Search results

1 – 10 of 72
To view the access options for this content please click here
Article

Huang-Jan Hsu, Shyh-Yuan Lee, Cho-Pei Jiang and Richard Lin

This study aims to compare the marginal fit, flexural strength and hardness for a ceramic premolar that is constructed using dental computer aided machining (CAM) and…

Abstract

Purpose

This study aims to compare the marginal fit, flexural strength and hardness for a ceramic premolar that is constructed using dental computer aided machining (CAM) and three-dimensional slurry printing (3DSP).

Design/methodology/approach

Dental CAM and 3DSP are used to fabricate a premolar model. To reduce the fabrication time for 3DSP, a new composition of solvent-free slurry is proposed. Before it is fabricated, the dimensions of the green body for the premolar model are enlarged to account for the shrinkage ratio. A two-stage sintering process ensures accurate final dimensions for the premolar model. The surface morphology of the green body and the sintered premolars that are produced using the two methods is then determined using scanning electronic microscopy. The sintered premolars are seated on a stone model to determine the marginal gap using an optical microscope. The hardness and the flexural strength are also measured for the purpose of comparison.

Findings

The developed solvent-free slurry for 3DSP can be used to produce a premolar green body without micro-cracks or delamination. The maximal marginal gap for the sintered premolar parts that are constructed using the green bodies from dental CAM is 98.9 µm and that from 3DSP is 72 µm. Both methods produce a highly dense zirconia premolar using the same sintering conditions. The hardness value for the dental CAM group is 1238.8 HV, which is slightly higher than that for the 3DSP group (1189.4 HV) because there is a difference in the pre-processing of the initial ceramic materials. However, the flexural strength for 3DSP is 716.76 MPa, which is less than the requirement for clinical use.

Originality/value

This study verifies that 3DSP can be used to fabricate a zirconia dental restoration device that is as good as the one that is produced using the dental CAM system and which has a marginal gap that is smaller than the threshold value. The resulting premolar restoration devices that are produced by sintering the green bodies that are produced using 3DSP and dental CAM under the same conditions have a similar hardness value, which is four times greater than that of enamel. The flexural strength of 3DSP does not meet the requirement for clinical use.

Details

Rapid Prototyping Journal, vol. 25 no. 7
Type: Research Article
ISSN: 1355-2546

Keywords

To view the access options for this content please click here
Article

F. Filser, P. Kocher and L.J. Gauckler

A new process called direct ceramic machining was successfully applied for the fabrication of dental restorations and technical components. It uses prefabricated, easy to…

Abstract

A new process called direct ceramic machining was successfully applied for the fabrication of dental restorations and technical components. It uses prefabricated, easy to machine ceramic blanks. The shape of a ceramic component is machined with enlarged contours to compensate for the sintering shrinkage. Afterwards the machined component is sintered to full density and thereby shrinks to its final dimensions. Technical components from 5 to 100 mm in size possessing features of 1/10th mm to several millimeters and dental restorations were fabricated sucessfully, and thus demonstrate the capability for rapid production of ceramic functional prototypes. The dimensional accuracy is about 20 μm with a relative accuracy of 0.1 per cent of the component's length. Thus accurate net‐shape of the components could be achieved without hard machining.

Details

Assembly Automation, vol. 23 no. 4
Type: Research Article
ISSN: 0144-5154

Keywords

To view the access options for this content please click here
Article

Kimberly Deranek, Steven Kramer and Sharon Siegel

This research compared the efficacy of process outcomes leveraging lean methods versus traditional pedagogy applied to dental education dependent on emerging technology…

Abstract

Purpose

This research compared the efficacy of process outcomes leveraging lean methods versus traditional pedagogy applied to dental education dependent on emerging technology. The pedagogical objective was to improve system efficiency without compromising traditional outcomes of effectiveness (quality).

