New Roots
by Jill Spotz
Barry Zweig, DDS
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bright smile is a highly coveted asset. Conversely, a smile with missing teeth is often an embarrassment. And while George Washington had to make due with an ill-fitted set of wooden dentures, elder statesmen, movie stars, models, and even ordinary people now have a far better option — dental implants.
That’s not to say that implants haven’t been around for quite a while. “Scientists have found 1,900 year old skulls with early, crude forms of implants,” says Barry Zweig, DDS, professor in the Department of Oral and Maxillofacial Surgery at UMDNJ-New Jersey Dental School (NJDS). “Today’s implants are made of a very bio-compatible metal — titanium — which bone fuses to easily and there is less chance of rejection by the body, compared to materials used in the past. Advances in implant designs, biomaterials, imaging and surgical techniques have resulted in today’s very high success rate.”
A dental implant essentially replaces the root of the tooth that has been lost. Because the device is placed within the jaw, Zweig explains that a certain quality and quantity of bone is required for implant placement. Once the implant is inserted, it takes a few months for the bone to fuse to the device — a process called osseointegration. The time depends on the type of implant used, and the quality of the jawbone and location. Implants can replace a single tooth, help support a fixed bridge, or even provide stability for a denture. “Patients who wear complete dentures notoriously have problems with movement resulting in an inability to enjoy eating certain foods, problems in speaking and socio-psychological concerns,” explains Zweig. “With just two implants, we can provide stability of the prostheses for these individuals and markedly improve their quality of life.”
Dentists at NJDS use a sophisticated technology that combines the use of CT scan and computer software to accurately diagnose, treatment plan and place implants. In the past, the dentist would take an x-ray of the patient’s jaw, along with clinical measurements, to determine implant positioning. “We were only capturing the bone two-dimensionally therefore, could determine vertical height, but not width or quality of bone,” explains Zweig. “There also was a lot of distortion and variability in the x-ray.” CT scans allow dentists to measure down to the millimeter the quantity of bone and thus the optimal location where the implant should be placed to achieve the best functional and aesthetic results.
Computerized treatment plan of a patient's dental implants
The dentist now has the capability to develop a computerized treatment plan. The results of the CT scan are reformatted into a software program called SimPlant® and forwarded to the dentist from the imaging center. Manufactured by a company called Materialise in Belgium, the software displays 3D images of the patient’s jaws. The dentist can view the results on a computer and determine the ideal position of the implants in relation to the patient’s specific anatomy and then choose the appropriate device from a library within the system. “This technology allows us to also determine the bone density, which has an effect on the type and number of implants used,” explains Zweig. “In the past we couldn’t accurately see the anatomy so the potential for injuring a vital structure such as a nerve was increased.”
Ironically enough Zweig took part in the original research to develop this product more than 20 years ago. Now the software is used world-wide. “We used cadaver jaws, CT scanned them, and then reformatted the results into the SimPlant® program,” he says. “We then took physical measurements of the jaws of the cadavers and compared the results to what was in the SimPlant® program. We were able to show that the software was extremely accurate.” At the time, Zweig and his colleagues were working with version one of the program. His computer is now running a more improved version 10.
Once the treatment plan is developed, Zweig uploads it to Materialise. The company creates a stereolithic model of the patient’s jaw based on the results of the CT scan and Zweig’s marked location for the implants. A series of CAD/CAM surgical templates or guides are also created that are used at the time of surgery for proper positioning of the implants. The model and surgical guides are automatically shipped to Zweig within just a few days of uploading the treatment plan. “This takes much of the guesswork out of implant placement,” explains Zweig. “The surgical templates even have exact diameter holes that correspond to our drills, making implant placement very accurate and predictable.”
Once the pre-planning is complete, the implants are surgically positioned in an outpatient setting. Following the placement of implants, there is a time period before the restoration is complete. The process may seem daunting to some patients. The majority of time is spent waiting for the bone to fuse to the implants before the prostheses can be fabricated. At NJDS, dentists in the Oral and Maxillofacial Surgery and Periodontics departments coordinate the placement of implants, while Prosthodontics manages the restorative phase. “The whole implant process has been streamlined and improved, making implant dentistry a desirable choice for many patients,” says Zweig.