Bite Force Research Articles

Biomechanics of biting in loggerhead shrikes: jaw-closing force, velocity and an argument for power.

Differences in the physical and behavioral attributes of prey are likely to impose disparate demands of force and speed on the jaws of a predator. Because of biomechanical trade-offs between force and speed, this presents an interesting conundrum for predators of diverse prey types. Loggerhead shrikes (Lanius ludovicianus) are medium-sized (∼50 g) passeriform birds that dispatch and feed on a variety of arthropod and vertebrate prey, primarily using their beaks. We used high-speed video of shrikes biting a force transducer in lateral view to obtain corresponding measurements of bite force, upper and lower bill linear and angular displacements, and velocities. Our results show that upper bill depression (about the craniofacial hinge) is more highly correlated with bite force, whereas lower bill elevation is more highly correlated with jaw-closing velocity. These results suggest that the upper and lower jaws might play different roles for generating force and speed (respectively) in these and perhaps other birds as well. We hypothesize that a division of labor between the jaws may allow shrikes to capitalize on elements of force and speed without compromising performance. As expected on theoretical grounds, bite force trades-off against jaw-closing velocity during the act of biting, although peak bite force and jaw-closing velocity across individual shrikes show no clear signs of a force-velocity trade-off. As a result, shrikes appear to bite with jaw-closing velocities and forces that maximize biting power, which may be selectively advantageous for predators of diverse prey that require both jaw-closing force and speed.

Sexual differences in bite force are not related to testosterone level in the wild-derived red junglefowl

Abstract Bite force is an important performance indicator of individual fitness that is closely related to food acquisition, male competition, and mating selection. It is also affected by a variety of factors and different mechanisms. Therefore, it is relatively difficult to understand the evolutionary driving forces of changes in bite force. In this study, the driving factors affecting the bite force of wild-derived red junglefowl (Gallus gallus jabouillei) were investigated from the aspects of morphological indicators and physiological characteristics. Results showed that the bite force of wild-derived red junglefowl was directly related to sex, showing obvious sexual differences. However, there was no correlation between the plasma testosterone level and bite force. The bite force of males was significantly greater than that of females, and the body index (i.e., PC1 of five body measures, namely body mass, body length, wing length, tail length, and tarsus length), the grasp index (i.e., tomial length × bill width) of males were significantly greater than those of females. Sexual selection may have played a key role in the evolution of bite force in the red junglefowl. Future studies should examine other key factors affecting changes in bite force to verify the correlation between secondary sexual characteristics and bite force in red junglefowls.

Evaluation of stress and strain on surgical screws and plates in mandibular trunk fractures at different positions of plates and screws: Finite Element Analysis

Introduction: To determine the most appropriate method for placement of plates and screws in terms of stress in mandibular body fractures using finite element analysis.
 Methods: First a model of the mandible reconstructed with Mimics software. This study employed various methods, including plates positioned parallel to the inferior border of the mandible with screws perpendicular to the bone; plates parallel to the inferior border of the mandible fixed with screws oriented at a 45-degree to the fracture line; plates positioned perpendicular to the fracture line fixed with screws perpendicular to the bone; plates perpendicular to the fracture line and fixed with screws oriented at a 45-degree to the fracture line. Then the software measured the stress within the screws and plates in each condition under the maximum bite force.
 Results: It was observed that in cases of favorable horizontal fractures, the stress exerted on the plates and bones is greater when the plates are aligned parallel to the lower border of mandible, compared to when the plates are positioned perpendicular to the fracture line. In the study of unfavorable horizontal fractures, when the plates were fixed perpendicular to the fracture line, higher magnitudes of stress were recorded compared to the stress observed in the plates positioned parallel to the inferior border of the mandible.
 Conclusion: In cases of mandibular body fractures with favorable horizontal orientations, the use of fixation techniques involving plates perpendicular to the fracture line is preferred due to the reduced stress exerted on the plates. In the unfavorable horizontal fractures, the stress levels do not exhibit significant variation between different fixations. Finally, it is not advisable to utilize screws positioned at a 45-degree angle to the fracture line, as it can lead to an increase in the displacement of the plates.

