Title: Orofacial Pain Assessment of Rats With Bite-Raising Splints
Wuyang Li (Presenter)
University of Pittsburgh
Xinyun Liu, University of Pittsburgh
Jorge Pineda Farias, University of Pittsburgh
Michael Gold, University of Pittsburgh
Alejandro Almarza, University of Pittsburgh
Objectives: To investigate whether a sudden change in occlusion is associated with the emergence of hypersensitivity in the TMJ area in adult male rats.
Methods: Perioral hypersensitivity was assessed before and after splint placement with the orofacial pain assay. Rats were trained to access a 5% sucrose solution via a window in the side of the cage. Cumulative contact time (CT) with the sucrose sipper tube was determined for each 10 min training and subsequent testing session. For testing, 18-pin wire arrays were placed in the window to provide bi-lateral mechanical stimulation of the face when the sucrose solution was accessed. Baseline data were collected 4 days before, 1 day after, and then once per week after splint placement. Splints consisted of dental resin poured to about 1 mm in thickness, which were applied unilaterally to the right maxillary molars.
Results: Increase in CT was observed during training, which plateaued by day three. CT was significantly decreased when mechanical stimulation was added (by 80%± 11%, p < 0.05). CT was decreased further still following splint placement (by 58% ± 16%, p < 0.05).
Conclusions: Our results are consistent with an increased sensitivity to noxious mechanical stimuli following altered TMJ loading. The orofacial pain assay appears to be a sensitive way to quantify changes in peri-orbital mechanical sensitivity. Additional experiments will be needed to confirm that the changes in behavior reflect an increase in nociception.