Objective: Potassium nitrate (KNO3) suppresses nociception induced by dental hypersensitivity (HYS). We aimed to examine the effects of KNO3 on the neural activity of the trigeminal spinal subnucleus caudalis (Vc) in HYS model rats.
Methods: KNO3 or vehicle was applied to the exposed dentin of HYS rats for 3 days. c-Fos expression and neuronal activity in the Vc after acetone treatment for cold stimulation were examined to evaluate the effects of KNO3 application on dentin.
Results: The number of c-Fos-immunoreactive cells in the Vc was lower in the group that received KNO3 (KNO3 group) than in the group that received vehicle (control group). Spike firing of Vc neurons in response to cold stimulation of the dentin was recorded before and after KNO3 application to the cavity, and the increased neural activity was effectively suppressed by KNO3 application. Scanning electron microscopy revealed that the dentin tubules were not occluded by deposits in any of the groups.
Conclusions: KNO3-induced suppression of Vc neuronal activity does not involve physical occlusion of the dentin tubules but likely involves suppression of Aδ or C-fiber activities in the tooth pulp, resulting in the suppression of Vc neuronal activities.
Keywords: Brain stem; Dentin desensitizing agents; Dentin sensitivity; Nociceptive neuron; Potassium nitrate; Trigeminal caudal nucleus.
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