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At least 1,243 records · Page 69Linked to original sources
PubMed1993

Enamel rehardening by soft cheeses.

The in situ rehardening effect by soft cheeses: unsweetened, sucrose-sweetened and strawberry marmalade-flavored, pH 4.5, 4.25 and 4.0 as compared to secreted saliva, was investigated on softened enamel. Ten volunteers wearing orthodontic removal appliances participated in the study. The intraoral test was chosen for measuring microhardness of enamel slabs inserted into the dental appliance. Average microhardness was calculated at three stages: at start (baseline), after exposing the enamel slabs to a citrus beverage (pH 3.3) for 30 minutes in vitro as a softening factor and then intra-oral exposure during 5 minutes to 125 g soft cream cheese mastication, unsweetened and sweetened (experimental), or to saliva secretion, pH 6.8, only by mouth movements (control). Significant rehardening effects on the softened enamel surfaces took place following mastication of the various soft cheeses and salivary secretion. The differences in the rehardening potentials of the cheeses as compared to that of saliva were significant. The rehardening effect of the cheeses decreased (not significantly) in the following order: unsweetened cheese, sucrose-sweetened marmalade flavored cheese and sucrose-sweetened cheese. In spite of the acidic pH of the soft cheese substrates,--the buffering capacity of the protein compounds and the Ca,PO4 ions neutralize a softening effect--the rehardening effect is probably due to an uptake of Ca and PO4 ions by the softened surface enamel from the cheese bolus consumed over the entire 5-minute period.

Adult↗
PubMed1995

A modified device for long term sampling of parotid saliva in various experimental conditions.

A parotid cup has been widely used as an intraoral device for the collection of parotid saliva. However, in long duration sampling, the cup tends to disconnect under circumstances such as mastication, sleep or physical exercise. We have designed a modified device of parotid cup for saliva collection to overcome these unfavorable conditions. The parotid cup was modified by fixing it to the bite-plate appliance which was adjusted individually to the occlusal plane in order to avoid disconnection of the cup under varying conditions. Using this device, we could measure salivary flow rate during mastication, sleep or physical exercise. Additional advantages of this device are that it is easy to make with acrylic resin and is inexpensive. The preliminary study using this device showed that flow rates of unstimulated parotid saliva varied from 0.06 +/- 0.04 ml/min. to 0.16 +/- 0.10 ml/min. (mean +/- s.d) from 7 a.m. to 12 p.m. in 7 subjects. In five subjects, the flow rate of parotid saliva during meal (lunch) was much higher than that of resting on a chair, playing table tennis, or sleeping at night for 6-8 hours. This might be considered due to the stimuli of the meal content. Flow rates of saliva were also examined with various stimuli. The results showed that salty pickled plum > sour lemon juice > 10% ascorbic acid > sweet milky candy > 1% ascorbic acid. These data suggest that our modified device is useful for various experiments in salivary research.

Dental Research↗
PubMed1994

[Preoperative and surgical protocols for better implant integration].

In implant placement, different bone densities require different implant types in order to achieve maximum stability. Therefore, careful preoperative planning is essential to diagnose and/or augment the bone, to select the correct size and type of implant for each individual case, and to establish the appropriate surgical protocol. This paper and presentation discuss the essentials for establishing such protocol, ie, the quality and quantity of bone, type and size of implants, surgery, progressive loading, and shifting of the mastication forces. Serious errors in planning first appear as short-term failures, and they indicate inadequacy in osseointegration in the healing phase or overloading caused by the superstructure. Less grave errors occur later as long-term failures, due to the width, depth, and density of the bone and the angulation of the implant. Appropriate components have to be used for different types of bone: Uncoated screws are the best solution for D1 and D2 types of bone; coated screws should be used in the presinus area and after nerve transpositioning. Cylindrical implants are best suited for subantral augmentation, using a narrow drill; the bone bed is progressively widened by a conic osteotome, and the technique provides a good stability. Free gingival transplant is indicated in cases with insufficient keratinized gingiva. Masticatory overloading can be avoided by reducing the occlusal table, decreasing cusp inclination, and anteriorizing the upper mastication areas.

