Immediate Impact of Clinical Dental Pain Expectation/Suffering on the Brain

Objectives: To investigate the functional-connectivity (FC) patterns of patients with dental hypersensitivity (DH) before and after pain in the clinical environment.
Methods: We examined 12 subjects with DH in a clinical setting, recording hemodynamic responses at primary somatosensory (SI) and bilateral prefrontal cortices (PFC), as well as self-reported pain ratings. We calculated the Pearson correlation coefficients between the signals collected from each channel pairs, respectively, before and after participants received dental pain stimuli. Then we examined the correlation between the FC changes of each channel and the participants’ self-reported pain ratings. Finally, we hypothesized a model under partial least square path modeling framework with participants’ reported pain scores, connectivities prior to the dental pain, and painful stimulus-evoked hemodynamic responses data collected from all participants. We used the plspm package in R to estimate the model coefficients.
Results: We found significant FC changes before and after dental pain between bilateral SI and PFC (p < .05). Moreover, we found that the PFC - SI connectivity changes were negatively associated with the self-reported pain scores across patients (p < .05). Significant interactions (p < .05) between connectivities prior to noxious stimulation (beta = 0.50), pain evoked hemodynamic responses (beta = 0.53), expectation (beta = 0.90), cold sensory (beta = 0.98), and self-reported pain rates were observed.
Conclusions: In summary, this study shows that dental pain experience in the clinical environment has an immediate effect on the patients' brains, by changing their FC. This study is the first step towards our understanding of the mechanisms underlying individual variations in dental pain expectation and its acute consequence in the brains of patients with DH. Further studies should be performed to confirm our findings and evaluate the long-term effects of dental pain on brain connectivity.