RESEARCH

Results in Minutes in an Office, not Hours off-site

One of four methods used to collect a patient's saliva involves a patient providing a sample in a tube until about a tablespoon of fluid has been collected.

New test results show a portable saliva test device developed by a U-M School of Dentistry professor could tell patients in just minutes if they have periodontal disease, which would be a major improvement over current methods which require hours of analysis at an off-site lab. The School of Dentistry's Dr. William Giannobile and Dr. Anup Singh of Sandia National Laboratories jointly developed the saliva test device.

Testing with the device has progressed to the point where a dentist would need only a drop of saliva from a patient and less than five minutes of time to analyze the sample in his or her office. Current sample analysis requires hours of time at a laboratory away from a dental office.

Giannobile, who also directs the Michigan Center for Oral Health Research, said that in recent months the Center has been conducting tests that are adaptable to using microfluidic technology.

"Using a miniaturized lab-on-a-chip approach, we have been able to separate and analyze proteins quickly, typically, within minutes of sample separation," he said. Established in 2003, the Center takes discoveries from research laboratories and attempts to find ways to use them to benefit oral health care professionals and their patients.

The saliva test kit measures a tissue-destructive enzyme, matrix metalloproteinase-8, a molecule which is released from cells that tend to migrate to periodontal lesions.

How it Works

There are four different methods used to collect a patient's saliva.

In the first, patients provide a saliva sample in a collector tube until about a tablespoon of fluid has been collected.

In the second, known as gingival crevicular fluid rinse, patients are asked to rinse with tap water for 30 seconds. They then rise with sterile saline solution for another 30 seconds, and then spit the saline into a collector tube, and finally rinse with tap water.

The third method requires patients to keep a saliva collection device in their mouth for 10 minutes. A cotton pad will soak fluid from the oral cavity as well as from the mucosa since the pad is enriched with salt solution. Afterwards, the collector is placed into a fabricated tube, broken in half, and is prepared for a centrifuge. Afterwards, fluids extracted from the cotton pad are analyzed.

In the final method, oral fluid samples are collected with paper strips which are placed into the gingival crevice for 30 seconds. The strips are then removed and put into a freezer at -80 degrees Celsius for storage and are later analyzed in a lab.

Highly Accurate Results

"Using just a very small sample of saliva, we found our tests to be highly accurate in identifying patients with periodontal disease, without the need for a more time consuming and comprehensive clinical examination," Giannobile said. "This method could one day be used to screen large patient populations which could have major implications for oral health."

From late 2005 through 2006, 130 patients were tested at MCOHR clinics in northeast Ann Arbor.

Collaborating with Giannobile are Dr. Mark Burns, professor with the U-M School of Chemical Engineering, and Dr. Christoph Ramseier and Janet Kinney, both MCOHR research fellows. The National Institutes of Health provided funding for the test studies. The lab-on-a-chip technology was developed and manufactured by Sandia National Laboratories, which has major research and developmental interests in national security, energy, and environmental technologies.

The results of an analytical test appeared in the March 27th issue of the Proceedings of the National Academy of Sciences of the United States.