Understanding the uses of CAD/CAM technology in dentistry

CAD/CAM dentistry is quickly digitizing a process long known for being time-consuming and nearly entirely manual. Using the latest design and manufacturing techniques, CAD/CAM has started a new era in dentistry characterized by faster procedures, more efficient workflow and a better overall patient experience. In this blog, we’ll take a deep dive into CAD/CAM dentistry, including how it works, what it involves, its pros and cons, and the technologies involved. 

What is CAD/CAM in dentistry? 

First, let’s define some terms. 

Computer-aided design (CAD) refers to the practice of creating a digital 3D model of a dental product with software, as opposed to a traditional wax-up. 

Computer-aided manufacturing (CAM) refers to techniques like CNC milling and 3D printing that are done by machines and controlled by software, as opposed to traditional processes like casting or ceramic layering, which are entirely manual. 

CAD/CAM dentistry describes the use of CAD tools and CAM methods to produce crowns, dentures, inlays, onlays, bridges, veneers, implants, and abutment restorations or prostheses. 

In the simplest terms, a dentist or technician would use CAD software to create the virtual crown, for example, which would be manufactured with a CAM process. As you can imagine, CAD/CAM dentistry is more replicable and scalable than conventional methods. 

The evolution of CAD/CAM dentistry 

The introduction of CAD/CAM dentistry has changed how dental practices and dental labs handle impressions, design, and manufacturing.  

Prior to CAD/CAM technology, dentists would take an impression of the patient’s teeth using alginate or silicone. This impression would be used to make a model out of plaster, either by the dentist or a technician in a dental lab. The plaster model would then be used to manufacture the personalized prosthetics. From end to end, this process required the patient to schedule two or three appointments, depending on how accurate the end product was. 

CAD/CAM dentistry and its associated technologies have made a formerly manual process more digital.  

The first step in the process can be done directly from the dentist’s office when the dentist records a digital impression of the patient’s teeth with an intraoral 3D scanner. The resulting 3D scan can be sent to a dental lab, where technicians open it in CAD software and use it to design a 3D model of the dental part that will be printed or milled. 

Even if a dentist uses physical impressions, dental labs can take advantage of CAD technology by digitizing the physical impression with a desktop scanner, making it available within CAD software.  

Advantages of CAD/CAM dentistry 

The biggest advantage of CAD/CAM dentistry is speed. These techniques can deliver a dental product in as little as one day — and sometimes the same day if the dentist designs and manufactures in house. Dentists can also take more digital impressions per day than physical impressions. CAD/CAM also allows dental labs to finish far more products per day with less effort and fewer manual steps. 

Because CAD/CAM dentistry is faster and has a simpler workflow, it is also more cost-effective for dental practices and labs. For example, there is no need to buy or ship materials for impressions or casts. In addition, dental labs can manufacture more prosthetics per day and per technician with these technologies, which can help labs deal with the shortage of available technicians. 

CAD/CAM dentistry typically requires fewer patient visits, too — one for the intra-oral scan and one for placement — which is much more convenient. It is also more comfortable for patients because they can be scanned digitally and avoid the unpleasant process of holding a viscous wad of alginate in their mouth for up to five minutes while it sets. 

Product quality is also higher with CAD/CAM dentistry. The digital accuracy of intraoral scanners, 3D design software, milling machines and 3D printers often produces more predictable results that fit patients more accurately. CAD/CAM dentistry has also made it possible for practices to handle complex restorations more easily. 

Applications of CAD/CAM dentistry 

The applications of CAD/CAM dentistry are primarily in restorative work, or the repair and replacement of teeth that have decay, damage, or are missing. CAD/CAM technology can be used to create a wide range of dental products, including: 

• Crowns 
• Inlays 
•  Onlays 
• Veneers 
• Bridges 
• Full and partial dentures 
• Implant restorations 

Overall, CAD/CAM dentistry is appealing because it is faster and easier while frequently delivering better results. 

How does CAD/CAM dentistry work? 

