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At least 55 records · Page 3Linked to original sources
PubMed2000

Effect of osseointegrated implants on the coordination of masticatory muscles: a pilot study.

STATEMENT OF PROBLEM: The neuromuscular network of masticatory function is, in part, coordinated with afferent information provided by the periodontal ligament (PDL). Osseointegrated implant-supported prostheses lack this PDL-derived proprioceptive feedback mechanism. PURPOSE: This pilot study was designed to address the hypothesis that implant patients acquire different patterns of functional coordination. Patients with implant-supported prostheses were characterized in regard to masticatory muscle tenderness and fatigue as well as changes in the coordinated activities of masticatory muscles during chewing and maximal occluding force. Results were compared with those of patients with natural teeth and interpreted to assess the functional outcome of implant therapy. MATERIAL AND METHODS: Fifty-seven volunteers (25 partially edentulous patients restored with implantsupported fixed prostheses; 32 control patients) were evaluated. A comprehensive set of clinical examinations was performed, including occlusal analysis and examination of masticatory muscle and TMJ. EMG recordings of 5 volunteers from each group were further evaluated. EMG activities of the masseter and anterior temporalis were recorded during habitual chewing and voluntary maximal occluding force. RESULTS: There were essentially no differences in the clinical evaluations between volunteers in the implant and control groups and no significant alterations in the masticatory muscle coordination for habitual chewing. During the maximal occluding force measurement, EMG recordings revealed a unique masticatory muscle coordination pattern in the implant group with a tendency to activate the working and nonworking side muscles simultaneously. CONCLUSION: Patients with implant-supported prostheses appeared to be well adapted to perform habitual masticatory functions. However, during a nonhabitual function such as maximal occluding force, our pilot data revealed a less coordinated masticatory muscle activity in the implant patients.

Adaptation, Physiological↗
PubMed1992

Myosin isoform transitions during development of extra-ocular and masticatory muscles in the fetal rat.

The late fetal development of rat extra-ocular and masticatory muscles was examined by myosin immunohistochemistry. The pattern of slow and neonatal myosin isoform expression in primary and secondary myotubes in these muscles was generally similar to that seen by others in limb muscles. We observed a consistent difference between the Sprague-Dawley and Wistar rats in the degree of maturity reached by all muscles studied at a particular age. In both strains, extra-ocular muscles were also about one day in advance of the masticatory muscles. Thus, secondary myotubes were first seen at E17 in Wistar extraocular muscles, at E18 in Sprague-Dawley extra-ocular muscles and Wistar masticatory muscles, and at E19 in Sprague-Dawley masticatory muscles. There was a strikingly early and complete type differentiation of primary myotubes in extraocular muscles, and tonic myosin first appeared before birth in presumptive extrafusal tonic fibres in the orbital layer of the oculorotatory muscles. Throughout the late fetal period, retractor bulbi was composed of fast myotubes only, but these myotubes were not arranged in classical clusters. In the masticatory muscles at E17/E18 some slow primary myotubes started to express tonic myosin, and these presumptive spindle bag2 fibres were located only in regions of the muscles known to contain spindles in the adult. Presumptive bag1 fibres appeared about a day later (initially without tonic myosin), and in the region of the spindle cluster in anterior deep masseter extrafusal secondary myotube production appeared to be suppressed.

Animals↗
PubMed1989

[Differentiation of the dormouse Eliomys quercinus (Linnaeus 1766) fro the murid Mus caroli (Bonhote 1902) based on the masticatory muscles].

Investigated were the masticatory musculature of the murid, Mus caroli, and the glirid, Eliomys quercinus. Differences between both species could be found, which includes different mastication. Mus caroli eats mixed food. The masticatory musculature admits mainly antero-posterior mandibular movements with a minimal transverse component. The food of Eliomys quercinus exists of mainly insects. The masticatory muscles, in particular the M. pterygoideus internus and the well developed M. zygomaticomandibularis, pars posterior, include high frequency of lateral movements between mastication.

Animals↗
PubMed2006

Evidence for MHC I-restricted CD8+ T-cell-mediated immunopathology in canine masticatory muscle myositis and polymyositis.

