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PubMed2004

Signs of temporomandibular disorders in tinnitus patients and in a population-based group of volunteers: results of the Study of Health in Pomerania.

The literature has documented a controversial discussion on the possible relationship of otogenous symptoms and craniomandibular dysfunction since the 1920s. Therefore, an investigation was conducted which consisted of two parts: a case study with population-based controls and a cross-sectional study. The aim of the first study was to screen a group of patients suffering from acute or chronic tinnitus for temporomandibular disorders (TMD) in comparison with a population-based group of volunteers without tinnitus. To this end, 30 patients (13 females and 17 males, age 18-71 years) suffering from acute hearing loss associated with tinnitus, isolated acute tinnitus, and chronically transient tinnitus were examined for symptoms of craniomandibular dysfunction. The results were compared with those of clinical functional analysis from 1907 subjects selected representatively and according to age distribution from the epidemiological 'Study of Health in Pomerania' (SHIP); the occurrence of tinnitus was ruled out in these control subjects. Statistical analysis was performed with Chi-square and Mann-Whitney U-tests. Sixty per cent of the tinnitus patients and 36.5% of the control subjects exhibited more than two symptoms of TMD (P = 0.004). Tinnitus patients had significantly more muscle palpation pain (P < 0.001), temporomandibular joint (TMJ) palpation pain (P < 0.001), and pain upon mouth opening (P < 0.001) than the general population group. No statistical differences were found in TMJ sounds, limitation of mandibular movement, or hypermobility of the TMJ. Furthermore, 4228 subjects of the population group examined in the epidemiological study were screened for co-factors of tinnitus with the help of a multivariate logistic regression model which was adjusted for gender, age, and a variety of anamnestic and examined data. Increased odds ratios (OR) were found for tenderness of the masticatory muscles (OR = 1.6 for one to three painful muscles and OR = 2.53 for four or more painful muscles), TMJ tenderness to dorsal cranial compression (OR = 2.99), listlessness (OR = 2.0) and frequent headache (OR = 1.84) A relationship between tinnitus and TMD was established in both examinations. Tinnitus patients seem to suffer especially from myofascial and TMJ pain. A screening for TMD should be included in the diagnostic survey for tinnitus patients.

Acute Disease↗
PubMed1999

Effect of masticatory function on the internal bone structure in the mandible of the growing rat.

The influence of changes in the masticatory function on bone mass, bone density and cortical thickness was analyzed in different functional units of the mandible of the growing rat. Young male albino rats were fed either a hard diet or a soft diet for 4 wk. Undecalcified coronal sections were selected from five mandibular regions and microradiographic images of the specimens alongside an aluminium stepwedge were obtained. Bone mass and density were measured at selected sites with a computer-aided image analysis system. Cortical thickness was measured on diagrams. The reduced masticatory function in the soft diet group produced different adaptive responses in the tested regions of the mandible. Some regions showed reduced cortical thickness (underneath the incisor and lateral to the first molar and some locations of the ramus), a few showed reduced bone density (medial to the first molar and in the ramus), and only one showed both (in the ramus). Reduced bone mass was associated mostly with thinner cortical bone rather than lower cortical bone density. Changes in cortical thickness and changes in bone density may be two different mechanisms for adjusting local mechanical properties in the mandible of the rat. Masticatory muscle function is a determinant for the amount and density of cortical and trabecular bone and may possibly influence results of orthodontic tooth movement and its possible relapse.

Absorptiometry, Photon↗
PubMed1985

[Topography of the infratemporal fossa in the newborn infant].

We compared in our investigations the shape and extent of the infratemporal fossa in newborn, children, and adult specimen. By macroscopical preparation we watched the course of the branches of the mandibular nerve and the maxillary artery and their relations to the masticatory muscles. For identifying of arterial and venous blood vessels the external carotid artery was injected with black ink. In the newborn a fibrous membrane was found coating the internal aspect of the mandibular ramus. The membrane is absent in adults.

Blood Vessels↗
PubMed1993

The incidence of TMJ dysfunction in patients who have suffered a cervical whiplash injury following a traffic accident.

Forty consecutive patients with a cervical whiplash injury were examined and compared with 40 matched controls. The incidence of signs and symptoms was high in both groups. Temporomandibular joint pain (P < .001), limitation of mouth opening (P < .01), and masticatory muscle tenderness (P > .01) were found significantly more frequently in the patient group, while the presence of joint sounds, deviation during mouth opening, and the overall presence of a symptom were not significantly different between groups. When asked whether they would seek treatment for the observed signs and symptoms, a significantly higher number of the whiplash group responded positively when compared to the control group. These findings warrant further study and suggest the benefit of a routine examination of the temporomandibular joint and masticatory system in patients with cervical whiplash injury.

