3D printing in dentistry – part 1

After subtractive manufacturing processes based on digital design (“Computer-Aided Design”, CAD) and digital manufacturing (“Computer-Aided Manufacturing”, CAM) have been used very successfully in dentistry for many years, three-dimensional (3D ) Focus on printing as an additive technology.

Alexander Prechtel, Marcel Reymus, Annett Kieschnick, Bogna Stawarczyk

The term “3D printing” has become popular, although it is better to speak of an additive manufacturing process, as further steps are required after printing to produce the final product. The beginnings of 3D printing lie in the 1980s when prototypes were produced additively for industry (“rapid prototyping”). In the following years, additive technologies have found their way into many industries and have sometimes become an indispensable element in series production. The areas of application for 3D printing in dentistry are diverse and are regularly expanding due to the ongoing development of new printing technologies and materials. For example, 3D printing is used to produce drilling templates for implantology, implant abutments, models for the production of dentures, implant models, models for digital orthodontics (aligner technology), splints, individual impression trays, frameworks made of metal alloys as well as fixed and removable dentures.

Advantages and disadvantages

Basically, the use of the relatively new technology of 3D printing in dentistry should be critically examined in terms of economic efficiency and advantages/disadvantages. Advantages of additive manufacturing are,

  • that three-dimensional objects with a complex geometry can be manufactured individually for the patient,
  • there is an efficient, resource-saving production effort,
  • and can be manufactured with high precision.

On the negative side, there is a complex digital workflow that requires technical know-how, the lack of clarity about the dentist's product liability, the (still) high material and process costs, and the post-processing of the printed object that is usually required. The digital collection and processing of patient data as part of the printing process also involves risks that require special attention in today's digitalized world.

Milled vs. printed. CAD/CAM milling technology can reach its limits, particularly with smaller radii (see milled rail, top illustration). This is where 3D printing offers advantages (see printed rail in the figure below).

Basically, the use of the relatively new technology of 3D printing in dentistry should be critically examined in terms of economic efficiency and advantages/disadvantages. Advantages of additive manufacturing are,

  • that three-dimensional objects with a complex geometry can be manufactured individually for the patient,
  • there is an efficient, resource-saving production effort,
  • and can be manufactured with high precision.

On the negative side, there is a complex digital workflow that requires technical know-how, the lack of clarity about the dentist's product liability, the (still) high material and process costs, and the post-processing of the printed object that is usually required. The digital collection and processing of patient data as part of the printing process also involves risks that require special attention in today's digitalized world.

Various 3D printing technologies are used in dentistry. The selective laser melting process (SLM) is suitable for additively processing metals such as titanium/titanium alloys and cobalt-chromium-molybdenum/precious metal alloys. Light-curing synthetic resins and plastics can be printed using stereolithography (SLA) and digital light processing (DLP), in which a light source (usually UV light) cures the material point by point.

Many techniques are available for processing plastics such as polycarbonate (PC), polyamide (PA) and acrylonitrile butadiene styrene (ABS); namely SLA, Selective Laser Sintering (SLS), Fused Filament Fabrication (FFF) and PolyJet Technology (PJ). Depending on the area of ​​application of the product in dentistry, the appropriate technology and the appropriate material must be selected and validated in order to obtain successful results.

A tray of a DLP/SLA printer filled with photosensitive resin. The object to be printed “grows” layer by layer from the liquid resin and hardens via polymerization.
Spool of a filament printer. A rod filament is heated by the heat head and applied layer by layer to the building platform using an extruder.

Good prospects

3D printing in modern dentistry is not a technical gimmick, but a revolutionary innovation that has enormous potential for the future that will challenge traditional, established manufacturing processes. The most important future developments include 3D printing of ceramic digitally colorable materials and material combinations so that a complete denture can be printed in one operation. However, technical and legal challenges still need to be solved so that digital 3D printing in dentistry can reach the level of traditional analog processes or even become better.

3D printing part 2

Printer materials and follow-up in focus

TEAM talk

for dentistry, dental technology, dental technology, science