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PubMed1996

Jaw muscle pain and its effect on gothic arch tracings.

Perceived changes in occlusion and decreased range of motion are often expressed by patients with masticatory muscle pain. The adverse loading of craniomandibular tissues that results from an inadequate maxillomandibular relationship in combination with the coexisting dysfunction is widely regarded as the cause of pain. This study was designed to test whether pain can cause significant changes in position of the mandible and therefore form the basis for any perceived changes in the maxillomandibular relationship. A second objective was to determine whether pain can cause changes in the mandibular range of motion. Five subjects who rated pain intensity on a visual analog scale were used in a single-blind, randomized, repeated-measures study design. Tonic muscle pain was induced by infusion of 5% hypertonic saline solution into the central portion of the superficial masseter muscle. Isotonic saline solution was used as a control, with subjects blinded to the type of substance given. The effect of pain on the position of the apex of the gothic arch tracing, the direction of the lateral mandibular border movements, and the mandibular range of motion was studied in a horizontal plane with minimal occlusal separation. Pain significantly affected the position of the apex of the gothic arch tracing in anterior (F = 11.46, p = 0.03) and transverse (F = 35.0, p = 0.004) directions. Similarly, pain affected the orientation of the mandibular lateral border movements (F = 12.44, p = 0.02) and their magnitude (F = 14.97, p = 0.01). All pain-induced effects proved to be reversible. The observed effect of pain can explain the perceived change of bite that is frequently noted by patients with orofacial pain. This study provided evidence of an alternative causal relationship between pain and changes in occlusal relationship and questions occlusal therapy as treatment, directed toward the elimination of the underlying cause in patients with masticatory muscle pain.

Adult↗
PubMed1988

Effects of fine-grained diet on annulospiral endings of muscle spindles in the masseter muscle in developing and adult mice.

In the masticatory muscles, neuromuscular spindles have a very important role in controlling the jaw movement since they act as stretch receptors in skeletal muscles. The continuous intake of fine-grained diet which is easily chewable leads to degeneration of the sensory endings of Ia fibers in many muscle spindles of the mouse masseter muscle in only 120 d after birth.

Animals↗
PubMed1989

MR imaging of muscles of mastication.

High-field MR imaging was used to study structural and physiologic alterations involving the muscles of mastication in 46 patients. Muscular abnormalities were often detected incidentally in conjunction with lesions of the CNS, cranial nerves, facial bones, and/or temporomandibular joint (TMJ). Specific pathologic alterations observed included anomalies of musculoskeletal development, muscle hypertrophy, atrophy (disuse and denervation), inflammatory disorders, injuries (including contusions, tears, and muscle rupture), posttraumatic musculoskeletal deformities, and reflex sympathetic dystrophy. Atrophy, fatty replacement, fibrosis, and contracture of selected muscles of mastication may accompany internal derangement of the TMJ in the absence of traumatic deformity. We conclude that MR is a highly accurate imaging method for detecting masticatory muscle disease. Nontraumatic anatomic and physiologic abnormalities of the muscles of mastication are uncommon disorders. Demonstrable muscle alterations frequently accompany fracture dislocations of the mandibular condyle neck and related facial bones onto which masticatory muscles attach.

Adolescent↗
PubMed2002

[Histological and ultrastructural characteristics of jaw-closing muscles. A review].

The aim of this work is giving, through a wide literature review, a detailed analysis of the histological and ultrastructural characteristics that distinguish masseter and temporal muscles from the other skeletal muscles. Furthermore we'll explain the functional meanings of these differences. We developed the following points: fibre type composition and relative frequency of the various fibre types, fibre size, myosin composition, capillarization and age-related changes. With standard staining method for the myofibrillar ATPase, besides the two main fibre types, I and II, in the masticatory muscles a moderate share of IM fibres with intermediate stainability, which usually don't appear in adult skeletal muscles, are shown. The relative frequency of the various fibre types is also peculiar, with a prevalence of type I fibres in almost every portion of the masseter and temporal muscles, which therefore are functionally slow muscles. Another unusual characteristic is also the mean diameter of type I fibres, that are commonly larger than type II fibres. This finding suggests that masticatory muscles are adapted to carry out specially prolonged and fatiguing tasks. The findings about contractile protein patterns and the changes in myosin heavy chain composition during ageing are also relevant. The deep differences between jaw-closing and limb and trunk muscles are reviewed on the basis of their special functional activities.

Aging↗
PubMed2004

The effect of clenching on condylar position: A vector analysis model.

