Objective: To measure the intensity of muscle strength and electrical activity of masseter and anterior temporal muscles based on BTX-A therapy in patients rehabilitated with total prostheses on zygomatic implants. Material and Methods: The object of the study was a sample of 20 individuals subjected to zygomatic implant surgery and rehabilitated with implant-supported prostheses, in order to obtain electromyographic data using an eight-channel module (EMG System do Brasil). The data were collected for three consecutive months: prior to the application (single dose) of BTX-A (30 U/ masseter muscle; 10 U/temporal muscle) and after 30 and 90 days of therapeutic treatment. Result: All muscle groups studied showed reduction of muscle electrical activity during voluntary contraction after 30 days of treatment (around 47%) (p < 0.001), which progressively reverted after 90 days of treatment. The anterior temporal muscles presented similar motor behavior, with activity reduction of 39% (p < 0.05). There was a reduction of 17.68% (p < 0.05) in mandibular force and an increase of 14.22% (p < 0.05) in mouth opening after 30 days of BTX-A administration. Conclusions: The results suggest that BTX-A significantly reduces muscle activity, in either the recruitment of motor units or muscle tone, in the first three months of therapeutic treatment. This therapy may also be useful as a preventive method for the failure of zygomatic implant-supported prostheses.KeywordsElectromyography; Dental implants; Prostheses on implants; Botulinum toxin.Keywords: Electromyogra phy; Dental implants; Prostheses on implants; Botulinum toxin.

The masticatory function is one of the most complex neuropsychological mechanisms in human motor performance and it depends on several factors, such as bite force, muscle coordination, morphology, and number of teeth in occlusion. Purpose: to evaluate the influence of different rehabilitation treatments such as complete and partial dentures, masticatory forces, and the dynamics of mandibular elevator muscles. Material and Methods: the maximum bite force (force transducer) and electrical activity (superficial electromyography) associated with the masseter and temporal muscles were quantified. These factors were evaluated at rest position and isometric contraction. The data were subjected to descriptive statistics and compared based on the experimental groups, through ANOVA and Tukey’s tests. Results: for bite force, the ANOVA test showed statistical difference between groups and Tukey’s test showed that the force measured in the removable partial dentures group was 44.75% lower than that of the control group, while for complete denture wearers, there was a reduction of 74.4% in bite force in relation to the control group. For electromyographic activity, there was no statistical difference between groups. Pearson’s correlation test (α=5%) showed positive correlation between the variables of bite force and electromyographic activity only for the control group. Conclusion: it was concluded that the loss of dental elements and their replacement with either partial or complete dentures has a great influence on bite force and electromyographic activity of the masseter and temporal muscles.

Objetivo: O objetivo deste estudo foi avaliar os efeitos da irradiação gama simulando uma dose total de radioterapia convencional em câncer de cabeça e pescoço na remodelação óssea e osseointegração de implantes em fêmures de ratos.Materiais e Métodos: Sessenta ratos receberam implantes de titânio rosqueado (Ti6Al4V) em ambos os fêmures. Os animais foram divididos: Sem Irradiação (N-Ir): Grupo N-Ir com implante somente; Irradiação Precoce (E-Ir): implante + irradiação após 24h; Irradiação Tardia (L-Ir): implante + irradiação após 4 semanas e Irradiação Prévia (P-Ir): irradiação + implante após 4 semanas. A irradiação foi fracionada em duas sessões de 15 Gy cada, totalizando 30 Gy. Os animais foram sacrificados aos 3 dias, 2 e 7 semanas após o tratamento. Marcadores imuno-histoquímicos Runx2 e coloração Picrosirius red, análise histomorfométrica (BIC e BAFO) e teste de torque reverso foram utilizados para avaliar a interface implante/osso e osso circundante. Os dados de Runx-2 (%), coloração picrosirius red (%), BIC e BAFO (%) e torque reverso (N/cm) foram submetidos aos testes ANOVA e Tukey para comparação entre grupos, ambos com α=0,05.Resultados: Os resultados mostraram que a expressão de Runx-2 foi diferente nos grupos irradiados quando comparados ao grupo N-Ir. Em geral, as análises de fibras colágenas nos grupos irradiados diferiram do grupo N-Ir. Em relação ao BIC, BAFO e teste de torque reverso, o grupo L-Ir apresentou resultados semelhantes ao grupo N-Ir, enquanto os demais grupos foram prejudicados pela radioterapia.Conclusões: A radiação ionizante afetou negativamente a remodelação óssea, e seu efeito depende de quando a radioterapia é aplicada, com retardo da osseointegração quando aplicada previamente ou próximo à cirurgia.