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Three cases of Actinomycosis involving the facial region are presented with a discussion of the problems which can be encountered in the diagnosis and localization of this infectious disease.
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Theoretical grounds were provided for a novel mastication test. In a group of 13 males and 12 females aged 17 to 25 with intact dentition and orthognathic occlusion the mastication was functionally assessed. Mastication effect was enhanced with increasing quantity of mastication movements, decreasing mastication capacity and efficiency. With forced mastication the effect increased, mastication capacity remained unchanged, the efficiency fell. As the test portion increased, the mastication effect, capacity and efficiency all increased. This is the first demonstration of linear correlation between mastication effect and the integral of bioelectric activity of major mastication muscles while mastication movements constant.
Anthropoids and tarsiers are the only vertebrates possessing a postorbital septum. This septum, formed by the frontal, alisphenoid, and zygomatic bones, separates the orbital contents from the temporal muscles. Three hypotheses suggest that the postorbital septum evolved to resist stresses acting on the skull during mastication or incision. The facial-torsion hypothesis posits that the septum resists twisting of the face about a rostrocaudal axis during unilateral mastication; the transverse-bending hypothesis argues that the septum resists caudally directed forces acting at the lateral orbital margin during mastication or incision; and the tension hypothesis suggests that the septum resists ventrally directed components of masseter muscle force during mastication and incision. This study evaluates these hypotheses using in vitro and in vivo bone strain data recorded from the circumorbital region of owl monkeys. Incisor loading of an owl monkey skull in vitro bends the face upward in the sagittal plane, compressing the interorbital region rostrocaudally and "buckling" the lateral orbital walls. Unilateral loading of the toothrow in vitro also bends the face in the sagittal plane, compressing the interorbital region rostrocaudally and buckling the working side lateral orbital wall. When the lateral orbital wall is partially cut, so as to reduce the width of its attachment to the braincase, the following changes in circumorbital bone strain patterns occur. During loading of the incisors, lower bone strain magnitudes are recorded in the interorbital region and lateral orbital walls. In contrast, during unilateral loading of the P3, higher bone strain magnitudes are observed in the interorbital region, and generally lower bone strain magnitudes are observed in the lateral orbital walls. During unilateral loading of the M2, higher bone strain magnitudes are observed in both the interorbital region and in the lateral orbital wall ipsilateral to the loaded molar. Comparisons of the in vitro results with data gathered in vivo suggest that, during incision and unilateral mastication, the face is subjected to upward bending in the sagittal plane resulting in rostrocaudal compression of the interorbital region. Modeling the lateral orbital walls as curved plates suggests that during mastication the working side wall is buckled due to the dorsally directed component of the maxillary bite force which causes upward bending of the face in the sagittal plane. The balancing side lateral orbital wall may also be buckled due to upward bending of the face in the sagittal plane as well as being twisted by the caudoventrally directed components of the superficial masseter muscle force. The in vivo data do not exclude the possibility that the postorbital septum functions to improve the structural integrity of the postorbital bar during mastication. However, there is no reason to believe that a more robust postorbital bar could not also perform this function. Hypotheses stating that the postorbital septum originally evolved to reinforce the skull against routine masticatory loads must explain why, rather than evolving a postorbital septum, the stem anthropoids did not simply enlarge their postorbital bars.
The essential oil and gum of Pistacia lentiscus var. chia, commonly known as the mastic tree, are natural antimicrobial agents that have found extensive uses in medicine in recent years. In this work, the chemical composition of mastic oil and gum was studied by GC-MS, and the majority of their components was identified. alpha-Pinene, beta-myrcene, beta-pinene, limonene, and beta-caryophyllene were found to be the major components. The antibacterial activity of 12 components of mastic oil and the oil itself was evaluated using the disk diffusion method. Furthermore, attempts were made to separate the essential oil into different fractions in order to have a better picture of the components responsible for its antibacterial activity. Several trace components that appear to contribute significantly to the antibacterial activity of mastic oil have been identified: verbenone, alpha-terpineol, and linalool. The sensitivity to these compounds was different for different bacteria tested (Escherichia coli, Staphylococcus aureus, and Bacillus subtilis), which suggests that the antibacterial efficacy of mastic oil is due to a number of its components working synergistically. The establishment of a correlation between the antibacterial activity of mastic oil and its components was the main purpose of this research. Mastic gum was also examined, but it proved to be more difficult to handle compared to the essential oil.
