Neuromuscular Position Research Articles

Overtreatment "Successes"--What Are the Negative Consequences for Patients, Dentists, and the Profession?

To describe how some management practices in the field of orofacial musculoskeletal disorders (also described as temporomandibular disorders [TMDs]) are based on concepts about occlusal relationships, condyle positions, or functional guidance; for some patients, these procedures may be producing successful outcomes in terms of symptom reduction, but in many cases, they can be examples of unnecessary overtreatment. The authors discuss the negative consequences of this type of overtreatment for both doctors and patients, as well as the impact on the dental profession itself. Special focus is given to trying to move the dental profession away from the old mechanical paradigms for treating TMDs and forward to the more modern (and generally more conservative) medically based approaches, with emphasis on the biopsychosocial model. The clinical implications of such a discussion are apparent. For example, it can be argued that the routine use of Phase II dental or surgical treatments for managing most orofacial pain cases represents overtreatment, which cannot be defended on the grounds of symptom improvement (ie, "successful" outcomes) alone. Similarly, there is enough clinical evidence to conclude that complex biomechanical approaches focusing on the search for an ideal specific condylar or neuromuscular position for the management of orofacial musculoskeletal disorders are not needed to produce a positive clinical result that is stable over time. Typically, overtreatment successes cannot be easily perceived by the patients or the treating dentists because the patients are satisfied and the dentists feel good about those outcomes. However, neither party knows whether an excessive amount of treatment has been provided. Therefore, both the practical and ethical aspects of this discussion about proper treatment vs overtreatment deserve attention.

Static mandibular condyle positions studied by MRI and condylar position indicator

We compared mandibular condyle positions as determined by magnetic resonance imaging (MRI) and a mechanical device, the condylar position indicator (CPI). Both methods assessed 3 mandibular positions in 10 asymptomatic males and 10 asymptomatic females, aged 23 to 37 years, free from temporomandibular disorders: maximum intercuspation, bimanually manipulated centric relation, and the unguided neuromuscular position. Bite registrations were obtained for bimanual operator guidance and neuromuscular position. 3 T MRI scans of both temporomandibular joints produced 3D data of the most superior condylar points in all 3 mandibular positions. Using mounted plaster casts and the same bite registrations, an electronic CPI displayed 3D data of its condylar spheres in these positions. The results showed interclass correlation coefficients ranging from 0.03 to 0.66 (95% confidence intervals from 0 to 0.8) and significantly different condyle positions between both methods (p = 0.0012, p < 0.001). The implications of the study emphasize that condyle position is unpredictable and variable. Its exact knowledge requires radiological imaging and should not rely on CPI assessments.

РЕЗУЛЬТАТЫ ПРИМЕНЕНИЯ ОККЛЮЗИОННЫХ ШИН У ПАЦИЕНТОВ С СИНДРОМОМ БОЛЕВОЙ ДИСФУНКЦИИ ВНЧС ПО ДАННЫМ КИНЕЗИОГРАФИИ

Subject. Syndrome of pain dysfunction of the temporomandibular joint is one of the common pathologies of TMJ. Patients with this diagnosis complain of a violation of the movements of the lower jaw, discomfort and pain in the joint. The writings of many authors contain a deep and comprehensive discussion of various aspects of this problem, and scientific justification is given that TMJ dysfunction is almost always accompanied by muscle symptoms. One method of treatment is the use of occlusal splints. In this regard, the task of determining the effectiveness of eliminating muscular-articular dysfunction using individual occlusal splints is relevant.&#x0D; The aim of the study was to determine the effectiveness of treatment of TMJ dysfunction with occlusal splints according to kinesiography.&#x0D; Methodology. The kinesiographic study on the Myotronics K7 apparatus consisted of sequentially performing functional tests (opening and closing the mouth, lower jaw movements to the side) and using the method of percutaneous electroneurostimulation. In the treatment of all patients, an occlusal positioner splint was used, which was made individually in an articulator using an interocclusal register in the neuromuscular position of the lower jaw. The average treatment period was 4.5 months with monthly adjustments to the occlusal splint.&#x0D; Results. As a result of treatment with the use of the occlusal splint, disturbances in the trajectory in the transverse (in 70 % of cases) and sagittal (in 65 % of cases) planes were eliminated, the position of the lower jaw in the neuromuscular position (in 100 % of cases) was normalized.&#x0D; Conclusions. Treatment of patients with TMJ dysfunction using individual occlusal splints is one of the most effective ways to treat this pathology.

