Scanning Accurately and Efficiently
Different types of equipment offer different advantages
Jeffry Tobon, CDT
Starting a digital workflow with as accurate a scan as possible is critical in any case, so understanding and utilizing the most appropriate scanning equipment is important. Intraoral scanning is a great tool for smaller cases such as single units and three-unit bridges, and for more complex cases when cross-arch accuracy is key, it can either be supplemented by photogrammetry or replaced with desktop scanning. Even as intraoral scanning becomes more widely adopted due to the convenience and efficiency it offers, desktop scanning will remain an important tool for the dental laboratory.
What are the most important differentiators among today's desktop scanners?
Most desktop scanners have the necessary cross-arch accuracy for complex cases. Once we get down to 4 µm vs 5 µm, it is difficult to discern any difference. Similarly, while different technologies can produce different scan speeds, most are very fast now. The most significant differentiator is probably whether a scanner is open or part of a closed system, and the software that subsequently can be utilized with them. Some scanners also may be more well-built and durable, while others may require repairs or replacement after a few years of frequent use. There are so many good scanners on the market today, though, that it is mostly a question of personal preference.
Does a laboratory need to understand intraoral scanners, or are all STL files the same?
Knowing what the dentist is using is important. Every intraoral scanner is different in how well it can capture the cross-arch accuracy, and that is critical in understanding which cases they are best utilized for and what supplemental data may be required. The laboratory should be able to advise the dentist on purchasing a scanner and how to use it, and then should be able to take into account the scanner's strengths and limitations when working with the STL file.
How is photogrammetry helpful?
Intraoral scanners can capture the tissue and the pre-operative impressions of the temporaries or the denture, and photogrammetry can then pick up the position of the implants. Desktop scanners can also accomplish this accurately—and often more affordably—because their field of view and distance from the model are both constant. However, photogrammetry can eliminate the need for a physical impression, verification jig, and poured model as part of the workflow. All three of these tools—intraoral scanners, desktop scanners, and photogrammetry scanners—are very useful in different workflows.
Understanding the strengths and limitations of each option and the best ways to utilize each is so important because if even one out of every 10 cases is not completely accurate, that one remake is very costly.
About the Author
Jeffry Tobon, CDT, is the president of Designlab Dental in Houston, Texas, and a co-founder of both Digital Dental Craftsmen and Chairside Solutions.