Center for Implant and Reconstructive Dentistry

Health Center Scientists Pioneer New Technique to Support Prosthetic Teeth

By Jim H. Smith

Martin Freilich, J. Robert Kelly, Liisa Kuhn and David Shafer discuss their technique to promote the growth of healthy new bone.

“It’s difficult to make the porcelain/metal combination match the color and translucency of natural teeth,” says Martin Freilich, D.D.S., Department of Oral Rehabilitation, Biomaterials and Skeletal Development." And porcelain is so hard, it can wear away other teeth it touches.” So Freilich and a team of dentists at the UConn Health Center wanted a better material to build the replacement teeth that would be attached to their dental implants. They turned to a fiber-reinforced composite used to construct luxury sailboats and high-performance airplanes. Remarkably strong, it offered significant advantages over porcelain. It doesn’t corrode; it’s not toxic; it’s a better match, aesthetically; and it can be repaired if damaged.

Excited about the new material, Freilich and his team set out to test it in prosthetic teeth supported by implants, recruiting healthy volunteers missing their upper teeth and their lower back teeth. Since the study was open to people ages 20 to 80, Freilich never expected a shortage of recruits. But when he and his associates began examining volunteers for their study, they soon found that fully two-thirds of prospects didn’t have enough jawbone for insertion of the implants that would hold the new composite teeth. That’s because when teeth are extracted, the underlying jawbone begins to shrink as it no longer experiences chewing forces. It’s called resorption, and dentists have known about it for years. It’s the same bone loss problem that astronauts suffer in zero-gravity conditions. Faced with dozens of people who could benefit from their new implant system except for their shrunken jawbones, Freilich and his colleagues decided to do something about it.

Team Effort Yields Novel Approach

Most dental implants, which are made of titanium, are about 10-12 millimeters (one-half inch) high and about four to five millimeters wide, dimensions generally considered necessary to achieve a secure contact with surrounding bone. For jawbone narrowed by resorption, bone tissue from other parts of the body can be grafted to the site to create additional width. For jawbone lacking height, however, there were no reliable options. Freilich and two colleagues, Robert Kelly, D.D.S., Ph.D., in the Department of Oral Rehabilitation, Biomaterials and Skeletal Development; and Rebecca Cochrane, D.M.D., Ph.D., then a post-doctoral fellow in the Department of Endocrinology, decided to try to compel vertical bone growth.

They came up with a novel idea. What if they designed significantly shorter implants and initially imbedded only the bottom part of the implant into the resorbed bone? The top part of the implant would be left above the bone but below the gum tissue and designed with special characteristics to guide the growth of new bone upward, providing a more secure implant to bone attachment. And what if the new, shorter implants were designed so that once new bone tissue was in place, another titanium shaft could be attached to the top of the implant and the process repeated? If implants could successfully direct new bone growth, they could be used in more patients.

To help address this challenge, Freilich turned to Lawrence Raisz, M.D., a Health Center endocrinologist with an international reputation in bone biology. Together, they analyzed the vast body of basic bone research carried out at the Health Center and elsewhere, and developed an extensive number of possible biological components and biomaterials to the new implant system. To narrow the possibilities, Freilich turned to Liisa Kuhn, Ph.D., a biomaterials scientist in the Department of Oral Rehabilitation, Biomaterials and Skeletal Development. Kuhn has a strong background in bone regeneration related to orthopedic hip and spine surgery. She has extensive experience working with various bone substitutes, especially combinations of calcium phosphate and growth factors that enhance bone growth.

In this model of a dental arch, a titanium implant supports an artificial crown.

It was Kuhn who suggested working with Mei Wei, Ph.D., from the university’s Department of Materials Science and Engineering in Storrs and an expert on applying calcium phosphate coatings to titanium surfaces using different coating techniques. Together, Kuhn and Wei are developing methods for the controlled release of growth factors from the calcium phosphate coatings.

In 2002, Freilich and David Shafer, D.M.D., an oral and maxillofacial surgeon at the Health Center, tested the new, coated implant on laboratory animals. “We were very lucky,” says Shafer. “Because of early success with that implant, we’ve been able to make rapid progress.”

Over the last three years, the team has continued to refine their implant model, employing a wide range of drugs and coatings. As their model has increasingly shown itself to be valid, its commercial potential is gaining recognition, according to Michael Newborg, executive director of the UConn Center for Science and Technology Commercialization.

Broader Implications for Bone Growth Therapy

Freilich’s research has implications not only for oral health, but also for treatment of orthopedic injuries and other musculoskeletal conditions calling for bone-growth therapy. “The surgeon general has identified advances in the prevention, diagnosis and treatment of musculoskeletal conditions as priorities to enhance the life of our aging population,” adds Raisz, who was an editor of the first Surgeon General’s report on bone health and osteoporosis released in 2004. “Every year, musculoskeletal conditions and injuries account for over 100 million visits to physicians’ offices, outpatient centers and emergency departments. That number will only increase as the number of individuals over age 50 continues to grow,” he says.

“The Health Center’s bone and connective tissue program, like its other signature programs in cardiology and cancer, is designed to encourage and support cutting edge translational research that applies basic science to the development of innovative health care for patients,” says Anne Horbatuck, R.N., director of the Musculoskeletal Institute. “The new implant technology is a wonderful example of the advances that can be made by linking our research and clinical expertise.”

With the progress made in implant technology, the Health Center is planning to devote more resources to implant and reconstructive dentistry. “The market for dental implants grows by about 25 percent every year, and most dentists throughout the region don’t do them,” says Thomas Taylor, D.D.S., M.S.D., head of the Department of Oral Rehabilitation, Biomaterials and Skeletal Development. “Our school can be a tremendous educational resource for dentists and for their patients.”

Medical implant manufacturers are keenly aware of the growing world market for dental implants, according to Magda Stayton, associate vice president for development. “Already, Straumann, USA, has donated $500,000 to the dental school. Philanthropic support like this is crucial to the establishment of the program that will help our students add implant dentistry to their repertoire of clinical skills and ensure our patients get the best treatment options.”

Article appeared in UConn Health Center Magazine, Summer 2006.