Estimated functional space of centric condyle positions in temporomandibular joints of asymptomatic individuals using MRI

Magnetic resonance imaging (MRI) studies on centric condyle positions lack 3D comparisons of guided and unguided methods, which are used for accomplishing centric relation reference positions. The purpose of this study was to describe the space, in which mandibular condyles are placed in vivo by dental intercuspation, Dawson’s bimanual manipulation, and neuromuscular position. Twenty asymptomatic individuals aged 23 to 37 years underwent separate bite registrations using bimanual manipulation and the unguided neuromuscular technique. Subsequent 3-Tesla MRI scans of both temporomandibular joints yielded 3D data of the most superior condylar points at maximum intercuspation and both centric relation positions. We found concentric condyle positions in maximum intercuspation but considerable variation of condyle position after bimanual manipulation and neuromuscular technique. Their 95% predictive confidence ellipses overlapped substantially and created a space of reference positions. Its smallest volume averaged 2 mm3 for a minimal convex hull (95% confidence interval 1.1–3.2) and 3.5 mm3 for a minimal ellipsoid hull (95% confidence interval 1.8–5.4). Visualized in vivo by MRI, condyle positions at bimanual manipulation and neuromuscular position were not predictable and showed substantial variation in asymptomatic subjects. Clinicians should be aware of the functional space and its effect on dental intercuspation.

Electronic central bearing point as registration method in individuals with and without temporomandibular disorders.

The aim of this study was to examine different central bearing point methods in patients with and without temporomandibular disorders (TMD) by an experienced and unexperienced examiner. The 20 fully dentulous subjects were screened for TMD based on the Research Diagnostic Criteria for TMD and distinguished into functional impaired and functional healthy groups. The mandibular relationship was recorded by an electronic central bearing tracing device (IPR-System, IPR GmbH, Oldenburg, Germany) with an integrated pressure sensor. Three bite registration methods were performed using this device: initial neuromuscular position, final neuromuscular position after dynamic sequences with the intraoral pin (=neuromuscular deprogramming), and centric relation guided manually by an experienced and an unexperienced examiner. The neuromuscular positions before and after neuromuscular deprogramming were not significantly different (paired t test as a group comparison test: transverse: p=0.369; sagittal: p=0.486). Both positions were significantly anterior in comparison to the manually guided centric relation (paired t test as a group comparison test: p<0.0001). The neuromuscular positions before and after deprogramming tend to have high scattering values. By means of the central bearing point method, the manually guided centric relation is the one which is sufficiently reproducible. It seems doubtful to take the significant anterior neuromuscular position for a definite reconstruction. Using the central bearing point method, the manually guided centric relation should be preferred, whereas the neuromuscular position should not be used for definite reconstructions.

Acute Respiratory Distress Syndrome (ARDS) in Preterm Infants withSevere Fetal Anemia: 2 Case Reports and Review of Literature

Background: Acute Respiratory Distress Syndrome (ARDS) is an entity not well recognized in the NICU and possibly mis-classified as severe RDS. Case report: We report two premature infants severely hypoxic at birth refractory to usual treatment of RDS who responded to neuromuscular blockade and prone position which have been proven to be effective in adult and child ARDS. Conclusion: A consensus definition, as well as criteria for the diagnosis of ARDS in the neonatal population is needed. A standard definition would allow comparisons to the adult and pediatric literature, as well as furthering research on the pathophysiology, epidemiology and effective management of ARDS in the neonatal population

Neuromuscular Orthotics in the Treatment of Craniomandibular Dysfunction and the Effects on Patients with Multiple Sclerosis: A Pilot Study

