous reconstructions of the jaw without CAD-CAM (2010-2015). Mann-Whitney U tests and Fisher’s exact tests were used to compare continuous and binary variables between both groups. RESULTS: We went from a fibula-based protocol, towards the selection of optimal vascularized bone for immediate placement of Osseo integrated implants. Bone flap survival was 94,7 % after 4 months. The three-year patient survival is 77,6 %. There were no significant prognostic factors for bone flap failure (such as smoking, radiotherapy or previous interventions). CONCLUSION: In-house VSP and CAD-CAM have evolved into a valuable strategies in maxillo-mandibular reconstruction that promote precision and allow for occlusion-based planning with quality of life, aesthetic outcome and minimizing donorsite morbidity as essential parts of the reconstruction even in high level oral cancers.

Clinical prospective evaluation of zirconia-based three-unit posterior fixed dental prostheses: Up-to ten-year results.

ObjectivesOnly a few studies exist, which assess the clinical long-term behavior of all-ceramic FDPs in the posterior region. The aim of the present prospective clinical study was to evaluate the clinical performance of posterior three-unit FDPs manufactured from Y-TZP after a service period up to 10 years. Methods55 patients received 59 three-unit FDPs in the posterior region of the maxilla or mandible. Abutment teeth were prepared and full-arch impressions were taken. Definitive casts were fabricated and optically scanned. Frameworks were fabricated with computer-aided design (CAD) and manufacturing (CAM) technology. Y-TZP frameworks were veneered and adhesively luted to the abutment teeth. Baseline and follow-up examinations (service time: ≥48months) were recorded by applying modified United States Public Health Services (USPHS) rating criteria. Cumulative survival rate was analyzed with Kaplan–Meier. Percentage of biological and technical complication was calculated. ResultsFifty-three patients with 57 FDPs attended the last follow-up visit and a mean observation period of the remaining was 6.3±1.9years was calculated. Biological complications occurred in 17.5%, technical complications in 28% of the FDPs. The 10-year cumulative survival rate amounted 85.0%. Three FDPs failed to survive, two due to a root fracture of the abutment tooth and one due to secondary caries. ConclusionsThree-unit FDPs made from Y-TZP, veneered with ceramic offer a treatment option with a high rate of chipping. However, the manufacturing processes nowadays are modified in order to avoid this complication. Clinical significanceThe results of the present investigation suggest that three-unit Y-TZP posterior FDPs may are a possible treatment option. However, a high rate of chipping can be expected.

Specifying temporal knowledge for workflows ontologies

Abstract A workflow is an automation of a process, in which participants (people or programs) are involved in activities for solving a set of tasks according to certain rules and constraints in order to attain a common goal. The concept of workflow appeared in business informatics. Currently the workflow techniques are used in many other fields such as medical informatics, bioinformatics, automation of scientific research, computer-aided design and manufacturing, etc. An ontology is a formal description (in terms of concepts, entities, their properties and relationships) of knowledge for solving a given class of problems. In particular, ontologies can be used in problems related to workflows. In this paper, we introduce a formalism that extends the language of the interval Allen’s logic, and show how this formalism can be applied to specify temporal knowledge in ontologies for workflows. For the extended Allen’s logic, we construct a deduction system based on the analytic tableaux method. We also show (by examples) how to apply the deduction method to query answering over ontologies written in the extended Allen’s logic.

Marginal Integrity of CAD/CAM Fixed Partial Dentures

Computer-aided design (CAD) and manufacturing (CAM) allows the milling of high strength zirconia fixed partial dentures (FPD), however bonding to an inert ZrO(2) ceramic surface may effect the marginal integrity of the FPDs. The aim of this investigation was to evaluate the marginal adaptation of zirconia FPDs at the interfaces between zirconia, cement, and tooth. 32 3-unit FPDs were fabricated of the CAD/CAM Y-TZP zirconia (Lava, 3M Espe, Germany) according to the manufacturers' instructions. Resin cements with corresponding primer and bonding systems were used to lute the FPDs: Compolute/EBS multi (3M Espe, Germany), Panavia F/ED (Kuraray, Japan), Variolink 2/Syntac classic (Ivoclar-Vivadent, FL) and RelyX Unicem/without treatment (3M Espe, Germany). Aualloy FPDs (BioPontostar, Bego, Germany) were cemented with RelyX Unicem and Harvard (Harvard, Germany) as the control. Marginal adaptation was evaluated with scanning electron microscopy using replica specimen before and after artificial aging. After aging, microleakage tests were performed with fuchsine solution. The interfaces between cement-tooth and cement-FPD were examined. At the interfaces (cement-tooth and cement-FPD), the systems showed a 95% or higher perfect margin before and after aging. Only Variolink2/Syntac had a marginal adaptation, lower than a 70% perfect margin. Generally, the fuchsine penetration was below 20%, only BioPontstar/Harvard andLava/Variolink2 showed penetration results between 80% and 100%. The success of the adhesive cementation of zirconia FPDs depends on the cement system. Under the conditions of this study, zirconia FPDs showed good to sufficient marginal integrity in combination with Panavia/ED, Compolute/EBS and RelyX Unicem.