STATEMENT OF THE PROBLEM: Clinicians often disagree about the acceptable position of the condyle in the articular fossa. Agreement as to what position the condyle-disk assembly assumes on the articular eminence while subjected to the forces of the elevator muscles of the mandible is important. PURPOSE: This simulation study investigated the position of the condyle-disk assembly on the articular eminence while subjected to the forces of the elevator muscles of the mandible during clenching. MATERIAL AND METHODS: Using the 2 conditions of static equilibrium, a vector analysis of a 2-dimensional model of the temporomandibular joint was developed. The dynamics of the condyle-disk assembly during muscle loading were analyzed. The vector sum of the masticatory muscle forces was determined by assuming that the maximum force developed by each contributing muscle was proportional with the physiologic cross section of the muscle. The effect of the resultant force vector of the combined muscle action applied to the condyle was analyzed for the orthogonal and acute angle situations. RESULTS: When the vector sum was orthogonal on the eminence, the condyle was in stable equilibrium. The stable equilibrium was found in the anterior-superior position in the fossa. When the vector sum was at an acute angle to the eminence, the condyle was subject to a translation force that displaced it into the anterior-superior equilibrium position. CONCLUSION: Within the limitation of this study, vector analysis suggested that the anterior-superior position of the condyle-disk assembly on the eminence was the most stable equilibrium position. All other tested positions of the condyle were less stable and maintained at the expense of other structures.

Algorithms↗
PubMed1989

[Relationship between muscular palpation and three dimensional incisal path at border movement of mandible].

Temporomandibular arthrosis was diversified phases of its development as well as complicated mode of its crisis, due to which no concrete clinical diagnostic procedure has been established yet. However, a close relation of occlusal disturbance with the crisis factor is suggested, and assessments have been made in the prosthetic dentistry, setting a viewpoint at the phases of mandibular movement. Particularly, incisal path at border movement of mandible is made the object for basic assessment since it exhibits intensified condition. On the other hand, importance is attached to Krogh-Poulsen's muscular palpation for diagnosis of the pain and contraction of the masticatory muscle which occur in temporomandibular arthrosis. However, though there is a close relation between the pain or abnormal contraction of the masticatory muscle and the phases of mandibular movement, these diagnostic procedures have been the studies which have dealt with the subjects separately. And no report is seen on the study made of the relation between the phases of incisal path at border movement of the mandible and Krogh-Poulsen's muscular palpation. Accordingly, with the purpose of investigating these relationships, the author has made assessment of the relationship between the result by Krogh-Poulsen's muscular palpation and the form (analogue form) of three-dimensional incisal path at border movement of the mandible summarized and standardized by TMJ gnathological instrument which is evaluated as a recording method with high clinical efficiency as a method with excellent reproducibility of mandibular movement and favorable manipulability. The subjects enrolled were patients with temporomandibular arthrosis and the so-called normal healthy subjects with normally functioning occlusion who are not conscious clinically of the abnormality of the stomatognathic system nor had similar anamnesis. And the following results have been obtained. 1. Results by Krogh-Poulsen's muscular palpation; 1) The 59 so-called normal healthy subjects were classified into 2 groups by Krogh-Poulsen's muscular palpation, and of these, the cases in whom no abnormality was observed were only 5, being 8.5%, and the cases in whom single or multiple test items showed abnormality were 54, being so high rate as 91.5%. The occurring frequency of 5 test symptoms in the 54 cases were; 22 cases with trismus-40.7%; 34 cases with temporomandibular sounds -63.0%; 20 cases with pain -37.0%; 36 cases with tenderness of the lateral pterygoid muscle -66.7%; and 25 cases with disturbance of lateral mandibular movement -46.3%.(ABSTRACT TRUNCATED AT 400 WORDS)

Humans↗
PubMed1989

Association between craniofacial morphology and fiber-type distributions in human masseter and medial pterygoid muscles.

Numerous experimental studies and clinical anecdotal evidence demonstrate a close interaction between masticatory muscle function and skeletal form. The purpose of this study was to determine whether a relationship existed between histochemical characteristics of human masseter and medial pterygoid muscles and cephalometric measurements of the 11 subjects from whom specimens were collected. Muscular specimens were obtained at the time of corrective surgery through incisions made to expose the mandibular ramus. Histochemical analysis was used to determine the size and distribution of fiber types. Angular and linear measurements were obtained from lateral cephalometric radiographs taken 1 week prior to surgery. Linear regression analysis revealed one significant negative correlation between ramus length and the percentage of Type I fibers in the medial pterygoid muscle. However, the results of this study do not support the hypothesis that a relationship exists between facial type and selected histochemical characteristics.

