Novel Air Stimulation MR-Device for Intraoral Quantitative Sensory Cold Testing

Area of Science:

• Neuroimaging
• Dental Research
• Somatosensory Science

Background:

• Cold air sensitivity is a common cause of dental discomfort.
• Existing MR-compatible devices for quantitative sensory testing of cold air stimuli are unavailable.
• Neuroimaging offers opportunities to link trigeminal neuron excitation to somatosensory perceptions.

Purpose of the Study:

• To construct and evaluate a novel MR-compatible, computer-controlled cold air stimulation apparatus (CASA).
• To enable quantitative sensory testing with controlled, graded cold air stimuli in an MR environment.
• To investigate brain responses associated with cold air-evoked dental sensations.

Main Methods:

• Construction of a multi-injector air jet system (AJS) with a cold exchanger and cooling agent.
• Testing the CASA device's feasibility through an fMRI stimulation experiment on a single subject with dentine cold sensitivity.
• Delivering repetitive, stable air stimuli at temperatures ranging from room temperature to -35°C and flow rates of 5-17 l/min.

Main Results:

• The CASA device successfully delivered stable, graded cold air stimuli (-35°C to room temperature) at controlled flow rates.
• Stimuli evoked perceptions similar to natural cold air sensations.
• fMRI analysis revealed brain activations in regions associated with acute pain processing, including the thalamus, insular and cingulate cortices, somatosensory, cerebellar, and frontal areas.

Conclusions:

• The novel CASA facilitates controlled, repetitive quantitative sensory testing with graded air stimuli and simultaneous brain response recording.
• This MR-compatible device is unique in its ability to deliver non-contact, natural-like stimuli over a wide temperature range to localized areas like the mouth.
• The CASA holds promise for advancing trigeminal and spinal somatosensory research, particularly for evaluating therapies for dentine hypersensitivity.