Long-term neuroplasticity of the face primary motor cortex and adjacent somatosensory cortex induced by tooth loss can be reversed following dental implant replacement in rats.
Tooth loss is common, and exploring the neuroplastic capacity of the face primary motor cortex (face-M1) and adjacent primary somatosensory cortex (face-S1) is crucial for understanding how subjects adapt to tooth loss and their prosthetic replacement. The aim was to test if functional reorganization of jaw and tongue motor representations in the rat face-M1 and face-S1 occurs following tooth extraction, and if subsequent dental implant placement can reverse this neuroplasticity. Rats (n = 22) had the right maxillary molar teeth extracted under local and general anesthesia. One month later, seven rats had dental implant placement into healed extraction sites. Naive rats (n = 8) received no surgical treatment. Intracortical microstimulation (ICMS) and recording of evoked jaw and tongue electromyographic responses were used to define jaw and tongue motor representations at 1 month (n = 8) or 2 months (n = 7) postextraction, 1 month postimplant placement, and at 1-2 months in naive rats. There were no significant differences across study groups in the onset latencies of the ICMS-evoked responses (P > 0.05), but in comparison with naive rats, tooth extraction caused a significant (P < 0.05) and sustained (1-2 months) decreased number of ICMS-defined jaw and tongue sites within face-M1 and -S1, and increased thresholds of ICMS-evoked responses in these sites. Furthermore, dental implant placement reversed the extraction-induced changes in face-S1, and in face-M1 the number of jaw sites even increased as compared to naive rats. These novel findings suggest that face-M1 and adjacent face-S1 may play a role in adaptive mechanisms related to tooth loss and their replacement with dental implants.
Department of Prosthodontic, Faculty of Dentistry, University of Toronto, Ontario, Canada.|Department of Oral Physiology, Faculty of Dentistry, University of Toronto, Ontario, Canada.
Limor
L
Avivi-Arber
Department of Oral Physiology, Faculty of Dentistry, University of Toronto, Ontario, Canada.
Jye-Chang
JC
Lee
Department of Oral Physiology, Faculty of Dentistry, University of Toronto, Ontario, Canada.|Department of Orthodontics, Faculty of Dentistry, University of Toronto, Ontario, Canada.
Mandeep
M
Sood
Department of Periodontics, Faculty of Dentistry, University of Toronto, Ontario, Canada.
Flavia
F
Lakschevitz
Department of Oral Physiology, Faculty of Dentistry, University of Toronto, Ontario, Canada.
Michelle
M
Fung
Department of Periodontics, Faculty of Dentistry, University of Toronto, Ontario, Canada.
Maayan
M
Barashi-Gozal
Department of Periodontics, Faculty of Dentistry, University of Toronto, Ontario, Canada.
Michael
M
Glogauer
Department of Oral Physiology, Faculty of Dentistry, University of Toronto, Ontario, Canada.
Barry J
BJ
Sessle
D000818:Animals; D001931:Brain Mapping; D015921:Dental Implants; D004195:Disease Models, Animal; D004576:Electromyography; D005071:Evoked Potentials; D007568:Jaw / Q000503:physiopathology; D008297:Male; D008963:Molar / Q000503:physiopathology / Q000601:surgery; D009044:Motor Cortex / Q000503:physiopathology*; D009473:Neuronal Plasticity / Q000502:physiology*; D011897:Random Allocation; D017207:Rats, Sprague-Dawley; D013003:Somatosensory Cortex / Q000503:physiopathology*; D014059:Tongue / Q000503:physiopathology; D016388:Tooth Loss / Q000503:physiopathology* / Q000628:therapy*
D015921:Dental Implants
face primary motor cortex; neuroplasticity; tooth loss