CAD/CAM dentistry
Author: George Ghidrai, MD
CAD/CAM dentistry is a field of dentistry and prosthodontics using CAD/CAM (computer-aided design and computer-aided manufacturing) to improve the design and creation of dental restorations, including crowns, veneers, inlays and onlays, fixed bridges, dental implant restorations, zirconia frames, dentures (removable or fixed), and orthodontic appliances.
CAD/CAM systems are utilized to process various types of dental materials :
- Zirconia is exclusively processed using computerized systems
- Porcelain, especially all-porcelain restorations (crowns, inlays, veneers)
- Dental composite, mostly when composite inlays or veneers are fabricated
- Metal alloys may also be milled or digitally produced.
CAD/CAM system
The CAD/CAM system
CAD/CAM are highly evolved computerized systems, consisting of 2 parts :
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Scanner
The scanner is a digital structure that creates a 3D image of the dental impression or dental cast. This image is called digital impression.
The digital impression draws the data into a computer. The main software then creates a virtual restoration (crown, bridge, inlay, veneer, removable denture etc.) and sends the data to the milling machine.
digital impression for a dental crown
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Milling machine
The milling machine is the part that fabricates the designed restoration by carving it out of a solid block of zirconia, ceramic or composite resin according to the information received from the computer.
cad/cam system milling machine
Process
After teeth preparation, the dentist makes a dental impression. The impression can then be used to create the dental cast.
The dental impression or the dental cast is placed inside the scanner. The scanner creates the digital impression.
Dentists can also use intraoral scanners to make a digital impression directly without any impression materials.
Specific clinical information is entered into the computer. The desired restoration is designed by the main software and the required data is sent to the milling machine.
The milling machine carves it out of a solid block of zirconium, ceramic or composite according to the information received.
If zirconium restorations or frames are manufactured, after milling, the zirconium core is placed inside special furnaces at high temperatures (1500 degrees Celsius or 2730 Fahrenheit) for 6-7 hours. This operation aims to increase the tensile strength of zirconium.
After completion, the structure is sent to the dental office for fitting.
Advantages
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High accuracy
CAD/CAM systems, especially the newly developed, are highly accurate. It is estimated that the system has a margin of error of less than 20 microns.
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Restorations can be completed in less time
Conventional prosthesis, such as crowns or bridges, have temporaries placed from one to several weeks while a dental laboratory produces the restoration.
Designed to provide a seamless workflow, in some cases, CAD/CAM systems allow practitioners to provide patients with crowns, inlays, onlays and veneers in a single appointment.
Drawbacks
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Aesthetics
When porcelain fused to metal restorations are manufactured, the porcelain layers are typically 60 to 100 micrometers in thickness. They are not comparable to traditionally fabricated dental restorations, which have multiple layers that are between 25 to 50 micrometers thick.
Likewise, they rely on superficial staining to achieve a more natural appearance, unlike hand-layered porcelain restorations, which possess a deep-set coloration due to the multi-layering.
However, when all ceramic restorations are designed, these are metal-free. A metal-free restoration is typically more aesthetically pleasing to the patient.
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Cost
Normally, CAD/CAM designed prostheses are more expensive then traditionally fabricated restorations because of the high acquisition cost of the computerized systems.
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buildup >> << Metal frame
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