Date of Graduation

Spring 2017

Degree

Master of Science in Biology

Department

Biology

Committee Chair

Paul Durham

Abstract

Temporomandibular joint disorders (TMD) is a debilitating orofacial pain condition that affects a significant portion of the population and is associated with a decrease in quality of life. Results from the Orofacial Pain Prospective Evaluation and Risk Assessment Study (OPPERA) study provide evidence that risk factors such as neck muscle tension, prolonged jaw opening, and female gender increase the likelihood of developing TMD. Routine visits to an orthodontist or dentist can result in injury to the jaw joint or muscles of mastication. I tested the hypothesis that neck muscle inflammation and female gender increase the risk of developing chronic pain in response to prolonged jaw opening. Young male Sprague-Dawley rats were injected with complete Freund's adjuvant in the trapezius muscle to promote sensitization of trigeminal ganglion neurons. After 8 days, both male and female animals were subjected to near maximal jaw opening for 20 minutes. Mechanical nocifensive thresholds were determined in response to von Frey filaments applied to the skin over the eyebrow, masseter muscle, and joint capsule. Near maximal jaw opening increased nocifensive responses to mechanical stimuli over the masseter area for 14 days but then returned to near baseline levels by day 21. However, muscle inflammation prior to jaw opening resulted in prolonged nociception that was observed up to 28 days post jaw opening. Our findings provide evidence that neck muscle inflammation promotes sensitization of trigeminal neurons such that prolonged jaw opening causes a sustained nocifensive response that was more severe in females.

Keywords

trigeminal nerve, temporomandibular joint disorder, peripheral sensitization, central sensitization, risk factors

Subject Categories

Biology

Copyright

© Neelima Chelliboina

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