Bone Density↗
PubMed1997

[The nasopharynx and deep spaces of the face: anatomy and applications to pathology].

Deep facial spaces are anatomically delineated by the layers of deep cervical fascia. They are located between the skull base and the hyoid bone. Each space contains specific anatomic structures, which can be responsible for specific pathologic processes. Deep facial spaces can be divided in two medial odd spaces (pharyngeal mucosal and retropharyngeal spaces), and in three lateral even spaces (retrostylian, prestylian, and masticator spaces). The dividing of these core tissues are useful for the analysis of the lesions found in this area. CT scan and MRI (with axial and coronal views) provide precise analysis. The main lesions are: -medially, adenoidal hyperplasias and squamous cell carcinomas (pharyngeal mucosal space), adenopathies and abscess (retropharyngeal space). -laterally, salivary tumors (prestylian space), adenopathies, schwannomas and paragangliomas (retrostylian space). Masticator space (and especially pterygopalatine fossa) is an important way of communication and is often involved by the extension of locoregional pathologic processes.

Adenoids↗
PubMed1998

Deep facial infections of odontogenic origin: CT assessment of pathways of space involvement.

PURPOSE: We investigated the pathways of spread of odontogenic infection in the facial and neck spaces. METHODS: CT scans of 45 patients with extensive spread of odontogenic infection into the facial and neck spaces were analyzed to document pathways of spread. RESULTS: Odontogenic infections arising in the mandible first spread upward, into the masseter and/or medial pterygoid muscles in the masticator space, and downward, into the sublingual and/or submandibular spaces, and then spread into the spaces or muscles adjacent to one or more of these locations. Infections from the masseter muscle spread into the parotid space to involve the temporalis and lateral pterygoid muscles. Infections from the medial pterygoid muscle spread into the parapharyngeal space to involve the lateral pterygoid muscle. Infections in the maxilla did not spread downward; instead, they tended to spread upward and superficially into the temporal and/or masseter spaces and deeply involve the lateral and/or medial pterygoid muscles in the medial masticator space. CONCLUSION: CT may be useful to depict the extent of infection and to plan treatment of extensive odontogenic infection, which can be life threatening when therapy is ineffective.

Adolescent↗
PubMed2025

Impact of Chewing Behavior Change on Cognition and Cerebral Hemodynamics.

BACKGROUND: Impaired chewing ability is a recognized risk factor for cognitive decline in older adults, potentially due to reduced neural stimulation in cognition-related brain regions. While short-term studies have demonstrated transient increases in neural activity from chewing, the sustained cognitive and neurophysiological effects of encouraging thorough chewing habits in daily life remain unclear. OBJECTIVE: This randomized controlled trial investigated whether promoting thorough chewing during meals could improve cognitive function and cerebral hemodynamics in older adults. METHODS: Fifty participants aged 65 y or older were randomly assigned to either a 1-mo intervention group, which used a wearable device to monitor and increase chewing strokes during meals, or a control group that maintained usual chewing habits. Chewing behavior, cognitive performance (including memory and executive function via the color Stroop test), and cerebral hemodynamics in the dorsolateral prefrontal cortex (DLPFC) were measured at baseline and after 1 mo. Statistical analyses included t tests, chi-square tests, 2-way analysis of variance with post hoc tests, Pearson correlations, and generalized linear models to evaluate group differences and associations between chewing and cognitive outcomes. RESULTS: Significant time-by-group interactions were observed for memory, F(1, 48) = 6.24, P = 0.043, and hemodynamic responses in the left DLPFC, F(1, 48) = 6.19, P = 0.013. The intervention group showed increased chewing frequency (P = 0.017), improved memory performance, and reduced left DLPFC responses compared with controls. Chewing frequency was positively correlated with Stroop test scores (r = 0.53, P = 0.010) and negatively with hemodynamic changes in the left DLPFC (r = -0.30, P = 0.040). Although improvements in other cognitive outcomes and hemodynamic measures favored the intervention group, these differences did not reach statistical significance. CONCLUSIONS: Promoting intentional chewing habits for 1 mo may enhance memory-related cognitive performance and neural efficiency in the DLPFC during working memory tasks in older adults. This nonpharmacologic, low-burden strategy warrants further research with longer interventions to support cognitive health and dementia prevention. TRIAL REGISTRATION ID: UMIN000044280Knowledge Transfer Statement:This study demonstrates that promoting thorough chewing habits in older adults can improve memory and enhance neural efficiency in the brain. Encouraging intentional mastication is a simple, nonpharmacologic approach that may help maintain cognitive health and prevent dementia, providing a practical strategy for clinicians and policymakers to support healthy aging.