Design/methodology/approach

The research team tested the efficacy of a lean A3 framework to identify, remove waste and redesign a technology-dependent simulation laboratory course (CAD/CAM/IR Restorative Dentistry). Students were also sensitized to time-in-chair to introduce a stronger patient focus. Baseline data collected from a control group were statistically compared to the research group's data after the course redesign. In addition, course time allocations were measured and then compared.

Findings

The results showed the interventions significantly reduced procedure cycle times without compromising quality. Additionally, the course was more efficiently conducted as measured by course time allocations.

Practical implications

This research demonstrated that the use of the A3 framework enhanced learning through process documentation, reengineering and systems optimization resolving issues of inefficiency associated with the CAD/CAM/IR pedagogy. This work is significant because it demonstrates the practice of using lean interventions to redesign and improve a technology-based healthcare course to maximize benefits.

Originality/value

This research is the first to examine how to leverage lean methods in a healthcare simulation laboratory, dependent on innovative technology, to educate and train future practitioners. This research applied statistical rigor in a controlled experiment to maximize its applicability and generalizability.

Details

International Journal of Quality & Reliability Management, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0265-671X

Keywords

To view the access options for this content please click here
Article

Ana R. Lapcevic, Danimir P Jevremovic, Tatjana M Puskar, Robert J. Williams and Dominic Eggbeer

The purpose of this paper is to analyse structure and measure hardness of Co-Cr dental alloy samples made with two different technologies, conventional casting method (CCM…

Abstract

Purpose

The purpose of this paper is to analyse structure and measure hardness of Co-Cr dental alloy samples made with two different technologies, conventional casting method (CCM samples) and additive direct metal laser sintering technology (DMLS samples), and to compare the results.

Design/methodology/approach

CCM samples were made in a conventional casting machine, using remanium 800+ Co-Cr dental alloy (Dentaurum, Ispringen, Germany). DMLS samples were fabricated out of EOS CC SP2 Co-Cr alloy (EOS, GmbH, Munich, Germany) using DMLS technology. Samples for structural analysis were plate-shaped (10 × 10 × 1.5 mm3) and for the hardness test were prismatic-shaped (55 × 10.2 × 11.2 mm3). Structure was analysed via an inverting microscope and colour metallography method.

Findings

CCM samples have a dense, irregular dendritic mesh, which is typical for the metallic phase of the Co-Cr dental alloy. DMLS alloy has a more homogenous and more compact structure, compared to CCM. Metals, the alloy basis consists of, form semilunar stratified layers, which are characteristic for the additive manufacturing (AM) technique. Hardness values of DMLS (mean value was 439.84 HV10) were found to be higher than those of CCM (mean value was 373.76 HV10).

Originality/value

There are several reports about possible use of AM technologies for manufacturing dental devices, and investigation of mechanical properties and biocompatibility behaviour of AM-produced dental alloys. Microstructure of Co-Cr alloy made with DMLS technology has been introduced for the first time in the present paper.

Details

Rapid Prototyping Journal, vol. 22 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

To view the access options for this content please click here
Article

Abbas Azari and Sakineh Nikzad

The goal of rapid mechanical prototyping is to be able to quickly fabricate complex‐shaped, 3D parts directly from computer‐aided design models. The key idea of this novel…

Abstract

Purpose

The goal of rapid mechanical prototyping is to be able to quickly fabricate complex‐shaped, 3D parts directly from computer‐aided design models. The key idea of this novel technology is based upon decomposition of 3D computer models data into thin cross‐sectional layers, followed by physically forming the layers and stacking them up; “layer by layer technique.” This new method of modeling has raised many attentions in dentistry especially in the field of surgery and implantology. The purpose of this review study is to represent the historical development and various methods currently used for building dental appliances. It is also aimed to show the many benefits which can be achieved by using this new technology in various branches of dentistry.

Design/methodology/approach

The major existing resources, including unpublished data on the internet, were considered.

