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 (Wilcoxon's rank-sum test, P<0.001). 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 (P=0.001). The percentage contribution of working-side muscular activity in the operated side was similar to reference values, but significantly inferior in the opposite side (P<0.001). 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 (P<0.01). 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.