Masticatory muscle myositis (MMM) is the most common inflammatory myopathy (IM) in dogs, associated with antibodies against myosin. To further elucidate the immunopathogenesis, we investigated muscles of 53 dogs with MMM, 32 dogs with polymyositis (PM), and 4 dogs suffering from both, with regard to the presence and location of CD4(+) and CD8(+)T cells, B cells, macrophages, major histocompatibility complex (MHC) class I and class II antigens, and autoantibodies. CD8(+)T cells were found in MMM (91%) and PM (75%), mostly paralleled (68% and 61%) by enhanced expression of MHC class I antigen on muscle fibers. CD8(+)T cells invading intact and neighboring necrotic muscle fibers were present in MMM (39%) and PM (42%). Dogs with MMM lacking intramuscular (26%) and circulating (36%) autoantibodies also had CD8(+) T-cell infiltrations and muscle-fiber lesions. Since MHC class I antigen and CD8(+) T cells were detected in the presence of CD4(+) T cells, regardless of antimuscular antibodies, we consider MMM and PM in the dog as a CD8(+) T-cell-mediated immunopathological disease that initiates muscle-fiber destruction and leads to production of myosin autoantibodies.

Animals↗
PubMed1987

Canine masticatory muscle disorders: a study of 29 cases.

The histopathologic features in temporalis muscle biopsies from 29 dogs with masticatory muscle disorders were characterized and used for their subgrouping: 2 without lesions, 3 with nonspecific changes, 7 with neurogenic atrophy, and 16 with myositis. The immunocytochemical and immunochemical features of the muscle biopsies and sera from those dogs were compared among the histopathologic subgroupings and compared with biopsies and sera from healthy dogs and dogs with polymyositis. Of the 14 biopsies from dogs with masticatory muscle myositis, 12 had immune complexes limited to type 2M fibers, whereas 13 of 16 sera samples had detectable antibodies against type 2M fibers. The immune complex deposition was found only in biopsies of dogs with masticatory muscle myositis, and the antibodies were detected in the sera of only one dog that did not have masticatory muscle myositis. Immunoblot assays revealed that the antibodies were most often directed against a 185 K protein, myosin heavy chain, and a band that appeared to be LC2-M (myosin light chain 2-masticatory).

Animals↗
PubMed2005

Botulinum toxins in dentistry--the new paradigm for masticatory muscle hypertonicity.

A variety of factors, such as stress, hormones, diet, drugs, trauma, and certain neuromuscular diseases, can lead to an increase in sympathetic muscle tone, which results in masticatory muscle hypertonicity and parafunction. Dentists have traditionally attempted to treat and prevent this transient disease with methods that are expensive, risky, irreversible, and not evidence-based. There is a need for a conservative reversible noninvasive treatment that is quick, easy, relatively inexpensive, long acting, and effective. Botulinum toxin, a natural protein, is one of the most potent biological substances known. Masticatory muscle relaxation can be reliably achieved by injecting measured doses of botulinum toxin into specific sites in the major muscles of mastication. A reduction in dystonia and pain with optimization of function is easily achievable with a site- and dose-specific injection protocol. The use of botulinum toxin offers the dentist an extremely effective tool to add to the armamentarium for treating conditions that derive from masticatory and other pericranial muscular conditions, and offers the general dentist who is not an expert in gnathology and occlusion a safe, effective treatment for controlling the symptoms of masticatory muscle hypertonicity.

Botulinum Toxins↗
PubMed2003

Volume and shape of masticatory muscles in patients with hemifacial microsomia.

OBJECTIVE: To test the following hypotheses in hemifacial microsomia (HFM): (1) the volumes of the masseter, lateral and medial pterygoid, and temporal muscles are reduced on the affected versus unaffected side; (2) significant differences exist between the degrees of right-left disproportion in these four masticatory muscles; (3) circumferential shapes of the masticatory muscles are more irregular on the affected versus unaffected side; and (4) the degree of masticatory muscle right-left disproportion can be judged by the degree of ear, mandibular, or dental anomalies. SUBJECTS AND METHODS: Ten preadolescent patients with HFM were studied using facial photographs, dental casts, cephalometric and panoramic radiographs, and helical computed tomography scanning and three-dimensional reconstruction technique. Volumes of masseter, lateral and medial pterygoid, and temporal muscles on both sides were measured. Muscle volume disproportion was expressed as the affected/unaffected ratio. Muscle circumferential irregularity was expressed as the ratio between the total circumferential length and corresponding cross-sectional area. RESULTS: Masticatory muscle volumes were significantly smaller on the affected versus unaffected side. No significant differences were observed between the degrees of disproportion of the four masticatory muscles examined. Circumferential shapes of masticatory muscles were significantly more irregular on the affected versus unaffected side. There were no significant relationships of the degree of ear, mandibular, or dental anomalies in relation to masticatory muscle disproportion. CONCLUSIONS: In HFM the masseter, lateral and medial pterygoid, and temporal muscles all have a significantly smaller volume on the affected versus unaffected side, and specific muscles were not severely affected in the present subjects. Furthermore, all four muscles showed a significantly more irregular shape on the affected versus unaffected side. Finally, the severity of masticatory muscle disproportion can probably not be judged by the degree of ear, mandibular, and dental anomalies in preadolescent patients with HFM.