Findings

Although, creating 3D objects in a layered fashion is an idea almost as old as human civilization but, this technology has only recently been employed to build 3D complex models in dentistry. It seems that in near future many other methods will develop which could change traditional dental practices. It is advisable to include more unit hours in dental curriculums to acquaint dental students with the many benefits of this novel technology.

Originality/value

It is hard to believe that the routine dental techniques were affected by revolutionary concepts originally theorized by engineering methods. It is a reality that in future, most of the restorative disciplines will be fully revised and the computer methods be evolved to an extent where dentistry can be performed by computer‐assisted methods with optimum safety, simplicity, and reliability.

Details

Rapid Prototyping Journal, vol. 15 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

To view the access options for this content please click here
Article

Bo Gao, Jiang Wu, Xianghui Zhao and Hua Tan

This paper aims to improve the efficiency and the quality of metal dental prostheses, reporting on the first patient‐fitted titanium (Ti) complete denture base plate…

Abstract

Purpose

This paper aims to improve the efficiency and the quality of metal dental prostheses, reporting on the first patient‐fitted titanium (Ti) complete denture base plate fabricated by integrating the technologies of computer‐aided design and computer‐aided manufacture (CAD/CAM) and laser rapid forming (LRF).

Design/methodology/approach

To make a complete Ti denture base plate, the traditional lost‐wax‐casting technique is commonly used in dentistry. In order to simplify this labor‐intensive process, a new method combined with LRF was invented. Initially, a maxillary edentulous plaster cast was converted to point cloud data by laser scanning system. Subsequently, point cloud data were reconstructed into a 3D solid digital cast, which is stored in standard triangulation language format. Thereafter the 3D denture base was sliced electronically into a sequence of layers defining the regions of the component and, based on it, the complete Ti denture base plate was built layer‐by‐layer using a laser additive manufacturing technology.

Findings

After CAD/CAM/LRF process, the Ti denture base plate was designed and successfully fabricated layer‐by‐layer. After the traditional dental finishing techniques, the complete Ti denture base plate was made and assessed by clinician and patient. The clinical evaluation on quality of fit was judged to be acceptable.

Originality/value

The CAD/CAM/LRF system is a potential candidate to replace the traditional lost‐wax‐casting technique and provides a new platform for the design and manufacturing of custom‐made Ti denture plates and other restorations especially for implant substructure and framework of partial removal of denture.

Details

Rapid Prototyping Journal, vol. 15 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

To view the access options for this content please click here
Article

Qin Lian, Wenquan Sui, Xiangquan Wu, Fei Yang and Shaopeng Yang

This paper aims to develop an additive manufacturing technique for complex zirconia ceramic dental bridges.

Abstract

Purpose

This paper aims to develop an additive manufacturing technique for complex zirconia ceramic dental bridges.

Design/methodology/approach

To carry out this study, a dental bridge model was obtained by three-dimensional reverse engineering, and a light-curable zirconia ceramic suspension was formulated. Zirconia bridges were manufactured by stereolithography and then treated by vacuum freeze drying, vacuum infiltration and sintering. The optimal scanning speed was determined according to the shape precision comparison. Then, characteristics of the sintered ceramic parts were tested as size shrinkage, relative density, surface Vickers hardness, surface roughness and microstructure.

Findings

The method for preparation of light-curable zirconia suspension (40 volume per cent solid loading) with a viscosity value of 127 mPa·s was proposed. The optimal laser scanning speed for zirconia bridge fabrication was 1200 mm/s. A relative density of 98.58 per cent was achieved; the obtained surface Vickers hardness and surface roughness were 1,398 HV and 2.06 µm, respectively.

Originality/value

This paper provides a potential technical method for manufacturing complex zirconia dental bridges and other small complex-shaped ceramic components which are difficult to be made by other manufacturing techniques.

