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At least 991 records · Page 55Linked to original sources

PubMed2004

Craniomandibular pain, oral parafunctions, and psychological stress in a longitudinal case study.

In a single case study, the most frequently suggested contributing factors to craniomandibular pain, viz., oral parafunctions and psychological stress, were studied in more detail. During a 13-week study period, questionnaires were completed, in which, among others, jaw muscle pain, bruxism behaviour, and experienced/anticipated stress were noted. During about 40% of the nights, nocturnal masticatory muscle activity (NMMA) was recorded, using single-channel electromyography (EMG). The number of NMMA events per recorded hour was scored, using a detection threshold of 10% of the maximum voluntary contraction level. This threshold was established in a separate study, in which EMG was compared with polysomnography. Stepwise regression analyses indicated, that morning jaw muscle pain could be explained by evening jaw muscle pain for 64% and by alcohol intake for another 2%. In turn, evening jaw muscle pain was explained by daytime clenching for 56% and by vacuum sucking of the tongue for an additional 6%. Finally, daytime clenching was significantly explained by experienced stress for 30%. Data of the recorded nights showed, that variations in NMMA did not contribute to variations in morning jaw muscle pain. This case study corroborates the paradigm that experienced stress may be related to daytime clenching and, in turn, to evening and morning jaw muscle pain.

Electromyography↗

PubMed1989

Differing effect of agonist and antagonist muscle relaxants on cat jaw muscles.

Mouth closure and an increased resistance to mouth opening follow succinylcholine administration in humans. To elucidate the effects of succinylcholine on masticatory muscle function, mouth opening in the cat, produced by a constant test force, was measured during steady state halothane anesthesia. After baseline measurements, either succinylcholine (0.3 mg.kg-1 of body weight) or vecuronium (0.1 mg.kg-1 of body weight) was infused intravenously, and mouth opening measurements were repeated for up to 30 min. Concomitantly, muscle relaxant effect was quantified by measurement of the neurally-evoked tibialis anterior muscle response. All animals given succinylcholine displayed active jaw closure, which was followed by an increased resistance to mouth opening. This increased resistance was present after cessation of fasciculations and during complete twitch suppression. It lasted beyond the time at which the limb muscle twitch had fully recovered. Vecuronium administration was associated with a decreased resistance to mouth opening without a closing action. The initial jaw closure and the subsequently increased resistance to mouth opening after succinylcholine administration during halothane anesthesia in the cat are comparable with mouth opening changes after succinylcholine administration during inhalation anesthesia in humans. The cat may serve as an animal model for study of the mechanisms involved in responses of jaw muscles to succinylcholine with use of techniques inappropriate in humans.

Animals↗

PubMed2002

[Functional state of maxillofacial muscles in patients with dentition defects depending on the number of missing antagonist pairs].

Changes in the functions of maxillofacial muscles were studied in patients with first-class defects of dentition. The mean biopotential of masticatory muscles in patients lacking 1 antagonist pair is 30.4% and in those lacking 4 pairs 59.5% lower vs. the norm. The bio-excess coefficient is 23.7% decreased in subjects lacking 1 antagonist pair and 52% decreased in those lacking 4 antagonist pairs. Hence, the function of maxillofacial muscles depends on the extent of dentition defect.

Adult↗

PubMed1987

Influence of food restriction during gestation on craniofacial growth of the weanling rat.

Holtzman rats were subjected to food restriction during gestation or lactation, or both periods (overall stress). At weaning, male pup skulls were measured and female brains and cranial masticatory muscles were weighed and a neuromuscular index was calculated. It was found that gestational protein-calorie malnutrition (PCM) without suckling restoration accounted for about 30% of the growth delay observed under overall stress. That effect disappeared after a normal suckling restoration. Under the same conditions of maternal food restriction in both periods, growth delay in the offspring was greater during lactation than gestation. As in lactation, craniofacial changes during gestational restriction were due to an adjustive response of bone growth to PCM. This response seemed to accrue from an altered relationship between the growth of the brain-less sensitive and highly restorable-and the growth of the masticatory muscles-more sensitive and less restorable. Some degree of delay in orthocephalization would be the skeletal outcome of such adjustive neuromuscular response.

Animals↗

PubMed1989

[Physiotherapy and muscle dysfunction].

This article gives information about the role of the physiotherapist on the patient with a craniomandibular dysfunction, caused by a masticatory muscle dysfunction. The approach of the physiotherapist is discussed and information about the relevant etiological factors and symptoms are described. The diagnostic procedure and therapeutic possibilities are considered next to the multidisciplinary approach.

