Exceptional Scanning Options Continue to Abound
Support, software, and features such as scanning articulators are among the key considerations
Rick Sonntag, RDT
Desktop scanners have long been considered an entry point for dental laboratories seeking to begin integrating CAD/CAM technology into their workflows. With lower price points than milling machines, desktop scanners allow laboratories to convert analog cases into digital files to design using CAD software, for fabrication either in-house or at a separate milling facility. Over the past decade, these scanners have become faster and more accurate, but perhaps most importantly, they have reached prices that are affordable for almost any laboratory, regardless of size.
The first thing a laboratory is likely to notice when starting to research desktop scanners is the sheer number of options. A wide variety of manufacturers offer this technology with numerous features. Almost all are very strong options; determining which is best for your laboratory is a matter of personal preference and individual needs.
Today's scanners offer several different methods for capturing 100% of the scannable area of an item. Processing technologies include blue LED, stripe light, structured light, white light, laser, and more. Some use only two scanning axes, while others use as many as five. The end results are not much different; for example, a two-axis scanner might have a stable scan table and cameras that move in a spherical motion to capture just as much information as a five-axis scanner.
Accuracy and Speed
Since the author's first scanner purchase more than 7 years ago, the speed and accuracy of the technology has improved dramatically. Manufacturers may now have reached the limit of accuracy, as most are within 5 or 10 μm. Milling machines and 3D printers limit the accuracy of the final product such that more precise scans would have little impact on the final product.
The real battleground now is the speed-versus-price-point ratio. Most of today's machines can scan a full-arch model in 1 minute or less, with some capable of doing it in as little as 12 seconds. Even the most affordable scanners are able to work at a pace that can positively impact a laboratory's workflow.
The ability to scan articulators has been one of the most significant advances in recent years. Many new scanners either are larger or feature an open design that is less restrictive of the size of the item being scanned. This is particularly advantageous for laboratories that work on a significant number of full-arch cases and full-mouth rehabilitations, which present challenges with bite scans. Any time the model needs to be taken off the articulator, an opportunity for error is introduced. By keeping the model on the articulator, the technician can confirm that the bite is 100% correct and that the same bite relationship will translate to the digital file. With an open design, it is possible to fit a fully adjustable articulator and scan the bite on it, which becomes extremely critical for cases mounted in centric relation (CR), for which there is not contact on every tooth. The technician may have only the first point of contact on a molar, needing to capture that CR bite precisely, with no chance whatsoever of any movement, in order to plan the case in CR. For any cases sent from dentists who have been trained at an institute such as the Dawson Academy, Pankey Institute, Kois Center, or Spear Education, having a scanner that can accommodate the articulator is almost a necessity.
Many of today's scanners also advertise impression scanning abilities. Anecdotally, the author has observed that the concavities of impressions can make obtaining an accurate, consistent scan more difficult than with a stone model. Many laboratories utilize models regardless, making this capability less useful, but for any laboratory that works on a significant number of model-less cases—single units, smaller bridges, etc—advances in desktop impression scanning could prove advantageous in the future.
As with any CAD/CAM tool, the user's skill and knowledge are likely to impact their ability to optimize a scanner's effectiveness.
The two most critical factors in obtaining precise scans involve the positioning of the scanner. Most important is subjecting it to minimal vibration by placing it on a surface that is either attached to a solid wall or heavy enough that it is unlikely to move at all during the scanning process. The second-most important factor is maintaining a consistent temperature, as scanners are very sensitive in that regard; temperature swings can negatively impact the accuracy of scans. The author recommends keeping scanners away from drafty areas, air conditioning units, heaters, and especially open windows.
Attention to detail can be a factor with some scanning processes more than others. For example, any metallic products, such as implant abutments, require an extra step such as spraying them to make them non-reflective. Cases that are mounted in CR are also very challenging because, as previously mentioned, typically not every tooth is in contact; the technician must be careful when positioning the model to not create any deviation from the original bite registration, which likely would result in adjustments being necessary either in the laboratory or chairside. Models that have limited landmarks are also very difficult to scan; for full-mouth cases, the more landmarks available to merge files, the more accurate the case will be. They are also very difficult to scan with few landmarks, short models, improperly poured models, etc.
The steps that follow the scan itself are important as well. The process begins with CAD software, of which exocad and 3Shape are the most popular options currently, with several other strong alternatives available.
Most CAD software systems include implant planning modules, crown-and-bridge designs, abutment designs, and removable modules. The level of openness usually depends on the reseller, pricing, and system limitations.
The major manufacturers already have taken steps to make purchase prices more affordable for small laboratories. Software renewal licensing fees have decreased or been bundled so laboratories can have multiple modules and pay much lower fees. Manufacturers are providing some very aggressive pricing.
While speed, accuracy, special features, and software are all important, the most crucial factor in purchasing a scanner is one of the most basic: customer support. Many laboratories have only one scanner, and when it requires maintenance, production can grind to a halt. Knowing that you have a team that will be behind you to troubleshoot in case of any issues, or sometimes even provide a loaner within a day or two, is critical.
A day may come when all cases are sent to the laboratory digitally. However, the price points on many of today's intraoral scanning systems continue to be prohibitive to approaching 80% to 90% market penetration in the near future. Laboratories will continue to receive analog impressions, and the ability to convert these impressions to accurate digital files quickly and efficiently via desktop scanners will continue to impact the effectiveness of the laboratory's workflow.
Fortunately, a number of excellent options are available on the market. Software preferences and special requirements vary for each laboratory, but great results can be achieved with almost any of today's scanner options.
About the Author
Rick Sonntag, RDT, is President of 4Points Dental Designs in St. Petersburg, Florida.