Types of 3D Printer: There are a range of different technologies used in 3D printing, but they all work off of the same concept where the print material is on top of or underneath a print platform which moves up or down after each layer of the print material is processed by lights or lasers or other techniques. The finished printed part is built layer by layer with just the material needed to create the part’s geometry used during the process. The actual mechanics of how this happens varies from printer to printer, and this includes why some print technologies are compatible with specific materials. Here is an overview of the 3D printing technologies most commonly used in dentistry:
- Stereolithography (SLA): A common technique for dental 3D printers because it can create highly detailed, smooth-surfaced objects in relatively short amounts of time, SLA printers use an ultraviolet laser to polymerize a liquid resin in the required pattern. SLA printed objects are built layer by layer with the print platform moving down to allow another layer of liquid resin to be polymerized on top of the preceding layer. SLA printers generally require a support material to hold the 3D printed parts in place during production.
- Digital Light Processing (DLP): DLP printers work in a similar fashion as SLA printers, but instead of using a laser to polymerize the liquid resin print material, these printers use specialized light projectors capable of only exposing the desired areas of the resin to the polymerizing power of the projected light. These printers offer highly detailed and smooth finished parts in a short print cycle, but like SLA printers, they often require special supports to be printed along with the parts being produced.
- Selective Laser Melting/Selective Laser Sintering (SLM/SLS): Both SLM and SLS printers are used to print metals and ceramics. These systems use lasers to fuse together the print material from its original powder form into solid, 3 dimensional shapes. The finished parts can be highly detailed with thin walls and complex geometries, but the print process can be time consuming. The lasers used for this printing technique require a lot of power, and the machines can be sizable, making SLS and SLM printers best suited for large scale production operations.
- MultiJet/PolyJet Printing: These systems use a similar polymerization process as SLA printers where a UV light source solidifies the material, however rather than having the material in a liquid tank, these printers use a print head similar to an inkjet printer to spray precise amounts of the material in place before polymerizing it. The process can produce highly detailed parts without support materials. This technique is also capable of printing with multiple materials or colors in the same production run. The trade off for the versatility of this print technique is a somewhat slower print process.
- LCD: LCD technology is differentiated by its light source – it uses an array of LEDs exposing UV light through an LCD screen. The screen only lets the light pass through areas that are to be cured, simplifying the process and removing the need for any moving parts. LCD 3D printers are calibrated for high accuracy and precision and are made with quality components that ensure the longevity of each machine. LCD printers produce consistently smooth application surfaces.
- Additional 3D printing technologies such as Fused Deposition Modeling and Binder Jetting are used in some industries, but these techniques do not currently produce parts with the detail and durability required for dental uses.
Types of Materials: The materials available for a 3D printer can be a big draw as different materials are used for different types of production. Some printers are designed for a single purpose and work with just one type of material, but most printers are now compatible with a range. The materials can be added to the printer in different formats such as proprietary cartridges, liquid to be added to a tank, or in a powder form. While most printers only accommodate a single format, some can accept 3rd party materials as well as materials produced by the printer manufacturer. Each material should be approved for dental use, and any printed materials intended for intraoral uses should have the proper certification for such clinical applications.
What Types of Data Can Be Used: Like most production systems, the output from a 3D printer is only as good as the data fed into it. Almost all dental 3D printers are open architecture systems capable of working with data in an STL format. Some can also work with data in another open format, PLY, or a range of other specialized 3D CAD model file formats. These files are usually sent to the printer after being designed in a CAD software application and prepared for printing in a CAM application. Some printers come with their own CAM software which is designed to work with the major dental CAD platforms. While a high degree of customization is available, most CAD and CAM applications automate processes to make it almost as easy to 3D print a CAD design as it is to send a file to a desktop printer.
How Much Can I Print: The amount of material that can be printed in a single run is called the build volume, and this differs greatly from printer to printer. Some systems are designed to quickly produce a single crown or bridge, while others feature a larger build platform for batch production of models or other parts. Making sure the printer’s capacity is appropriately sized for your planned tasks is a key consideration when deciding on a printer for your practice or lab.
What Are Supports: Some 3D printers require the printing of an additional support material to hold the printed object’s shape while it is being created. This is necessary because gravity can change the shape of an object before it is fully polymerized. The supports help keep the part in the proper shape and then can be removed with a spray of water or dissolved in a solvent after the part is removed from the printer. While this step is rarely complicated, it is important to factor the time this takes when evaluating the efficiencies of your new 3D printer’s workflow.
What Happens When It Comes Out of the Printer: After a part comes out of the printer it often requires some finishing before it is ready for use. Different materials will require different amounts of finishing, but it rarely requires any trimming, contouring or shaping. Often the finishing step is just the removal of the support material or an external polymerization. Some of the newest 3D printers integrate these finishing steps into the production cycle in order to produce fully finished parts at the end of the print run. It is important to understand what needs to be done with the material after it is printed, especially if this will require additional equipment that you will need to purchase along with the printer.
Print Speeds: Speed is one of the biggest factors in determining if 3D printing will be a more efficient production technique for your practice or lab. Different printers can produce parts at different speeds, and this often is determined by both the material being used and the size and complexity of the job being printed. Be as specific as possible with the way you plan to use the printer when evaluating how fast it can print your parts.