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Repeated clenching causes plasticity in corticomotor control of jaw muscles
Author(s) -
Iida Takashi,
Komiyama Osamu,
Obara Ryoko,
BaadHansen Lene,
Kawara Misao,
Svensson Peter
Publication year - 2014
Publication title -
european journal of oral sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.802
H-Index - 93
eISSN - 1600-0722
pISSN - 0909-8836
DOI - 10.1111/eos.12101
Subject(s) - masseter muscle , transcranial magnetic stimulation , stimulus (psychology) , silent period , neuroplasticity , medicine , repeated measures design , motor cortex , motor control , muscle contraction , physical medicine and rehabilitation , psychology , stimulation , anatomy , statistics , mathematics , psychiatry , psychotherapist
This study tested the effect of short‐term tooth‐clenching on corticomotor excitability of the masseter muscle using transcranial magnetic stimulation ( TMS ). Fifteen subjects with normal stomatognathic function participated. All subjects performed a tooth‐clenching task ( TCT ) on five consecutive days. The TCT consisted of 10, 20, and 40% of maximum voluntary contraction in a randomized order within 1 h. All subjects underwent TMS in four sessions: pretask day 1 (baseline), post‐task day 1, pretask day 5, and post‐task day 5. Motor‐evoked potentials ( MEP s) from the masseter and the first dorsal interosseous ( FDI ) muscles were obtained using TMS in four sessions. Motor thresholds decreased, after the TCT , for the masseter muscle MEP s. Masseter muscle MEP s were dependent on stimulus intensity and on session, whereas FDI muscle MEP s were only dependent on stimulus intensity. Post‐hoc T ukey tests demonstrated significantly higher masseter muscle MEP s post‐task on day 5 with 80 and 90% stimulus intensity and above when compared with pre‐ and post‐task day 1 values. Our results suggest that the performance of repeated TCT s can trigger neuroplastic changes in the corticomotor control of the jaw‐closing muscles and that such neuroplastic changes may contribute to the mechanism underlying the clinical manifestations of tooth clenching.