CAD/CAM dentistry follows a straightforward process, and in cases where all processes are done in-house, can be completed in as little as 45 minutes. The steps typically include: 

1. Preparation: The dentist removes any decay to ensure the patient’s teeth are ready for scanning and restoration. 
2. Scanning: Using a handheld intraoral scanner, the dentist captures 3D images of the patient’s teeth and mouth. 
3. Design: The dentist (or another member of the practice) imports the 3D scans into the CAD software and creates a 3D model of the restoration product. 
4. Production: The custom restoration (crown, veneer, denture, etc.) is either 3D printed or milled. 
5. Finishing: This step depends on the type of product and material, but may include sintering, staining, glazing, polishing and firing (for ceramic) to ensure accurate fit and appearance. 
6. Placement: The dentist installs the restorative prosthetics in the patient’s mouth. 

Digital impressions and scanning 

One of the biggest advantages of CAD/CAM dentistry is that it uses digital impressions, which are more comfortable for patients and help dentists get a 360-degree view of the impression. In this way, digital impressions make it easier for dentists to ensure the preparation is well done so the lab can make the best possible restoration without the need for another patient appointment to make further adjustments. 

Digital impressions are made with intraoral 3D scanners, which are slim handheld devices that are placed directly in the patient’s mouth to scan the teeth in seconds. Some of these wand-like devices even feature thinner tips to accommodate patients who can’t open their mouths very wide. 

These scanners may use video or LED light to quickly capture high-resolution, full-color images of the patient’s teeth and mouth. Scanned images can be exported directly into CAD software for design with no intermediate steps. The digital images are more accurate, more detailed, and less prone to error than conventional analog (physical) impressions.

Another important benefit of this approach is that the dentist can ensure there is enough space for the antagonist and check the quality of occlusion. In addition, the dental lab can receive the digital impression a few minutes after it is prepared and reviewed by the dentist without the time or cost typically associated with shipping a physical impression. 
 

CAD workflow for dentistry 

After the 3D scan is brought into the CAD software application, the dentist or a design specialist can use the software to create the crown, veneer, denture, or implant. 

These software applications often guide the user through the process of creating a product that matches the shape, size, contour and color of the patient’s tooth. The software may allow the user to adjust thickness, angle, cement space and other variables to ensure the proper fit and occlusion. 

CAD software may also include specialized tools, such as a contact analyzer, occlusion checker, virtual articulator, or anatomy library, all of which help enhance the design. The path of insertion axis may also be determined. Many CAD applications also use artificial intelligence (AI) to simplify, streamline and automate many of these steps or provide suggestions for the user to follow. 

CAD software can also assist with material selection because each material offers a different combination of flexural strength, mechanical strength and translucency. 

CAM manufacturing in dentistry  

After the design of the dental product is finalized within the CAD software, the file is sent to the CAM software that drives the 3D printer or CNC mill. 

Depending on the type of CAM software and output equipment, production may happen completely automatically or require a technician to initiate the process. Some practices have their own CAM systems in house while others outsource manufacturing by sending the CAD files to a manufacturing center. 

Additive manufacturing, or 3D printing, builds up dental products one layer at a time. Different technologies are used depending on the material involved.

For resin products such as dental models, cast patterns, and surgical guides, two of the most common technologies in dentistry are stereolithography (SLA) and digital light processing (DLP). 

With SLA, a laser beam hits a container filled with liquid resin, solidifying select particles. DLP works in much the same way as SLA but uses a digital light projector instead of a laser. As a result, DLP can expose the full layer or resin while the laser used in SLA has to move around to do this. In general, SLA is more accurate but DLP is faster. Depending on the  
type of prosthetics, one technology or the other will be more suitable. 

Both of these methods require post-processing. Solvent washing or spinning removes excess resin and in some cases support structures need to be removed. 
 

For metal products, which are typically final prosthetics, two of the most common 3D printing techniques are selective laser melting (SLM) and direct metal laser sintering (DMLS). Both work similarly to SLA but use a much higher powered laser to melt the metal powder and shape the final crown, bridge, RPD frame, or orthodontics appliance. 
 
Both SLM and DMLS require post-processing heat treatment to ensure the material maintains its strength and shape over time.  

Milling, on the other hand, is a subtractive process that removes material from a solid block or disc to create the dental product. The CAM software translates the digital 3D file into a toolpath that cuts away all unnecessary material around the part in the most efficient way possible while maintaining a balance of speed, quality, and operating cost.

