Electromyographic study of activity of the masseter and anterior temporalis muscles in patients with temporomandibular joint (TMJ) dysfunction: comparison with the clinical dysfunction index.

OBJECTIVES: A comparison was made between the electromyographic patterns specific to patient with temporomandibular disorders and that of normal healthy patients. STUDY DESIGN: Electromyographic tests were carried out during rest and function of the masseter muscles and anterior temporalis muscles in a homogeneous group consisting of 95 patients for whom such pathology and its different degree of severity had been previously studied by means of a Helkimo Test. The electromyographic exploration results were compared to those of a control group consisting of 31 healthy subjects. RESULTS: There were significant differences among patients with a different degree of clinical dysfunction, as well as between these and the control group. These differences were more important during maximum effort clenching and mastication. During maximum effort clenching, differences in masseteric activity were observed between control group and group III, between groups I and II and between groups I and III. Meanwhile, differences in temporalis activity were significant among all groups except between groups I and II. The multiple comparison analysis demonstrated the existence of significant statistical differences between healthy subjects and patients with severe TMD. However, the linear combination of these electromyographic (EMG) variables led us to elaborate four linear functions that classify all subjects into four well defined groups. Once extreme cases were eliminated, our EMG classification revealed an 80% match with that of the Helkimo Test. We thus conclude that in many cases, classification using electromyographic criteria matches that established by the Helkimo Test.

Electromyographic comparisons between clenching, swallowing and chewing in jaw muscles with varying occlusal parameters.

UNLABELLED: The aim of this study is to determine the influence of Angle molar class, presence of a posterior crossbite, anterior guidance, as well as gender in the muscular activity of the masticatory system in a population of healthy dental students. STUDY DESIGN: Surface electromyography recordings are made for the masseter, anterior and posterior temporalis and digastric muscles; in three different tests: clenching at maximum intercuspation, swallowing and chewing. RESULTS: The results obtained show that: men achieve a higher masseter activity at maximum effort than women. Women achieve higher values than men, for the digastric muscles in deglution. Angle class II show higher activity than other classes for the temporalis muscle in deglution, while class III show higher activity than other classes for all muscles in maximum effort. The anterior guidance does not cause significant differences. The presence of a posterior crossbite affects the behaviour of anterior temporalis and masseter muscles. CONCLUSION: The results of this study show the influence of the occlusal parameters on the muscular activity of the stomatognatic system.

Consistent patterns of variation in macrobenthic assemblages and environmental variables over multiple spatial scales using taxonomic and functional approaches.

Spatial variability of environmental factors and macrobenthos, using species and functional groups, was examined over the same scales (100s of cm to >100 km) in intertidal sediments of two transitional water systems. The objectives were to test if functional groups were a good species surrogate and explore the relationship between environmental variables and macrobenthos. Environmental variables, diversity and the multivariate assemblage structure showed the highest variability at the scale of 10s of km. However, abundance was more variable at 10s of m. Consistent patterns were achieved using species and functional groups therefore, these may be a good species surrogate. Total carbon, salinity and silt/clay were the strongest correlated with macrobenthic assemblages. Results are valuable for design and interpretation of future monitoring programs including detection of anthropogenic disturbances in transitional systems and propose improvements in environmental variable sampling to refine the assessment of their relationship with biological data across spatial scales.

Electromyographic study of activity of the masseter and anterior temporalismuscles in patients with temporomandibular joint (TMJ) dysfuction: Comparison with the clinical dysfunction index

Objectives: A comparison was made between the electromyographic patterns specific to patient with temporomandibulardisorders and that of normal healthy patients. Study design: Electromyographic tests were carriedout during rest and function of the masseter muscles and anterior temporalis muscles in a homogeneous groupconsisting of 95 patients for whom such pathology and its different degree of severity had been previously studiedby means of a Helkimo Test. The electromyographic exploration results were compared to those of a controlgroup consisting of 31 healthy subjects. Results: There were significant differences among patients with a differentdegree of clinical dysfunction, as well as between these and the control group. These differences were moreimportant during maximum effort clenching and mastication. During maximum effort clenching, differences inmasseteric activity were observed between control group and group III, between groups I and II and betweengroups I and III. Meanwhile, differences in temporalis activity were significant among all groups except betweengroups I and II. The multiple comparison analysis demonstrated the existence of significant statistical differencesbetween healthy subjects and patients with severe TMD. However, the linear combination of these electromyographic(EMG) variables led us to elaborate four linear functions that classify all subjects into four well definedgroups. Once extreme cases were eliminated, our EMG classification revealed an 80% match with that of theHelkimo Test. We thus conclude that in many cases, classification using electromyographic criteria matches thatestablished by the Helkimo Test (AU)

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Electromyographic comparisons between clenching, swallowing and chewing in jaw muscles with varying occlusal parameters

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The aim of this study is to determine the influence of Angle molar class, presence of a posterior crossbite, anterior guidance, as well as gender in the muscular activity of the masticatory system in a population of healthy dental students.Study design: Surface electromyography recordings are made for the masseter, anterior and posterior temporalis and digastric muscles; in three different tests: clenching at maximum intercuspation, swallowing and chewing.Results: The results obtained show that: men achieve a higher masseter activity at maximum effort than women.Women achieve higher values than men, for the digastric muscles in deglution. Angle class II show higher activitythan other classes for the temporalis muscle in deglution, while class III show higher activity than other classes for all muscles in maximum effort. The anterior guidance does not cause significant differences. The presence of a posterior crossbite affects the behaviour of anterior temporalis and masseter muscles.Conclusion: The results of this study show the influence of the occlusal parameters on the muscular activity of the stomatognatic system (AU)