Modulation of mastication during experimental loosening of complete dentures.
OBJECTIVE
Suction is achieved when complete dentures are first fitted, but it fades during the months following insertion, when it is increasingly complemented by muscular denture control. The aim of this study was therefore to investigate the extent to which patterns of mastication are altered by experimental failure of physical retention.


METHODS
Seven edentulous volunteers had maxillary replica dentures made, with fine tubes incorporated so that alternating positive and negative air pressure could be generated under the fitting surface. Mandibular movements, EMG, and pressure under the denture base were recorded during unilateral chewing.


RESULTS
The change of physical retention passed undetected by all subjects; they continued chewing apparently undisturbed. However, during air injection, the mandibular excursions were slightly slower (nonsignificant) and demonstrated a reduced variance (P < or = .05). The muscle activity showed significantly longer bursts (P < or = .05), and peak activity occurred later in the cycle (nonsignificant).


CONCLUSIONS
Sudden failure of denture retention seems to initiate an immediate and effective modulation of centrally generated muscular activity patterns.
Müller
Frauke
F
Department of Adult Oral Health, St Bartholomew's and the Royal London School of Medicine and Dentistry, London. fmueller@mail.uni-mainz.de
Heath
M Robin
MR
Ferman
Anthony M
AM
Davis
Graham R
GR
D000368:Aged; D000399:Air Pressure; D003819:Denture Bases; D003779:Denture Design; D003781:Denture Retention; D003824:Denture, Complete; D003827:Denture, Complete, Upper; D004576:Electromyography; D006801:Humans; D008334:Mandible / Q000502:physiology; D008406:Masseter Muscle / Q000502:physiology; D008409:Mastication / Q000502:physiology*; D016555:Matched-Pair Analysis; D008875:Middle Aged; D009068:Movement; D012815:Signal Processing, Computer-Assisted; D013223:Statistics as Topic; D018709:Statistics, Nonparametric; D013499:Surface Properties; D013703:Temporal Muscle / Q000502:physiology; D013997:Time Factors; D014159:Transducers