Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Bite Force”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19Linked to original sources
PubMed1992

Application and validation of a three-dimensional mathematical model of the human masticatory system in vivo.

A previously described three-dimensional mathematical model of the human masticatory system, predicting maximum possible bite forces in all directions and the recruitment patterns of the masticatory muscles necessary to generate these forces, was validated in in vivo experiments. The morphological input parameters to the model for individual subjects were collected using MRI scanning of the jaw system. Experimental measurements included recording of maximum voluntary bite force (magnitude and direction) and surface EMG from the temporalis and masseter muscles. For bite forces with an angle of 0, 10 and 20 degrees relative to the normal to the occlusal plane the predicted maximum possible bite forces were between 0.9 and 1.2 times the measured ones and the average ratio of measured to predicted maximum bite force was close to unity. The average measured and predicted muscle recruitment patterns showed no striking differences. Nevertheless, some systematic differences, dependent on the bite force direction, were found between the predicted and the measured maximum possible bite forces. In a second series of simulations the influence of the direction of the joint reaction forces on these errors was studied. The results suggest that they were caused primarily by an improper determination of the joint force directions.

Adult↗
PubMed1995

Functional characteristics of retrognathic patients before and after mandibular advancement surgery.

PURPOSE: The purpose of this investigation was to compare morphologic parameters and functional performance between controls and a sample of patients with mandibular retrognathia prior to surgical correction, and to examine how oral motor function adapts after treatment. PATIENTS AND METHODS: Twenty-four retrognathic female patients were compared with 26 female controls before and up to 3 years after mandibular advancement surgery. Measures of skeletal morphology, mandibular range of motion, maximum isometric bite force, and levels of electromyographic activity in the anterior and posterior temporalis and masseter muscles during isometric bites were made on all subjects over time. One-way analysis of variance was used to compare the controls, the patients before surgery, and the patients after surgery. RESULTS: Surgical lengthening of the mandible averaged 7.3 mm, bringing most skeletal measures into the normal range. There were no significant differences in jaw muscle mechanical advantage between patients and controls before surgery, but surgery significantly reduced mechanical advantage of the anterior temporalis and masseter muscles. Jaw hypomobility was apparent at 6 weeks after surgery, but returned to normal values within 12 to 24 months. Before surgery the patients had maximum isometric bite forces less than half those of controls. Bite forces steadily increased after surgery, approaching normal values within 2 years. Before surgery the patients' muscle activity levels per unit of bite force were equivalent to those of controls or somewhat higher. After surgery some of the patients' muscles had significantly lower levels of muscle activity per unit of bite force than did controls. CONCLUSION: The results of this study suggest that correction of mandibular retrognathia by mandibular advancement surgery produces some significant functional benefits.

Adolescent↗
PubMed2003

Occlusal and TMJ loads in subjects with experimentally shortened dental arches.

To determine whether shortened dental arches (SDAs) cause functional overloading of the teeth and the temporomandibular joints, which has been implicated in periodontal diseases and temporomandibular disorders, we investigated the influences of SDA on occlusal and joint loads. Bite force and masticatory muscle electromyograms were recorded in five dentate subjects who clenched maximally on intra-oral appliances, creating symmetrical SDAs experimentally. Muscular forces estimated from the recorded electromyograms were fed into a finite element jaw model for calculating bite forces and joint loads. Comparison between the measured and the calculated bite forces ensured that the joint loads were representative. The bite force on each tooth increased with missing molar occlusions, while joint loads decreased. The bite force per root surface area was always greatest on the most posterior tooth, and these values were most constant. The findings provide no evidence that SDA causes overloading of the joints and the teeth, which suggests that neuromuscular regulatory systems are controlling maximum clenching strength under various occlusal conditions.

Adaptation, Physiological↗
PubMed1990

Electromyographic heterogeneity in the human temporalis muscle.

This study examined the possible existence of regional differences in activation of the temporalis muscle. Since the muscle is fan-shaped, its fibers pull in different directions. This suggests regional specialization for different motor tasks. EMG activity was registered by six bipolar fine-wire electrodes inserted anteroposteriorly across the muscle belly. Muscle signals were recorded during different static bite tasks for which both the direction and magnitude of bite force were specified. The results showed that the ratio of activities of the six muscle regions changed with the direction of bite force. This indicates a partitioning of the excitatory command to the muscle's motoneuron pool. Alteration in activity with changing bite-force direction was generally the smallest in the anterior-most region of the muscle, the largest in the posterior-most region, and the intermediate in the interjacent regions. Generally, all muscle regions exhibited the highest EMG activity when the bite force was in an approximately posterolateral direction. The muscle was activated uniformly only for bites in this preferential direction. Activity in the regions appeared to be scaled up or down in a linear way according to the desired bite-force level. The results indicate that the direction of pull of the muscle and the maximal force it can produce are not fixed, but depend on the direction of bite force.

