Showing papers on "Dental laboratory published in 2002"

Crowns and extra-coronal restorations: materials selection.

Abstract: Materials selection is the second in the series on crowns and other extra-coronal restorations. Some of us are less than inspired by dental materials science. Nevertheless, many of the things that concern us clinically with crowns and their alternatives are based on material properties. We worry about the strength of the restoration, how well it fits and its aesthetics. We also worry about wear, occlusal control and biocompatibility. Not least of our concerns are dental laboratory charges, which inevitably have to be passed on to the patient.

Microwave polymerization system for dentistry

Abstract: A microwave polymerization system for dentistry utilizes specifically controlled microwave energy to cure polymer materials so as to produce dental prosthetics, such as dentures, bridges and crowns, that are made in an extra-oral setting such as a dental laboratory or dental office, and to create dental composites for fillings and veneers that are used in an intra-oral setting directly in the patient's mouth Unlike the microwave energy delivered by commercial microwave ovens, the system utilizes metered and controlled microwave energy that is preferably continuous and voltage controlled, and regulates the application of this microwave energy by use of various feedback and control mechanisms The metered and controlled microwave energy enables a higher degree of conversion of monomers into polymer chains in the polymerization process, thereby enhancing the physical and biocompatibility characteristics of both dental prosthetics and dental composites made from polymers

In vitro study of transmission of bacteria from contaminated metal models to stone models via impressions

Abstract: The purpose of this study was to determine the risk of microbiological transmission into the dental laboratory via impressions and dental stone models. Metal master models were contaminated with Bacillus subtilis and Streptococcus sanguis. Impressions in alginate, polyvinylsiloxan, and polyether were used, and models were cast in two brands of dental stone. Samples were taken from the impression surfaces before and after casting, and sections from the stone models were taken by a technique developed for this study. After incubation, the numbers of colonies were counted and the numbers of colony-forming units per milliliter were calculated. The reductions were statistically significant but considered to be clinically insignificant. The conclusion is that even after severe contamination, the risks to dental laboratory personnel are minimal. "Normal" hygienic procedures are recommended instead of disinfection.

Orthodontic soldering techniques: aspects of quality assurance in the dental laboratory.

Abstract: Background: In Germany, the dental technician is required by the Medical Products Act (MPG) to produce workpieces of high safety and quality and to document these properties. Soldering continues to be the prevailing joining technique in the dental laboratory, although problems arise from the susceptibility to corrosion and the low strength of soldered joints. This study aimed to reveal sources of defects in dental laboratory workpieces in order to achieve optimization in terms of quality assurance. Material and Methods: The joints were produced by various dental technicians using three different soldering techniques. These joining techniques were investigated for their quality and their corrosion properties during immersion in ferric chloride, orthodontic appliance cleanser, and artificial saliva. Observance of the soldering instructions by the dental technicians was checked. Corrosion attack was confirmed by scanning electron microscopy and by measuring the ion concentrations of copper, silver and zinc in the corrosive agents, using atomic emission spectroscopy with stimulation by inductively coupled plasma (ICP-AES analysis). Results and Discussion: Incomplete filling of the soldering gap, porosities resulting from the production process, poor corrosion properties, and in particular a high variability of the measured values point to insufficient reliability of two soldering techniques. Variations in quality were also detected among the technicians' modes of operation. Conclusion: The analyses confirm the need for quality assurance of soldering techniques and for increased support for alternative joining techniques such as laser welding in the future. The results of the studies on laser welding are presented in a separate publication.

The dental laboratory dilemma in America.

Abstract: Dentistry has lost some of its "touch" with the technical, laboratory aspects of the profession. More cooperation is needed between dentists and laboratory technicians in their education, in practice, and at the organizational level.

The changing roles of the dentist and dental laboratory

Abstract: There are growing pressures on the relationship between the profession and laboratories, including increased use of sophisticated prosthetic services, rapid evolution of materials, more "educated" patients, declining numbers of laboratory training programs and relatively reduced hours in dental schools in traditional prosthodontics subjects, and consolidation in the dental laboratory industry. Restorative services represent the greatest cost/value center in most practices, and the ADA's "Future of Dentistry Report" calls for the profession reasserting its "control" in this area. It is proposed instead that a partnership among the profession, laboratories, manufacturers, and education represents the most effective way to guide the emerging future of restorative dentistry for the benefit of patients and the concerned parties.

The articulator: a diagnostic instrument.

Abstract: The success of dental restorations depends on how we view the existing occlusion. Clinicians may be confounded with what aspects of the occlusion will contribute to the success of a restoration. This information can be reviewed with the dental laboratory when it is stored in a dental articulator in the form of dental casts with simulated movements.