The purpose of this pilot study was to identify, measure and document an effect on the subjective multiple sclerosis symptoms and compare it to any objective data changes in the neuromuscular system of the head and neck, following the correction of the jaw position using a neuromuscular orthotic. The hope is to provide clinical evidence of improvement in the disease long-term without relying on the subjective evidence of remissions and exacerbations reported by the patient. The evidence found in the current pilot study measured improvement of head position, jaw position, jaw function, and airway in the neuromuscular bite position, which correlated with the improvement of subjective symptoms of craniomandibular dysfunction and multiple sclerosis. Studies show that the bite affects blood flow in the brain, which may explain the improvement of the patients in the current study.

Ocular microtremor during general anesthesia: results of a multicenter trial using automated signal analysis.

Ocular microtremor (OMT) is a fine physiologic tremor of the eye related to neuronal activity in the reticular formation of the brainstem. The frequency of OMT is suppressed by propofol and sevoflurane and predicts the response to command at emergence from anesthesia. Previous studies have relied on post hoc computer analysis of OMT wave forms or on real-time measurements confirmed visually on an oscilloscope. Our overall aim was to evaluate an automated system of OMT signal analysis in a diverse patient population undergoing general anesthesia. In a multicenter trial involving four centers in three countries, we examined the accuracy of OMT to identify the unconscious state and to predict movement in response to airway instrumentation and surgical stimulation. We also tested the effects of neuromuscular blockade and patient position on OMT. We measured OMT continuously by using the closed-eye piezoelectric technique in 214 patients undergoing extracranial surgery with general anesthesia using a variety of anesthetics. OMT decreased at induction in all patients, increased transiently in response to surgical incision or airway instrumentation, and increased at emergence. The frequency of OMT predicted movement in response to laryngeal mask airway insertion and response to command at emergence. Neuromuscular blockade did not affect the frequency of OMT but decreased its amplitude. OMT frequency was unaffected by changes in patient position. We conclude that OMT, measured by an automated signal analysis module, accurately determines the anesthetic state in surgical patients, even during profound neuromuscular blockade and after changes in patient position.

A Revised View of the Dynamics, Physiology, and Treatment of Occlusion: A New Paradigm

A new perspective is proposed regarding the functional dynamics of occlusion, the masticatory muscles, and mandibular placement. Each is analyzed on the basis of a new criterion: force. Stomatognathic function is represented as an ongoing equilibrium maintained between the three-dimensional set of individual occlusal forces and the three-dimensional set of bilateral muscle forces. Mandibular placement is of prime importance, mediating as it does between the two. The conclusion is drawn that occlusion and the muscles can correlate optimally with each other only when the mandible occupies its neuromuscular position (NMP), herein defined as that placement where muscle accommodation is at its absolute minimum. The conclusion is that only the muscles themselves are capable of establishing the NMP and that customary conventional technology is inadequate. A new technology, hydrostatics, is needed to create the special (not existing naturally) occlusal conditions essential to optimally integrating occlusion, mandibular placement, and muscles. Preliminary EMG data is offered in support of this conclusion.

What do we learn from motor unit action potentials in surface electromyography?

This article gives an overview of what multichannel surface electromyography can teach us about a motor unit. Background information is given about the generation of surface electromyography in general and surface motor unit potentials in particular. Furthermore, we describe how surface motor unit potentials are related to several motor unit characteristics, such as size, location, neuromuscular junction position, fiber length, fiber type, and metabolic fiber properties. In addition, we show how the spatial characteristics of multichannel surface electromyography can be used to obtain single-surface motor unit potentials. The possibilities, challenges, and problems are discussed. Finally, several examples of surface motor unit potential analyses are given.