Role of Whey Protein in the Treatment Outcome of Maxillofacial Trauma Patients: An Interventional Study.

Maxillofacial fracture severely affects the diet of the patients leading to reduction of body weight. Facial trauma affects the muscles of mastication and the bones of face leading to reduction in bite force. The purpose of our study was to investigate the effect of whey protein supplement in the postoperative period of maxillofacial trauma patients with respect to body weight, bite force and callus formation. Patients were divided into control group and study group having 20 patients each. The control group received usual modified diet for maxillofacial fracture and study group received same diet along with whey protein for 6weeks. There was mean weight loss of 3.15kg in control group whereas there was no weight loss of in the study group. There was statistically significant increase in bite force in the study group compared to the control group with p value < 0.05. Early callus formation was seen in study group compared to control group. Our results showed that patients who were supplemented with whey protein had no loss of body weight, better masticatory efficiency, better healing of the fracture sites and overall early recovery.

Investigation of Bruxism wear behavior of titanium alloy biomaterials; experimental and 3D finite element simulation

Bruxism can be defined as the process of direct contact with teeth and dental materials with an involuntary jaw-tightening movement. In this process, teeth and dental materials can be exposed to various damage mechanisms. This study aims to realize the mechanism of bruxism with finite element analysis and in vitro rotating chewing movement analysis. Within the scope of the study, cp-Ti, Ti-5Zr, and Ti-5Ta materials were subjected to wear tests in the finite element analysis and in vitro rotating chewing movement method under the determined Bruxism chewing test conditions. Test specimens with cylindrical geometry were exposed to a direct every-contact wear mechanism for 30 s under 150 N bruxism chewing bite force. The bruxism chewing cycle continued for 300 min at a frequency of 2 Hz. Microanalysis of the wear surfaces of the samples after the experimental study was carried out with Scanning Electron Microscopy. The results obtained within the scope of this study showed that the Bruxism wear resistance increased by adding zirconium and tantalum to pure titanium material. This result shows that pure titanium material, which is known to have poor wear resistance, can be improved with Zr and Ta alloys. It is clinically important that the success rate in the treatment process increases with the increase in wear resistance. However, the micro-cracks observed in the microstructure may have occurred in the sub-surface, which is a show of the fatigue wear mechanism.

저작관련근의 스트레칭이 타액 분비율과 교합력 변화에 미치는 영향

Objectives: The purpose is to confirm the relationship between bite force and saliva through muscle exercise or stretching related to chewing, and to confirm the activation of the caustic muscles accordingly to help improve and prevent bite force and saliva secretion. Methods: From November 14 to November 20, 2023, among adults aged 19 or older living in Busan Metropolitan City, a study was conducted on those who are not undergoing dental treatment or have no restrictions on bowing activities. Results: The most positive results were found in Group 4, which performed Chin Tuck Against Resistance, stretching and massage together. Conclusions: I think it is necessary for various subjects to find ways to exercise easily and conveniently strengthen their work-related sources.

Effect of Hollow Denture on Masticatory Performance and Bite Force of Highly Resorbed Edentulous Ridge Cases: A Crossover Study

Effect of Hollow Denture on Masticatory Performance and Bite Force of Highly Resorbed Edentulous Ridge Cases: A Crossover Study

Muscle and joint mechanics during maximum force biting following total temporomandibular joint replacement surgery

