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Aging population benefits from dental research (10/8/97)

During the next decade the fastest growing segment of the population of the United States will be those over 65 years of age. Health professionals are doing research today to help these people remain active and vigorous well into old age.

Cardiovascular problems are among the most prevalent health problems in our country. Many heart patients take medications that result in side effects such as dry mouth or a burning tongue. Some have dental problems, such as tooth loss, and this leads to deterioration of general health.

A team of scientists from the Dental School and Graduate School of Biomedical Sciences at The University of Texas Health Science Center at San Antonio have joined forces to find solutions to some of the oral health problems associated with aging. One project is a $3.5 million, five-year grant from the National Institute of Dental Research (NIDR), with co-investigators Michele Saunders, DMD, professor, and Eleanore Paunovich DDS, assistant professor, both in the department of dental diagnostic science; John Rugh, PhD, research director of the dental school and acting chairman and professor, department of orthodontics; and Roger J. M. McCarter, PhD, professor in the departments of physiology, orthodontics and dental diagnostic science. Dr. Saunders is a leading authority on oral health and aging and is director of the San Antonio Oral Health and Aging Center grant.

"Dr. Rugh and I have joined forces to test the idea that the decline of oral health with age is due in part to the loss of function in the joints and muscles," Dr. McCarter said. "Dr. Rugh works with people, and I develop animal models. Drs. Saunders and Paunovich are studying the quality of life in conjunction with oral health.

"We are trying to determine why some patients lose their ability to chew food as they grow older," Dr. McCarter said. "This inability to masticate properly contributes to deterioration in general health and increased fatigue in the muscles of the jaw. This could have important functional consequences in overall nutrition."

"Basically, we are trying to determine how the elderly are affected when they lose their teeth," Dr. Paunovich said. "We are measuring the masseter (jaw) muscle in the same population used by the other investigators and we correlate our results with theirs to determine bite force and chewing efficiency."

Many factors enter into the investigation, such as arthritis and other degenerative diseases of the jaw, the number of missing teeth, and so forth. In addition, differences between males and females are being recorded, as are dissimilarities between the Mexican American and European American populations.

"It's a very well known fact that people lose muscle mass as they grow older," Dr. McCarter said. "It is not known whether such a loss also occurs in the muscles of mastication. This is a subject of great national concern. Dr. Rugh's research suggests this does indeed occur, since his elderly subjects have less chewing strength."

"Another very important link has been established with Dr. Paunovich's research," Dr. McCarter said. "She has been looking non-invasively, using ultrasound to check the jaw muscles of the same control group of 1,100 individuals."

"There are ethnic differences in certain areas of research. These differences aren't a factor, according to the preliminary data, but age and gender are," Dr. Paunovich said. "The older we get, the smaller the cross section of the jaw muscle, which is in line with what is known about decreased function in other muscles of the body.

"We are trying to quantify the changes in an elderly person's ability to chew food with data reflecting the function of the muscle," Dr. Paunovich said, "and also see if the impact of other elements in the oral cavity, like tooth restorations or missing teeth, or a toothache or other pain in the mouth, have an effect."

Exercise and diet contribute to oral health just as these factors contribute to general health. "If we walk every day," Dr. Paunovich said, "and eat fresh, crunchy fruits and vegetables or a chewy steak, oral health is maintained for a longer period."

"Exercise does make a difference," Dr. McCarter said. ''This is one way to combat the loss of muscle mass. An exercise regimen for the muscles of the jaw might prevent many of the changes that take place as people age."

Ultrasound reveals both the quality, meaning the type of muscle fibers, and the contrast of the muscle. The researcher holds a probe lightly against the patient's cheek and signals are emitted and returned. When the probe is turned, a longitudinal picture is shown which gives the contrast.

"I'm a clinician, trying to bridge clinical research and biology. The results of our research are especially exciting for patients with temporomandibular (jaw) joint dysfunction (TMJ)," Dr. Paunovich said. "One of my greatest frustrations in the past has been the joint pain and muscular problems these patients suffer.

"Ultrasound gives us another relatively inexpensive -- as opposed to MRI -- and non-invasive diagnostic tool," Dr. Paunovich said. "In addition, sound waves have no known side effects."

In the future this group of scientists will continue to assess the human chewing function of the aging population. Data on muscle cross-sections obtained from ultrasound will be correlated with bite force data to determine changes in muscle strength, and further studies will be conducted to find the effects of medications on age-related diseases.

These findings will be compared with the results found by still another research group working under the same NIDR grant. Dottie Johnson, MA, director of the Sialochemistry Laboratory and a research associate professor in the department of community dentistry, Chih-Ko Yeh, DDS, PhD, assistant professor in dental diagnostic science and research dentist with the Geriatric Research, Education and Clinical Center at the South Texas Veterans Health Care System, and Michael Dodds, PhD, director of the Salivary Function Clinic and associate professor in community dentistry, are studying decreased saliva flow in older people which brings about loss of taste, speech defects, and an overall degeneration in general health.

"In the future, we hope to begin another project using ultrasound in salivary gland assessment," Dr. Paunovich said, "since results from such research would give us additional answers.

"The most exciting thing about this project is that we have been able to take clinicians, academicians and basic scientists and weave together their research findings to focus on a very big health issue," Dr. Paunovich said. "The quality of this research is more meaningful because, for the first time, we have taken the results developed by these groups working together and melded them to reach a major goal. Because of this, the research findings are more rounded and much more valid."

Contact: Jan Elkins (210) 567-2570