Inside Scoop on Tooth Tissue Informs Biomaterials Choice

This is part of an occasional series on course directors in the School of Dentistry.

In the clinic, dental students learn the “what” and “how”: What methods and materials can restore tooth and, from the top faculty practitioners, how to diagnose problems and perform delicate procedures.

But the “why” often is equally important, and UCSF students benefit from internationally-known scientists who shift from their labs into the classroom.

Stefan Habelitz, PhD, professor of preventive and restorative dental sciences, is a materials scientist and chemist who sheds light on why one chooses a specific material to restore a tooth.

For almost 20 years, Habelitz has researched the intricate processes of tooth tissue formation. He digs deep, figuratively speaking, into the microworld of enamel, the tooth’s thin but tough outer covering, and dentin, the underneath bony tissue that forms the bulk of the tooth.

He also directs the Introductory Biomaterials Science course for International Dentist Program students who have degrees from their home countries and are preparing to practice in the U.S. The course, similar to one he teaches first-year students, focuses on the structure and properties of dental restoration materials. Students also learn about interaction between materials and tissue in the oral cavity.

“The course teaches the students to think critically, especially after they diagnose a problem and decide on a treatment and restorative material,” said Habelitz.

There are a wide variety of proven materials to repair or strengthen a faulty tooth – amalgams, acrylics, gold, ceramics, zirconia, just to name a few. But there is more to picking a proven, resilient and tough product for a specific dental problem and procedure.

The material must be biocompatible and not impede or harm living tissue or even other restorative material in the treated oral cavity. Can it stand up to or affect a tiny environment of moisture and differing temperatures, acid level and stresses? Can the material trigger allergies or irritate surrounding tissue in larger amounts?

And the practitioner also has to consider, for her or his patients, aesthetics and costs.

Habelitz’s course clicks quickly with students in the School of Dentistry’s two-year IDP regimen. They have clinical experience and likely worked with biomaterials before, and it’s often an “aha” when they understand the “why.”

Students in the traditional four-year DDS curriculum take the biomaterial course in their first year, along with other biomedical sciences classes, and they may not apply the information until they get to the clinic after their second year.

Habelitz, who received his master’s degree in materials engineering and doctorate in chemistry in his native Germany, came to UCSF in 1999 for postdoctoral research. He never imagined himself as a teacher, but he developed a liking and knack for explaining materials engineering principles applied to dentistry.

Now his teaching style is based on “cherrypicking” the most important concepts of materials design and engineering and “explaining and keeping it simple.”

Habelitz’s research is anything but simple, although quite intriguing. One project, “Remineralization of Dentin Caries Lesions,” attempts to recover lost dental tissue function via a polymer-induced mineralization process.

Another, “Mimicking Enamel Formation In-Vitro,” induces a protein, which is key in growth and crystallization in enamel, to form nanofibers that guide mineral growth at the nanometer scale comparable to processes in the enamel matrix.

A third study, “Micropatterned Porous Membranes for Dental Tissue Synthesis,” examines the potential of these membranes for reconstituting cellular organization of dental progenitor cells mimicking early stages of tooth formation.

Perhaps these studies may lead one day to repair carious dentin or to microscopically-engineered proteins and nanostructures to grow enamel – like the real thing.

In the meantime, the supply of biomaterials will grow and be utilized. And dentists will enjoy their profession better understanding why and which is the best fit for the patient.

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