Donald Nixdorf, D.D.S., M.S.

Because pain is subjective, a quandary for investigators is how to measure it—an issue faced by CAPS scholar Donald Nixdorf, assistant professor in the School of Dentistry. Nixdorf investigates chronic orofacial pain, experienced by some patients with temporomandibular disorders (TMD) or following dental treatments such as root canal therapy. A standardized means to measure pain will help researchers classify it and assess treatment effi cacy.

“When people feel pain, there is an underlying biological event within the brain,” says Nixdorf. “The challenge is to identify this signal and be able to quantify it.” To do this, Nixdorf plans to employ two approaches: psychophysics and functional magnetic resonance imaging (fMRI). Psychophysics aims to measure the relationship between physical magnitude and the corresponding perceived or subjective magnitude, while fMRI is used to determine how the brain responds to physical stimuli. “Using this approach we plan to measure those components of chronic pain disorders likely to indicate chronicity, hoping to apply this knowledge in clinical practice by relating outcomes to signs and symptoms,” says Nixdorf.

Nixdorf’s previous psychophysical investigations examined the tactile sensibility of subjects with TMD pain versus normal controls. He assessed pain response to three tactile stimuli, revealing that one stimulus was repeatable with good ability to classify subjects with TMD pain correctly and fair ability to classify subjects who did not have pain. Working with faculty in the Center for Magnetic Resonance Research, as well as a graduate student in the Master of Science in Dentistry program and a physics engineer, Nixdorf is developing a method of administering a tactile stimulus within a subject’s mouth during functional imaging. Pain-free individuals feel this stimulus as touch but not pain, unlike individuals with chronic pain, who tend to experience the stimulus as painful. Nixdorf hopes this approach will allow him to observe non-invasively how brains of individuals with chronic pain function differently than those of people without pain.

As a CAPS scholar, Nixdorf is provided 75 percent protected time to conduct his research. “My research is in an exploratory phase,” he says, “and through the CAPS program, I have been able to develop a framework to start looking at my research questions and access cutting-edge technologies to help answer them.”