Increased occlusal vertical dimension induces cortical plasticity in the rat face primary motor cortex

Kato, Chiho; Fujita, Köichi; Kokai, Satoshi; Ishida, Takeshi; Shibata, Motoshi; Naito, Satomi; Yabushita, Tomohiro; Ono, Takashi

doi:10.1016/j.odw.2013.08.003

Cited by 4 publications

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“…But transection of the infraorbital nerve (supplying sensory innervation to the vibrissae) results in a significant decreased excitability of vibrissal-M1 2 to 3 wk later, with no changes in the extent of vibrissal motor representation (Franchi 2001). Changes to the rat dental occlusion induced by orthodontic tooth movement produce time-dependent changes in jaw and tongue motor representations (Sood et al 2015), and increasing the occlusal vertical dimension produces increased jaw and tongue motor representations (Kato et al 2012). A decreased number of occlusal contacts produced by unilateral extraction of the rat mandibular incisor results in a significantly increased number of jaw and/or tongue sites within the face-M1 7 to 14 d later (Avivi-Arber et al 2010b), but molar tooth extraction results in decreased jaw and tongue representation 1 to 2 mo later (Avivi-Arber et al 2015).…”

Section: Discussionmentioning

confidence: 99%

Dental Occlusal Changes Induce Motor Cortex Neuroplasticity

2015

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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.

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Section: Discussionmentioning

confidence: 99%

Dental Occlusal Changes Induce Motor Cortex Neuroplasticity

2015

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“…Emerging evidence from animal and human studies indicates that neuroplastic changes in the properties of the face‐SMCx can be induced by alterations in somatosensory inputs to the face‐SMCx from the orofacial region (e.g., as a result of nerve injury, noxious stimulation, orthodontic tooth movement, incisor tooth trimming, or extraction) and by altered motor function associated with learning of novel oral motor skills. These neuroplastic changes can be manifested, for example, as a change in motor (and/or sensory) representations and/or in the ICMS threshold intensities for evoking motor responses (i.e., increased or decreased excitability) (e.g., Adachi et al, , 2008; Boudreau et al, , ; Avivi‐Arber et al, ,b, 2011b; Kato et al, ; Arce et al, ; Sessle et al, ; Awamleh et al, ; Sood et al, ). Consistent with a large number of studies focusing on limb‐M1 and vibrissal‐M1 (for review, see Ebner, ; Teskey and Kolb, ; Kleim, ; Young et al, ), these studies suggest that face‐SMCx neuroplasticity may be crucial for the ability of animals and humans to adapt to intraoral changes and learn new or relearn lost orofacial motor skills.…”

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confidence: 99%

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

Avivi‐Arber

Lee

Sood

et al. 2015

J of Comparative Neurology

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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.

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“…Mapeamentos por ICMS com distância de 500µm entre os pontos são comuns na literatura (Franchi, 2000;Avivi-Arber et al, 2010;Kato et al, 2012).…”

Section: Comportamento De Ansiedadeunclassified

“…Em geral estudos experimentais sobre sensibilização central e atividade do córtex motor utilizam EMG para quantificar os movimentos mandibulares (Adachi et al, 2008;Avivi-Arber et al, 2010;Kato et al, 2012) o qual não foi utilizado no presente estudo, pois o mesmo baseou-se na visualização direta do observador. Este método foi escolhido por já ter sido utilizado em trabalhos anteriores (Fonoff et al, 2009) permitindo a visualização tanto das vibrissas quanto dos movimentos mandibulares, pois neste caso não foi o objetivo neste estudo identificar os músculos específicos envolvidos, mas apenas a presença dos movimentos mandibulares.…”

Section: Comportamento De Ansiedadeunclassified

“…Observamos no presente estudo que na região orofacial, a indução da DP em um único dente foi o suficiente para, em 14 dias, ocasionar uma reorganização do mapa motor. Outro estudo experimental em que realizaram o mapeamento do M1 também mostra que as alterações neuroplásticas ocorrem em torno dos 14 dias após a indução da alteração periférica, neste caso, alteração da dimensão vertical de oclusão(Kato et al, 2012). Estudo clínico em humanos demonstrou alterações na representação cortical motora também em torno de 14 dias após o tratamento de uma condição dolorosa(Lickteig et al, 2013).…”

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Avaliação da sensibilidade mecânica, ansiedade e neuroplasticidade cortical motora em ratos submetidos à doença periodontal experimental

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Increased occlusal vertical dimension induces cortical plasticity in the rat face primary motor cortex

Cited by 4 publications

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Dental Occlusal Changes Induce Motor Cortex Neuroplasticity

Dental Occlusal Changes Induce Motor Cortex Neuroplasticity

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

Avaliação da sensibilidade mecânica, ansiedade e neuroplasticidade cortical motora em ratos submetidos à doença periodontal experimental

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