The effect of age on the function of the masticatory system--an electromyographical analysis.
BACKGROUND
Old age is the last stage of human life and, unfortunately, the ageing rhythm of the oral cavity and masticatory system seems to be rather accelerated. Hence, there is a reduction in the amount of food ingested, establishing the imbalance of nutritional phenomena.


OBJECTIVE
To assure a better quality of life for the elderly, it is necessary to understand their masticatory system.


METHODS
An electromyographical analysis of the masticatory system in 10 individuals aged between 60-75 years (group 1) and 10 between 23-30 years old (group 2) was carried out. The analysis was performed using a MyoSystem-Br1 electromyographer with differential active electrodes. The test was registered during positioning and functional conditions, such as chewing, and the muscles assessed were the temporalis and masseter. Data were normalised by maximum voluntary contraction (MVC), and the results were analysed statistically using independent t-test during the comparison between groups.


RESULTS
Statistical significance (p < or = 0.05) was found in the analysis of various activities, in which the elderly showed greater electromyographical activity values relative to their MVC during the different mandibular positions, such as left laterality. While the elderly subjects revealed values of 30% relative to their MVC, the young revealed 10%. However, during masticatory activities, the elderly revealed values of up to 79%, and the young of 108%, relative to their MVC, such as when they are chewing peanuts.


CONCLUSIONS
It could be concluded that the elderly show hyperactivity of masticatory musculature during posture maintenance and a slight hypoactivity of this musculature during chewing when analysed side by side with young individuals.
Galo
Rodrigo
R
Electromyography Laboratory, Morphology, Stomatology, and Physiology Department, Ribeirão Preto School of Dentistry, São Paulo University, 14040-904 Ribeirão Preto, Brazil.
Vitti
Mathias
M
Santos
Carla Moreto
CM
Hallak
Jaime Eduardo Cecílio
JE
Regalo
Simone Cecílio Hallak
SC
D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000502:physiology; D001732:Bite Force; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008406:Masseter Muscle / Q000502:physiology*; D008409:Mastication / Q000502:physiology*; D008875:Middle Aged; D013703:Temporal Muscle / Q000502:physiology*