Company brushes up on better
dental implants and prosthetics

NEWARK, N.J. — Orthogen Corp., a subsidiary of Bio-Lok International Inc., has developed a new dental implant with microgrooves designed to improve how bone and soft tissue grow into it.

Pioneered by researchers at the University of Medicine and Dentistry of New Jersey (UMDNJ) and Rutgers University, the device has already been implanted in 70 patients in Italy. Clinical trials are starting in the United States and Bio-Lok President Bruce Hollander said he hopes the U.S. Food and Drug Administration will approve the implant’s use by the end of the year.

Orthogen President Harold Alexander said that the small tech implant would cost only $20 or $30 more than a conventional one.

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The group is now trying to apply the microgroove technology to more safely attach permanent prosthetics, such as an artificial hand or foot, through skin and into bone. Currently, the risks of infection make attaching a permanent or long-term prosthetic through the skin impractical.

Hollander noted that a more near-term application for such a “transcutaneous,” or through the skin, implant could include screws used to repair orthopedic injuries such as shattered wrists that need to hold bones in place with external hardware.

Alexander, editor of the applied biomaterials section of the Journal of Biomedical Materials Research, said the company has won a $500,000 grant from the National Institutes of Health to develop its technology for use in artificial limbs and orthopedic devices. The project will also attempt to connect nerves in a limb to an electromechanical prosthetic. Such a neuromechanical system would be a true bionic limb.

Alexander said the goal of the NIH study is to prove the feasibility of the technology. If the Orthogen-led research succeeds, it could begin a product development phase in a few years.

John Ricci, an associate professor of prosthodontics and biomaterials at UMDNJ, said that the dental implant is the immediate commercial opportunity. He explained that titanium dental implants have for many years been microtextured to encourage bone growth around the implant. Microgrooves offered a way to direct that growth around the “collar” of an implant — the section where metal implant, bone and gum tissue come together.

The problem with current implants, said Cary Shapoff, a periodontist who has tested a prototype of Orthogen’s product in a pilot study, is that patients tend to lose bone around the top, or crest, of the implant after surgery. “After the implant had healed at the end of three months, I didn’t see any of the crestal bone loss you’d expect with a typical implant,” he said. Shapoff is a clinical consultant to Orthogen.

Dental implants have become a popular alternative to dentures and bridges. Today, more than two million implants are done each year, a figure that has tripled in the last decade. According to the Centers for Disease Control and Prevention, the average American loses a dozen teeth — including wisdom teeth — by the age of 50.

In the late 1980s, Ricci and his mentor, Alexander were working at the Hospital for Joint Diseases in New York City when they started looking to improve how a dental implant would interact with bone and soft tissue. By 1991 they had hit on a method for engraving 12- and 8-micron grooves with a laser in the implant’s collar and formed Orthogen.

Research in animals showed that 12-micron grooves, about the width of bone cells, encouraged cells to grow along the groove. Trial and error efforts revealed that 8-micron grooves promoted gum tissue to attach.

Better bone growth and gum tissue attachment help seal off the implant from bacteria that can migrate down and create a pocket between the implant and adjacent bone. Such a gap can cause disease that could loosen the implant.

Dental implant maker Bio-Lok, a public company based in Deerfield Beach, Fla., acquired Orthogen in 2000.

Back at UMDNJ, the microgrooved dental implant has spawned another small tech project — building a matrix of “cellular corrals” with MEMS technology to control and guide the growth of tissues such as bone.

Ricci said that New Jersey Institute of Technology’s Microelectronics Research Center a few blocks away helped his team design and fabricate a template for a flat surface covered with microscopic, short-walled squares and rectangles of different sizes. Using the MEMS structure as a mold, the final surfaces were cast out of clear polystyrene plastic. Researchers are studying how various cells grow in corrals of different dimensions and with different wall heights.

One of the goals for the cell corral research, said Ricci, is to see if the tiny confined areas can control growth so that bone cells, for example, don’t lose their bone cell characteristics as the divide and replicate. “We want to see if we can get them to retain their differentiation over longer periods of time in culture,” said Ricci.


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