Technology is leading to a paradigm shift in all areas of healthcare. In dentistry, there have been significant changes in this direction. Along with new digitization tools, manufacturing processes and materials are evolving at such a high rate that they are changing the understanding of new data and redefining the approach to workflows. The rapid development of these new dental materials complicates the decision-making process for dental professionals, how research is conducted and how quickly evidence is gathered to support these new decisions and protocols.
Applying a science-based approach to digital dentistry
Forward-thinking dental professionals seeking detailed results with new 3D printing materials may become frustrated, asking the same questions as with traditional materials. To avoid disappointment, the following areas of research should be considered when evaluating a new 3D printing solution.
Compare production options and categories
Understanding modern materials starts with understanding the various production methods for which they are used. Three key areas of difference are presented here, in order of increasing specificity.
Comparison of traditional and digital production
Today, the digital clinical process includes four main steps: digitization of the patient's dental data (using intraoral scanning, CBCT, photography, and static and dynamic occlusion), design (using CAD software), manufacturing (milling or 3D printing) and the final stages of the manufacturing process (thermoforming or others). Just as we understand the traditional workflow, we need to understand how intraoral scanning and CAD methods can affect the print result.
Some aspects remain the same. For example, the consequences of not following manufacturer's protocols and instructions are the same for both traditional and digital workflows: an inaccurate low-quality intraoral scan will result in a defective virtual model, just as a bad impression will result in an inaccurate model.
Some aspects have changed. With a digital workflow, accuracy and error-freeness can be quantified, for example, by scanning the surface and comparing it to a digital impression (photo 1). This is fundamental to predicting how all components will adapt within the oral cavity, and has the added benefit of reassurance, both for clinician and patient, that prostheses and appliances fit the patient's condition with sufficient accuracy.
Photos 1a and 1b: Surface analysis of the occlusal splint (a) and guide cap (b)
In addition, the timing of the production of digital products can affect the patient's appointment schedule. For example, for full prosthetics, the digital workflow requires half the number of appointments compared to traditional workflows. Moreover, in case of loss or breakage, the production of a new denture can be easily repeated using existing digital files.
Milling vs. 3D printing
Milling has been used in dentistry longer than 3D printing. The most significant difference between the two technologies is how they are conducted. Milling, or subtractive manufacturing, begins with a single piece of material such as polymethyl methacrylate (PMMA) or zirconia, using cutting tools to remove the material until the final shape is achieved. Whereas, 3D printing, or additive manufacturing, in contrast, uses different processes to give the original material its final shape, layer by layer. Dental 3D printers typically use a viscous liquid resin that reacts with light to become solid, using a laser or other light source to selectively expose the product to light and polymerize it in place.
Given the difference in the nature of production processes, it is necessary to take into account various design parameters. When milling, limitations such as milling radius compensation are taken into account during the design and preparation of a restoration or splint. With 3D printing, there are fewer design constraints, but preparing the file for making the part requires more attention, such as orienting the part in the printer (photo 2) and using secure holding structures to hold the part during the printing process (photo 3).
Photo 2: Model design for the production of clear aligners and retainers printed horizontally with a base directly on the assembly platform (1) or vertically with calipers (2).