SU‐FF‐T‐162: Development of a Patient‐Specific Lung Phantom Using 3D Imaging and Rapid Prototyping

Purpose: Physical human phantoms have been widely used in verification of external radiotherapy treatment plans, study of exposures outside of the target regions, and calibration of whole‐body counter for nuclear medicine procedures and for radiation safety bioassays. Existing phantoms are mostly crude in anatomical representations, although realistic 3D images of patients are available. This paper presents a method of fabricating a physical phantom of the lung using patient‐specific medical images and computer aided design (CAD) and manufacturing (CAM). Methods: Medical images have been used to construct the VIP‐Man model from Visible Human images. The voxelized data from the lung of VIP‐Man were translated into 3D polygon mesh models. The models were then corrected and scaled to the actual size of the organ. A 3D rapid prototyping machine (i.e., a 3D printer) was used to develop a physical mold of 3D polygon mesh lung. The mold was filled with lung tissue‐equivalent foam, which matched the density and effective atomic number of the lung tissue. Results: Using the methods described above the lung of the VIP‐Man model in STL format was used to fabricate an identical 3D tissue‐equivalent phantom. Conclusions: A method has been developed to rapidly prototype physical lung phantoms using CAD and CAM capabilities. Currently, there is no method that automates this complicated process of creating 3D organ phantoms. A major research effort in this task is to develop an integrated software method that will streamline image processing and 3D printing.

A mixed isomorphism approach for kinematic structure enumeration graphs based on intelligent design and manufacturing

When using graph theory for kinematic structure enumeration, the isomorphism identification of graphs is an important and complicated problem. The problem is known to be an NP-complete problem. This paper presents a mixed algorithm based on a mapping property, a genetic algorithm, and a simulated annealing algorithm for the isomorphism identification problem. A validity encoding scheme was developed by considering the mapping relationship between two graphs, and some reset measures for the crossover and mutation operators were developed based on the characteristics in which the encoding cell could not be reiterated. A simulated annealing algorithm was introduced into the mixed algorithm to prevent premature convergence in resolution, and some other measures were developed for improving the efficiency, based on the parameter selection. An example shows that the mixed algorithm is a valid algorithm for the isomorphism identification of kinematic structure graphs in mechanism design. It will be a reliable isomorphism identification algorithm for intelligent computer-aided design (CAD) and manufacturing (CAM).

Advanced Manufacturing Technology and Organization Structure: Empowerment or Subordination?

Advanced manufacturing technology (AMT) includes such technologies as computer-aided design (CAD) and manufacturing (CAM), as well as computer-integrated manufacturing (CIM). Numerous case studies have found that organization structure (e.g., centralization of decision making) changes when firms introduce AMT, but the findings from such studies have been inconsistent. This paper reports the findings of a large-sample study of the relationship between AMT and organization structure. Two alternative patterns in the relationship between these two concepts were considered. The Marxist perspective, which holds that automation is used by managers as a tool to subordinate the workforce, leads to predictions that AMT will be associated with increasing differentiation (more hierarchical levels and job classifications), centralized decision making, and high levels of formalization (management by rules). The Idealist perspective, which involves the belief that managers should use new technologies to empower the workforce, leads to predictions that AMT will be associated with less differentiation, decentralized decision making, and limited formalization. The study was conducted using questionnaires, which were returned by general managers from 185 firms in the metalworking industries (SIC codes 33-37). The findings provide some support for both perspectives, as AMT was associated with both decentralization of decision making and formalization. We interpret these results as stemming from the characteristics of AMT, particularly integration, flexibility, and risk. Seen in this light, organizations have less need to centralize decisions, as AMT's capacity for integration allows information to be brought together at lower levels of the firm, and its flexibility allows departments to more easily adapt to decisions made by other departments. The risk and expense associated with AMT, however, may lead firms to institutionalize those practices associated with effective use of the technology through formal rules. In other words, formalization may be a mechanism for safely decentralizing. In general, researchers are urged to strike a balance between focusing on the intentions of management and the constraints of the technology when they study technology and organization.

NIDDESC: Meeting the Data Exchange Challenge Through a Cooperative Effort

The application of computer-aided design (CAD) and manufacturing (CAM) techniques in the marine industry has increased significantly in recent years. With more individual designers and shipyards using CAD within their organizations, the pressure to transfer CAD data between organizations has also increased. The Navy/Industry Digital Data Exchange Standards Committee (NIDDESC) provides a mechanism for public and private organizations to cooperate in the development of digital data transfer techniques. Organizationally, NIDDESC is a cost-sharing venture between private firms and government organizations. This effort arose from the Naval Sea Systems Command (NAVSEA) in cooperation with the National Shipbuilding Research Program. The members include leading professionals in the marine industry from several major design firms, private shipyards, naval shipyards, and government laboratories. All members are directly involved in CAD/CAM in their organizations and together represent a broad spectrum of experience and perspectives. NIDDESC has many subcommittees devoted to specific areas of digital data transfer. The basic objective is to develop an industry-wide consensus on product data models for ship structure and distribution systems. Efforts include contributions to the Initial Graphics Exchange Standard, the Product Data Exchange Standard, preparation of a Recommended Practices Manual and the analysis of ship production data flows. NIDDESC has made contributions to the development of CALS standards, including MIL-STD-1840, DOD-IGES, SGML, and MIL-D-28000.

CADAM Applications in the Design and Evaluation of Aircraft Displays

The Grumman F-14D fleet air superiority fighter represents a step forward in the application of integrated controls and displays to the reduction of the high workload in the multiple task operational environment. System requirements necessitate the implementation of an avionics display system that would present flight status information efficiently and in a manner most conducive to enhancing F-14D pilot and Radar Intercept Officer (RIO) performance. In order to accomplish this, Human Factors Engineers at Grumman Corporation elected to utilize multi-color Computer Aided Design and Manufacturing (CADAM) in the design and evaluation of the Weapon Status Panel, Head-Up and Multi-Function display systems. The multi-color CADAM was used because of its unique ability to present this information efficiently, realistically and at the earliest stage in the design phase. This paper discusses the rationale for using the color CADAM as a design and evaluation tool and presents examples of specific computer generated display formats for use in the F-14D tactical fighter cockpit avionics system.