Accidents, Traffic↗
PubMed2001

Activity of jaw-opening and jaw-closing muscles and their influence on dentofacial morphological features in normal adults.

The purpose of this study was to determine the relationship between the dentofacial morphology and the function of masticatory muscles estimated by kinesiological measurements during isotonic jaw-opening (O) and closing (C) muscle contractions. We examined 26 male adult subjects who had no history of masticatory dysfunction. Three kinesiological parameters, the maximum force (F(max)), maximum velocity (V(max)) and maximum power (P(max)) were measured in both O and C muscles. Correlation analysis was performed between these parameters and dentofacial morphological features determined on lateral roentgenographic cephalograms. The F(max) (C), V(max) (O), log O/C of V(max), and P(max) (O) significantly correlated with anterior overbite. P(max) (C) significantly and negatively correlated with SN-ArG. Furthermore, log O/C of P(max) significantly and negatively correlated with SNA, SNB and ArG/GMe, and positively with SN-ArG. These results, combined with our previous findings that electromyographic muscle activity during isometric contraction correlated significantly with mandibular morphology, indicate that the dentofacial morphology is influenced by the function of both O and C muscles.

Adult↗
PubMed2000

Increased in vivo levels of neurotransmitters to trigeminal motoneurons: effects on craniofacial bone and TMJ.

The results of chronic, in vivo delivery of excitatory and inhibitory neurotransmitter substances upon the craniofacial skeleton are of ongoing interest to clinician and basic scientist alike. Our purpose was to document and compare the effects of biodegradable glycine, glutamate, and thyrotropin-releasing hormone (TRH) microspheres upon the craniofacial skeleton and TMJ of actively growing rats. Glycine, glutamate, TRH, and blank microspheres were stereotactically implanted in proximity to motoneurons within the trigeminal motor nucleus in order to test the following null hypotheses: (1) neurotransmitter microspheres implanted near trigeminal motoneurons of growing rats have no significant effect on the craniofacial skeleton and temporomandibular joints of implanted animals, and (2) there are no significant differences between the relative effects of glutamate, TRH (excitatory to trigeminal motoneurons), and glycine (inhibitory to trigeminal motoneurons) implants upon the craniofacial skeleton and temporomandibular joint. Fifty male Sprague-Dawley rats underwent stereotactic neurosurgery at 35 days; five rats each were killed at 14 and 21 days postoperative for data collection and comparison between glycine-, glutamate-, TRH-, blank-microsphere, and sham-surgery rats. Glycine rats had significantly (P < or = 0.05, 0. 01) smaller implant-side cranial dimensions and mandibular condyles, all glycine rats showed increased gracility of implant-side bones, and deviation of their facial skeleton away from the implant-side; this was in contrast to the generally larger implant-side bony structures in both glutamate and TRH rats. The two null hypotheses were both rejected. Due to their inhibitory and excitatory effects upon trigeminal motoneurons, masticatory muscles, and their neuromuscular generation of biomechanical forces that affect bone, the neurotransmitter substances glycine, glutamate, and TRH appear to play an important role in the growth and development of the mammalian craniofacial skeleton and TMJ.

Animals↗
PubMed1973

Some characteristics of self-stimulation behavior of dogs.

Self-stimulation was studied in dogs chronically implanted with electrodes in different points within the basal forebrain. The animals exhibiting pure self-rewarding behavior were defined as "optimal" and "good self-stimulators", whereas those with concomitant aversive phenomena were incorporated into the third category called "self-stimulation-withdrawal". In "optimal self-stimulators" a remarkable resistance of the response to extinction was noted. A strong negative attitude toward food was found in four dogs upon stimulation of the self-rewarding loci. Penile erection accompanied self-stimulation in two animals. Sniffing at first always followed incentive brain stimulation, but later it appeared at the beginning of each experiment and/or preceded the bouts of pressing. A rise of hypothalamic temperature was noted in mast of the animals. In some cases this was equal to or exceeded 1 degree Celsius. The temperature increase was accompanied by intense panting between the bouts. Seizures appeared locally as contractions of masticatory muscles and sometimes developed into a generalized fit. Anatomically the "reward area" in the dog extends from the septum and the preoptic area to the mammillary bodies and reaches laterally to the internal capsule.

Animals↗
PubMed1997

Craniofacial abnormalities associated with congenital fiber type disproportion myopathy.

Congenital Fiber-Type Disproportion myopathy (CFTD) is a relatively rare muscular disorder due to predominance and reduction in size of type 1 fibers, with large type 2 fibers. After a review of the clinical and histopathological aspects of the disease, the present work described craniofacial skeletal and EMG features of a 9-year-old child affected by CFTD. Narrow maxillary arch, incompetent lips, severe skeletal open bite, and EMG evidence of weakness of masticatory muscles, were found in the examined patient. All these findings are fully consistent with previously-reported craniofacial features of patients affected by myotonic disorders (muscular dystrophy), and they may represent important diagnostic signs of a congenital muscular disease.