Adolescent↗
PubMed1997

Rigid fixation and strain patterns in the pig zygomatic arch and suture.

PURPOSE: In orthognathic surgery, rigid fixation is routinely used to hold together bone fragments that may experience heavy force from attached masticatory muscles. Internal fixation plates are assumed to hold bony parts rigidly, but the mobility at such sites subjected to normal masticatory function has not been measured. The purpose of this study was to investigate in vivo the degree to which a linear plate immobilizes separated bones, specifically sutures. MATERIALS AND METHODS: Three female miniature pigs (Sus scrofa) had 1.3-mm Synthes titanium plates placed across the suture in the zygomatic arch. Foil strain gauges were used to record load deformation in the zygomatic and squamosal (temporal) bones and across the vertical and horizontal parts of the suture. Strain was recorded in vivo during mastication and in anesthetized pigs with electrical stimulation of masticatory muscles. RESULTS: Strain at the suture was not reduced from normal levels. The plate induced increases in strain within the bones, but the changes were slight. CONCLUSION: The results indicate that linear "rigid fixation" does not immobilize sutures.

Animals↗
PubMed1994

[A case of nodular type of muscular sarcoidosis with limitation of mandibular opening].

A 68-year-old woman who complained of limited mandibular opening and left buccal swelling was admitted to our department. Histological examination of muscle biopsy specimens from the left buccal region revealed noncaseating granulomas. MR examination showed diffuse swelling and high signal intensity of the left masticatory muscles on T1- and T2-weighted images. Palpable nodules were present in the muscles of the body and the limbs. The ACE value was high and the lung biopsy specimens showed non-caseating granulomas. From these findings, the patient was diagnosed as having nodular type of muscular sarcoidosis complicated by contracture of the left masticatory muscles. There are some previous reports of nodular type of muscular sarcoidosis with flexion contracture of the fingers. Therefore, contracture of the muscles is suggested to be an important cause of muscular dysfunction in the disease.

Aged↗
PubMed2000

EMG power spectrum and motor unit characteristics in the masseter muscle of the rabbit.

Masticatory muscles contain a large variety of motor units with different physiological and morphological properties. In this study, we tested the hypothesis that a relationship exists between the mechanical and myo-electric properties of single motor units in the masseter muscle of the rabbit. It was expected that faster-contracting motor units, which usually have a relatively large number of fibers with large diameters, should have faster action potentials with larger amplitudes than slower motor units. Single motor units were stimulated. A two-dimensional force transducer registered mechanical parameters of the units. EMG electrodes were used to determine amplitude and frequency parameters of the action potentials of the same units. The results showed that faster-contracting motor units indeed produced action potentials with higher conduction velocities. However, faster motor units had no significant larger amplitude of the action potential. Small but significant positive correlations were found between the tetanic peak force and the amplitude of the action potentials. Little difference was found among the various frequency and amplitude parameters, respectively, making them equally suitable to describe the action potential. Surprisingly, a negative correlation between the amplitude and frequency parameters of the action potential was found, which may result from variability in arrival times of action potentials at the electrode site. Regional differences in the frequency parameters were found between the anterior and posterior parts of the superficial masseter.

Action Potentials↗
PubMed1999

Masticatory force and function in patients with hemispheric brain infarction and hemiplegia.

Recent functional animal studies have reported that the motor control of masticatory muscle function is bilaterally guided by both hemispheres, which may fundamentally differ from the cortical control of limb muscle function. In this study, we investigated whether unilateral cortical brain infarction induces different impairments in masticatory and upper limb motor performance. Evidence of the importance of both hemispheres in controlling masticatory movements would be greater if the masticatory function were shown to be unimpaired in patients with severe hemiplegia. The masticatory function of 16 patients with severe hemiparesis caused by brain infarction in the region of the middle cerebral artery was studied by means of interview, clinical examination, and bite-force measurements. Finger-thumb grip-force measurements and clinical examination of the upper limbs were also performed for evaluation of the effect of infarction on upper limb motor function. Localization of the infarction was confirmed with computer tomography and magnetic resonance imaging. The Scandinavian Stroke Scale demonstrated that each patient had a major unilateral cortical infarction which had caused a marked handicap with a serious impairment of upper limb function on the contralateral side. The clinical examination revealed no major signs of temporomandibular disorders, and the masticatory muscles, when examined by palpation, contracted symmetrically. None of the patients with unilateral brain infarction showed any differences in bite forces between the healthy and paralyzed sides. These results indicate that, in hemiparetic patients, great differences may exist between the motor performances of the masticatory and upper limb muscles. The present investigation clinically illustrates the importance of both hemispheres in the control of masticatory function and movements.