Total temporomandibular joint replacement (TMJR) surgery is the established treatment for severe temporomandibular joint disorders. While TMJR surgery is known to increase mouth-opening capacity, reduce pain and improve quality of life, little is known about post-surgical jaw function during activities of daily living such as biting and chewing. The aim of this study was to use subject-specific 3D bite force measurements to evaluate the magnitude and direction of joint loading in unilateral total TMJR patients and compare these data to those in healthy control subjects. An optoelectronic tracking system was used to measure jaw kinematics while biting a rubber sample for 5 unilateral total TMJR patients and 8 controls. Finite element simulations driven by the measured kinematics were employed to calculate the resultant bite force generated when compressing the rubber between teeth during biting tasks. Subject-specific musculoskeletal models were subsequently used to calculate muscle and TMJ loading. Unilateral total TMJR patients generated a bite force of 249.6 ± 24.4 N and 164.2 ± 62.3 N when biting on the contralateral and ipsilateral molars, respectively. In contrast, controls generated a bite force of 317.1 ± 206.6 N. Unilateral total TMJR patients biting on the contralateral molars had a significantly higher lateral TMJ force direction (median difference: 63.6°, p = 0.028) and a significantly lower ratio of working TMJ force to bite force (median difference: 0.17, p = 0.049) than controls. Results of this study may guide TMJ prosthesis design and evaluation of dental implants.

Impact of clear aligner therapy on masticatory musculature and stomatognathic system: a systematic review conducted according to PRISMA guidelines and the Cochrane handbook for systematic reviews of interventions

BackgroundClear aligner therapy has gained popularity as a minimally invasive orthodontic treatment option. However, its impact on the masticatory musculature and the stomatognathic system is an area of growing interest, as it involves the adjustment of occlusion and tooth movement. This systematic review aims to comprehensively assess and synthesise existing evidence regarding the influence of clear aligner therapy on the masticatory musculature and the stomatognathic system.MethodsAn exhaustive search was performed on electronic databases that adhered to PRISMA guidelines. Clinical studies that evaluated the impact of patients receiving aligner orthodontic treatment on the muscles of the mastication and stomatognathic systems were included. A standardised data extraction form was devised for relevant variables. Two reviewers extracted the data variables. ROB-2 was used for bias evaluation in the selected studies.ResultsA total of six studies met the inclusion criteria. The wearing of clear aligners significantly impacted the muscles of mastication. Muscle activity and discomfort showed a significant alteration in the initial days of appliance placement. but this observation was temporary, with no significant changes thereafter in subsequent follow-up. Bite force reduction was also noted. All the studies evaluated showed good methodological quality.ConclusionThe review found that aligned orthodontic treatment may have a variable impact on muscles of mastication, with a potential for initial exacerbation of symptoms followed by possible improvement. However, due to the limited number of studies and their heterogeneous nature, further robust research is recommended to fully understand the relationship between aligned orthodontic treatment and masticatory muscles.

Linking shape conspicuous asymmetry with shape covariation patterns and performance in the insect head and mandibles.

Bilateral symmetry is widespread across animals, yet, among bilaterians, many cases of conspicuous asymmetries evolved. This means that bilaterally homologous structures on the left and right sides display divergent phenotypes. The evolution of such divergent phenotypes between otherwise similarly shaped structures can be thought to be favored by modularity, but this has rarely been studied in the context of left-right differences. Here, we provide an empirical example, using geometric morphometrics to assess patterns of asymmetry and covariation between landmark partitions in a grasshopper with conspicuously asymmetric mandibles. Our morphometric data confirm the presence of strictly directional conspicuous asymmetry in the mandibles and surrounding structures. Covariance patterns and tests hint at a strong integration between mandibles despite their divergent morphologies, and variational modularity with the head capsule. While mandibles have been selected to achieve a key-and-lock morphology by having interlocking shapes, the developmental modularity required to achieve this seems to be overwritten by developmental and/or functional integration, allowing the precise matching required for feeding. The consequent conflicting covariation patterns are reminiscent of the palimpsest model. Finally, the degree of directional asymmetry appears to be under selection, although we find no relationship between bite force and mandible shape or asymmetry.

Phenotypic differentiation despite gene flow: Beak morphology, bite performance, and population genetics of Loggerhead Shrikes (Lanius ludovicianus).