The purpose of this investigation is to detect vertically and buccolingually the occlusal force on the lower first molar in function and to make a two-dimensional vector analysis concerning the occlusal force. The subminiature occlusal force measuring apparatus, which makes use of two-dimension load cell, is developed with the apparatus equipped in the corona on the natural root of the tooth, each occlusal force on the single tooth is detected, when three subjects clench and masticate four kinds of test-foods. Conclusions are as follows: 1. Average occlusal force exerts 3.6 kgf during light clenching and 25.7 kgf during heavy clenching. The average direction of occlusal force against the tooth axis exerts 21.2 degrees during light clenching and 19.5 degrees during heavy clenching. 2. The masticatory force intensity exerts the differences in the phases of mastication and the properties of the test-foods. The maximal masticatory force is 33.1-7.9 kgf during the initial phase and 9.6-5.1 kgf during the last phase of mastication. 3. Average direction of masticatory force against the tooth axis is 19.9 degrees during the initial phase and 27.8 degrees during the last phase of mastication. 4. The operating period of masticatory force per cycle is 0.331 second on the average during the process of mastication. The longest period is in the initial phase of mastication, and as the mastication proceed it gradually decreases.
PURPOSE: The objective of this study was to determine whether elevator and depressor muscle activity during 5 minutes of mastication is affected by the presence of a prosthetic appliance in elderly patients. MATERIALS AND METHODS: Thirty edentulous subjects (EG) and 30 age-matched dentate subjects (DG) were studied. Surface electromyographic (EMG) recordings were obtained from the anterior temporal muscle, masseter muscle, and the submandibular group in the region of the anterior belly of the digastric muscle on the left and right sides. Muscle activity was recorded during maximal voluntary contraction (MVC) in the intercuspal position, maximal opening (Omax), and during 5 minutes of mastication. Elevator muscle activity during mastication was expressed as a percentage of maximal muscle activity in the intercuspal position (%MVC), and depressor muscle activity was expressed as a percentage of maximal opening (%Omax). The effect of 3 factors was investigated using a mixed analysis of variance design: the factor of muscle, with 6 muscles involved; the factor of time (5 minutes of mastication); and the factor of dental status, where some participants had their own natural dentition and others had complete dentures. RESULTS: The results revealed significant effects for the factors "muscle" and e" (P < .001 for the factor "muscle"; P < .001 for the factor "time"). The time by group interaction was significant (P = .046). In the EG, muscle activity gradually decreased during the 5-minute interval of mastication, while in the DG it decreased more rapidly from the first to the third minute and then increased until the fifth minute. There was also a significant effect regarding the presence of natural teeth or complete dentures (P < .034). Complete denture wearers had higher muscle activity relative to %MVC or %Omax than dentate subjects. CONCLUSIONS: Muscle activity during 5 minutes of mastication depended greatly on the presence of the prosthetic appliance, since edentulous subjects had to use higher potentials of muscle activity (%MVC or %Omax) than age-matched dentate subjects, and were unable to increase activity at the end of mastication. The difference in chewing patterns and activity between complete denture wearers and dentate subjects should be explained to patients prior to prosthetic treatment to help them adjust their expectations.