Adult↗
PubMed2004

Effects of cross-sectional area on human bite studied with raw carrot and surimi gel.

The effects of the cross-sectional area of food samples on bite force with molar teeth were investigated using raw carrots and surimi gels. We evaluated human bite force for food samples with different sizes between the upper and lower molars using a multiple-point sheet sensor and electromyography (EMG). The bite force curve and EMG clearly showed textural characteristics of the carrot and gel. In particular, the first peak in the bite curves corresponded to breaking point in the compression test. With increasing cross-sectional area of both foodstuffs, the bite force and contact area increased and the average stress to which the specimen was subjected (mean stress) tended to decrease, while the stress produced between the teeth and the specimen (active stress) did not change. Chewing rhythm and EMG activities were not greatly influenced by sample size. These findings suggest that higher bite force might cause difficulty in biting food with a larger cross-sectional area.

Bite Force↗
PubMed1995

Functional evaluation after TMJ surgery.

Oral function was evaluated in 30 patients (25 women and five men) after TMJ surgery by means of bite force measurements. Twenty-seven discectomies and three condylectomies had been performed. The follow-up period was, on average, 2.5 years. The mean bite force values on the function level 'biting as when chewing' was for the whole group 125.3 N on the right side and 128.8 N on the left side. The maximal bite force was on average 362.5 N and maximal endurance time on average 32 s. All test results showed big ranges. No significant differences between right and left side or operated and non-operated side could be found on the tested function level 'biting as when chewing'. The found bite force values were high in comparison with another similar study. The results were also compared with another group of patients (n = 6) who were examined before and 6 months after surgery. As far as bite force reflects oral function the results are indeed very encouraging.

Bite Force↗
PubMed1991

Biomechanical changes in the rabbit masticatory system during postnatal development.

Using dissection, biometry, and two three-dimensional mechanical models, the postnatal changes of the rabbit masticatory muscles were studied by analyzing their three-dimensional orientation, their strength and fiber lengths, and certain functional consequences of these changes. The first mechanical model uses length-tension relationships of the muscles and predicts the maximum bite force as a function of mandibular position. It shows that young rabbits are able to generate large bite forces at a wider gape than adult animals and that the forces are directed more vertically. In spite of the postnatal changes the mechanical advantage of the system remains about equal. However, the muscles are reoriented so that they exert a larger degree of parallel action, suggesting a larger bite force magnitude but a smaller range of bite force directions. The second model-predicts this range. It shows that during postnatal development a relative gain occurs in the possibilities for the system to exert forces directed rostrodorsally. In all other directions the capability to exert force decreases. The results suggest that during development the possibility of the system to generate large bite forces is increased at the cost of a restriction in the range of jaw excursion and that a restriction takes place in the range of possible force directions that can be exerted at the molars.

Animals↗
PubMed1988

A 10-year follow-up study of the masticatory system after treatment with osseointegrated implant bridges.

Twenty-one patients with osseointegrated implant bridges (OIB), with an average age of 65 yr, were functionally examined at a 10-yr follow-up. Altogether 27 OIBs, supported by 138 fixtures, were examined. The examination comprised an anamnestic and clinical examination and registration of bite force. 90% of the patients were very satisfied with the outcome of the treatment. According to the anamnestic dysfunction index (Ai), 80% of the patients were symptom free in their masticatory system. The occlusal state was found to be good. Seventy-five percent of the patients were found to have only mild dysfunction of their masticatory system or to be symptomless according to the clinical dysfunction index (Di). The bite force ranged from 3 to 118 N at gentle biting, from 25 to 250 N at "biting as when chewing" and from 77.5 to 495.5 N at maximal bite force. On average the bite force had improved significantly at all bite-force levels tested compared to an examination 10 yr earlier. It is concluded that oral function in patients with OIBs is very favorable.

Aged↗
PubMed1997

Effect of mandibular setback surgery on occlusal force.