Previous studies of Loggerhead Shrikes (Laniidae: Lanius ludovicianus) in North America have indicated considerable intraspecific genetic and phenotypic differentiation, but the congruence between genetic and phenotypic differentiation remains obscure. We examined phenotypic differences in beak shape and bite force among geographic groupings across a 950 km range, from the lower Imperial Valley to the upper Central Valley of California, USA. We integrated these analyses with a population genetic analysis of six microsatellite markers to test for correspondence between phenotypic and genetic differences among geographic groups. We found significant phenotypic differentiation despite a lack of significant genetic differentiation among groups. Pairwise beak shape and bite force distances nevertheless were correlated with genetic (F ST) distances among geographic groups. Furthermore, the phenotypic and genetic distance matrices were correlated with pairwise geographic distances. Takentogether, these results suggest that phenotypic differences might be influenced by neutral processes, inbreeding (as indicated by high heterozygosity deficiencies we observed), local adaptation, and/or phenotypic plasticity.

Functionally mediated cranial allometry evidenced in a genus of rock-wallabies.

In assessments of skeletal variation, allometry (disproportionate change of shape with size) is often corrected to examine size-independent variation for hypotheses relating to function. However, size-related trade-offs in functional demands may themselves be an underestimated driver of mammalian cranial diversity. Here, we use geometric morphometrics alongside dental measurements to assess craniodental allometry in the rock-wallaby genus Petrogale (all 17 species, 370 individuals). We identified functional aspects of evolutionary allometry that can be both extensions of, and correlated negatively with, static or ontogenetic allometric patterns. Regarding constraints, larger species tended to have relatively smaller braincases and more posterior orbits, the former of which might represent a constraint on jaw muscle anatomy. However, they also tended to have more anterior dentition and smaller posterior zygomatic arches, both of which support the hypothesis of relaxed bite force demands and accommodation of different selective pressures that favour facial elongation. By contrast, two dwarf species had stouter crania with divergent dental adaptations that together suggest increased relative bite force capacity. This likely allows them to feed on forage that is mechanically similar to that consumed by larger relatives. Our results highlight a need for nuanced considerations of allometric patterns in future research of mammalian cranial diversity.

Mechanical traits as drivers of trophic interaction between macrodetritivores and leaf litter.

In ecosystems, the rates of resource consumption by animals drive the flows of matter and energy. Consumption rates are known to vary according to consumer energy requirements, resource nutrient content and mechanical properties. The aim of our study is to determine how mechanical constraints, compared to energetic and nutritional constraints, explain the variation in leaf litter consumption rates by macrodetritivores. In particular, we focus on the impact of litter toughness. To this end, we propose a non-linear model describing leaf litter consumption rates of detritivore as a function of litter toughness. We also investigate a possible match between bite force and litter toughness, since consumer-resource co-occurrence is thought to be driven by the match between invertebrate mandibular traits and resource toughness. Our study was designed as follows: leaf litter from oak and hornbeam was exposed to field physical and microbial decomposition in aquatic and terrestrial ecosystems for selected time periods before it was offered to eight macrodetritivore taxa (three forest stream taxa and five forest soil taxa) in no-choice laboratory feeding experiments. Our findings show that, compared to energetic and nutritional constraints, mechanical traits have a greater impact on litter consumption rate by detritivores. After subtracting the contribution of the detritivore body mass, we report that litter consumption rates depend primarily on litter toughness. A sigmoid function is best suited to characterize the relationship between mass-independent consumption rate and litter toughness. We note that the parameters of our sigmoid model are taxon-specific, suggesting biomechanical thresholds and biological differences among taxa. Interestingly, we found no correlation with detritivore bite force, suggesting that food processing by detritivores does not only depend on mandibles strength.

Effect of Upper first premolars extraction During Orthodontic Treatment on Distribution of Bite Force.

Effect of Upper first premolars extraction During Orthodontic Treatment on Distribution of Bite Force.

Influence of occlusal appliances on the masticatory muscle function in individuals with sleep bruxism: A systematic review and meta-analysis.