Humans↗
PubMed2000

Brief communication: bilateral aplasia of the condyles in a 1,400-year-old mandible from Israel.

A rare pathological mandible, manifesting bilateral absence of the condyles, is discussed. The pathology was identified as hemifacial microsomia. The mandible, dated to the Byzantine period in Israel, manifests bilateral aplasia of the condyles and extreme shortness, but normal width, of the body. The extremely well-developed coronoid process, the grooved masseter insertion area, and the manifestation of a medial pterygoid tubercle (MPT) suggest hypertrophy of the occlusal muscles. The presence of a large MPT is considered a Neanderthal autapomorphy. Studying the biomechanic forces acting on the deformed mandible in hemifacial microsomia patients may shed light on the mastication process in Neanderthals.

Adult↗
PubMed1996

Morphological changes in the masseter muscle and its motoneurons during postnatal development.

BACKGROUND: It has been suggested that the morphological properties of the masseter muscle are changed by the masticatory activity pattern. In the rat, the activity pattern of the muscle alters from sucking to biting around 3 weeks after birth. The working hypothesis in this study is that the unique alteration in masticatory activity has an important influence on the development of the masseter muscle and its motoneurons. METHODS: We examined the morphological changes in the muscle fibers of the superficial masseter muscle and its motoneurons from 2 days to 280 days after birth in the rat. The change in masseter muscle activity sucking and biting was confirmed by electromyography. To label motoneurons innervating the muscle, horseradish peroxidase was injected into the muscle. The muscle and lower brain stem were sliced and processed histochemically to measure the diameters of muscle fibers and its motoneurons in the trigeminal motor nucleus. In addition, composition of myosin heavy chain (MHC) isoforms of the muscles were analyzed using gradient sodium dodecyl sulphate-polyacrylamide gel electrophoresis. RESULTS: There was a rapid growth in both types of muscle fibers (fast-twitch oxidative glycolytic muscle fibers and fast-twitch glycolytic fibers) for 42 days after birth, and then a gradual growth lasting until 280 days after birth. Particularly, rapid growth of the muscle fibers was seen between 21 days and 42 days after birth. A large amount of neonatal type MHC disappeared between 21 days and 42 days after birth. In the motoneuron, there was a rapid growth of motoneurons by 42 days after birth but no significant growth was seen thereafter. CONCLUSIONS: These results suggest that the alteration of mastication activity from sucking to biting has a significant influence on morphological development of both types of muscle fibers, but not on that of motoneurons innervating the masseter muscle.

Animals↗
PubMed1996

Patterns of bone strain in the zygomatic arch.

BACKGROUND: The transmission of force through the skull is complicated by the irregular form of the bones, the interposed sutures, and the multiplicity of loads from the teeth, muscles, and environment. The in vivo relationship between bone strain and muscle function in the mammalian skull is best investigated empirically. METHODS: We studied the zygomatic arch of pigs (Sus scrofa) by simultaneous strain gauge recording and electromyography. Seventeen juvenile animals were used, employing multiple strain gauges arranged either in rosettes or strips. Strain was recorded during mastication and muscle stimulations. Bony architecture was examined on sectioned specimens. RESULTS: Strain patterns were complex even in this beamlike structure. During masseteric contraction, the more anterior zygomatic bone showed in-plane bending such that its lower border became more convex, and the major principal strain axis (tension) was parallel to the masseter muscle. The posterior squamosal bone was slightly bent in the opposite direction, and the major principal strain was rotated 45-60 degrees from the masseteric line of action. Strain magnitudes in the squamosal were larger than those in the zygomatic. Woven bone composing the surface of the arch appeared denser in the zygomatic bone, where its predominant orientation corresponded with compressive strain. In the squamosal bone trabeculae were more regularly arranged, but their orientation did not correspond with strain axes. CONCLUSIONS: The magnitude differences are probably related to the different architecture of the zygomatic and squamosal bones, whereas the different strain patterns primarily reflect the influence of the sutures in selectively damping or transmitting loads. In particular, the zygomatic bone may be loaded by three-point, distributed-load bending, whereas the squamosal, loaded at only two points, may be sheared. We conclude that each cranial bone functions in a unique strain environment, with the sutures serving to redirect loading.

