Technical Advantages of Dental 3D Printing

Guide: There have been many arguments about the application of 3D printing in dentistry, but a recent study by the Graduate School of Dentistry of Tohoku University in Japan has provided quantifiable evidence for its benefits compared with traditional methods.

On October 4, 2022, Antarctic bears learned that scientists from Tohoku University in Japan compared the dimensional accuracy of DLP 3D printed and milled resin composite crowns, and determined the acceptable print shape of abutments. Their research results show that the dimensional accuracy of the 3D printed version is higher, indicating that the products produced by this method have improved in technology.

The research was published in the Dental Materials Journal with a paper entitled "Comparison of the accuracy of resin composite crowns fabricated by three dimensional printing and milling methods".

Links to related papers:https://www.nanjixiong.com/thread-157407-1-1.html

Generally speaking, doctors seem to prefer familiar things to innovation. Although the tried and tested method has many advantages, it often requires updated technology to solve persistent problems. Researchers have been trying to provide the best possible treatment to meet medical and aesthetic needs. 3D printing has solved some of these problems. Dentists can use this technology to produce implants, orthodontic retainers, and dental arch models. Before the invention of 3D printing technology, the CADCAM technology for dentistry was patented in France by Dr. Francois Duret in 1975. He was an early pioneer in the use of computer-assisted dental therapy.

△ Chart: Color chart of the overall deviation between the design of molar crown and scanning data. Blue and red represent the negative deviation and positive deviation relative to the benchmark respectively. Image source: Journal of Dental Materials 2022

3D printing using CAM system is a promising, fast and economical digital manufacturing technology for dental prostheses. Various materials, including metals, ceramics and resins, can be used for 3D printing. Resin materials, used for barrel photopolymerization methods such as digital light processing (DLP) and stereo lithography (STL), can be used for a wide range of dental applications, such as temporary crowns, casting models, denture bases and occlusal splints. DLP method provides rapid printing and high accuracy for the fabrication of dental prostheses. In the DLP method, objects are designed according to CAD, and resin filled barrels are used for layer by layer photopolymerization on the platform.

At present, traditional resin materials are used for 3D printing casting models or temporary crowns, and will not be used in the oral cavity for a long time. It is reported that the new resin composite used for 3D printing can disperse the occlusal stress and has high durability under occlusal load. These resin composites may not only provide high physical durability, but also provide excellent dimensional accuracy for making permanent dental prostheses. The edge and internal fit of 3D printed crowns are often compared with milled resin composite crowns. However, the dimensional accuracy of 3D printed crowns and the acceptable abutment shape are still unclear.

Methods and limitations

In the latest research of Northeast University, the researchers first made the abutment (the supporting structure for placing the crown), and then made the model of the crown using CAD. They used two methods to make these models -- traditional milling, which is an example of subtractive manufacturing, and DLP 3D printing. The product is superimposed on the design data, and it is found that the model generated by the latter method is more accurate and has fewer minor differences, as shown in the above figure.

△ Flow chart for evaluating crown dimensional accuracy.

This study also has its limitations. First, the researchers tested only one form of 3D printing and one form of traditional manufacturing. Because each method has its own advantages, changes in each method may produce different results. Dental additive manufacturing can also be achieved through stereo lithography (SLA) and selective laser sintering (SLS), which may have different accuracy levels. As far as the feasibility of 3D printing technology in the dental field is concerned, "fracture resistance" and "biocompatibility" need to be further studied. Even if a product is technically excellent in shape, it will not be automatically transformed into perfect use. In addition, production is constrained by a shortage of trained staff and high initial costs. However, the accuracy of these 3D printed crowns is encouraging. You can learn more here.

Source: Polar Bear 3D Printing Network