Details

Rapid Prototyping Journal, vol. 24 no. 1
Type: Research Article
ISSN: 1355-2546

Keywords

To view the access options for this content please click here
Article

Frank Alifui‐Segbaya, Paul Foley and R.J. Williams

Rapid manufacture‐produced cobalt chromium alloys are beginning to be used in dentistry but there are few published results relating to their properties. The purpose of…

Abstract

Purpose

Rapid manufacture‐produced cobalt chromium alloys are beginning to be used in dentistry but there are few published results relating to their properties. The purpose of this paper is to determine the corrosion resistance of a rapid manufacture‐produced dental alloy and compare it to a standard dental casting alloy.

Design/methodology/approach

In accordance with ISO 22674, ten samples of each alloy were fabricated in approximately 45 mm×10 mm×2 mm rectangular prisms, a sample number in excess of the standard requirements. The groups were further divided into those with highly polished surfaces and those with electrobrightened surfaces. Each sample was immersed in artificial saliva, suspended by a nylon thread for 42 days at 37°C. Readings for cobalt, chromium and molybdenum ions released into solutions were obtained using an atomic absorption spectrometer at 1, 4, 7, 14, 21, 28, 35, and 42 day intervals at a detection limit of one part per million.

Findings

Ion release of cobalt, chromium and molybdenum was well within the threshold prescribed by the standard. The alloys were safe for use as dental devices with respect to the above metals. The rapid manufacture alloy however performed better. In addition the data indicated that for both alloys, there was no discernable difference between a polished and an electrobrightened surface.

Originality/value

The rapid manufacture alloy studied shows a safe level of corrosion resistance with respect to cobalt, chromium and molybdenum according to ISO definitions. Further biocompatibility tests are recommended.

Details

Rapid Prototyping Journal, vol. 19 no. 2
Type: Research Article
ISSN: 1355-2546

Keywords

To view the access options for this content please click here
Article

Abdollah Afshar, Mohsen Shirazi, Masoud Rahman and Esmaeil Fakheri

The purpose of this paper is to evaluate the galvanic corrosion of nitinol orthodontic wires with six dental alloys in artificial saliva and consider the effect of…

Abstract

Purpose

The purpose of this paper is to evaluate the galvanic corrosion of nitinol orthodontic wires with six dental alloys in artificial saliva and consider the effect of initiated localized corrosion and real surfaces of anode and cathode on galvanic current.

Design/methodology/approach

Linear polarization and cyclic polarization curves for each alloy in de‐aerated Duffo and Castillo's artificial saliva are obtained. Galvanic corrosion investigation is conducted by polarization curve intersection and mixed potential theory methods. In order to verify the initiation of localized corrosion, scanning electron microscopy is used.

Findings

Initiation of localized corrosion on the anode increases the galvanic current up to 45 times and therefore considering the effect of localized corrosion on galvanic corrosion is necessary. Placing stainless steel brackets or Aristaloy amalgam in direct contact to nitinol arch wire is not recommended.

Originality/value

In order not to underestimate the galvanic corrosion between two alloys, it is recommended to consider the effects of localized corrosion and anode/cathode surface area ratio. In this paper, an electrochemical method for estimating these factors is proposed.

Details

Anti-Corrosion Methods and Materials, vol. 56 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

To view the access options for this content please click here
Article

JAROSLAV MACKERLE

This bibliography is offered as a practical guide to published papers, conference proceedings papers and theses/dissertations on the finite element (FE) and boundary…

Abstract

This bibliography is offered as a practical guide to published papers, conference proceedings papers and theses/dissertations on the finite element (FE) and boundary element (BE) applications in different fields of biomechanics between 1976 and 1991. The aim of this paper is to help the users of FE and BE techniques to get better value from a large collection of papers on the subjects. Categories in biomechanics included in this survey are: orthopaedic mechanics, dental mechanics, cardiovascular mechanics, soft tissue mechanics, biological flow, impact injury, and other fields of applications. More than 900 references are listed.

Details

Engineering Computations, vol. 9 no. 4
Type: Research Article
ISSN: 0264-4401

Keywords

1 – 10 of 72