Adolescent↗

PubMed2006

Visual input effect on EMG activity of masticatory and postural muscles in healthy and in myopic children.

AIM: The purpose of this study was to evaluate the activity of Anterior Temporal, Masseter, Sternocleidomastoid and Anterior Digastric muscles in response to changes in visual input in subjects with defective vision by means surface electromyography. METHODS: A total of 20 children, aged between 7 and 13 years, were evaluated. In the study group 10 children with myopic defects were enlisted, selected among patients afferent to the paediatric dentistry clinic. Ten subjects with normal vision, the control group, were chosen through the Pair Matching procedures, so that each myopic child had a matching age case control. Both study group and control group patients maintained mandible at rest with teeth apart and were submitted to a 15-sec electromyography (EMG) recording with closed eyes followed by a 15-sec EMG recording with open eyes. RESULTS/STATISTICS: The Root Mean Square (RMS) values were elaborated to obtain means and standard deviation. Statistical analysis was undertaken using the Student's T-test for independent samples. Analysis of the results demonstrated a marked difference in tonic activity of temporal anterior muscles at open eyes between the myopic and the normal groups. CONCLUSION: The findings suggest that in the evaluation of masticatory muscles tenderness, such as episodic tension type headaches, attention should be paid to vision defects.

Adolescent↗

PubMed2003

Relation between vertical facial morphology and jaw muscle activity in healthy young men.

The aim of the current investigation was to quantitatively analyze the relation between the activity of masticatory muscles and the inclination of the mandibular plane in a group of 73 healthy white men aged 20-36 years. The three-dimensional coordinates of soft-tissue landmarks gnathion and left and right gonion were digitized using an electromagnetic computerized instrument, the orientation of mandibular plane relative to the true vertical was computed and projected on the anatomical sagittal plane. The electromyographic (EMG) potentials of left and right masseter and temporalis anterior during maximum voluntary teeth clenching were recorded, and the mean EMG amplitude calculated. Two groups of men with opposite facial morphology were then selected: all men with a steep mandibular plane (higher than the mean plus one standard deviation) entered a first group (10 'long face' subjects), while all men with a relatively more horizontal mandibular plane (lower than the mean minus one standard deviation) entered a second group (13 'short face' subjects). Mean EMG potentials computed in the two groups were compared by using Student's t -test for independent samples. All the EMG potentials recorded during maximum voluntary clench in the 'long face' men were lower than that recorded in the 'short face' men, with statistically significant differences for all four analyzed muscles (p < 0.05). In conclusion, a non-invasive three-dimensional method confirmed that facial morphology and muscular function are significantly related, at least in men with a sound stomatognathic apparatus.

Adult↗

PubMed2001

Effects of prolonged gum chewing on pain and fatigue in human jaw muscles.

Gum chewing has been accepted as an adjunct to oral hygiene, as salivary stimulant and vehicle for various agents, as well as for jaw muscle training. The aim of this study was to investigate the effects of prolonged gum chewing on pain, fatigue and pressure tenderness of the masticatory muscles. Fifteen women without temporomandibular disorders (TMD) were requested to perform one of the following chewing tasks in three separate sessions: chewing a very hard gum, chewing a soft gum, and empty-chewing with no bolus. Unilateral chewing of gum or empty chewing was performed for 40 min at a constant rate of 80 cycles/min. In each session, perceived muscle pain and masticatory fatigue were rated on visual analog scales (VAS) before, throughout, and after the chewing task. Pressure pain thresholds (PPTs) of masseter and anterior temporalis muscles were assessed before and immediately after the chewing tasks, and again after 24 h. The VAS scores for pain and fatigue significantly increased only during the hard gum chewing, and after 10 min of recovery VAS scores had decreased again, almost to their baseline values. No significant changes were found for PPTs either after hard or soft gum chewing. The findings indicate that the jaw muscles recover quickly from prolonged chewing activity in subjects without TMD.

Adult↗

PubMed1980

Craniofacial, occlusal, and masticatory anatomy in bats.

