title: Dental Occlusal Changes Induce Motor Cortex Neuroplasticity.
abstract: Modification to the dental occlusion may alter oral sensorimotor functions. Restorative treatments aim to restore sensorimotor functions; however, it is unclear why some patients fail to adapt to the restoration and remain with sensorimotor complaints. The face primary motor cortex (face-M1) is involved in the generation and control of orofacial movements. Altered sensory inputs or motor function can induce face-M1 neuroplasticity. We took advantage of the continuous eruption of the incisors in Sprague-Dawley rats and used intracortical microstimulation (ICMS) to map the jaw and tongue motor representations in face-M1. Specifically, we tested the hypothesis that multiple trimming of the right mandibular incisor, to keep it out of occlusal contacts for 7 d, and subsequent incisor eruption and restoration of occlusal contacts, can alter the ICMS-defined features of jaw and tongue motor representations (i.e., neuroplasticity). On days 1, 3, 5, and 7, the trim and trim-recovered groups had 1 to 2 mm of incisal trimming of the incisor; a sham trim group had buccal surface trimming with no occlusal changes; and a naive group had no treatment. Systematic mapping was performed on day 8 in the naive, trim, and sham trim groups and on day 14 in the trim-recovered group. In the trim group, the tongue onset latency was shorter in the left face-M1 than in the right face-M1 (P < .001). In the trim-recovered group, the number of tongue sites and jaw/tongue overlapping sites was greater in the left face-M1 than in the right face-M1 (P = 0.0032, 0.0016, respectively), and the center of gravity was deeper in the left than in the right face-M1 (P = 0.026). Therefore, incisor trimming and subsequent restoration of occlusal contacts induced face-M1 neuroplasticity, reflected in significant disparities between the left and right face-M1 in some ICMS-defined features of the tongue motor representations. Such neuroplasticity may reflect or contribute to subjects' ability to adapt their oral sensorimotor functions to an altered dental occlusion.
authors: Department of Oral Physiology, Faculty of Dentistry, University of Toronto, Toronto, Canada Department of Prosthodontics, Faculty of Dentistry, University of Toronto, Toronto, Canada Limor.avivi.arber@utoronto.ca.
authors: L
authors: L
authors: Avivi-Arber
authors: Department of Oral Physiology, Faculty of Dentistry, University of Toronto, Toronto, Canada.
authors: J-C
authors: JC
authors: Lee
authors: Department of Oral Physiology, Faculty of Dentistry, University of Toronto, Toronto, Canada.
authors: B J
authors: BJ
authors: Sessle
mesh_terms: D000818:Animals; D003766:Dental Occlusion; D004576:Electromyography; D007180:Incisor / Q000601:surgery; D007568:Jaw / Q000294:innervation / Q000502:physiology; D008297:Male; D008310:Malocclusion / Q000503:physiopathology; D009044:Motor Cortex / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014059:Tongue / Q000294:innervation / Q000502:physiology
keywords: muscle; orofacial; plasticity; sensorimotor; teeth; trigeminal