Direct digital manufacturing of complex dental prostheses

Abstract

Over the last decade Reverse Engineering, Computer-Aided Design, Computer- Aided Manufacturing and Rapid Prototyping (RE, CAD, CAM, RP) have been applied to medicine and dentistry (Gibson, 2005). Diagnostic tools have become increasingly more sophisticated and medical imaging technology can now present patient data with high precision. Virtual planning environments allow data visualization and manipulation. Many dedicated CAD/CAM systems were introduced to the medical and dental community (Rudolph et al., 2003). With RP there came a way to produce custom physical models of patient anatomy providing doctors the means for tactile interaction which facilitates preoperative planning of complex surgeries. In addition, RP-generated replicas act often as basis for customization of treatment devices such as craniofacial plates. RP-techniques are also used to create custom treatment aides such as dental drilling guides (Ref. Materialise website) that transfer the digital planning to the patient in a reliable way. Because of cost advantages and standardizing possibilities it?s clear that digitizing and automation have gained an important place in the fabrication of medical products. However, many dental metal parts are still being produced by manual and inefficient conventional methods. Offering a digital solution to the dental profession implies a real challenge because patient and dentist set high requirements on quality, material and precision. No existing CAD/CAM system can totally replace the traditional dental practices, but emerging technologies may expand the capabilities of future systems (Strub et al., 2006). In recent years, Rapid Prototyping evolved to Rapid Manufacturing (RM) because of technical improvements of Layer Manufacturing (LM) processes and due to the possibility to process all kinds of metals (Levy et al., 2003). (Figure presented) Dental applications could take advantage of this evolution by using LM not only for plastic devices like visual anatomical models or one-time surgical guides, but also for functional implants or prostheses with long-term consistency made from a biocompatible metal (Abe et al., 2000). Selective Laser Melting (SLM) has taken the lead as Direct Digital Manufacturing (DDM) technique for metal parts. SLM (Fig. 7.1) is a layer-wise material addition technique that allows generating complex 3D parts by selectively melting successive layers of metal powder on top of each other, using the thermal energy of a focused and computer controlled laser beam (Over et al., 2002; Kruth, Mercelis et al., 2005). The competitive advantages of SLM are geometrical freedom and material flexibility (metals). Dental parts, like crowns, bridges and frameworks, are very suitable to be produced by SLM due to their complex geometry, low volume, strong individualization and high aggregate price.Moreover, the manufacturing of multiple unique parts in a single production run enables mass customization. This chapter discusses the use of SLM as RM technique for metal frameworks for complex dental prostheses. Procedures are described for dental data capture, for digital design and for manufacturing by SLM. Quality control has been performed on produced frameworks and the procedures were validated by clinical cases. © Springer 2008.