Adolescent↗
PubMed2002

Afferent and cortical control of human masticatory muscles.

Like most other muscles, the human masticatory muscles are controlled by descending signals from the cortex and other supraspinal structures, as well as afferent signals arising in receptors in muscles, skin and other tissues. However, the special functional roles of the masticatory system, and in particular the fact that the muscles on both sides are usually used together, has led to some special adaptations of function.

Humans↗
PubMed1994

Morphology and analysis of the development of the human temporomandibular joint and masticatory muscle.

The calcification levels of the mandible and the temporal bone of human fetuses, which ranged from 12 to 32 weeks of gestation, were systematically investigated with a soft X-ray analyzer linked to an image analyzer. The profile of the condylar process (head) revealed high levels of calcification, in contrast to that in the mandibular fossa of the temporal bone. The basal portion of the condylar process and the mandibular notch exhibited moderate calcification from 12 weeks of gestation. The weight and the cross-sectional areas of the muscle and the muscle fibers in masticatory muscles (masseter, temporal, medial, and lateral pterygoid muscles) are all increased gradually during development from 12 to 32 weeks of gestation. These changes in calcification and in cross-sectional area of muscle suggest that muscle development may be related to bone calcification during formation of the mandible.

Aged↗
PubMed1999

[The mechanical action of Dirol chewing gum on the periodontal tissues and masticatory muscles].

Regional hemodynamics, bioelectric activity of masticatory muscles, and compactness of mandibular bone were studied by the rheographic method for measuring periodontal bloodflow, by electromyography, and echo-osteometry in 52 volunteers after 4-week regular chewing of Dirol chewing gum. Congestive hyperemia develops in periodontal tissues; functional activity of masticatory muscles and compactness of mandibular bone are normal.

Adult↗
PubMed2006

Analgesic action of gabapentin on chronic pain in the masticatory muscles: a randomized controlled trial.

Chronic masticatory myalgia (CMM) can be defined as constant pain in the masticatory muscles for more than 6 months and is influenced by the central nervous system. The antiepileptic agent gabapentin acts centrally and is used for managing different types of chronic pain conditions. The objective of this study was to evaluate the analgesic action of gabapentin on CMM. In this 12-week randomized controlled clinical trial 50 patients were randomly allocated into two study groups: 25 received gabapentin and 25 received placebo. The outcome measures utilized were pain reported on a VAS (VAS-pain), Palpation Index (PI) and impact of CMM on daily functioning reported on a VAS (VAS-function). Thirty-six patients completed the study. Gabapentin showed to be clinically and statistically superior to placebo in reducing pain reported by patients (gabapentin=51.04%; placebo=24.30%; P=0.037), masticatory muscle hyperalgesia (gabapentin=67.03%; placebo=14.37%; P=0.001) and impact of CMM on daily functioning (gabapentin=57.70%; placebo=16.92%; P=0.022). It can be concluded from this study that gabapentin is effective for the management of CMM.

Adolescent↗
PubMed1989

[Histochemical muscle fiber characterization of the masticatory muscles of the Wistar rat (Rattus norvegicus Berkenhout)].

224 muscle biopsies of the mandible adductors of the Wistar rat have been analyzed enzyme-histochemically for the investigation of their muscle fibre types. The myofibrillar adenosine triphosphatase (ATPase) and the succinic dehydrogenase (SDH) have been used in this investigation. The major part of the chewing musculature consists of muscle fibres of the type II, which can be subdivided into 3 subtypes, type IIA, IIB and TR.

Adenosine Triphosphatases↗
PubMed2001

Masticatory muscle function and transverse dentofacial growth.

