Neuromuscular coordination of masticatory muscles in subjects with two types of implant-supported prostheses.
OBJECTIVE
To compare the electromyographic (EMG) characteristics of masticatory muscles in patients with fixed implant-supported prostheses and implant overdentures.


METHODS
Nineteen subjects aged 45-79 years were examined. Fourteen were edentulous and had been successfully rehabilitated with (a) maxillary and mandibular implant-supported fixed prostheses (seven patients); (b) mandibular implant overdentures and maxillary complete dentures (seven patients). Five control subjects had natural dentition or single/partial (no more than two teeth) tooth or implant fixed dentures. Surface EMG of the masseter and temporal muscles was performed during unilateral gum chewing and during maximum teeth clenching. To reduce biological and instrumental noise, all values were standardized as percentage of a maximum clenching on cotton rolls.


RESULTS
During clenching, temporal muscle symmetry was larger in control subjects and fixed implant-supported prosthesis patients than in overdenture patients (analysis of variance, P=0.005). No differences were found in masseter muscle symmetry or in muscular torque. Muscle activities (integrated areas of the EMG potentials over time) were significantly larger in control subjects than in implant-supported prosthesis patients (P=0.014). In both patient groups, a poor neuromuscular coordination during chewing, with altered muscular patterns, and a smaller left-right symmetry than in control subjects were found (P=0.05). No differences in masticatory frequency were found.


CONCLUSIONS
Surface EMG analysis of clenching and chewing showed that fixed implant-supported prostheses and implant overdentures were functionally equivalent. Neuromuscular coordination during chewing was inferior to that found in subjects with natural dentition.
Functional Anatomy Research Center, Laboratorio di Anatomia Funzionale dell'Apparato Stomatognatico, Dipartimento di Anatomia Umana, Facoltà di Medicina e Chirurgia and Facoltà di Scienze Motorie, Università degli Studi di Milano, Italy. farc@unimi.it
Virgilio F
VF
Ferrario
Gianluca M
GM
Tartaglia
Michele
M
Maglione
Massimo
M
Simion
Chiarella
C
Sforza
D000222:Adaptation, Physiological; D000368:Aged; D000704:Analysis of Variance; D001732:Bite Force; D016022:Case-Control Studies; D019094:Dental Prosthesis, Implant-Supported; D003826:Denture, Complete, Lower; D003828:Denture, Overlay; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008409:Mastication / Q000502:physiology*; D008410:Masticatory Muscles / Q000502:physiology*; D008875:Middle Aged; D009119:Muscle Contraction