LaserCUSING® | Laser Sintering | LaserMelting
- additive processes in dental technology
In digital dental technology, additive processes such as LaserCUSING®, Laser Sintering and LaserMelting for the production of dental structures are becoming more and more popular. There are many different procedures and terms. But what's the difference?
Ultimately, all terms describe the same process, which we at CADdent® call LaserMelting. But where do the many different terms come from?
The process behind the terms LaserMelting, LaserCUSING® and Laser Sintering.
The basis for the dental SLM (Selective Laser Melting) manufacturing process is the digital design data from dental frameworks, which were created with the help of dental scanners and design software - in the dental industry, 3Shape, exocad or Dental Wings are usually used. These designs - often in the form of STL data – are digitally transmitted to us from the dental laboratory via our upload tool or via the order entry on the website.
After a random feasibility check of the orders, the data is prepared for the actual production process. This means, the digital construction is virtually divided into individual layers and transmitted to the dental laser system for production.
Before the laser process can start, the storage container is filled with laser powder. A metal plate - the so-called manufacturing platform - is inserted into the cabin space of the laser system, on which the support structure (support pins) is first built in the process and later the frameworks. The metal powder is applied in layers, therefore the manufacturing platform is lowered by the desired layer height (usually approx. 30 µ).
Then the first layer of fine-grain metal powder is applied to the platform by means of a coater.
When exposed to light, the powder is melted through at the points where the dental metal frameworks arise and thus bonded to the previous layer. The exposure is carried out by the laser system according to the shell-core principle, which results in a comparatively smooth surface of the component. This process is repeated until the design data has been fully implemented. After completion of the manufacturing process, the remaining unmelted powder is removed with a brush. At the end of the manufacturing procedure this material can be processed in a resource-saving manner and reused for further processes.
After the excess powder has been removed, the supporting plate is heat-treated. The reason for this is that each layer begins to cool down immediately after exposure and the associated melting process and thus each layer changes its physical state on its own. Due to the different temperature zones within the structure, tensions arise which, without a subsequent heat treatment after the laser process, can lead to distortions in the dental framework. The heat treatment following the LaserMelting, LaserCUSING® or Laser Sintering process is also referred to as structural firing. The recommendation of the laser powder manufacturer Dentaurum is 60 minutes and 1,140 °C for the LaserMelting CoCr material remaniumstar®. Close to the melting point, the metal structure created in the laser construction process is rearranged and the tensions are released.
Whether LaserCUSING®, SLM (selective laser melting),
DMLS (direct metal laser sintering) or LMF (laser metal fusing)
- the process is (almost) always the same.
The users have put their own stamp on this dental technology production process through various names, some of which have been legally protected. EOS coined the term Laser Sintering - or as EOS itself calls it - SLS (selective laser sintering). With laser sintering the energy expenditure is lower than with the laser melting process, because the metal powder is not completely melted, but only the shell of the powder grains are, so that they only bond superficially with the previous layer. This creates cavities, which are at the expense of stability. In its early days, additive manufacturing was frowned upon among dental technicians. Since the terms laser melting and laser sintering were often used interchangeably, it was often difficult for customers to be convinced of the technology that brings so many advantages. Today, EOS systems also work with the laser melting process (DMLS - direct metal laser sintering), even if they have adopted the term laser sintering for this process.
Significantly less energy is used for laser sintering. It is also more time-saving, which is why the process is still often used in manufacturing of prototypes. In this area, unlike in the dental industry, a homogeneous metal structure is of secondary importance. At CADdent® we also work in the area of manufacturing of prototypes with the LaserMelting process. Here you can find out more about rapid prototyping at CADdent®.
Further processing of LaserMelting frameworks
Again and again we are asked whether dental frameworks that were manufactured using the selective LaserMelting process require special treatment before veneering. The answer is simple: they do not! Treat lasered frameworks the same as you used to treat your cast frameworks. At CADdent® we only use proved and tested materials in our LaserMelting process. The material composition is identical for casting and laser technology, there are only small deviations in the physical properties of the material.
Advantages of all additive technologies in the creation of dental frameworks
The advantage of the additive process lies in the homogeneity of the resulting metal structure. In contrast to the casting technique, no so-called shrinkage cavities are formed in LaserMelting.
Whether LaserCUSING®, Laser Sintering or LaserMelting - the additive processes have a lot ahead of the subtractive processes. In this way even the most delicate interdental spaces can be implemented with additive processes and no “milling shadows” remain.
Almost every conceivable structure can be implemented in the LaserMelting process. Challenges can only arise with prefabricated parts such as attachments and bolts. If you have planned such a work, please contact us in advance. Our experts will be happy to check the feasibility for you individually.
Here you can find out more about the advantages of the LaserMelting process.
CONCLUSION
Each company has its own name for the additive manufacturing of dental frameworks. LaserCUSING® is the name of the Concept Laser process, for example. The term is made up of “Concept Laser” and “Fusing”. The name DMLS was coined by EOS, which means “direct metal laser sintering”. The Italian company Sisma3D speaks of LMF "Laser Metal Fusion", etc. However, almost all names describe the same process in principle. We at CADdent® have decided on a laser melting process due to the higher stability and thus better quality in the dental area.