Highlights We examined reorganization of masticatory muscle activity in chronic TMD patients. A functional index of EMG for maximal clenching and gum chewing was introduced. TMD patients have reduced cooperation and coordination between masticatory muscles. TMD patients recruited the balancing side more than the control group. Worse functional index was associated with more severe symptomatology. AbstractObjective To investigate whether reorganization of muscle activity occurs in patients with chronic temporomandibular disorders (TMD) and, if so, how it is affected by symptomatology severity.Methods Surface electromyography (sEMG) of masticatory muscles was made in 30 chronic TMD patients, diagnosed with disc displacement with reduction (DDR) and pain. Two 15-patient subgroups, with moderate (TMDmo) and severe (TMDse) signs and symptoms, were compared with a control group of 15 healthy subjects matched by age. The experimental tasks were: a 5s inter-arch maximum voluntary clench (MVC); right and left 15s unilateral gum chewing tests. Standardized sEMG indices characterizing masseter and temporalis muscles activity were calculated, and a comprehensive functional index (FI) was introduced to quantitatively summarize subjects' overall performance. Mastication was also clinically evaluated.Results During MVC, TMDse patients had a significantly larger asymmetry of temporalis muscles contraction. Both TMD groups showed reduced coordination 3 between masseter and temporalis muscles' maximal contraction, and their muscular activity distribution shifted significantly from masseter to temporalis muscles. During chewing, TMDse patients recruited the balancing side muscles proportionally more than controls, specifically the masseter muscle. When comparing right and left side chewing, the muscles' recruitment pattern resulted less symmetric in TMD patients, especially in TMDse. Overall, the functional index of both TMDmo and TMDse patients was significantly lower than that obtained by controls.Conclusions Chronic TMD patients, specifically those with severe symptomatology, showed a reorganized activity, mainly resulting in worse functional performances.

The measurement of tongue strength contributes to the study of oro-facial physiology. The objective of this study was to investigate the influence of gender on tongue strength in young adults and to determine the differences in this strength between tongue regions. This study was conducted on 50 healthy volunteers (17 men and 33 women) with a mean age of 23 years, with no oro-facial myofunctional alterations. The strength of the anterior portion and of the dorsum of the tongue was analysed with a calibrated electronic dynamometer. The subjects were asked to apply maximum force. Men showed higher tongue strength values than women both in the anterior portion and in the dorsum of the tongue (P<0·05), and the strength of the anterior portion of the tongue was lower than that of the dorsum in both genders (P<0·05). We conclude that gender and region influenced tongue strength.

The objective of this study was to determine whether dentofacial deformities (class II and class III) influence maximum isometric tongue strength compared with a group without deformities. A total of 126 adult patients participated in the study. Of these, 45 had a class II diagnosis (14 men and 31 women) and 81 a class III diagnosis (35 men and 46 women), all of them with indication of orthognathic surgery. Fifty adult volunteers (17 men and 33 women) with no changes in dental occlusion (class I) and with no clinical signs of dysfunction of the temporomandibular joint represented the control group. Tongue strength (in N) was measured with a dynamometer. The maximum strength of the anterior portion was determined with the instrument positioned on the retroincisor region and the maximum strength of the dorsum with the instrument positioned in the region of the hard palate. Data were analysed statistically by analysis of variance (anova) and by the Pearson correlation test. No significant difference (P > 0·05) in tongue strength in the anterior or dorsal region was observed between the groups with dentofacial deformities or between these groups and the control. The tongue strength of the anterior and dorsal regions was not influenced by the dentofacial deformity.

Purpose: To present the measures for tongue pressure in Brazilian young adults, considering specific tasks, and to verify the differences regarding gender and according to the tasks. Methods: Fifty-one volunteers aged 18 to 28 years, of both genders with normal occlusion and without speech disorders were evaluated. We used the Iowa Oral Performance Instrument in the evaluation of tongue pressure (kilopascal) during specific tests of elevation, protrusion, swallowing, and lateralization, in addition to the endurance test (seconds). The analysis was conducted using analysis of variance, followed by the Tukey's multiple comparison test, adopting a 5% men compared with women for the protrusion and lateralization tasks. The measures of the protrusion and elevation tasks did not differ for men but were higher in both genders than those of the lateralization and the swallowing tests. There was no difference in lateralization according to side in both the genders. Conclusion:The measures for the tongue pressure in Brazilian young adults were determined by specific tasks. Gender influenced the pressure of the tongue values for the protrusion and lateralization tasks. Elevation and protrusion tasks measures were higher than those of the lateralization and swallowing tasks. RESUMOObjetivo: Apresentar valores para a pressão da língua em adultos jovens brasileiros, considerando provas específicas e possíveis diferenças quanto ao gênero e tipo de prova. Método: Foram avaliados 51 voluntários de 18 a 28 anos, ambos os gêneros, com boa relação dento-oclusal e sem alterações de fala. Utilizou-se o Iowa Oral Performance Instrument na avaliação da pressão da língua (Kilopascal) durante as provas de elevação, protrusão, deglutição e lateralização, além do teste de resistência (segundos). Na análise dos resultados foi utilizado o ANOVA, seguido do teste de comparações múltiplas Tukey, adotando o nível de significância de 5%. Resultados:Os valores obtidos, respectivamente para homens e mulheres, na prova de elevação foram 63,94±12,92 e 50,27±15,29, na protrusão 60,22±13,62 e 44,30±12,95, na deglutição 33,94±12,06 e 34,27±13,25, na lateralização à direita 44,15±10,47 e 31,85±8,46, na lateralização à esquerda 43,15±10,22 e 29,55±8,91, e no teste de resistência 24,85±10,95 e 17,35±6,71. Os homens apresentaram valor maior nas provas de protrusão e de lateralização; os valores das provas de protrusão e elevação não diferiram entre si para o gênero masculino, mas foram maiores que a lateralização e a deglutição em ambos os gêneros; não houve diferença na prova de lateralização em relação ao lado em ambos os gêneros. Conclusão: Valores de pressão da língua em adultos jovens brasileiros foram determinados para provas específicas; o gênero influenciou nos valores das provas de protrusão e lateralização; os valores obtidos nas provas de elevação e protrusão foram maiores que na lateralização e deglutição.

Introduction:The bite force is influenced by the occlusal condition. In children with posterior crossbite the results are controversial. Purpose: To investigate the influence of posterior crossbite in maximal isometric bite force (MIBF) in children with mixed dentition. Methods: In this cross-sectional study, 32 children participated, 21 of them belonging to the posterior cross-bite group (10 girls and 11 boys, mean age 9.2 years) and 11 to the control group (6 girls, 5 boys, mean age 9.3 years). The children were evaluated by an orthodontist for occlusal diagnosis and characterization of the groups, by otorhinolaryngologists for evaluation of respiratory symptoms and by a speech therapist to identify the clinical and MIBF myofunctional orofacial condition. The dynamometer was placed in the molar region and the children were instructed to bite it as hard as possible three times alternately. For data analysis, Student's t-test for independent samples was used. The level of significance was set at 5%. Results: While comparing the groups crossbite vs. control, there was no significantly difference; also, among only children belonging to the crossbite group, there was no difference between the sides (crossed bite vs. Noncrossed one). Conclusion: The presence of posterior crossbite did not influence the maximal isometric bite force in children with mixed dentition.