Adult↗
PubMed1989

Muscle function and craniofacial morphology: a clinical study in patients with myotonic dystrophy.

The occlusal traits and the craniofacial morphology were studied in patients with an altered muscle function caused by myotonic dystrophy. Twenty-four adult patients were examined and compared with a matched group of healthy individuals. The condition of the masticatory muscles was evaluated by measuring the maximal bite force. The dental arches and the occlusal traits were analysed on dental casts. Lateral cephalograms were taken in the patients with myotonic dystrophy to study the craniofacial morphology. It was found that the patients suffering from myotonic dystrophy had weak masticatory muscles, which might be caused by the disease. A high prevalence of malocclusions (postnormal occlusion, anterior open bite and lateral cross bite) was found among these patients. Their craniofacial morphology showed a vertical aberration, characterized by a large angle between the mandibular and palatal planes and a steep mandible. These findings seem to be most pronounced in patients with an early onset of the disease and support the hypothesis that reduced muscle function may cause changes in the craniofacial morphology.

Adult↗
PubMed1993

Pressure pain thresholds in patients with craniomandibular disorders before and after treatment with acupuncture and occlusal splint therapy: a controlled clinical study.

Fifty-five patients (46 women and 9 men) with craniomandibular disorders and a history of pain of at least 6 months' duration participated in this trial. The patients were randomly assigned to three groups: one group to receive acupuncture; one group to receive occlusal splint therapy; and one group to act as controls. Pressure pain threshold, clinical dysfunction score, and visual analog scale measures were used to evaluate patients before, immediately after, and 6 months after treatment. A moderate, but statistically significant, correlation was found between pressure pain threshold and the number of tender spots in the masticatory muscles (tau = -.43; P < .001), degree of tenderness in the masticatory muscles (tau = -.43; P < .001), clinical dysfunction score (tau = .32; P < .001), and the visual analog scale (tau = -.25; P < .01). The short-term results showed a statistically significant improvement in all evaluations for both treatment groups. No significant differences were found in the control group. The improvements resulted in significant differences between the control and each treatment group immediately after treatment. At the 6-month follow-up, no significant differences in pressure pain threshold or clinical dysfunction score were found in the two treatment groups compared with the short-term results.

Acupuncture Analgesia↗
PubMed1996

Diclofenac sodium as an alternative treatment of temporomandibular joint pain.

In a double-blind study, diclofenac sodium (Voltaren), 50 mg two or three times a day, was compared with placebo in 32 patients with pain localized to the temporomandibular joint (TMJ). The patients were allocated into two equally large groups. A visual analog scale was used to estimate the pretreatment degree of pain. The treatment effect was assessed as the frequency of joint and muscle pain and by the patients' own evaluation of improvement. The change in the clinical condition was assessed by tenderness to palpation of the TMJ and masticatory muscles and by mandibular mobility. The frequency of TMJ pain showed a greater reduction in the diclofenac group than in the placebo group, and there was a significant reduction of daily TMJ pain in the diclofenac group. The diclofenac group also showed a significant decrease in tenderness to palpation of the masticatory muscles in comparison with the placebo group. The patients with short duration of pain showed the best response to diclofenac. There was no evidence in this study to prove that diclofenac should be used as a primary treatment of TMJ pain, but it could be used as a complement to other treatments of acute TMJ pain.

Adult↗
PubMed1999

Case report of malocclusion with abnormal head posture and TMJ symptoms.