Skull measurements from ten anatomically and behaviorally diverse genera of bats show marked variation in positioning of the face upon the cranium but a relative stability of the site of the mandibular fossa. Factors associated with maintaining occlusion in bats which exhibit dorsally-inclined maxillary toothrows include dorsally angulated mandibular bodies and elevated condyles. Detailed comparisons are made between the generalized morphology of Myotis lucifugus and anatomical extremes represented by Rhinolophus lepidus, Mormoops megalophylla, and Pteropus giganteus. In these four bats, masticatory movements of the teeth and temporomandibular joints, despite marked interspecific variation, appear to relate to a common pattern. The beginning of jaw opening is important for maximal occlusal shear, particularly in Pteropus. Observed differences in the histology of the temporomandibular joints reflect postulated differeces of pressure patterns within them. Differences in skeletal and dental morphology, together with variations in size and orientation of masticatory muscles, could account for known and postulated differences in the four respective chewing patterns, with no major variation from the known muscle firing sequences of Myotis lucifugus. Basic patterns of interaction between central nervous system and masticatory musculature would therefore appear to have undergone minimal modification. This accords with the concept that neural control of mastication is a relatively conservative mechanism; as such, it would appear to have imposed significant limitation upon adaptive change in bats.

Animals↗

PubMed1978

The myofascial pain dysfunction: dental symptoms and psychological and muscular function. An overview. A preliminary study by team approach.

Patients with myofascial pain dysfunction (MPD) are traditionally seen by dentists. No organic lesions are found, and there is accumulating evidence that psychological factors influence both the onset and the development of the disorder, thus calling for a multiprofessional investigation approach. This report presents a preliminary study by a team consisting of a psychiatrist, a dentist and a physiotherapist. 25 patients with MPD diagnosis were examined. Almost all of the patients had tense muscles in neck and back, indicating that muscular tension is not a local phenomenon in the masticatory muscles. It was possible to distinguish two main categories of MPD patients, the 'typical MPD patients' and the 'multiproblem patients'. Problems that need further investigation are pointed out.

Adolescent↗

PubMed1978

[Electromyographic findings on the external pterygoid muscle during activator therapy for distal bite].

First the author describes how the activator after Herren works, and the part played by the masticatory muscles. In a long-term study the functional behaviour of the external pterygoid muscle during activator therapy on children was investigated by electromyographic recording. Its results are discussed and compared to conclusions from experiments carried out by Petrović et al. concerning the growth of condylar cartilage in rats treated with a device of the postural hyperpropulsive type ("hyperpropulseur").

Activator Appliances↗

PubMed1997

Histopathologic and biochemical changes in the muscles affected by distraction osteogenesis of the mandible.

Lengthening of the canine mandible using an intraoral distraction device was performed in order to study the effects of distraction on the associated muscles of mastication. Biopsies of the masseter and digastric muscles were taken after lengthening at four different time intervals to assess the temporal changes in the masticatory muscles of 10 dogs. Biopsies of the muscles on the contralateral side also were taken from 6 of these dogs before lengthening to establish a control group. Each biopsy was analyzed histologically and spectophotomerically for RNA, DNA and protein content. The digastric muscle underwent transient atrophy with initiation of distraction but regenerated completely after 48 days of fixation. The masseter muscle was unchanged initially but showed evidence of atrophy only after 20 mm of distraction it continued to exhibit evidence of atrophy during fixation. Protein synthesis was decreased significantly during periods of atrophy in the masseter; no such change was noted in the digastric. Unlike the masseter, the digastric fibers lie in a plane parallel to the vector of distraction. These findings suggest that any muscle affected by skeletal distraction in the same plane or vector (e.g., digastric) adapts with compensatory regeneration and hypertrophy. Moreover, those muscles lying in a different plane (e.g., masseter) show persistent evidence of atrophy with decreased protein synthesis.

Animals↗

PubMed1990

Treatment of temporomandibular joint dysfunction by intraoral vertical ramus osteotomy.

The purpose of this study was to determine if the intraoral vertical ramus osteotomy is an effective treatment for anterior disk displacements with reduction and associated temporomandibular joint pain and dysfunction. Success with this procedure was predicated on producing a more functional articular disk-condyle relationship by anterior and inferior repositioning of the condyle. The prospective study was undertaken of nine (eight female and one male) patients (mean age of 25.8 years) with anterior disk displacement with reduction and associated temporomandibular joint pain and dysfunction (mean duration of pain of 6.8 years). History, clinical dysfunction, and pain indices were used to determine the frequency and severity of temporomandibular joint dysfunction. The incidence of ear pain, muscle fatigue, tinnitus, headaches, and clicking was also assessed. The severity of the pain experience in the masticatory muscles and temporomandibular joints was evaluated through the use of a pain index. The severity of the pain experience and temporomandibular joint dysfunction in all of the patients was significantly reduced or totally eliminated during the period of followup. Surgical treatment of anterior disk displacement with reduction by intraoral vertical ramus osteotomy resulted in improved temporomandibular joint function and resolution of symptoms.