Most dental milling machines are 5-axis systems that can produce very complex parts, such as implant bars or full arch bridges. The fifth axis allows the milling machine to tilt the block of material to reach undercuts and axes of insertion that would not be possible with a 3-axis system. It’s important to note that these milling machines have become much smaller and more compact as the market for CAD/CAM dentistry has grown, so they can easily fit in a dental office. 

Materials for CAD/CAM dentistry

The type of CAM equipment a dental practice or dental lab uses will largely be determined by the type of material the product requires. Common material choices include: 

• Porcelain for optimal aesthetics (appearance) but lower strength in anterior restorations 
• Resin for greater flexibility in full- or partial-coverage restorations 
• Polymethyl methacrylate (PMMA) for temporary restorations 
• Ceramics (lithium disilicate) for high flexural strength in full-coverage, posterior restorations 
• Zirconia for superior mechanical strength in crowns and posterior restorations 
• Metal (cobalt-chrome) for RPD implant bars and orthodontics appliances  

CAD/CAM and implant dentistry

Implant dentistry focuses on replacing missing teeth. The implant system typically consists of an implant body that is surgically inserted in the patient’s jaw where the root of the tooth would normally be, as well as an implant abutment that attaches to the body and extends through the gum tissue, and a crown.  

CAD/CAM dentistry can be used to create every part of the implant system, typically with CNC milling of titanium for the implant and abutment. The crown may be made from zirconia, porcelain fused to metal (PFM), ceramic (lithium disilicate) or gold, depending on its location, the dentist’s preference, and the patient’s budget. Temporary crowns (for placement while final crowns are made) can be made from PMMA or resin. 

CAD/CAM techniques can also be used to create bite splints that help patients avoid grinding their teeth at night, as well as surgical guides, which are sleeves made of resin that are placed on the patient’s jaw to help the surgeon drill the implants in the correct location.

Disadvantages of CAD/CAM dentistry 

Like any technology in dentistry, CAD/CAM techniques do have some disadvantages to consider. For dental practices and labs, cost can be a barrier. The initial investment — including the software, 3D printers, milling machines, and post-processing equipment — can be steep.

There is also a learning curve involved with CAD/CAM techniques. Without help from automated solutions, there can be a lot of manual work associated with digital file preparation and data management that dental technicians are unlikely to be familiar with. This is because CAD/CAM dentistry is so relatively new that its techniques are not usually covered in technicians’ training. 

Often, staff will need to learn how to use several software tools – for intraoral scanning, CAD and CAM. And if you buy a new mill or 3D printer, staff may have to learn yet another software application. Not to mention the fact that the ongoing labor shortage may make it difficult to find enough trained dental technicians for a large practice or lab, let alone highly qualified dental technicians with strong CAD/CAM skills. 

Future trends in CAD/CAM dentistry 

CAD/CAM dentistry continues to evolve. Because these technologies are digital, dental labs are seeing regular improvements in efficiency and ease of use. 

Two recent examples include AI and “smart automation.” In certain software platforms, AI is used to automate all of the CAM steps, including:

• File classification and segmentation 
• Part orientation 
• Hollowing 
• Part labeling 
• Support generation 
• Nesting 
• Slicing and hatching 

In a larger operation, such as a dental lab, AI can automate the entire pre-production workflow. Specifically, the software can learn how to: 

• Classify parts into pre-defined categories (crown, abutment, veneer, etc.) 
• Identify regions of interest on parts and apply labels and supports accordingly 
• Suggest the correct rotational orientation for each part 
• Maximize 2D and 3D nesting density 
• Plan production based on machine and technician availability, due dates and other factors 

This reduces the need for dental labs to hire skilled operators for 3D printers and CNC mills while also making these systems more efficient by minimizing the time required for file preparation and manufacturing. Extracting more value from these machines with a smaller staff is critical for maximizing profitability in this fast-growing market.

Software that streamlines your digital workflows 

CAD/CAM dentistry is already making dental production faster and easier for many labs, and it will likely become the default approach.  

To give your practice or lab an edge in productivity, learn more right now about Oqton dental software that streamlines workflow for CAD/CAM dentistry in numerous applications.