Abnormal cervical muscle function can cause abnormal head posture, adversely affecting the development and morphology of the cervical spine and maxillofacial skeleton, which in turn leads to facial asymmetry and occlusal abnormality. There can be morphologic abnormalities of the mandibular fossa, condyle, ramus, and disk accompanying the imbalance of the cervical and masticatory muscles activities. Two normally growing Japanese female patients with Class II Division 1 malocclusion presented with TMJ symptoms and poor head posture as a result of abnormal sternocleidomastoid and trapezius cervical muscle activities. One patient underwent tenotomy of the two heads of the sternocleidomastoid muscle and the other patient did not. In addition to orthodontics, the 2 patients received physiotherapy of the cervical muscles during treatment. Both were treated with a functional appliance as a first step, followed by full multi-bracketed treatment to establish a stable form of occlusion and to improve facial esthetics with no head gear. This interdisciplinary treatment approach resulted in normalization of stomatognathic function, elimination of TMJ symptoms, and improvement of facial esthetics. In the growing patients, the significant response of the fossa, condyle, and ramus on the affected side during and after occlusal correction contributed to the improvement of cervical muscle activity. Based on the result, early occlusal improvement, combined with orthopedic surgery of the neck muscles or physiotherapy to achieve muscular balance of the neck and masticatory muscles, was found to be effective. Two patients illustrate the potential for promoting symmetric formation of the TMJ structures and normal jaw function, with favorable effects on posttreatment growth of the entire maxillofacial skeleton.

Birth Injuries↗
PubMed1989

[Electromyographic study of masticatory dysfunction in patients with unilateral cleft lip and palate and reversed occlusion].

UNLABELLED: Masticatory dysfunction in patients with unilateral cleft lip and palate was studied on the basis of electromyograms of the masticatory muscles. The purpose of the study was to elucidate the origin of the dysfunction by means of comparisons among electromyograms of masticatory muscles in cases of normal occlusion, reversed occlusion and reversed occlusion caused by unilateral cleft lip and palate. Subjects were 10 cases of normal occlusion (10y2m-11y10m), 10 cases of reversed occlusion (7y2m-11y2m) and 20 cases of unilateral cleft lip and palate (8y0m-14y3m). In each subject, electromyograms of the masseter and anterior venters of the temporal muscles at the isometric-contraction phase were recorded by means of the surface-electrode method with mandible loads of 1-5 kg. The electromyograms were analyzed quantitatively by means of an electromyographic device called a Turn Counter. Relations between loads and amplitude as well as numbers of turns were examined. At the same time maximum masticatory pressure and occlusal contact points were measured and then examined in comparison with electromyographic findings. RESULTS: 1. Correlation coefficients between loads and amplitudes as well as numbers of turns decreased among the groups in this order: normal occlusion, reversed occlusion and cleft-caused reversed occlusion. Significant differences were observed between the normal-occlusive group and the reversed and cleft-caused reversed-occlusive groups. 2. No. difference was observed between the normal-occlusive and reversed-occlusive groups in terms of correlation coefficients between total sums of amplitudes and turns of the 4 masseter muscles (right and left masseters and anterior venters of the temporal muscles) and loads. Correlation coefficients in the cleft group were significantly smaller than those in the other 2 groups. 3. Because of great differences in regression coefficient among individuals, no synergic contraction pattern of the 4 mastication muscles (right and left masseter and temporal muscles) could be specified. 4. The A/T ratio of masseters in the cleft group was significantly smaller than those in the normal- and reversed-occlusive groups. 5. Under maximum load, the activity ratio of the 4 masseter and temporal muscles was 1:1 in the normal- and reversed-occlusive groups, whereas temporal-muscle activity predominated over masseter-muscle activity in the cleft group. 6. Maximum masticatory pressure decreased in the order: normal-occlusive, reversed-occlusive, and cleft caused occlusive. No correlation with electromyographic findings was observed.(ABSTRACT TRUNCATED AT 400 WORDS)

Child↗
PubMed2007

Myogenous temporomandibular disorders: diagnostic and management considerations.

Myogenous temporomandibular disorders (or masticatory myalgia) are characterized by pain and dysfunction that arise from pathologic and functional processes in the masticatory muscles. There are several distinct muscle disorder subtypes in the masticatory system, including myofascial pain, myositis, muscle spasm, and muscle contracture. The major characteristics of masticatory myalgia include pain, muscle tenderness, limited range of motion, and other symptoms (eg, fatigability, stiffness, subjective weakness). Comorbid conditions and complicating factors also are common and are discussed. Management follows with stretching, posture, and relaxation exercises, physical therapy, reduction of contributing factors, and as necessary, muscle injections.

Analgesics↗
PubMedDate not supplied

[The functional basis for a new method of surgical intervention in phlegmons of the infratemporal space].

Studies of bioelectrical activity of masticatory muscles in patients with phlegmons of the infratemporal space revealed that limited opening of the mouth in such patients is not related to increased tone of the masticatory muscles and that the pain syndrome is accompanied by tonic tension of the muscles. A new functionally based method for opening the phlegmons of the infratemporal space is suggested.

Cellulitis↗