Cortical Activation Resulting from Painless Vibrotactile Dental Stimulation Measured by Functional Magnetic Resonance Imaging (fMRI)

Abstract

There have been few investigations on hemodynamic responses in the human cortex resulting from dental stimulation. Identification of cortical areas involved in stimulus perception may offer new targets for pain treatment. This initial study aimed at establishing a cortical map of dental representation, based on non-invasive fMRI measurements. Five right-handed subjects were studied. Eight maxillary and 8 mandibular teeth were stimulated after the vibratory perception threshold was determined for each tooth. Suprathreshold stimulation was repeated thrice per session, in a total of three sessions performed on three consecutive days. Statistical inference on cluster level identified increased blood-oxygen-level-dependent signal during vibratory dental stimulation, primarily in the insular cortex bilaterally and in the supplementary motor cortex. No significant brain activation was observed in the somatosensory cortex with this stimulation protocol. These results agree with previous findings obtained from invasive direct electrical cortical stimulation of the human insula.

Brain Activations in Response to Vibrotactile Tooth Stimulation: a Psychophysical and fMRI Study

“…At the highest frequency (100 Hz) no significant activity was found in the primary or secondary somatosensory cortex, a finding in agreement with the study of Ettlin et al (2004) who stimulated at 80 Hz and supporting the theory that this is outside the range of activity of PDLMs.…”

“…Ettlin et al (2004) delivered nonpainful stimulation to eight maxillary and eight mandibular teeth and studied the response to a suprathreshold vibratory stimulus, delivered using a compressed air piston to drive a stimulation rod at a fundamental frequency of 80 Hz and a maximum force of 4.0 N. The main finding was that dentinal stimulation resulted in activation in the supplementary motor area (SMA) and insular cortex. However, no significant activation was observed in the primary or secondary somatosensory cortex.…”

“…However, despite there being no significant difference in detection threshold between 50 and 100 Hz stimuli, changes between these two stimulation frequencies were nonetheless seen in sensory, parietal, and frontal regions, and so such changes can therefore be attributed solely to the frequency effects. Also, it should be noted that all forces applied in this study were ϳ20-fold less than those used by Ettlin et al (2004) and thus more localized. It is likely that in Ettlin's study the vibratory stimulus applied to individual teeth spread to other teeth via interdental contacts and the trans-septal fiber system.…”

Neural mechanisms of nociception during orthodontic treatment

“…Yamamoto et al (47) reported that in the rat a subset of neurons in the insular cortex (IC) responds to mechanical stimulation of oral structures. In agreement with this study, a functional magnetic resonance imaging (fMRI) study of humans reported activation of the IC and supplementary motor cortex during vibratory stimulation of teeth (48). Taken together, these studies suggest that the IC is another possible PDL-related cortical region.…”

Design and construction of a magnetic resonance compatible multi-injector gas jet delivery system

“…15 Painful stimulation occurs peripherally via exposed dentine surfaces; however, the biological events in the human central nervous system ͑CNS͒ related to dental pain perceptions are largely unknown and have only recently become the target of investigations in human subjects. 16 Oral pain in mucositis patients. Cancer ranks as the second leading cause of mortality in the United States.…”