Animals↗
PubMed1997

A comparison of masticatory function in patients with or without reconstruction of the mandible.

BACKGROUND: The functional benefits of mandibular reconstruction following a composite resection remain unclear. Although microvascular surgical techniques have dramatically increased the predictability of bone and soft-tissue reconstruction towards presurgical anatomic norms, the specific factors responsible for improved function remain controversial. Objective measures of masticatory function need to be more clearly determined before the predictability and efficacy of reconstructive approaches is established. METHODS: We evaluated objective measures of oral function and patient reports of function in 10 reconstructed mandibulectomy patients, 10 without reconstruction, and 10 controls. Measures of oral function included bite force assessed at the first molar and incisal edge, a measure of tongue and cheek function, and patient reports of food they could eat. RESULTS: Both reconstructed and nonreconstructed patients presented decreased biting force, a more restricted diet, and compromised cheek and tongue function as compared with normals. However, reconstructed patients had significantly better measures of tongue function and ability to eat a varied diet than did nonreconstructed patients. Of the objective measures used to measure masticatory performance, bite force was poorly correlated, whereas measures of tongue function strongly correlated with successful mastication. CONCLUSION: Both reconstructed and nonreconstructed patients presented with a significant functional deficit when compared with normals, with reconstructed patients having better overall function than nonreconstructed patients.

Aged↗
PubMed1996

Mandibular form and function in North American and European Adapidae and Omomyidae.

Previous experimental and comparative studies among a wide variety of primate and nonprimate mammals provide a unique source of information for investigating the functional and phylogenetic significance of variation in the masticatory apparatus of Eocene primates. To provide a quantitative study of mandibular form and function in Eocene primates, the scaling of jaw dimensions and the development of symphyseal fusion was considered in a broad sample of North American and European Adapidae and Omomyidae. Statistical analyses indicate a significant size-related pattern of symphyseal fusion across Eocene primates, with larger taxa often having a greater degree of fusion than smaller species; this trend is also evident at the family level. As adapids are mostly larger than omomyids and these taxa show allometry of symphyseal fusion, this may explain why no omomyids evince complete fusion. Controlling for jaw size, species with greater symphyseal fusion tend to have more robust jaws than those with a lesser amount of fusion. Upon further examination, a primary reason why adapids have more robust mandibles than omomyids is associated with the presence of taxa with fused symphyses, and thus more robust jaws, in the adapid sample, whereas no omomyids have fused symphyses. In addition, there is little indication of a dietary effect, as measured by molar shear-crest development, on symphyseal fusion. Moreover, as there is no correlation between molar shear-crest development and skull size, this also points to the absence of a size-related pattern of dietary preference underlying the allometry of symphyseal fusion. Based on the interspecific and ontogenetic allometry of symphyseal ossification in Eocene primates, jaw-scaling patterns are used to further examine the functional determinants of fusion in this group. This study indicates that greater dorsoventral shear during mastication is a more likely factor than lateral transverse bending ("wishboning") in the evolution of symphyseal fusion among "late-fusing" mammals like adapids and omomyids. Given that wishboning is an important functional determinant of symphyseal form in recent anthropoids, apparently the evolutionary development of marked wishboning occurs only in taxa that shift the timing of fusion to a growth stage preceding the onset of weaning (before adult masticatory patterns are fully developed) and perhaps first ossified the symphysis to counter elevated dorsoventral shear stress. As early anthropoids probably consisted of members varying interspecifically and ontogenetically in the degree of ossification, it is especially informative to analyze the adaptive setting in which anthropoid symphyseal fusion evolved from a similar primitive "prosimian" perspective. Finally, since taxa with fused symphyses are widely distributed across mammals, a similar analytical framework could be directed profitably at unraveling the functional and evolutionary significance of symphyseal fusion in other mammalian clades.

