For two decades, digital dentistry meant simply capturing an image of teeth with a dental camera. The skilled work of making crowns and bridges was entirely in the hands of craftsmen at dental labs. During the last couple of years, this sce- nario has changed. The German company KaVo has seen the future and it is fully digital. KaVo has developed a complete computer-based system with stand- alone components that automate the process of preparing inlays, onlays, crowns, bridges, veneers, and frameworks in an almost unlimited range of mate- rials for dental laboratories.
Dental lab work has traditionally involved a great deal of craftsmanship to create a decent-quality appliance from an impression. Faced with increased demand and higher labor costs, dental labs outsource work to places with lower
labor costs, and often incur losses in productivity, profitability, and quality.
KaVo designed its Everest system to change all that.
The Everest process starts with a 3-D scanner that can capture a model of a tooth stump in about four minutes with an accuracy of 20 µm. The scanner can be operated easily with one hand and provides good coverage of complex shapes. It looks like a microwave oven with a turntable that tilts. A single-button push sets the scanner in motion. It captures data from 15 different angles and produces 15 partial point clouds that are automatically aligned and merged into a single point cloud with 1:1 precision compared to the original. The scanner is easy to calibrate, and an adjustment once a week is sufficient to ensure high precision.
The second step is to process the order through Everest control software, which is automated and pre-installed in the computer connected to the scanner.
There are four modules in the control software: scan, surface, CAD, and CAM.
The scan module forms the user interface to the scan unit. With a few menu- guided steps, the operator can control the scan process for both stone and wax Figure 9.4. The KaVo Everest system includes a 3-D scanner, reverse engineering software, a 5-axis milling machine, a sintering machine, computer, desk, and material. Copyright © KaVo Dental Corp., Lake Zurich, IL, USA, www.kavousa.com. Reproduced with permission.
Figure 9.5. Everest 3-D Scanner. Copyright © KaVo Dental Corp., Lake Zurich, IL, USA, www.kavousa.com.
Reproduced with permission.
184 9 Reverse Engineering in the Medical Device Industry
models. For direct scanning of production copings, KaVo uses special gypsum, which permits reflection-less exposure to guarantee reliable measurement of shiny surfaces. Scan data are automatically passed to the surface module.
The surface module imports two data sets. One set is from the tooth stump, also called a die, and another is from the wax model of the oversized crown. The first step is to align the 15 different scans of die relative to the surface of the crown and combine the die and the crown into the same orientation. This forms the basis of the mathematical surface calculation that is performed automati- cally. A preparation line is automatically detected on the die, and the oversized
Figure 9.6. On top, the Everest software interface. On bottom, a screen shot of the surface module. Copy- right © KaVo Dental Corp., Lake Zurich, IL, USA, www.kavousa.com. Reproduced with permission.
crown is cut according to the line. The die and the crown are then oriented and automatically adjusted so that there is no undercut. All of the operations in the surface module can be run automatically or interactively for operator-assisted modifications. Bridges are prepared in a similar process. Once the crown or bridge surface is prepared, the file is passed on to the CAD module.
The CAD module enables operators to design the final copings or bridges on the computer screen. The software automatically positions the digital model and trims these to the gingival. The model can also be individually positioned or scaled. The finished design is now ready for the CAM module.
The CAM module automatically calculates cutting data and takes into account the properties of the material that will be used for the final product. It also com- putes the blank size and avoids collisions automatically.
Everest Engine is a desktop 5-axis numerical control milling machine. No cut- ting or grinding task is geometrically too complex for the system. After the crown or other dental appliance is manufactured, the material is sintered, if required. on a microprocessor-controlled thermal unit that operates without supervision.
In an age of compromised quality due to outsourcing, KaVo’s Everest system makes it cost-effective to keep production of dental devices in the experienced hands of dental technicians. All work can be conducted on-site, providing greater control over production schedules and quality.
The KaVo Everest system is a complete reverse engineering system that com- bines all four technological advances described in the introduction: new 3-D scanners, automated reverse engineering software, a fabrication machine that produces one-of-a-kind custom devices in large quantities, and new medical- grade fabrication materials.
Like Invisalign, KaVo is an example of how a visionary company can position itself as a market leader by being the first in its industry to adopt state-of-the-art technology. Others will follow, once the leaders pave the road.