Beef cattle fitted with esophageal (four steers/pasture) or ruminal and duodenal (six calves/pasture; beginning BW +/- SE = 267 +/- 6 kg) cannulas grazed midgrass prairie rangeland (excellent range condition; MIDGRASS) or plains bluestem (Bothriochloa ischaemum var. Plains) pasture (BLUESTEM) in mid-May, late-June, mid-August, and mid-October of 1990 and 1991. Nitrogen in masticate samples collected from MIDGRASS was lowest (P < .05) in June and August across both years. The N in BLUESTEM masticate peaked (P < .05) in August 1990, but N was lowest (P < .05) in August 1991. The detergent fiber content of masticate from both forages increased (P < .05) as the grazing season advanced from May through August; fall regrowth in October occasionally resulted in a small decrease (P < .05) in fiber content. In vitro OM disappearance (IVOMD) followed a pattern similar to N content. The IVOMD of BLUESTEM masticate was greater (P < .05) than that of MIDGRASS masticate. The ruminal ammonia N concentration (milligrams/deciliter) in cattle grazing BLUESTEM (4.5) usually was greater (P < .05) than in cattle grazing MIDGRASS (3.3). In situ OM and N disappearance was greater (P < .05) from BLUESTEM masticate than from MIDGRASS masticate in May, June, and August. The ruminally degraded N:ruminally degraded OM ratio (grams/kilograms) estimated from in situ digestion suggested that cattle grazing MIDGRASS during the mid-summer of both years and BLUESTEM in August 1991 may have been marginally deficient in ruminally degraded N. Plains bluestem pasture would complement MIDGRASS by providing better quality grazing during the mid-summer.
The craniofacial haft resists forces generated in the face during feeding, but the importance of these forces for the form of the craniofacial haft remains to be determined. In vivo bone strain data were recorded from the medial orbital wall in an owl monkey (Aotus), rhesus macaques (Macaca mulatta), and a galago (Otolemur) during feeding. These data were used to determine whether: the interorbital region can be modeled as a simple beam under bending or shear; the face is twisting on the brain case during unilateral biting or mastication; the interorbital "pillar" is being axially compressed during incisor loading and both axially compressed and laterally bent during mastication; and the interorbital "pillar" transmits axial compressive forces from the toothrow to the braincase. The strain data reveal that the interorbital region cannot be modeled as a anteroposteriorly oriented beam bent superiorly in the sagittal plane during incision or mastication. The strain orientations recorded in the majority of experiments are concordant with those predicted for a short beam under shear, although the anthropoids displayed evidence of multiple loading regimes in the medial orbital wall. Strain orientation data corroborate the hypothesis that the strepsirrhine face is twisted during mastication. The hypothesis that the interorbital region is a member in a rigid frame subjected to axial compression during mastication receives some support. The hypothesis that the interorbital region is a member in a rigid frame subjected to lateral bending during mastication is supported by the epsilon1/absolute value epsilon2 ratio data but not by the strain orientation data. The timing of peak shear strains in the medial orbital wall of anthropoids does not bear a consistent relationship to the timing of peak shear strain in the mandibular corpus, suggesting that bite force is not the only external force influencing the medial orbital wall. Strain orientation data suggest the existence of two distinct loading regimes, possibly associated with masseter or medial pterygoid contraction. Regardless of the loading regime, all taxa showed low strain magnitudes in the medial orbital wall relative to the anterior root of the zygoma and the mandibular corpus. The strain gradients documented here and elsewhere suggest that, in anthropoids at least, local effects of external forces are more important than a single global loading regime. The low strain magnitudes in the medial orbital wall and in other thin bony plates around the orbit suggest that these structures are not optimally designed for resisting feeding forces. It is hypothesized that their function is to provide rigid support and protection for soft-tissue structures such as the nasal epithelium, the brain, meninges, and the eye and its adnexa. In contrast with the face of Otolemur, which appears to be subjected to a single predominant loading regime, anthropoids may experience different loading regimes in different parts of the face. This implies that the anthropoid and strepsirrhine facial skulls might be optimized for different functions.
