Over the past decade, conventional procedures for the laboratory fabrication of ceramic restorations have been augmented with new materials and technologies. These innovations often enable the involved steps (ie: shade matching, framework design, milling) to be completed with greater efficiency, making them valuable adjuncts to the dental laboratory. The infusion of computer-aided design/computer-assisted machining (CAD/CAM Technology) now enables technicians to mill high-strength materials that provide the combined advantages of strength and esthetics; these substructures can then be layered with the ceramist’s artistic skills, rendering a durable, esthetic restoration for today’s patients.
Recently, there have been several advancements and enhancements to laboratory based CAD/CAM systems for the fabrication of all-ceramic restorations. Systems and materials from Sirona Dental Systems, 3M ESPE, Ivoclar Vivadent, KaVo, Nobel Biocare and others continue to make vast improvements on existing technology and materials. Understanding the systems’ implications can assist laboratories in remaining competitive, productive, and profitable. Incorporating today’s CAD/CAM equipment and accessories has equated to hiring an extra ceramist enabling me to greatly increase productivity without increasing payroll expenses. Thanks to the growth within the CAD/CAM arena, there are now several in-lab systems available in the marketplace.
For purposes of this article, my references are based on using the Sirona InLab System. Some of the advancements I discuss in this article are exclusive to this system, while others may have applications to other laboratory-based CAD/CAM systems. All of these systems offer different advantages and considerations, so be sure to research all of them to determine which is right for you.
When Ivoclar Vivadent, Inc. introduced its new comprehensive all-ceramic system IPS e.max, among the system’s components was the IPS e.max CAD block. There were several aspects of this lithium disilicate CAD/CAM ceramic—which is indicated for anterior and premolar copings—that were of significant interest to me. First, it is part of a system that is unified by one common veneering ceramic. What I call multimedia complex cases can now be fabricated with a harmonious esthetic look. Secondly, the material is not sintered or infiltrated so special ovens or processes are needed. Instead, conventional ovens can be used. Finally, the IPS e.max CAD process of developing an all-ceramic coping that is ready for glazing takes about 50 minutes (ie, computerized coping design, milling, margin adjustment, and crystallization); about 3 minutes are spent in hands-on time. It is also worth mentioning that the lithium disilicate material minimizes wear on the CAD/CAM milling instruments. Additionally, the absence of shrinkage means that manual adjustments are easily achieved.
As part of its new comprehensive all-ceramic product line, Ivoclar Vivadent also introduced IPS e.max ZirCAD. It is a yttrium-stabilized zirconium oxide block for copings and frameworks that require high strength including anterior and posterior single- and multiple-unit bridges. According to the manufacturer, this new addition to high-strength CAD/CAM materials demonstrates a flexural strength of more than 900 MPa. IPS e.max ZirCAD blocks are available in four sizes—the C15 and C15L block for fabricating single-crown copings and the B40 and B40L block for bridge frameworks and batch processing. This is an example of a product that combines both pressable and CAD/CAM technologies. The resulting frameworks can either be veneered with IPS e.max Ceram veneering ceramic or the IPS e.max ZirPress material can be pressed onto them to achieve the desired esthetic results.
A new dental digitizer was introduced last year (inEos, Sirona Dental Systems). To me, it makes laboratories using CAD/CAM technology more productive. The inEos for the Sirona inLab CAD/CAM systems can be used to digitally scan single- and multiple-unit bridge restorations, as well as antagonist data. It can scan up to the full-arch directly from the master model. Scannable stone or optically reflective contrasting powder may be required. From a productivity perspective, the inEos dental digitizer is capable of scanning up to 20 units per hour. What is good about inEos is that it is user-friendly for the entire laboratory. No dental expertise is required. Additionally, it is easily added on to any inLab system, and it can readily serve multiple inLab systems to accommodate the needs of high-volume laboratories. As a result, those laboratories incorporating the inEos and inLab CAD/CAM system for the fabrication of all-ceramic restorations may be able to respond to clinician needs more efficiently and productively, while still producing the highest-quality restorations possible. Unlike past Sirona CAD/CAM units, the new streamlined system that takes advantage of inEos digital scanner enables the scanning and milling units to operate independently. While one framework is being milled, the die for another can be scanned.
CAD/CAM copings and frameworks require models and dies to be poured so that they can be optically scanned for the purposes of creating a virtual, 3-dimensional on-screen model. However, the optical scanner must be able to register significant data points on the dies. For this reason, CAD/CAM manufacturers advocate the use of scannable stone materials, or at the very least, optically reflective contrasting powder that is sprayed onto the dies before scanning. I prefer using contrasting powder and, when the die is trimmed, blocking it out with scanning wax. This scanning wax is actually a new product that is soon to be released from Germany’s Dentaco. It contains a contrasting material allowing the die to be reflected into the scanner for digitizing. I also use Dentaco’s contrasting spray (scan’spary) which provides an even and thorough application, and produces consistently accurate scans. Up until recently, Dentaco’s only produced a contrasting medium spray that was originally intended for use when scanning preparations intraorally (ie, for in-office CAD/CAM restorations). This particular contrasting spray—which I have used—is very expensive because the propellants it must contain to ensure patient’s safety. It is highly effective and predictable. In response to laboratory needs, Dentaco will introduce within the next few weeks a large volume bottle of the contrasting spray suitable for laboratory use. Best of all, it will cost approximately 90% less than originally priced.
FINAL THOUGHTS:
Where ceramists were once limited to metal-ceramic restorative options, recent innovations in material science and laboratory fabrication techniques now enable labs to achieve superlative results that continue to drive patients’ aesthetic expectations. And, when it comes to fabricating all-ceramic restorations, today’s CAD/CAM solutions for the dental laboratory are helping technicians, ceramists, and laboratory owners realize greater efficiency, productivity, and profitability.
As material and equipment manufacturers continually introduce new and innovative products that further advance this fabrication method, all participants in the dental treatment process—laboratory, dentist, and ultimately, the patient, continue to benefit. By educating yourself implementing the CAD/CAM technology—including but not limited to those products discussed here—laboratories can remain competitive when it comes to providing this increasingly demanded restorative option.