Dental Occlusal Changes Induce Motor Cortex Neuroplasticity

Area of Science:

• Neuroscience
• Oral biology
• Motor control

Background:

• Dental occlusion modifications can disrupt oral sensorimotor functions.
• The face primary motor cortex (face-M1) controls orofacial movements and exhibits neuroplasticity in response to altered sensory or motor inputs.
• Understanding neuroplasticity is key to explaining patient adaptation to dental restorations.

Purpose of the Study:

• To investigate if repeated incisor trimming and subsequent occlusion restoration induce neuroplasticity in the rat face-M1.
• To compare changes in jaw and tongue motor representations between hemispheres after occlusal alteration.

Main Methods:

• Used Sprague-Dawley rats with continuously erupting incisors.
• Performed repeated trimming of the right mandibular incisor to alter occlusal contacts for 7 days.
• Mapped jaw and tongue motor representations in face-M1 using intracortical microstimulation (ICMS) in naive, trimmed, and recovered groups.

Main Results:

• Incisor trimming led to shorter tongue onset latency in the left face-M1 compared to the right.
• After occlusion recovery, the left face-M1 showed increased tongue representation sites and jaw/tongue overlapping sites.
• The center of gravity for tongue representation shifted deeper in the left face-M1 post-recovery.

Conclusions:

• Incisor trimming and occlusion restoration induce significant neuroplasticity in the rat face-M1.
• Hemispheric differences in motor representations suggest adaptive mechanisms in oral sensorimotor function.
• This neuroplasticity may underpin the ability to adapt to altered dental occlusion.