IADR Abstract Archives
Hemodynamic Changes in Prefrontal Cortex during Pain Stimulation in Gingiva
Objectives: Elucidating the transmission mechanism of pain signals from the orofacial area not only aids our understanding of pain mechanisms, but also provides useful information for the development of pain mitigation methods. In the present study, the involvement of the pain-inhibitory-system in the trigeminal area was investigated through an analysis of activation status over time in the prefrontal cortex (PFC) using functional near-infrared spectroscopy (fNIRS) when a mildly pain stimulus was given to the gingiva.
Methods: Using 28 healthy male volunteers (average age 30.1±4.2 years) as subjects, mild, intermittent, acute pain stimulus was administered six times over one minute through the implementation of pocket probing in the gingiva surrounding the right maxillary central incisor. In PFC, the levels of oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb) were measured using a fNIRS measurement system and the connected 22-channel probes. Average values for both oxy-Hb and deoxy-Hb levels were calculated for four stages at rest for 20 seconds prior to the pain stimulus and three 20 second intervals within the one minute of stimulation and were used as representative values for each subject. Subsequently, statistically analyzed (ANOVA, Scheffe’s, p<0.05) using the representative values obtained from all subjects were conducted and change due to pain was investigated.
Results: Oxy-Hb level decreased the most during the 20-second stage directly after the start of stimulation. This change was seen mainly on the contralateral side, after which it returned to the resting baseline from before the pain stimulus. Change in deoxy-Hb level was not observed.
Conclusions: It was suggested that for healthy males, a mechanism exists to mitigate pain involving the pain-inhibitory-system in the 20 seconds after feeling mild pain to the gingiva. These results provide useful information for understanding the mechanism of acute pain suppression in the oral cavity.
Methods: Using 28 healthy male volunteers (average age 30.1±4.2 years) as subjects, mild, intermittent, acute pain stimulus was administered six times over one minute through the implementation of pocket probing in the gingiva surrounding the right maxillary central incisor. In PFC, the levels of oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb) were measured using a fNIRS measurement system and the connected 22-channel probes. Average values for both oxy-Hb and deoxy-Hb levels were calculated for four stages at rest for 20 seconds prior to the pain stimulus and three 20 second intervals within the one minute of stimulation and were used as representative values for each subject. Subsequently, statistically analyzed (ANOVA, Scheffe’s, p<0.05) using the representative values obtained from all subjects were conducted and change due to pain was investigated.
Results: Oxy-Hb level decreased the most during the 20-second stage directly after the start of stimulation. This change was seen mainly on the contralateral side, after which it returned to the resting baseline from before the pain stimulus. Change in deoxy-Hb level was not observed.
Conclusions: It was suggested that for healthy males, a mechanism exists to mitigate pain involving the pain-inhibitory-system in the 20 seconds after feeling mild pain to the gingiva. These results provide useful information for understanding the mechanism of acute pain suppression in the oral cavity.