The purpose of this study is to test various masticatory-stress hypotheses about the evolution and function of well-developed browridges of higher primates. This was done by measuring and analyzing patterns of in vivo bone strain recorded from three-element rosette strain gages bonded to the supraorbital region and to other portions of the bony face of Macaca fascicularis and Papio anubis during mastication and incision. The magnitude and direction of the principal strains recorded support Endo's hypothesis that the supraorbital region during mastication and incision is bent in the frontal plane (Endo, 1966). Our data do not, however, support his hypothesis that the supraorbital region is bent more during incision than during mastication. The data also demonstrate that overall levels of supraorbital strain are not larger in more prognathic subjects. Most importantly, the data indicate that the supraorbital region of nonhuman catarrhines is strained very little during mastication and incision. This indicates that there is much more supraorbital bone than is necessary both to counter masticatory loads and to provide an adequate safety factor to failure for these loads. This in turn suggests that the macaque and baboon browridges can be considerably reduced in size and still maintain these required structural characteristics. Thus, our experiments provide no support whatsoever for those hypotheses that directly link browridge morphology to masticatory stress (cf. Endo, 1966; Russell, 1983, 1985). A recent review of Endo's original work indicates that this latter statement is also true for humans (Picq and Hylander, 1989). We conclude, therefore, that there is no good reason to believe that enlarged browridges in living and/or fossil primates are structural adaptations to counter intense masticatory forces. The evolution of browridge morphology in primates is best explained on the basis of factors related to the position of the brain relative to the orbits (Moss and Young, 1960). When these structures are widely separated, as in gorillas, the large intervening space must be bridged with bone. In addition, enough bone must be present within the supraorbital and bridged regions to prevent structural failure due to non-masticatory external forces associated with highly active primates (e.g., accidental traumatic forces applied to the orbits and neurocranium). This requirement results in both pronounced browridges and in much more supraorbital bone than is necessary to counter routine cyclical stress during mastication and incision. This in turn explains why bone strains recorded from the supraorbital region are extremely small relative to other portions of the primate face during mastication and incision.
The trigeminal principal sensory nucleus (NVsnpr) contains both trigemino-thalamic neurons and interneurons projecting to the reticular formation and brainstem motor nuclei. Here we describe the inputs and patterns of firing of NVsnpr neurons during fictive mastication in anaesthetized and paralysed rabbits to determine the role that NVsnpr may play in patterning mastication. Of the 272 neurons recorded in NVsnpr, 107 changed their firing patterns during repetitive stimulation of the left or right sensorimotor cortex to induce fictive mastication. Thirty increased their firing tonically. Seventy-seven became rhythmically active, but only 31 fired in phase with mastication. The others discharged in bursts at more than twice the frequency of trigeminal motoneurons. Most rhythmic masticatory neurons were concentrated in the dorsal part, and those which fired during the jaw closing phase of the cycle were confined to the anterior pole of the nucleus. Most of these cells had inputs from muscle spindle afferents, whereas most of those firing during jaw opening had inputs from periodontal receptors. Non-masticatory rhythmical neurons had receptive fields on the lips and face. The majority of rhythmical masticatory units were modulated during fictive mastication evoked by both the left and right cortices and only four changed their phase of firing when switching from one cortex to the other. When coupled with the finding that NVsnpr neurons exhibit spontaneous bursting in vitro[Sandler et al. (1998) Neuroscience, 83, 891], the results described here suggest that neurons of dorsal NVsnpr may form the core of the central pattern generator for mastication.
Eighty-one sensory neurons in the rostral trigeminal sensory nuclei (main sensory nucleus, nucleus oralis, and the lateral border zone of the motor nucleus) were recorded in urethan-anesthetized rabbits before and during mastication. Receptive-field characteristics were described, and responses evoked by electrical stimulation of the inferior alveolar and infraorbital nerves, sensorimotor cortex, and thalamus were recorded. Forty-four percent of neurons were stimulated by the movements of mastication; nevertheless, evidence is presented that the excitability of the 49 neurons that receive low-threshold mechanoreceptor inputs is depressed during mastication for the following reasons: The spontaneous activity of seven cells was inhibited during movement. The probability of firing in response to stimulation of the peripheral nerve on sensorimotor cortex was decreased during mastication. There was usually a corresponding increase in the latency of the action potentials. Injections of local anesthetic (prilocaine hydrochloride, 4%) into the receptive field of the neuron did not prevent the decrease in excitability during mastication. Fourteen neurons that received inputs from periodontal pressoreceptors were recorded medial to most of the low-threshold group. The excitability of six of these was reduced during jaw closure and during the occlusal phase of movement, that is, within the period in which they would be activated by pressure on the teeth. The rest were tonically suppressed. Eighteen neurons recorded in the lateral border zone of the motor nucleus had receptive fields that were of high threshold or were undefined. They responded to stimulation of the peripheral nerve at high threshold. The excitability of most of these neurons was strongly phase modulated during mastication. They were most excitable during jaw closure or during the occlusal phase of movement and inexcitable during opening. The excitability of the others was tonically depressed. In most cases, the changes in excitability described did not seem to be due to the patterns of activity of the neurons that were generated by the movements. We conclude that the pattern elaborated by the central pattern generator includes selective modifications of sensory transmission. One reason for this is to suppress reflex responses to low-threshold inputs while maintaining the protective response to tissue damage.
