Different brain responses to pain and its expectation in the dental chair

A dental appointment commonly prompts fear of a painful experience,yet we have never fully understood how our brains react to the expectation of imminent tooth pain once in a dental chair. in our study,21 patients with hypersensitive teeth were tested using nonpainful and painful stimuli in a clinical setting. subjects were tested in a dental chair using functional near-infrared spectroscopy to measure cortical activity during a stepwise cold stimulation of a hypersensitive tooth,as well as nonpainful control stimulation on the same tooth. patients' sensory-discriminative and emotional-cognitive cortical regions were studied through the transition of a neutral to a painful stimulation. in the putative somatosensory cortex contralateral to the stimulus,2 well-defined hemodynamic peaks were detected in the homuncular orofacial region: the first peak during the nonpainful phase and a second peak after the pain threshold was reached. moreover,in the upper-left and lower-right prefrontal cortices,there was a significant active hemodynamic response in only the first phase,before the pain. subsequently,the same prefrontal cortical areas deactivated after a painful experience had been reached. our study indicates for the first time that pain perception and expectation elicit different hemodynamic cortical responses in a dental clinical setting. © international & american associations for dental research 2015.