How to Choose a Dental Printer?
In the 21st century, the digital technology has a great influence on dentistry, especially the 3D printing technology. With the development of technology, the types of 3D printers have become richer, among which the most widely used in dentistry is the light-curing 3D printer. Choosing the applicable light-curing 3D printer is critical for dental labs and clinics. This section will help you gain an in-depth understanding of light-curing technology and provide recommendations for choosing a dental printer.
The principle of light-curing 3D printing technology
Light-curing 3D printing technology is collectively called SLA (Stereo Lithography Appearance), the earliest 3D printing technology. The principle of SLA is irradiating photopolymer with UV light of a specific wavelength, which decomposes the photoinitiator to produce active substances, triggering the cross-linking polymerization of the resin and realizing the transition from liquid to solid.
The development of light-curing printing technology
Based on the principles of SLA, the first SLA 3D printer debuted in 1988. The 3D printer uses a galvanometer system to control a UV beam to scan the surface of the photopolymer, hardening the resin, and then stack it layer by layer to form a complete print. Before printing, the model needs to be sliced layer by layer, and each layer is irradiated according to a specific path by the laser beam. After curing the first layer, the build platform lowers to create room for the next layer, and then the sweeper moves across the resin surface to ensure even distribution, followed by repeating the curing and lowering process until the print is finished.
SLA achieves high-accuracy printing. But the higher the accuracy, the slower the speed. Increasing the speed means increasing the power and frequency of the laser to ensure that the resin absorbs enough energy, avoiding insufficient reaction. Besides, the galvanometer method is not suitable for large 3D printers, because, with the increase of the beam inclination, the light dot presented on the resin surface will become larger and elliptical, the energy density will be reduced, and the printing accuracy will greatly decrease. Therefore, it is necessary to have independent X-axis and Y-axis motions to ensure the consistency of the light dot during the printing process. But the new problem coming with is the accuracy decrease of vibration during motion. In short, the increase of the irradiating speed is limited.
So what else can you do to increase printing speed?
Traditional SLA technology is thought of as dot exposure, so it is necessary to plan the path and scan dot by dot. If it can project a layer pattern of slices like a projector, it can print a whole layer at one time. This is DLP technology. It replaces the laser emitter with a projector, using ultraviolet light to directly irradiate and cure the whole layer. In this way, the speed of printing is greatly increased. However, DLP technology also has shortcomings, such as resolution limitations. Conventional 1080P optical machine, projecting an area of 192mm*108mm, creates only 100μm for a single pixel, which is a low accuracy in dentistry. Of course, if not considering the platform size and cost, it can achieve high accuracy by projecting a small size with a 4K optical machine. In addition, every optical machine may have verticality deviation in the assembling process. Even if it is adjusted, if the printer is not horizontal enough when placed, it is still not vertical between the resin surface and the optical machine, resulting in printing distortion. So that's why the lift-style DLP printer appeared.
The lift-style printer optical machine is mounted below the resin vat, which uses a release film that is translucent and does not adhere to the print easily. When curing, the platform falls to the bottom of the vat keeping a space of one layer, then the light source is emitted through the release film to cure the resin. Because of the low adhesion of the release film and the high adhesion of the metal build platform, the hardened resin will be glued on the platform, and then stacked layer by layer. This lift-style structure does not require too high the horizontality of the printer's placement, but the verticality of the optical machine and the vat bottom and platform is very important, and the manufacturer needs to control the deviation within a small range when assembling. In addition, the lift-style printer must glue the model to the platform to ensure the success of printing, so the first few layers of printing must be over-cured, so that they can be tightly bonded to the platform. Secondly, this kind of printer can not print too large and too heavy models, avoiding the falling of the model.
Due to high stability and durability, DLP printers have been widely used in all walks of life. In addition to ultra-large format industrial printers still use traditional SLA technology, small format high-frequency industrial printers always use DLP technology. Why the emphasis on industrial production scenarios? The main reason is the expensive component. The price of core optical machines has remained high because of limited options.
This situation lasted until around 2017. Due to the popularity of smartphones, the resolution of LCD screens is getting higher and higher, and some people have a whim, is it possible to replace the projector in a DLP printer with the LCD screen and combine it with UV light? Based on this idea, a lift-style 3D printer using the LCD screen of a mobile phone appeared. The first generation of printers used color screens, which had poor light transmittance, low durability, poor light uniformity, and poor stability, but the price was cheap. It was at this time that the CHITU team saw the potential of LCD development and made the world's first offline control scheme based on Single-Chip Microcomputer, as well as the supporting CHITUBOX slicing software. Subsequently, the LCD technology was getting more popular and the LCD printer market has started explosive growth. With the development of screen technology, printers are becoming more and more stable, from color screens to monochrome special screens, with resolutions ranging from 1080p to 2k, and even the highest 16k nowadays, with higher and higher accuracy. Although there is still a gap between the stability of LCD and DLP printers, due to the low price and high accuracy, LCD printers are widely applied in model figures, dentistry, jewelry, and other industries.
How to choose the suitable printer
Through the above technical analysis, it can be found that SLA, DLP, and LCD printers have their advantages and disadvantages, and it needs to consider the application scenarios to select the suitable printer. So what printer is suitable for dentistry?
At present, SLA printers are rarely used in dentistry due to their slow speed. The most used are DLP and LCD printers. The application of DLP printers in dentistry is already mature. The sink-style large-format machine has good stability and high efficiency, and the requirements for the surface accuracy of the model are not too high for orthodontics and splints, so this kind of printer is usually used in large-scale printing such as orthodontic factories, splint factories, and other fields. However, the price of a Single-Chip Microcomputer is very high, ranging from 50,000, so a sink-style DLP printer is more suitable for mass production scenarios.
For general dental labs, many scenarios need to be printed, such as restoration, implant guides, denture bases, etc. This kind of lab is more suitable for the lift-style DLP or LCD printer with a medium format. For clinics, because the printing frequency is relatively low and the printer scene is more simple, it is recommended to choose a small-format and high-accuracy printer. The stability and durability of DLP printers will be better, but generally speaking, their volume is much larger than LCD printers. If you're concerned about durability, you can choose a DLP printer, or if you're concerned about cost-effectiveness, you can choose an LCD printer.
In the current market, there are many dental special printers, which are adapted with resin materials and optimized in advance to ensure easy use by dental professionals. This kind of printer not only has high accuracy but also can be ready to use with the materials recommended by the manufacturer. The disadvantage is the limited material options, and the price of the material always includes a lot of service costs. Generally speaking, the materials of the manufacturer will be more expensive. In addition, to reduce after-sales, most manufacturers have locked the window for parameter adjustment, and if there is a problem with the printing parameters, it is necessary to search for after-sales assistance to solve it. If you have the budget and expect a printer to be ready to use right out of the box, then a dental machine is recommended. These special printers include DLP and LCD types. There is no obvious difference in accuracy, even LCD is better, the main difference is durability.
In addition, conventional consumer printers are more used in the figure model industry. But for economic benefits, it is also very common to use consumer LCD printers in dentistry. The price of this kind of printer is lower, but you need to configure the parameters of materials and printing process by yourself, and the cost of getting started will be higher. The advantage is that the choice of materials is very wide, and the material cost will be much lower. In terms of printer quality, the flagship printer of the consumer class in 2024 will not be worse than the dental special printer. If you are familiar with the parameters of slicing software, want to choose the material freely, start at a lower cost, and don't want to be limited by the printer manufacturer, you can choose a consumer LCD printer.