Child↗
PubMed2006

Is the human masticatory system devoid of recurrent inhibition?

The aim of the present study was to investigate the existence or otherwise of a functional recurrent inhibitory system (Renshaw cell system) in the motoneurons that innervate human masticatory muscles. In a previous study, L: -acetylcarnitine (L: -Ac), a substance known to potentiate recurrent inhibition in humans was found to alter, in a specific way, the discharge variability, and the synchronous activity of motor units depending on the presence or absence of recurrent inhibition in the corresponding motoneuron pool. Using a similar paradigm, we have recorded the tonic discharge activity of motor unit pairs from the masseter muscle during voluntary isometric contraction while subjects were undergoing continuous intravenous saline (SAL, NaCl 0.9%) perfusion. Following a brief baseline-recording period, the subjects were given a test injection of either L: -Ac or isotonic saline (SAL) in a double blind manner. The variability, synchronization, and coherence between the motor unit discharges were analysed during three successive periods: pre-injection, during injection, and post-injection, each lasting 2-3 min. Neither L: -Ac nor SAL injection induced a significant change in the inter-spike interval (ISI) or the coefficient of variation of the ISIs in the motor units tested. There were also no significant changes in the pattern of synchronous activity or in the coherence, which reflects the common frequency content of the unit discharges. Reminiscent of what had been observed previously with motoneurons without recurrent inhibition in the Abductor Digitorum Minimi muscle, the lack of effects of L: -Ac injection on the firing behaviour of masseter motoneurons may suggest that classical Renshaw cell inhibition is lacking in this motoneuron pool.

Acetylcarnitine↗
PubMed2000

Improved clinical use of Twin-block and Herbst as a result of radiating viscoelastic tissue forces on the condyle and fossa in treatment and long-term retention: growth relativity.

Understanding mechanisms of action for orthopedic appliances is critical for orthodontists who hope to treat and retain the achieved corrections in patients with initial Class II mandibular retrognathism. That knowledge can help orthodontists produce clinically significant bone formation and avoid compression at the condyle-glenoid fossa region. It also assists us to understand the differences between short-term and long-term treatment results. It was previously thought that increased activity in the postural masticatory muscles was the key to promoting condyle-glenoid fossa growth. By analyzing results from several studies, we postulate that growth modification is associated with decreased activity, which leads to our nonmuscular hypothesis. This premise has its foundation on 3 key specific findings: significant glenoid fossa bone formation occurs during treatment that includes mandibular displacement; glenoid fossa modification is a result of the stretch forces of the retrodiskal tissues, capsule, and altered flow of viscous synovium; observations that glenoid fossa bone formation takes place a distance from the soft tissue attachment. The latter observation is explained by transduction or referral of forces. Evidence is presented, therefore, that the 3 trigger switches for glenoid fossa growth can similarly initiate short-term condylar growth modifications because the 2 structures are contiguous. These are displacement, several direct viscoelastic connections, and transduction of forces. Histologic evidence further shows that stretched retrodiskal tissues also insert directly into the condylar head's fibrocartilaginous layer. The impact of the viscoelastic tissues may be highly significant and should be considered along with the standard skeletal, dental, neuromuscular, and age factors that influence condyle-glenoid fossa growth with orthopedic advancement. These biodynamic factors are also capable of reversing effects of treatment on mandibular growth direction, size, and morphology. Relapse occurs as a result of release of the condyle and ensuing compression against the newly proliferated retrodiskal tissues together with the reactivation of muscle activity. To describe condyle-glenoid fossa growth modification, an analogy is made to a light bulb on a dimmer switch. The condyle illuminates in treatment, dims down in the retention period, to near base levels over the long-term.

Activator Appliances↗
PubMed1987

[Craniofacial growth under the influence of blood supply. 10. Arthrosis of the temporomandibular joint].

Unilateral and bilateral deformation of the temporomandibular joint was observed in young rats after unilateral ligature of the common carotid artery. They involved both the mandibular condyle and the mandibular fossa and were usually associated with a reduction in the dry weight of the masticatory muscles on the ligated side. This leads to the assumption that muscular atrophy is causally related to arthropathy of the temporomandibular joint. The methodological approach to induce changes in the temporomandibular joint may be used as a model of arthrosis of that joint.

Age Factors↗
PubMed1995

Application of polynomial regression modeling to automatic measurement of periods of EMG activity.

