I’ve Got You Under My Skin

July 1, 2005
Articles and meetings have been discussing digital radiography ad nauseum, present company included.

Articles and meetings have been discussing digital radiography ad nauseum, present company included. There is a thirst for knowledge on the basics of this technology, implementation, return on investment, and more. Many of the current users, however, are looking for the next level. One area of interest is implant planning. Several of the digital radiography companies now are including a database with a variety of implant designs in their software. If properly calibrated, the dentist can overlay the image of the selected implant in the edentulous space, and perhaps predict which one will be the best fit. This is, at best, a simple schematic since there is no real way to look at the bone thickness and density, or the precise buccal to lingual location of nerve canals or bone concavities from a two-dimensional picture. A CT scan or MRI would certainly be of great value. But once the information is in the dentist’s hands, how could that be put into practical use? I have mentioned previously in this column that there are now in-office units that can perform these scans. Imaging Sciences (iCat), J. Morita (Accuitomo), NewTom, and Hitachi are examples. Still, once the practitioner has these images, they have to be interpreted properly to aid in the treatment planning of procedures.

Enter the world of rapid prototyping and stereolithography. These are common terms in other industries that are involved in design-and-build products. Small machine parts and rocket engines are prototyped with these new computerized units. Imagine an engineer developing a new cellular phone case. The design can be easily done with CAD programs. But, until recently, these specifications had to be sent to a special firm that could read the specs and build the prototype at a high cost. There are now “three-dimensional printers” that will take the program and - with the push of a button - quickly build the case out of layers of plastic, metal filings, cornstarch, or other inexpensive materials. The case could be looked at, handled, and - if changes are necessary - reprogrammed and remade for a few dollars in a short period of time. Web sites like stratasys.com or zcorp.com can give you some insight into these units.

Taking this information into our arena is seemingly a simple transition. A patient who is going to receive implants will have a set of study models taken. A diagnostic waxup is done to see where the teeth can be ideally placed. At this point, a lab can fabricate an appliance with radiopaque points, cylinders, or other markers that the patient will wear during the radiographic scan. This helps to locate the future position of the teeth. Once the scan is done, new dental 3D software can use the database of implant sizes and shapes, and superimpose them on the scan in real dimensions - unlike the two-dimensional simulations mentioned previously.

Once the implants are positioned, the CAD system can build a template with guide holes that fit right over the bone, based on the 3D scan. The software also has told us what the length of the implant will be. Thus, self-limiting drills and the implants can be sent to the dentist along with this surgical stent. All the operator has to do is put the correct size drill through the guide hole, and drop it to the predetermined, self-limited length. The implant will easily follow. The dentist can purchase the software, do the planning, and transmit the images for fabrication, or the entire process also can be handled by the software/implant company, or by a lab that specializes in this technique. Look at some examples at simplant.com, implant3d.com, ident-surgical.com, cadimplant.com, or implantlogic.com. I spent some time learning from Anton Voitik at Hermansondental.com, a full-service dental lab in Minneapolis. For a reasonable fee, the lab handles the complete process from the study models to the surgical stent. This permits the dentist to take advantage of the technology without having to learn all of the details. The next logical step is to remove the dentist from the picture and have a robotic system handle everything - the idea of the Israeli-based Tactile Technologies.

I must thank Eliezar Ganon from Columbus, Ohio, for helping me with some of the research on this exciting new arena. Eli has conducted a comprehensive study of all available (and some future) products, and has become a terrific resource for dental technology information. Visit his Web site at designtechnologygizmo.com. I hope to give you a more comprehensive look at this arena at a future time.

Dr. Paul Feuerstein installed one of dentistry’s first computers in 1978. For more than 20 years, he has taught technology courses. He is a mainstay at technology sessions, including annual appearances at the Yankee Dental Congress, and he is an ADA Seminar series speaker. A general practitioner in North Billerica, Mass., since 1973, Dr. Feuerstein maintains a Web site (www.computersindentistry.com) and can be reached by e-mail at [email protected].