PURPOSE: This study investigated the effect of mandibular setback surgery on occlusal force and evaluated the extent to which postsurgical changes in such force can be explained by the type of operation, the duration of maxillo-mandibular fixation (MMF), and the changes in the mechanical advantage of the jaw musculature. MATERIALS AND METHODS: Maximal molar bite force was measured before surgery and at MMF removal, and 3, 6, and 12 months thereafter in 26 patients with mandibular prognothism. To correlate bite force and skeletal change, the cephalometric tracings were measured, tabulated, and statistically analyzed. RESULTS: Mean bite force was 13.7 kg before surgery, 7.6 kg at MMF removal, 14.2 kg at 3 months, 19.7 kg at 6 months, and 26.1 kg at 12 months post-surgery. The bite force was positively correlated with the surgical change in mandibular plane angle and mandibular body length. The recovery of bite force was significantly affected by the type of operation and duration of MMF. CONCLUSIONS: To hasten recovery and increase bite force after orthognathic surgery, long periods of MMF and injury to the masticatory muscles should be avoided.

Adolescent↗
PubMed2005

Alterations of temporalis muscle contractile force and histological content from the myostatin and Mdx deficient mouse.

Myostatin (GDF8) and dystrophin are critical molecules for muscle organisation. Myostatin is involved in regulating muscle growth and development, whereas dystrophin is part of the dystrophin-glycoprotein complex (DGC), which anchors the cytoskeleton to the sarcolemma. We examined temporalis muscle morphology and function in myostatin deficient and dystrophin deficient (Mdx) mice in order to determine how myostatin and dystrophin affect bite force and muscle fibre composition. Bite forces from 4-month-old myostatin-/-, dystrophin deficient (Mdx) and normal control mice were measured by load cell and field stimulation of the temporalis muscle. Tissue sections were stained with haemotoxylin and eosin (H&E) and the periodic acid-Schiff reaction (PAS) to assess morphology and fibre type differences. A positive relationship between bite force and muscle mass for both genetic models was observed. Both Mstn-/- and Mdx mice showed significant elevation in bite force and muscle mass. Histological examination revealed greater muscle fibre cross-sectional area variability in Mdx mice (ANOVA, F=5.6, P<0.01). Surprisingly, the Mstn-/- mice demonstrated a disproportionate increase in bite force at higher stimulation frequencies with comparison of regression lines for force-frequency data (ANOVA, F=3.46, P<0.07). Muscle fibre typing using a PAS staining technique revealed significantly more type IIx/b glycolytic muscle fibres in the Mstn-/- mice. Our results suggest that histopathologies associated with Mdx mice did not diminish gross temporalis structure or function, whilst the force-frequency changes associated with Mstn-/- mice were reflected in an elevation of type IIx/b fibres.

Animals↗
PubMed1995

Masseter muscle activity in denture wearers with superior and poor masticatory performance.

A cross-sectional study tested the hypothesis that denture wearers with superior and poor chewing ability use similar masseter muscle effort and biting forces during mastication. Masticatory performance tests on the preferred chewing side and swallowing threshold tests were conducted with peanuts and carrots in 70 denture wearers, 35 with superior (SP) (mean 46.3%) and 35 with poor (PP) (mean 30.7%) masticatory performance. Right and left masseter muscle electromyographic (EMG) activity was recorded during the masticatory tests and peak bite force during chewing was estimated from the bite force--EMG ratios on guided maximal biting trials. Bite force under maximal pressure did not differ significantly between the two groups. Neither the total mean EMG activity of the preferred and nonpreferred side masseter muscles nor the mean peak biting forces exerted by the two groups differed significantly (p > 0.05). This was true when denture wearers restricted chewing to their preferred side for a given number of strokes or chewed the test food freely until ready to swallow. The only significant differences (p < 0.05) were evident in the ratios of the preferred to nonpreferred side masseter EMG activity during chewing. The ratios were 1.2 for peanuts and 1.3 for carrots in the SP group compared to 1.8 for both foods in the PP group. Similar patterns of bilateral activity in the SP group and unilateral activity in the PP group were evident for the swallowing threshold tests. The results indicated that application of more equivalent force by the right and left masseter muscles during unilateral chewing is consistent with improved chewing ability in denture wearers.

Adult↗
PubMed2005

The role of peripheral N-methyl-D-aspartate receptors in muscle hyperalgesia.