Adolescent↗

PubMed1987

The mandibular rest position and electromyography--a review.

The objective of clinical methods for the establishment of the rest position of the mandible is to establish a position at which masticatory muscle activity is minimal. Several methods are in clinical use but these methods may not elicit a position which is coincident with the lowest level of muscle activity as determined electromyographically.

Electromyography↗

PubMed1979

Histochemical characteristics of the masseter and temporalis muscles of the rhesus monkey (Macaca mulatta).

The histochemical characteristics, cross-sectional area and capillary of the skeletal muscle fibers of the anterior and posterior regions of the superficial masseter and the temporalis muscles are described for juvenile and adult rhesus monkeys of both sexes. Slow twitch fatigue resistant (S), fast twitch fatigue resistant (FR) and fast twitch fatigable (FF) fibers were found in varying proportions throughout the muscles; however some fibers with an intermediate myofibrillar ATPase activity were observed in the anterior masseter. No significant differences for any of the variables were found between male and female juveniles for a specific muscle sample site. However, considerable variation was found between juvenile and adult and between adult male and female monkeys in the percentages of different fiber types and the cross-sectional area of fibers in specific regions of the superficial masseter and temporalis muscles. We conclude from these observations that significant differences in function exist both within and between the different masticatory muscles of rhesus monkeys. Functional differences may result from the pronounced sexual dimorphism evident in the dentofacial complex of the rhesus monkey.

Adenosine Triphosphatases↗

PubMed2005

Craniodental biomechanics and dietary toughness in the genus Cebus.

The tufted capuchin (Cebus apella) has been used in a number of comparative studies to represent a primate with craniofacial morphology indicative of hard-object feeding. Researchers have specifically referred to the tufted capuchin as a seed predator. Craniofacial features exhibited by the tufted capuchin, such as thick cortical bone in the mandibular corpus and symphysis, and a broad face associated with large masticatory muscles, permit the production and dissipation of relatively high masticatory forces. These morphologies, however, cannot distinguish between the tufted capuchin's propensity to exert higher forces when opening food with its anterior dentition or with its cheek teeth. It is also unclear whether these are adaptations for biting or chewing foods. This study uses a constrained lever model to compare the masticatory adaptations of C. apella to other cebids and atelids. Results show that the temporalis and masseter muscles in C. apella and C. olivaceus are more anteriorly positioned relative to nine other platyrrhine taxa. This condition, which appears to be ancestral among the Cebinae, increases force production at the incisors and canines while compromising third molar function. Cebus apella, has exaggerated this pattern. Field data on dietary toughness show that both capuchins typically select foods of low toughness, but on occasion, C. apella ingests food items of exceptional toughness. Thus, C. apella appears to maintain these biomechanical relationships by producing particularly high but relatively infrequent bite forces, particularly at the incisors and canines. However, adaptations for anterior dental use do not tightly constrain the diet of Cebus apella. This approach can be used to clarify the dietary adaptations of fossil taxa.

Anatomy, Comparative↗

PubMed1996

Signs and symptoms of temporomandibular disorders in adolescent violin players.

Signs and symptoms of temporomandibular disorders (TMDs) and the frequency of radiologically observed abnormalities in the condyles of temporomandibular joints (TMJs) of adolescent violin players (VP group) were investigated in a group of 31 music students and in their age- and sex-matched controls (C group). All subjects underwent a routine clinical stomatognathic examination, a standardized interview, and radiography of the condyles. The VP group reported a higher frequency of the subjective symptoms: pain in the TMJ when chewing, a feeling of stiffness in the TMJ, and clenching of the teeth. Clinically, the VP group showed a greater range of maximal protrusion and of maximal laterotrusion to the right, and a greater frequency of deviation to the right on opening. They also showed more palpatory tenderness in the masticatory muscles and pain in the TMJ on maximal opening. The number of playing years and the number of weekly playing hours correlated with several signs and symptoms of TMDs. In terms of radiologic findings in the condyles of the TMJs there was no difference between the groups. It is concluded that intense violin playing may have a predisposing role in the etiology of TMDs in adolescence.

Adolescent↗

PubMed1985

Temporalis muscle-galea flap in facial reanimation.

When substantial destruction of the facial nerve occurs as a result of trauma, measures to animate the face, such as transfer of masticatory muscles, must be considered. Unfortunately, these techniques have been limited by a difficult reeducation process for the patient and failure of these muscles to reach sufficiently large areas. A method of extending the temporalis muscle with galea allows rotation into important areas of the face. Case presentations illustrate specific indications, advantages, and disadvantages of this technique.

Adult↗