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Title:

Electromyographic evaluation of implant-supported prostheses in hemimandibulectomy-reconstructed patients

 

Objectives:

To assess the clinical conditions, patient’s satisfaction and functional outcomes in oral neoplasia patients with hemimandibulectomy, bone reconstruction and implant- supported prosthesis.

 

Material and methods:

Twelve patients after mandibular resection (with and without condyle), reconstruction and successful fixed implant-supported prosthesis rehabilitation were examined. Patients underwent clinical evaluation and filled in a questionnaire about their satisfaction toward oral functions. Surface electromyography (EMG) of the masticatory muscles was performed during a 15-s unilateral gum chewing test. EMG potentials were standardized as percentage of a maximum clench on cotton rolls and compared with reference data obtained from 20 healthy subjects.

 

Results:

Excellent clinical and radiological parameters were found. Patients stated a decreased post-rehabilitation satisfaction toward mastication and phonetics, but an increased attention to oral care. Only patients with condylar resection reported augmented esthetic scores. In both the resected and the remaining sides, chewing frequency was higher in the patients than in the reference group. Pooled muscle activities (sum of the integrated areas of the EMG potentials over time) were larger in patients than in control subjects, particularly in the non-operated side. The percentage contribution of working-side muscular activity in the operated side was similar to reference values, but significantly inferior in the opposite side. The patterns of muscle contraction during unilateral chewing were more variable in the reconstructed patients than in control subjects; the difference was significant only in the non-operated side.

 

Conclusion:

Post-rehabilitation median scores of the questionnaire indicated a positive judgment of the treatment. EMG analysis showed that functional recovery in hemimandibulectomy patients was satisfactory, although some alterations were observed in the non-operated side of mastication.

 

Practical tip

The analysis of the involvement of the masticatory muscles in a dynamic chewing act occurs during a 4-channel examination and provides for the introduction of two one-sided chewing tests after the maximum voluntary contraction examination on the cotton rolls. Specifically, it is necessary to explain to the patient that he will be asked to chew a chwingum (a bolus that is not consumed over time) on one side of the mouth for a period of 15 seconds, and then on the opposite side for 15 seconds too. When performing this movement, make sure that the patient is kept upright and the shoulders still.