The present study demonstrates that intramuscular administration of N-methyl-D-aspartate receptor antagonist AP5 dose-dependently attenuates complete Freund's adjuvant (CFA) induced muscular hyperalgesia. CFA significantly reduced mean bite force and success rate in the rats trained to produce a specific bite force. Pretreatment with AP5 reversed the overall magnitude of reduction in mean bite force and success rate in CFA inflamed rats, and significantly facilitated the recovery of these measures to pre-injection level. AP5 treatment 1 day after the CFA injection had little effect on CFA-mediated changes in bite force measurements. These data suggest that peripheral N-methyl-D-aspartate receptors play a critical role in the development of persistent muscle hyperalgesia, and provide important new insights for therapeutic alternatives that can be directed at the periphery.

2-Amino-5-phosphonovalerate↗
PubMed1993

An electromyographic study of whether the digastric muscles are controlled by jaw-closing proprioceptors in man.

Whether in the oral system the digastric muscles (which lack muscle spindles) are under the control of proprioceptive information from the masseter muscles (which contain muscle spindles) was investigated by analysing whether and how the masseters and digastrics showed coordinated behaviour during a static, forceful bite. Subjects were asked to maintain a 100-N force for 15 s with and without visual guidance; bite force exerted, and masseter and digastric electromyograms (EMGs) were recorded. Under visual guidance all subjects co-contracted their digastric muscles during the isometric bite. They held the force for a short time, followed by periods with fluctuations (peak-to-peak force amplitude about 15-20 N). Fluctuations in bite force correlated with the masseter EMGs, the maximum in the correlogram occurring at about -50 ms with the force lagging the masseter. In 75% of the subjects a significant periodic component in the masseter and in the force spectra was found at about 4 Hz. This was also seen in the amplitude spectra of the forces, which showed in 80% of the subjects a significant elevation between 7-10 Hz as well. No correlation between the digastric EMGs and the bite forces, and between the EMGs of masseter and digastric could be detected. Spectra of digastric EMGs showed no prominent maxima. When subjects were deprived of visual feedback, maxima at -50 ms in the cross-correlation functions of the masseters and the forces were reduced considerably; periodicities of +/- 250 ms disappeared.(ABSTRACT TRUNCATED AT 250 WORDS)

Bite Force↗
PubMed1989

Relationships between the size and spatial morphology of human masseter and medial pterygoid muscles, the craniofacial skeleton, and jaw biomechanics.

The relationship between human craniofacial morphology and the biomechanical efficiency of bite force generation in widely varying muscular and skeletal types is unknown. To address this problem, we selected 22 subjects with different facial morphologies and used magnetic resonance imaging, cephalometric radiography, and data from dental casts to reconstruct their craniofacial tissues in three dimensions. Conventional cephalometric analyses were carried out, and the cross-sectional sizes of the masseter and medial pterygoid muscles were measured from reconstituted sections. The potential abilities of the muscles to generate bite forces at the molar teeth and mandibular condyles were calculated according to static equilibrium theory using muscle, first molar, and condylar moment arms. On average, the masseter muscle was about 66% larger in cross section than the medial pterygoid and was inclined more anteriorly relative to the functional occlusal plane. There was a significant positive correlation (P less than 0.01) between the cross-sectional areas of the masseter and medial pterygoid muscles (r = 0.75) and between the bizygomatic arch width and masseter cross-sectional area (r = 0.56) and medial pterygoid cross-sectional area (r = 0.69). The masseter muscle was always a more efficient producer of vertically oriented bite force than the medial pterygoid. Putative bite force from the medial pterygoid muscle alone correlated positively with mandibular length and inversely with upper face height. When muscle and tooth moment arms were considered together, a system efficient at producing force on the first molar was statistically associated with a face having a large intergonial width, small intercondylar width, narrow dental arch, forward maxilla, and forward mandible. There was no significant correlation between muscle cross-sectional areas and their respective putative bite forces. This suggests that there is no simple relationship between the tension-generating capacity of the muscles and their mechanical efficiency as described by their spatial arrangement. The study shows that in a modern human population so many combinations of biomechanically relevant variables are possible that subjects cannot easily be placed into ideal or nonideal categories for producing molar force. Our findings also confirm the impression that similar bite-force efficiencies can be found in subjects with disparate facial features.

Adult↗
PubMed2002

Masticatory ability in 80-year-old subjects and its relation to intake of energy, nutrients and food items.