We have developed a new algorithm for automatic detection and measurement of on/off periods of EMG burst and examined validity and reliability of the measuring technique. Mean EMG amplitude (M) during a semi-stationary state of an EMG data array [EMG] is calculated. Because M was determined to be significantly correlated with g(T(on)) (or g(Tend)) which represent amplitude on a polynomial regression curve g(t) which best-fitted to the [EMG], the estimate ]g(T(on) (or ĝ(T(end)) is calculated by substituting M into a regressive equation f(M) which explains the association between the M and g(T(on)) (or g(T(end)). T(on) and T(end) are human-determined on/off burst times for the [EMG]. The on/off periods of the EMG burst are finally computed as roots of the g(t) when ĝ(T(on)) and ĝ(T(end)) are subtracted from the constant of the polynomial. Application of the current method to the human masticatory muscle activity during chewing revealed that the absolute differences between human- and computer-determined measurements were smaller than 10 ms, and these measurements did not differ significantly. We conclude that the proposed algorithm is useful and effective for automatic detection and measurement of on/off periods of EMG burst.

Adult↗
PubMed2006

Treatment outcome of short- and long-term appliance therapy in patients with TMD of myogenous origin and tension-type headache.

The aim was to compare the short- and long-term effect of a stabilization appliance with a control appliance in myofascial pain patients suffering from episodic or chronic tension-type headache. Sixty patients (mean age 29 +/- 12 years) with temporomandibular disorders (TMD) of myogenous origin and headache were studied in this prospective controlled study. Seventy-seven per cent of the patients reported episodic and 23% chronic tension-type headache at the start of the study. The 60 patients were randomly assigned to a treatment group (stabilization appliance) or to a control group (control appliance). The patients were interviewed regarding symptoms of headache and myofascial pain and clinically examined for masticatory muscle tenderness. At the 10-week and the 6- and 12-month evaluations of appliance therapy, the treatment outcome of tension-type headache was studied. At the 10-week evaluation, 17 patients dropped-out from the control group by requesting another appliance and receiving a stabilization appliance. Another patient in the control group dropped out later during the trial. In an intent-to-treat analysis, significant differences in improvement of headache between treatment and control groups were found at the follow-ups. A 30% reduction of muscles tender to palpation correlated significantly to improvement of headache at all follow-ups. The stabilization appliance seems to have a positive effect on tension-type headache, both in a short- and in a long-term perspective in patients with TMD with pain of myogenous origin.

Adult↗
PubMed1996

The nonsurgical treatment of a Class II open bite malocclusion.

This case was treated by residents in the postgraduate orthodontic program at the University of Florida under the supervision of Dr. Hocevar. A treatment regimen that he developed to increase the strength and endurance of the masticatory muscles was used. The patient performed prescribed daily clenching and chewing exercise with resilient posterior bite-blocks and wore a hard acrylic posterior biteplane the remainder of the time. It was hoped that this approach would increase the chances of treatment success and stability.

Adolescent↗
PubMedDate not supplied

Structural characteristics and functional significance of the buccal fat pad (corpus adiposum buccae).

Corpus adiposum buccae (c.a.b.) was studied on 42 human subjects (fetuses and adults) using microdissection under magnifying glass after injection of the great vessels of the head with plastics, transparency technique of Spalteholtz and current histological methods. In fetuses, c.a.b. appeared as a well-developed mass located between Buccinator and inferior border of the Masseter. In adults, it emanated three prolongations among which the anteriorly directed molar prolongation was more conspicuous in edentulous old people. Externally, it was covered by a fine conjunctival wrap, which sent septa dividing the buccal fat pad in a series of minute fibroadipous compartments. C.a.b. contained a rich vascular network deriving from the branches of the facial and maxillary arteries. In this vascular net a more developed artery emanated branches to the prolongations of the c.a.b. The veins were tributaries of the pterygoid venous plexus. Beside the vessels, c.a.b. contained also lymphatics and myelinated nerves. The authors postulated that c.a.b. assumed the following functions: a) It filled up the masseter-zygomaticus-buccinator space forming an amortizing and a slipping platform for the masticatory muscles in action; b) in the baby, it resisted to the negative pressure which acted into the buccal cavity during sucking; c) its rich venous net, provided with valve-like structures, may be implicated in the exo-endocranial blood flow by means of the pterygoid plexus.

Adipose Tissue↗
PubMed1981

Clinical findings during the course of temporomandibular arthropathy.

During the painful phases of temporomandibular arthropathy, the mobility is restricted, pain is present in the affected joint on maximal horizontal movement, and the joint capsule and masticatory muscles are tender. As the joint pain ceases, mobility improves and crepitation may appear. Crepitation is the most frequent finding in patients with lasting symptoms. Contralaterally, the muscular reaction is less impressive and of shorter duration. TMJ clicking may appear contralaterally as the symptoms of arthropathy disappear. The man change in signs takes place as pain disappears. However, signs still change years after debut of arthropathy.

Humans↗