Effect of occlusion status on the time required for initiation of recovery in response to external disturbances in the standing position.
BACKGROUND
To examine whether occlusion status contributes to improvement of postural balance.


METHODS
Thirty healthy adolescents (15 males and 15 females; mean age, 20.3; standard deviation (SD) 1.6 years) with no equilibrium or stomatognathic function abnormalities were examined. Occlusion is a term meaning "jaw clenching." Occlusion status was evaluated by measuring masseter activity using the EMG system. Balancing ability was evaluated using the EquiTest system, which measures sway of the center of gravity produced by rapid movement of force plates as an external disturbance (three intensity levels). The time required for initiation of recovery after application of the disturbance was calculated by measuring displacement of the center of foot pressure. Data were compared according to occlusion status.


RESULTS
Little difference in latency was observed following a small disturbances; however, the greater the disturbance the shorter the latency with occlusion, while without occlusion, latency increased with increasing disturbance. A statistically significant interaction (P<0.001) between occlusion and external disturbance was also found.


CONCLUSIONS
This study suggested that occlusion contributes to maintenance of postural balance and improvement of stability when unexpected sway occurs in the standing position.
Hosoda
Masataka
M
Department of Rehabilitation Medicine, Tokyo Medical and Dental University Graduate School, 1-5-45 Yushima, 113-8519 Tokyo, Japan. ma-hosoda@ryotokuji-u.ac.jp
Masuda
Tadashi
T
Isozaki
Koji
K
Takayanagi
Kiyomi
K
Sakata
Kiyoshi
K
Takakuda
Kazuo
K
Nitta
Osamu
O
Morita
Sadao
S
D000058:Accidental Falls; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008406:Masseter Muscle / Q000502:physiology; D004856:Postural Balance / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D013997:Time Factors