The present study was carried out to investigate whether there was any modulation of the spinal monosynaptic reflexes during mastication in the healthy humans and urethane-anesthetized rabbits and to elucidate the central neural mechanisms responsible for the modulation in the urethane-anesthetized rabbits. 1. Human soleus H-reflex was significantly facilitated during the rhythmical jaw movements and rhythmical gum chewing. 2. There was no significant difference in the magnitude of the facilitation between the jaw-opening and -closing phases. 3. In the rabbits, monosynaptic reflex (MSR) volleys recorded from the tibial nerve (TIB) innervating the crural extensors and the common peroneal nerve (CP) innervating the crural flexors tonically increased in amplitude during the masticatory movements induced by either intraoral stimulation or repetitive stimulation of the cortical masticatory area (CMA). 4. Antidromic field potentials in the anterior horn of the lumbar cord evoked by the stimulation of TIB and CP increased during the CMA-induced actual and fictive mastication. 5. There was no significant change in the amplitude of the directly evoked antidromic potential in the primary afferents by intraspinal stimulation during the CMA-induced mastication compared with the resting state. It was concluded that (1) the MSR of the crural muscles undergoes a tonic non-reciprocal facilitation during mastication, (2) the stomatognathic afferents induced during mastication are not essential for the facilitation, and (3) an increase in the excitability of motoneurons is mainly involved in the facilitation of the MSR during mastication.
PURPOSE: This study investigated the possibility of objectively evaluating denture tolerance with different designs of upper major connector through electroencephalographic examination. METHODS: Nine healthy dentate subjects wore five designs of palatal plates (All palatal type, Anterior palatal type, Horseshoe type, Palatal bar type, and Palatal strap type). Electromyograms (EMG) from the masseter and the posterior temporal muscles during mastication and electroencephalograms (EEG) before and after mastication were simultaneously recorded and analyzed. In addition to evaluation by visual analogue scale (VAS), questionnaire surveys consisting of five comfort parameters were also done. RESULTS: VAS values showed uncomfortable feeling for all questions on wearing each type of palatal plate, particularly the Total palatal type, Horseshoe type, and Palatal strap type. There were no significant differences between control and all palatal plates in EMG evaluations. After mastication, %alpha in EEG decreased and %beta increased, both significantly, compared with those before mastication. The slope of 1/f fluctuation in alpha-wave increased after mastication significantly. The variation of EEG (%alpha, %beta and 1/f fluctuation in alpha-wave) before and after mastication were similar to the results of VAS value. CONCLUSIONS: Denture tolerance with different design of upper major connector influenced the higher center of the brain and suggested that the possibility of detecting changes might be indicated electroencephalographically.
The primary purpose of this study was to test various hypotheses about symphyseal stress in primates. First, those patterns of symphyseal strain that would be associated with various hypothetical patterns of symphyseal stress were formulated. Then these hypothetical patterns of stress and strain were tested by comparing the formulated bone strain pattern with actual in vivo symphyseal bone strain patterns. Patterns of in vivo symphyseal bone strain were determined by bonding rosette and/or single-element strain gages to the midline of the middle and lower third of the labial aspect of the symphysis of six adult Macaca fascicularis. Following recovery from the anesthetic, bone strain was recorded during mastication, incision, and isometric biting. Symphyseal bone strain was also recorded during yawning, licking, and threat behaviors. The data suggest that during the power stroke of mastication, the macaque symphysis is predominately sheared dorsoventrally and/or twisted about a transverse axis and bent by lateral transverse bending of the mandibular corpora. During lateral transverse bending of the mandibular corpora, the labial aspect of the macaque symphysis experiences compressive bending stress, while the lingual aspect experiences tensile bending stress. During the opening stroke of mastication and during other jaw opening behaviors, the macaque symphysis is bent by medial transverse bending of the mandibular corpora. At this time the labial aspect of the symphysis experiences tensile bending stress, while its lingual aspect experiences compressive bending stress. During both the power and opening strokes of mastication, the macaque mandible is bent in the plane of its curvature, and therefore the mandible acts as a curved beam. This