This systematic review answers the question: "Does occlusal appliance use influence masticatory muscle function of dentate individuals with sleep bruxism?". The literature search included six databases, grey literature, and manual search for articles. Randomized and non-randomized clinical trials were included comparing muscle function of sleep bruxers before and after receiving occlusal appliances. Risk of bias was assessed with risk of bias assessment for randomized and non-randomized clinical trials tool. Twelve studies, three represent randomized clinical trials, were included. Risk of bias was considered low, moderate, or serious. Meta-analyses indicated that soft and hard appliances did not influence muscle activity and bite force of bruxers. Qualitative analysis showed that occlusal appliance use did not influence masticatory performance and muscle volume. However, it was effective in reducing tongue force. Certainty of evidence was considered very low for muscle activity when evaluated with hard appliances, and for bite force evaluated with both appliance materials. Low certainty of evidence was observed for muscle activity with soft appliances. Based on the findings of this meta-analysis, occlusal appliances do not affect masticatory muscle function of sleep bruxers. Regardless of appliance material, the activity of masseter and temporal, and bite force of sleep bruxers was not influenced.

The comparison between various methods of mandibular reconstruction based on finite element analysis.

The Mandible can be damaged by pathological factors, tumors, trauma, infection, and needs a surgical operation for reconstruction and restoring function. There are different methods for the reconstruction of mandible. Based on the surgical approach, primary reconstruction of mandible by reconstruction plate after resection is necessary for maintaining mandibular symmetric and esthetic of the lower third of the face. A finite element model of mandible and masticatory muscles was produced from a normal person (male with 35-year-old). The normal model was resected from the left sixth tooth to the second tooth. The pathological model was reconstructed in different conditions by macro plate. Different conditions were analyzed and compared based on bite force on right fifth tooth, stress developed on screws and macro plate. The finite element analysis results showed that maximum bite force and lower stress on screws were seen in the pathological model (condition 5) when one macro plate and six screws were inserted in the mid-body. The findings showed that the use of two macro plates causes lower stress on it than when we use one. Use of one macro plate and six screws is the best choice in mandibular immobilization which decrease the stress applied on bone and increase the bite force. Because of less stress developed on macro plates and screws, use of two macro plates or one macro plate in mid-body area are also preferred.

Characterizing the microstructures of mammalian enamel by synchrotron phase contrast microCT

The enamel of mammalian teeth is a highly mineralized tissue that must endure a lifetime of cyclic contact and is inspiring the development of next-generation engineering materials. Attempts to implement enamel-inspired structures in synthetic materials have had limited success, largely due to the absence of a detailed understanding of its microstructure. The present work used synchrotron phase-contrast microCT imaging to evaluate the three-dimensional microstructure of enamel from four mammals including Lion, Gray Wolf, Snow Leopard, and Black Bear. Quantitative results of image analysis revealed that the decussation pattern of enamel consists of discrete diazone (D) and parazone (P) bands of rods organized with stacking arrangement of D+/P/D-/P in all mammals evaluated; the D+ and D- refer to distinct diazone bands with juxtaposed rod orientations from the reference plane. Furthermore, the rod orientations in the bands can be described in terms of two principal angles, defined here as the pitch and yaw. While the pitch angle increases from the outer enamel to a maximum (up to ≈ 40°) near the dentin enamel junction, minimal spatial variations are observed in yaw across the enamel thickness. There are clear differences in the decussation parameters of enamel across species that are interpreted here with respect to the structural demands placed on their teeth. The rod pitch and band width of enamel are identified as important design parameters and appear to be correlated with the bite force quotient of the four mammals evaluated. Statement of significanceThe multi-functionality of tooth enamel requires both hardness and resistance to fracture, properties that are generally mutually exclusive. Ubiquitous to all mammalian teeth, the enamel is expected to have undergone adaptations in microstructure to accommodate the differences in diet, body size and bite force across animals. For the first time, we compare the complex three-dimensional microstructure of enamel from teeth of multiple mammalian species using synchrotron micro-computed tomography. The findings provide new understanding of the “design” of mammalian enamel microstructures, as well as how specific parameters associated with the decussation of rods appear to be engineered to modulate its fracture resistance.

Oro-facial function and quality of life in children and adolescents with large horizontal maxillary overjet-A case-control study.