The effect of different condylar positions on masticatory muscle electromyographic activity in humans

Objectives. The purpose of this study was to determine a condylar position that permitted the greatest total temporalis and masseter muscle activity in maximum static clench. Study Design. Twenty normal adults, 9 women and 11 men, were evaluated to determine masseter and temporalis activity in maximum static clench with mandibular condyles in different therapeutic positions. Bimanually manipulated, leaf gauge, centric occlusion, and neuromuscular condylar positions were studied. Results. When mandibular condyles were placed anteroinferiorly in a neuromuscular position, total masticatory muscle recruitment was the greatest. In a bimanually manipulated or a leaf gauge position, mandibular condyles were positioned superoposteriorly, producing the least amount of muscle recruitment. Conclusions. The result of any therapeutic position should be an improvement in muscle function. With respect to balance and activation, a neuromuscular condylar position proved to be the position capable of recruiting the greatest motor unit activity when compared with a bimanually manipulated position, a leaf gauge position, and a neuromuscular position.

Clinical study of location and reproducibility of three mandibular positions in relation to body posture and muscle function

Clinical studies have confirmed the adequate reproducibility of both centric occlusion and centric relation when used as reference positions during treatment; however, the reproducibility of the neuromuscular position has been found inadequate. This study evaluated the location and reproducibility of these three mandibular positions in relation to body posture, sitting and supine, and bilateral muscle activity before and after the insertion of a flat mandibular positioning device equilibrated to balance the muscle functions, as shown by two electromyography biofeedback instruments. Intraoral recordings were made in 11 young subjects with complete natural dentition. Acrylic resin clutches that supported a screw point in the maxillary arch and painted glass in the mandibular arch were used and positioned not to interfere with the occlusion. The distances of the screw scratch from two of the edges of the painted glass were used to measure the anteroposterior and mediolateral locations with a micrometer. The reproducibility was evaluated by measuring the scratch surface by measuring the weight of the print cutouts made from photographs of the scratches taken with a stereoscope. The location and reproducibility of centric occlusion and centric relation were not affected by body posture. A more precise posterior neuromuscular position was obtained in the supine position. The insertion of a mandibular positioning device did not affect centric occlusion but gave a more precise centric relation. Neuromuscular position became as precise as centric occlusion and was located anteroposteriorly between centric occlusion and centric relation.

Fabrication of a Maxillary Complete Denture Utilizing the Neuromuscular or Centric Occlusion Position

The patient was unable to wear a maxillary complete denture that had been made from a verifiable record in the centric jaw relation position or terminal hinge position. When she brought her teeth together, only a few touched. Clinical examination showed that this patient had a discrepancy of approximately 3 mm anteroposteriorly and a discrepancy of 1 mm mediolaterally between the terminal hinge position and the centric occlusion or neuromuscular position. A new denture was made for the patient. The neuromuscular position was used as the starting position and as the position of maximum intercuspation (centric occlusion), and the terminal hinge position was used as a mounted border position of reference for occlusal adjustment and equilibration.

An evaluation of terminal hinge position and neuromuscular position in edentulous patients. Part II. Duplicate mandibular dentures

The purpose of Part II of this study was to determine whether or not a denture fabricated to the neuromuscular position (NMP) could be as functional as one fabricated to the terminal hinge position (THP). Two mandibular dentures were fabricated for each of six edentulous subjects, one to the THP and one to the NMP, along with only one maxillary denture each. The subjects had no prior knowledge of the two mandibular dentures in order to determine the clinical significance of a difference in the two positions. These results were evaluated by clinical methods. It was concluded that the NMP is clinically acceptable for intercuspation of artificial teeth on complete dentures.

An evaluation of terminal hinge position and neuromuscular position in edentulous patients. Part I. Maxillomandibular recordings

The purpose of this investigation was to obtain information about the terminal hinge position (THP) and the neuromuscular position (NMP) in the edentulous population. The difference between the two positions was evaluated anteroposteriorly and mediolaterally to determine horizontal differences and reproducibility between days. In 25 edentulous subjects, five recordings were made at the neuromuscular position with no dentist guidance and five recordings at the terminal hinge position with dentist guidance; on a second day, the recordings were repeated. The differences between positions were evaluated by statistical methods. It was concluded that: (1) there is a discrepancy between the THP and the NMP for all edentulous subjects examined, (2) the NMP is anterior and medial or lateral to the THP, and (3) the NMP is not as reproducible as the THP.