Dental 3D printing: Additive manufacturing is also becoming increasingly important in the field of dentistry and dental technology, among other things for economic reasons. The article provides an overview of processes, areas of application and potential.
Veronika Greil, Munich
While in subtractive manufacturing the workpieces are milled or ground from a complete blank using CAD/CAM-supported processes, in additive manufacturing (3D Print) built layer by layer. The manufacturing process consists of several steps:
- 3D model acquisition (intraoral scan or scan in the laboratory)
- Creating an STL file (design of the object including support structures)
- 3D Print
- post processing
First, the data to create a 3D model is generated. The digital impression can be taken directly on the patient using an intraoral scan. Alternatively, the conventionally manufactured plaster model is available for data acquisition. The CAD design of the object to be printed and, if necessary, the support structures are then carried out. An STL file will be created. STL files can be used for both subtractive and additive manufacturing (Computer Aided Design CAD).
After determining the printing parameters (e.g. layer thickness or exposure time) and defining the manufacturing options, the next step in the manufacturing process is the actual manufacturing - 3D printing (Computer Aided Manufacturing CAM). Depending on the printing system, the final step focuses on post-processing of the workpieces, e.g. B. with SLA or DLP printing: removal of the support structures, manufacturer-specific cleaning and post-polymerization.
Designing an individual impression tray in the design software (1) and then transferring it to the 3D printer software (2)
Dental 3D printing: advantages and disadvantages
3D printing of polymers has now found its way into many areas of application and is proving to be a more attractive manufacturing process compared to subtractive manufacturing. In contrast to subtractive manufacturing, in which the restoration is milled out of a complete blank, with 3D printing you only use the amount of material that is necessary for the object to be printed and the support structures. The ability to render voids further reduces the amount of material required. In addition, additive manufacturing offers great object freedom and individual color design. Individual complex components can therefore be produced quickly and cost-effectively using this process with relatively little effort, without the need for molds, aids or the like.
Another enormous advantage is that several restorations can be manufactured at the same time, which enables more economical and faster production. In addition, the devices required for additive manufacturing are generally simpler and significantly cheaper to purchase.
The limits of additive manufacturing are set by the often limited precision and lower mechanical properties compared to subtractively machined blanks that are industrially produced under optimal conditions. The printing direction as well as the conversion rate and errors between the individual layers can have a negative impact on the stability and mechanical properties.
Test specimens 3D printed using the DLP process
Areas of application for dental 3D printing
The importance of additive manufacturing methods in dentistry is continually increasing. The materials used depend on the respective area of application and the required material properties. In addition to conventional polymers, ceramic-infiltrated polymers are processed for definitive fixed restorations and polymers with added hydroxyapatite for patient-specific implants for reconstruction in the head and neck area.
Requirements placed on dental 3D printing include high precision, dimensional accuracy after storage, sufficient mechanical properties such as abrasion resistance and low brittleness, good surface quality and biocompatibility.
Established areas of application for 3D printing in dentistry are:
- Model making
- Auxiliary structures such as impression trays, rails and implant drilling templates
- Temporary devices
- Definitive dentures
- Reconstructions in the head and neck area
Advantages and disadvantages of 3D printing polymers
3D printed implant drilling template after post-processing
outlook
3D printing can be easily integrated into the already established digital workflow of computer-assisted dentistry and time-consuming work steps can be optimized and simplified. At this point in time, however, there is still little knowledge about 3D printed restorations and their clinical properties. However, the constant development and establishment of new additive manufacturing processes reveal the great untapped potential of digital dentistry.