Large horizontal maxillary overjet (overjet) is associated with reduced bite force (BF) and number of contacts, which influence the chewing effectivity (CE). Oral health, oro-facial function (OF) and malocclusion have great impact on psychological well-being and quality of life (QoL). The aims of the study were to examine OF, temporomandibular disorders (TMD), BF, CE, QoL and well-being in children and adolescents with large overjet. The study was a case-control study including healthy children with large overjet in the study group compared to a control group of healthy children with neutral occlusion, all 9-14 years old. OF was examined by use of Nordic Orofacial Test-Screening (NOT-S), Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) and registration of morphological and functional occlusion. QoL and well-being were examined using KIDSCREEN-10 and Strengths and Difficulties Questionnaire. The study and control groups included 37 and 32 participants, respectively. Significantly increased NOT-S score (p < .001) and reduced BF (p = .011), numbers of contacts (p < .001) and CE (p = .005) were found in the study group. BF, numbers of contacts and CE were negatively associated with erupting canines and premolars. No significant difference was found in age, gender, dental eruption, TMD diagnosis or QoL between the groups. Significantly increased emotional symptoms (p = .007), hyperactivity (p = .043) and total difficulties score (p = .009) were found in the study group. The study group showed higher NOT-S score and reduced BF, number of contacts and CE. No difference in QoL were found between the groups, although reduced well-being and increased emotional symptoms, hyperactivity and total difficulties were found in the study group.

The stress distribution of a primary molar tooth restored with stainless steel crown using different luting cements

BackgroundThe aim of this study is to evaluate the stress distributions of a primary molar tooth restored with a stainless steel crown (SSC) using resin and glass ionomer luting cements by Finite Element Analysis (FEA).MethodsOriginal DICOM data of a primary molar was used to create a 3D model. One model was prepared as a tooth model with SSC. A 30 μm cement layer was used in model. Two different luting cements were tested in the study: self-cure adhesive resin cement, and glass ionomer cement. Vertical and oblique loads of 330 N were applied to simulate maximum bite force and lateral forces in the occlusal contact areas of the models. Maximum von Mises stress values in the models were evaluated as MPa.ResultsThe maximum von Mises stress value was observed in the force application and general occlusal contact areas for all models. The maximum von Mises stress values were higher in the tooth model with SSC using self-cure adhesive resin cement (478.09 MPa and 214.62 MPa) than in the tooth model with SSC using glass ionomer cement (220.06 MPa and 198.72 MPa) in both vertical and oblique loading, respectively.ConclusionsDepending on the magnitude of the bite force on the SSC, fracture of the luting cement materials could occur if the stress exceeds the endurance limit of the luting cement. Cementation with glass ionomer cement may help to reduce stress levels in SSC restorations of primary molars in children.

Unveiling the Influence of the Curve of Spee on Bite Force and Chewing Ability: A Comparative Study.

To investigate the impact of the curve of Spee (CS) accentuation on bite force, chewing ability, and additionally, other factors that influence chewing ability and bite force such as restorations, caries, gender, habits, and TMJ problems. 231 participants (118 male and 113 female, mean age = ±27.96 years) were recruited for this cross-section study. Participants completed a data collection sheet in which age, gender, Angle's classification of malocclusion, overjet, overbite, TMJ problems, habits, restorations, and caries experience were recorded. Two examiners made a lower impression, chewing ability test and measured the bite force for each participant. Measurement of the CS was obtained digitally from the poured dental cast, and the categorization was as follows: flat (<1 mm), normal (1-2 mm), or deep (>2 mm). The mean maximum bite force (MBF) was 468.722 N for participants with flat CS, 389.822 N for normal CS, 647.08 N for deep CS, and 384.667 N for reverse CS. The average MBF was higher for participants with deep CS (p < 0.05). MBF force was higher in males. However, BMI was not significantly related to MBF values. Participants with normal and flat CS have comparable chewing capacity (p > 0.05). Also, a significant difference in bite force and chewing ability was found between the three categories of CS (p < 0.05). Bite force variations across various CS types were linked to gender and habits. Chewing ability showed no differences concerning gender, habits, TMJ problems, caries, or restorations, emphasizing CS's significant impact on bite force while showcasing the unchanged nature of chewing ability amidst diverse factors.