Numerous experimental and clinical studies have shown an association between masticatory muscle function and craniofacial growth. The present series of studies focuses on the influence of masticatory muscle function on some basic mechanisms in craniofacial growth as well as on the effect of the functional capacity of the masseter muscle on the width of the maxillary dental arch in human subjects. The animal experimental model used to study the influence of masticatory muscle function was a non-invasive one that produced a decreased functional demand of the masticatory system in growing rats by feeding them a soft diet. The influence of reduced masticatory muscle function on the transversal dimensions of the premaxilla, maxilla (including the dental arch) and the calvaria was studied on dry skulls using a high precision non-contact measuring system. Moreover, a methodological study was carried out to study the influence of one preparation method on the dimensions of dry rat skulls, using axial contact radiographs. The effect of different functional demands on sutural dimensions and sutural bone apposition was studied on frontal undecalcified sections of the rat snout using automatic image analysis. For the quantification of sutural dimensions contact microradiographs were used, while for sutural bone apposition the bone level at certain time intervals was marked with calcein. In the clinical part of this thesis the relationship between maxillary dental arch width and masseter muscle thickness in humans was studied using ultrasonography. Masticatory muscle function was found to influence the transverse growth of the skull at areas under direct muscle influence as well as the dental arch width in regions with molars under eruption. The methodological study indicated that direct comparisons between measurements on fresh specimens and those on dry rat skulls are not permissible, since the dimensions of the dry rat skull are smaller than those of the original fresh specimens. The dimensions and morphology of the facial sutures as well as the sutural bone apposition were negatively affected by reduced masticatory function. The experimental findings of the present study might indicate some of the underlying mechanisms of the clinical findings, where subjects with thicker masseter muscles were found to have a broader maxillary dental arch.

Adolescent↗
PubMed1995

Weakness in mouse masticatory muscles by repetitive contractions with forced lengthening.

The etiology of myofascial tenderness and pain of masticatory muscles in humans is difficult to understand. Parafunctional oral habits such as tooth grinding or vigorous chewing are thought to be factors. The objective of this study was to determine if masticatory muscles are susceptible to weakness and injury induced by repetitive, dynamic, forced-lengthening contractions. Results would support the hypothesis that contraction-induced injuries could occur in hyperactive masticatory muscles of humans in response to parafunctional oral habits. Mice were anesthetized and randomly assigned to three groups: non-treated controls, treated by repetitive passive jaw opening, or treated by repetitive isometric tetanic contractions with lengthening by jaw opening. In each treatment group, masticatory muscle injury was evaluated by contractile tension, plasma creatine kinase, and muscle glycogen. Contractile tension was determined at different stimulation frequencies and was significantly decreased 5 min, 4 h, and 72 h after repetitive contraction/lengthening. Plasma creatine kinase was significantly elevated at 4 but not at 72 h post-treatment in mice subjected to repetitive contraction/lengthening. Masticatory muscle glycogen was not significantly different in any groups at 4 or 72 h post-treatment. These results indicate that contraction injuries can be induced in masticatory muscle of mice by forced lengthening contractions which simulate eccentric contractions.

Analysis of Variance↗
PubMed1997

Comorbidity between myofascial pain of the masticatory muscles and fibromyalgia.

This study compared myofascial pain of the masticatory muscles to fibromyalgia. Study data show that, in both myofascial pain and fibromyalgia patients, facial pain intensity and its daily pattern and effect on quality of life are very similar. This indicates that fibromyalgia should be included in the differential diagnosis for myofascial pain of the masticatory muscles. However, with the higher prevalence of neurologic and gastrointestinal symptoms, and the stronger words used to describe the affective dimension of pain, it is apparent that fibromyalgia may be a more debilitating condition than myofascial pain of the masticatory muscles. Since the intensity of facial pain was strongly and significantly correlated to the body-pain index in fibromyalgia but not in myofascial pain patients, it can be concluded that facial pain may be part of the clinical manifestations of fibromyalgia, but it is unlikely to be related to body pain in myofascial pain patients. On the other hand, while body pain is episodic in most myofascial pain patients, it is constant and more severe in the majority of fibromyalgia patients. This difference in the pain patterns suggests that body pain in fibromyalgia and myofascial pain could have different etiologies. The lack of correlation between the intensity of pain and the length of time since onset also supports the concept that myofascial pain of the masticatory muscles and fibromyalgia are unlikely to be progressive disorders.

Adult↗