is important because it results in elevated levels of stress along the lingual aspect of the macaque symphysis, particularly during the power stroke of mastication. During the power stroke of incision, the local effects of the bite force are unknown; however, at this time the lower half of the macaque symphysis is both sheared dorsoventrally and bent due to twisting of the mandibular corpora about their long axes. The results of this stress analysis have implications for understanding the mechanical attributes of symphyseal structure. In order to counter dorsoventral shear, the most important symphyseal attribute is to have adequate cross-sectional area of bone in the plane of the applied stress. In contrast, both the cross-sectional area of bone and symphyseal shape is important in order to counter stress effectively during symphyseal torsion and the three symphyseal bending regimes.(ABSTRACT TRUNCATED AT 400 WORDS)
Single-element and/or rosette strain gages were bonded to mandibular cortical bone in Galago crassicaudatus and Macaca fascicularis. Five galago and eleven macaque bone strain experiments were performed and analyzed. In vivo bone strain was recorded from the lateral surface of the mandibular corpus below the postcanine tooth row during transducer biting and during mastication and ingestion of food objects. In macaques and galagos, the mandibular corpus on the balancing side is primarily bent in the sagittal plane during mastication and is both twisted about its long axis and bent in the sagittal plane during transducer biting. On the working side, it is primarily twisted about its long axis and directly sheared perpendicular to its long axis, and portions of it are bent in the sagittal plane during mastication and molar transducer biting. In macaques, the mandibular corpus on each side is primarily bent in the sagittal plane and twisted during incisal transducer biting and ingestion of food objects, and it is transversely bent and slightly twisted during jaw opening. Since galagos usually refused to bite the transducer or food objects with their incisors, an adequate characterization of mandibular stress patterns during these behaviors was not possible. In galagos the mandibular corpus experiences very little transverse bending stress during jaw opening, perhaps in part due to its unfused mandibular symphysis. Marked differences in the patterns of mandibular bone strain were present between galagos and macaques during the masticatory power stroke and during transducer biting. Galagos consistently had much more strain on the working side of the mandibular corpus than on the balancing side. These experiments support the hypothesis that galagos, in contrast to macaques, employ a larger amount of working-side muscle force relative to the balancing-side muscle force during unilateral biting and mastication, and that the fused mandibular symphysis is an adaption to use a maximal amount of balancing-side muscle force during unilateral biting and mastication. These experiments also demonstrate the effects that rosette position, bite force magnitudes, and types of food eaten have on recorded mandibular strain patterns.
High-speed, high-resolution data (frontal plane) were collected from 6 Sprague-Dawley rats by opto-electronic mandibular tracking (OMT), followed by microcomputer analysis of individual chew cycles. Mastication comprised rapidly alternating, unilateral cycles with variable degrees of lateral translation. There was no evidence of bilateral mastication (simultaneous chewing on both left and right sides). Analysis revealed significant (p less than or equal to 0.01) differences between whole-cycle, slow-open (SO) phase, fast-open (FO) phase, fast-close (FC) phase, and slow-close (SC) phase duration, height, width, and velocity during mastication of standardized foods (pellets and slurry). Regression analysis between millimetres of vertical/horizontal movement (Y) and vertical/horizontal velocity (X) revealed differences during these mastications. Whole-cycle and SO-phase regression equations had the greatest disparity between pellet and slurry chewing for both vertical and horizontal movements. Correlation coefficient analysis between movement and velocity data indicated that (1) vertical correlations were smaller than horizontal ones, (2) slurry correlations were greater than pellet ones except for whole cycles, (3) FO phase had the largest movement/velocity correlation during both pellet and slurry mastication, and, that (4) SC phase had the smallest movement/velocity correlation. Vertical and horizontal movements during pellet FC phase were significantly (p less than or equal to 0.01) greater than slurry ones; both vertical and horizontal movements during pellet SC phase were significantly (p less than or equal to 0.01) less than slurry ones. This phase-isostasy was also detected during vertical movements in SO and FO phases.(ABSTRACT TRUNCATED AT 250 WORDS)