Journal of Craniomandibular Function, 02/2013

Occlusal dysfunctions are considered as a risk factor for orofacial parafunctional activity. It is assumed that occlusal disorders intensify the normal activation of the masticatory musculature, which has been observed as a response to stressors. In order to verify this hypothesis, test subjects with and without occlusal dysfunctions were compared under stress conditions with regard to their masseter muscle activity and further psychophysiological stress indicators. Out of 168 students of dentistry, 25 test subjects were each selected for the risk group (test subjects with occlusal dysfunctions) and the control group (test subjects without occlusal dysfunctions). The test subjects showed no acute symptoms of pain or dysfunction, and no such symptoms were known from their respective case histories. After a period of rest, the test subjects performed a mental arithmetic test (MAT), with a subsequent phase of recovery. The activity of the masticatory and frontalis musculature, skin conductivity and pulse frequency were recorded. Thetest subjects answered questionnaires on mood, personality variables and habitual stress management. The groups showed no differences either in the rest phase, the MAT phase or the recovery phase with regard to the medium activation level of the masseter muscle. With regard to the MAT phase, however, the masseter muscle activity of the control group was found to decrease, whereas the test subjects with occlusal disorders even showed a tendential increase. We interpreted this as an indication that occlusal dysfunctions can play the role of "latent dysfunctional factors" within the context of the aetiology of orofacial myoarthropathic disorders. Keywords: Occlusal dysfunction, bruxism, TMD aetiology, stress responses, stress induction, electromyogram, skin conductivity, cardiac frequency, dimensions of personality

The aim of this article was to investigate how reduced vertical dimension (RVD) potentially affects the projection of the body's center of gravity (COP). Twelve subjects were treated with a properly fitting full denture in correct jaw relation and a duplicate test prosthesis, with a vertical dimension reduced by 7 mm, fabricated for each individual. Posturography was performed on standing subjects using the Zebris Pressure Distribution Measurement System. The subjects maintained random maximum clenching phases (15 s) under EMG monitoring of the masseter muscles. The effect of clenching on COP was documented in randomized order. Clenching was tested in correct maximum occlusion and significant RVD. Posturography was performed with the subjects' eyes open and closed. A statistically significant effect of clenching on COP with an RVD by 7 mm was only proven in the anteroposterior direction during clenching with eyes closed. Marked RVD can change the tone and/or posture of musculoskeletal organs outside the stomatognathic system; initial causality suggests a descending cause-and-effect chain. The experimentally induced effects were weak and only manifest when visual balance control was absent. Keywords: body's center of gravity, body posture, occlusion, posturography, vertical dimension

Digital articulation provides a possibility of overcoming the limitations of mechanical models. With the help of electronic measuring systems such as the Jaw Motion Analyzer, masticatory movements can be traced even while force is applied and the movement patterns can be displayed in a digital articulator. Thus, real chewing movements can be assessed, which could be of advantage in the future for the computer-assisted creation of restorations that will be more and more customized. New approaches for visualization will be possible that will not only enable the display of the contact points, but also deliver extensive data on the occlusal space during closing movements or the changes of the interocclusal distance in function.The occlusal surfaces of the mandibular and maxillary dental arches were digitalized using a 3D scanner, and real mandibular movements were recorded with the ultrasonic measuring system Jaw Motion Analyzer. A coupling component designed for clinical use in the patient's mouth was utilized for precise referencing of the movement and scan data. The aim was to visualize the jaws during mastication. To analyze intercuspation, the system generates dynamic images, on which closing movements/dynamic occlusion and contact areas are highlighted. The mandibular motion could also be used to create an envelope surface to reproduce the maximum possible spatial expansion of the mandibular motion tracings. Such an envelope surface is a type of virtual functionally generated path (FGP) bite registration. It can be applied to design virtual occlusal surfaces and it enables the ability to quantify the occlusal space firmly, while considering the variability of occlusal function. Early results will be presented and illustrated with a case study. Keywords: digital dental articulator, dynamic occlusion, functional bite registration, functionally generated path, jaw motion, occlusal contacts, occlusion, variability, virtual FGP, virtual occlusion

Orofacial pain occurs in a wide variety of disorders and dysfunctions of the craniomandibular system. Their treatment requires careful clarification by way of differential diagnosis. This paper describes the case of a female patient suffering from facial pain following a parotidectomy for the removal of a pleomorphic adenoma. Analgesic therapy with pregabalin, performed on account of the suspected diagnosis of "neuropathy," did not result in any significant reduction of pain. With the aid of diagnostic filters used in pain psychology, the pain-related impairment of mood and physical well-being were determined. This showed that psychosocial factors played a tendentially more minor role in the continuance of symptoms. In addition to the psychosocial diagnostic filters, a corresponding clinical examination was performed. This resulted in a series of somatic findings, which were classified as temporomandibular dysfunctions. Through the restoration of the lost support areas, the remedying of occlusal dysfunctions and the relief of the affected tissue was gained, continuous improvement of symptoms was achieved, and ongoing freedom from pain obtained. Keywords: diagnostic filters in pain psychology, pleomorphic adenoma, pain chronification, pain therapy, occlusal therapy, interdisciplinary treatment