OBJECTIVE: The aim of the present study was to analyse the relationship between masticatory ability (self-assessed masticatory ability and bite force) and intake of energy, nutrients and food items in a population sample of elderly subjects. DESIGN AND SUBJECTS: From a population sample of 80-year-old people, 160 individuals (74 men and 86 women) took part in an odontological study. MAIN OUTCOME MEASURES: A dental examination including bite force recording, a questionnaire focusing on self-assessed masticatory ability, and a dietary interview. SETTING: Department of Geriatric Medicine, Göteborg University, Sweden. RESULTS: The dental status among the participants varied much (from edentulous in both jaws--22%--to more than 20 natural teeth--30%). The mean maximum bite force was higher in men (165 N) than in women (105 N). Bite force was significantly correlated to the Eichner index and to the number of teeth. One third of the subjects reported no masticatory problem, whereas 18% identified > or = 3 such problems. The intake of energy and nutrients varied much but the means were well above recommended values. The correlations between dental status and bite force on one side and dietary intake on the other side were in general weak and most often statistically non-significant. Impaired general health and reduced dentition were both associated with more masticatory problems. CONCLUSION: The examined sample of 80-year-old subjects had a great variation in dental status, bite force and self-assessed masticatory ability, but these factors had only a minor influence on dietary selection and intake, which on average were well above recommended values.

Aged↗
PubMed1989

[Research related to pressures under dentures. The effect of differences in impression pressure with special reference to unilateral mandibular free-end edentulousness].

The purpose of this paper is to investigate the difference of impression pressure under denture bases made by the pressure impression-taking method, which considers the resiliency of ligaments under abutment teeth and mucosa under dentures, and under those made by the non-pressure impression-taking method, and then analyzed its influence on the distribution of pressure curve produced by bite force with the case of unilateral mandibular free-end edentulousness. The findings were as follows: 1. As for the pressures under the dentures, dentures made by the pressure impression-taking method in all cases showed an apparent increase at the mesial part, while at the distal part, a decrease was detected in three out of five patients. 2. The pressure curve caused by bite force tended to rise sharply immediately before the application of maximum bite force. 3. Ratio of pressures resulting from the increased bite force tended to increase with dentures using the non-pressure impression-taking method, while dentures using the pressure impression-taking method showed a clear tendency to equalize toward 0.5, regardless of the values of the bite force.

Bite Force↗
PubMed1989

Blood-flow and metabolic response in a contracting canine masticatory muscle.

The mechanical and metabolic characteristics of the canine masseter muscle of seven adult dogs, aged 3 years, weighing 45-55 kg, were evaluated by electrically provoked contractions. The masseter muscle was exposed by careful surgery and stimulated by two silver electrodes placed in the anterior and posterior aspects of the muscle. The bite force was measured with a force transducer. Glycogen, glucose-contents together with lactate, pyruvate, creatine phosphate, NADH and NAD were analysed fluorimetrically. Intra-muscular oxygen tension was continuously recorded by a flexible silver electrode. Blood-flow was measured by the 133Xenon clearance technique. Biopsies were taken at rest and after stimulation. The registered bite force revealed an initial peak, representing maximal force production and thereafter a rapid decline in power output. During the following stimulation events the bite force curve showed decrease in amplitude concerning maximal force as well as duration of bite force production. The blood-flow and oxygen tension were significantly reduced at the end of stimulation. However, after recovery these parameters were normalised to initial values. The glycogen and glucose were depleted after stimulation. The lactate concentration increased about three to four times. The observed changes in NAD and NADH indicate a hypoxic situation in the muscle cells. The oxygen deficit in conjunction with the intramuscular blood-flow impairment and the metabolite variations reflect the energy and redox state in the muscle and may contribute to the decline in bite force production.

Animals↗
PubMed2000

Biting and chewing in overdentures, full dentures, and natural dentitions.

It has been suggested that the provision of dental implants can improve the oral function of subjects with severely resorbed mandibles, possibly restoring function to the level experienced by satisfied wearers of conventional complete dentures. Nevertheless, a quantitative comparison has never been made and can be drawn from the literature only with difficulty, since studies differ greatly in methodology. To make such a comparison, we measured bite force and chewing efficiency by using identical methods in subjects with overdentures, complete full dentures, and natural dentitions. Our results indicated that bite forces achieved with overdentures on dental implants were between those achieved with artificial and natural dentitions. Chewing efficiency was significantly greater than that of subjects with full dentures (low mandible), but was still lower than that of subjects with full dentures (high mandible) and overdentures on bare roots. Differences in the height of the mandible revealed significant differences in chewing efficiency between the two full-denture groups. Furthermore, subjects with a shortened dental arch exerted bite forces similar to those of subjects with a complete-natural dentition, but their chewing efficiency was limited due to the reduced occlusal area. For all groups combined, a significant correlation was found between maximum bite force and chewing efficiency. Nearly half of the variation in chewing efficiency was explained by bite force alone.

Adult↗