Advances in light-curing units: four generations of LED lights and clinical implications for optimizing their use: Part 2. From present to future.

UNLABELLED: The first part of this series of two described the history of light curing in dentistry and developments in LED lights since their introduction over 20 years ago. Current second- and third-generation LED light units have progressively replaced their halogen lamp predecessors because of their inherent advantages. The background to this, together with the clinical issues relating to light curing and the possible solutions, are outlined in the second part of this article. Finally, the innovative features of what may be seen as the first of a new fourth-generation of LED lights are described and guidance is given for the practitioner on what factors to consider when seeking to purchase a new LED light activation unit. CLINICAL RELEVANCE: Adequate curing in depth is fundamental to clinical success with any light-activated restoration. To achieve this goal predictably, an appropriate light source needs to be combined with materials knowledge, requisite clinical skills and attention to detail throughout the entire restoration process. As dentists increasingly use light-cured direct composites to restore large posterior restorations they need to appreciate the issues central to effective and efficient light curing and to know what to look for when seeking to purchase a new light-curing unit.

Three generations of LED lights and clinical implications for optimizing their use. 1: from past to present.

In the present era of adhesive dentistry light-curing units are essential pieces of surgery equipment for everyday practice. The success and longevity of light-activated resin sealants, photo-cured restorations and orthodontic treatments are related to the efficacy of the light-curing process. Energy efficient blue LED lights are rapidly replacing their halogen lamp predecessors as the standard light source. Manufacturers are producing materials with different initiators and not all of these materials can be properly polymerized with blue LED lights.

Time-resolved simultaneous measurement of group index and physical thickness during photopolymerization of resin-based dental composite.

Light-activated resin-based dental composites are increasingly replacing dental amalgam. However, these materials are limited by inefficient setting reactions as a function of depth that constrain the maximum extent of cure. Insufficient curing can contribute to an overall reduction in biocompatibility of the material. We demonstrate dynamic refractive index measurements of a commercial dental composite throughout cure using spectral domain low coherence interferometry. Our results show a linear relationship between the change in refractive index and polymerization-induced reduction in physical thickness during light-activated curing. This relationship between the optical and physical density demonstrates the potential of this technique as a unique noninvasive tool for measurement of the conversion degree of curing dental composite materials.

Zirconia-based all-ceramic crowns and bridges: three case reports.

UNLABELLED: The search for a clinically viable all-ceramic bridge framework has been monotonous. Until recently, few materials appear to have the necessary physical and aesthetic properties. However, the development of yttrium tetragonal zirconia polycrystals, and its adoption for use in dentistry by CAD CAM technology, may hold promise as a crown and bridge framework, this being considered suitable for single and multiple units. However, to date, no long-term clinical studies have been reported. This paper describes three cases in which zirconia frameworks were used in crowns and bridges. CLINICAL RELEVANCE: For the patient wishing to receive a non-metal crown or bridge, novel zirconia-based systems hold promise.

Trends in indirect dentistry: 8. CAD/CAM technology.

UNLABELLED: Computer-aided design (CAD) and computer-aided manufacturing (CAM) of indirect restorations became available to dentistry over 15 years ago, providing replication and digitization of the complex topography of tooth structure. There are now many applications, providing better mechanical properties, improved marginal integrity and enhanced aesthetics, compared with traditional indirect techniques. Whether a restoration is fabricated by traditional or modern computerized systems, three functional stages are required; data acquisition, design and manufacture. It is the purpose of this paper to describe the applications of CAD and CAM in contemporary indirect dentistry. CLINICAL RELEVANCE: Reliable CAD/CAM techniques, some of which may reduce the number of patient visits, are now available for the production of a variety of ceramic restorations.