A.R.T. can simulate one year's worth of chewing in under a day.

Gaining a better understanding of a tooth’s structure or studying the body’s chewing mechanisms might sound fundamental and well established, but researchers quickly point out they still have a lot to learn.

Is there a better, more efficient way to fill cavity-stricken teeth? How will common dental materials hold up under the strain generated by years of chewing? And how do conditions such as bone cancer and osteoporosis impact dental health and react to treatments?

For nearly 20 years, the Minnesota Dental Research Center for Biomaterials and Biomechanics (MDRCBB) – a center based within the School of Dentistry – has strived to answer such questions.

In the process, researchers have developed and adapted dental innovations and technology such as micro-CT scanners and Artificial Resynthesis Technology (A.R.T.) that may soon shape dental health care delivery.

Micro-CT scanners: Exposing the intersection of a tooth’s form and function

Micro-CT technology is already improving the way dentists monitor and approach restorative procedures. The technology assembles X-ray images to create a 3D look at the insides of physical objects.

With the aid of such high-resolution digital imagery, researchers can study the internal architecture of tissues and materials in a non-invasive way. (For a glimpse at what these images look like, check out this Flickr slideshow.)

“We’re engineers; we’re interested in how a structure's form and function interact,” said associate professor Dr. Alex Fok, director of MDRCBB and restorative sciences expert. “Whether it’s a tooth, a piece of bone or a piece of food, microstructures determine mechanical performance.”

According to Fok, dentists dedicate a high percentage of their time to replacing existing restoration work. Restorations can fail for a variety of reasons, but often the culprit can be defects or gaps between the restoration and a patient’s tissue. Micro-CT technology reveals such defects in a nondestructive way, allowing practitioners to better understand the failure mechanism and adjust their treatment accordingly.

By providing visual markers of how chewing impacts the internal microstructures of food, CT scanners can also help U of M researchers better understand sensory parameters such as crispiness and crunchiness and how dental treatment can affect their perception. Bone biologists can also use the technique to observe changes in bone morphology, leading to better treatment for osteoporosis and cancer patients.

“Micro-CT technology can help us design better-fitting dental implants and orthopaedic devices,” said Fok. “This technology has the ability to directly impact patient care in a positive way.”

Something to chew on: the U of M can simulate a year’s worth of chewing in just one day

In the mid 1980’s, University of Minnesota researchers had an idea: to better test how dental restorative products can impact human teeth over time, why not develop a machine that can replicate the chewing motion.

Then they took the idea a step further. A.R.T., short for Artificial Resynthesis Technology, is effectively a mechanical mouth able to simulate a year’s worth of human chewing in less than a day.

In the human chewing cycle, the teeth come together with the lower arch offset to one side from the upper arch. As the lower arch slides into central alignment with the upper arch, the force between the teeth rises from zero to about three pounds and back to zero again. This part of the chewing cycle usually takes about a quarter of a second. Researchers estimate the average person goes through this functional cycle about 300,000 times in a year.

A.R.T. replicates 300,000 chewing cycles – and the accompanying wear the cycle has on teeth – in just 21 hours.

The machine doesn’t just feature teeth clinking together, either; the technology is programmed to recreate the exact masticatory motions and forces involved in chewing.

A.R.T. is invaluable for researchers working on new restorative dental materials. In the past, human volunteers were required to test materials and the results took much longer. The process is accelerated with A.R.T., providing valid results in just days.

Faster trial periods mean more time and resources devoted to innovation, advancement and discovery.

“That’s the beauty of all the scientists in this laboratory,” said Maria Pintado, an associate professor at MDRCBB and biomaterials expert. “They look at what is missing in terms of existing research and they then couple that with current needs in dentistry. Then they go out and develop that technology.”

-- Jay Boller