Animals↗
PubMed1998

Ontogeny, function, and scaling of the mandibular symphysis in papionin primates.

In vivo study of mastication in adult cercopithecine primates demonstrates a link between mandibular symphyseal form and resistance to "wishboning," or lateral transverse bending. Mechanical consideration of wishboning at the symphysis indicates exponentially higher stresses along the lingual surface with increasing symphyseal curvature. Lengthening the anteroposterior width of the symphysis acts to resist these higher loads. Interspecific adult cercopithecine allometries show that both symphyseal curvature and symphyseal width exhibit positive allometry relative to body mass. The experimental and allometric data support an hypothesis that the cercopithecine mandibular symphysis is designed to maintain functional equivalence--in this case dynamic strain similarity--in wishboning stress and strain magnitudes across adult cercopithecines. We test the hypothesis that functional equivalence during masticatory wishboning is maintained throughout ontogeny by calculating relative stress estimates from morphometric dimensions of the mandibular symphysis in two cercopithecine primates, Macaca fascicularis and M. nemestrina. Results indicate no significant differences in relative stress estimates among the two macaque ontogenies and an interspecific sample of adult papionin primates. Further, relative stress estimates do not change significantly throughout ontogeny in either species. These results offer the first evidence for the maintenance of functional equivalence in stress and strain levels during postnatal growth in a habitually loaded cranial structure. Scaling analyses demonstrate significant slope differences for both symphyseal curvature and width between the ontogenetic and interspecific samples. The distinct interspecific cercopithecine slopes are realized by a series of ontogenetic transpositions in both symphyseal curvature and width. Throughout papionin ontogeny, symphyseal curvature increases with less negative allometry, while symphysis width increases with less positive allometry versus the interspecific pattern. As symphyseal curvature and width are inversely proportional to one another in estimating relative stresses, functionally equivalent stress levels are maintained both ontogenetically and interspecifically, because the relatively slower rate of allometric increase in symphyseal curvature during growth is compensated for by a slower rate of allometric increase in symphyseal width. These results indicate the primacy of maintaining functional equivalence during growth and the need for ontogenetic data in understanding the evolutionary processes that affect form-function relations as well as the interspecific patterning of adult form across a clade.

Analysis of Variance↗
PubMed2000

Strain in the braincase and its sutures during function.

The skull is distinguished from other parts of the skeleton by its composite construction. The sutures between bony elements provide for interstitial growth of the cranium, but at the same time they alter the transmission of stress and strain through the skull. Strain gages were bonded to the frontal and parietal bones of miniature pigs and across the interfrontal, interparietal and coronal sutures. Strains were recorded 1) during natural mastication in conjunction with electromyographic activity from the jaw muscles and 2) during stimulation of various cranial muscles in anesthetized animals. Vault sutures exhibited vastly higher strains than did the adjoining bones. Further, bone strain primarily reflected torsion of the braincase set up by asymmetrical muscle contraction; the tensile axis alternated between +45 degrees and -45 degrees depending on which diagonal masseter/temporalis pair was most active. However, suture strains were not related to overall torsion but instead were responses to local muscle actions. Only the coronal suture showed significant strain (tension) during jaw opening; this was caused by the contraction of neck muscles. All sutures showed strain during jaw closing, but polarity depended on the pattern of muscle usage. For example, masseter contraction tensed the coronal suture and the anterior part of the interfrontal suture, whereas the temporalis caused compression in these locations. Peak tensile strains were larger than peak compressive strains. Histology suggested that the skull is bent at the sutures, with the ectocranial surface tensed and the endocranial surface predominantly compressed. Collectively, these results indicate that skulls with patent sutures should be analyzed as complexes of independent parts rather than solid structures.

Animals↗
PubMed2001

Coca chewing in prehistoric coastal Peru: dental evidence.

In this study, we describe the dental health of four prehistoric human populations from the southern coast of Peru, an area in which independent archaeological evidence suggests that the practice of coca-leaf chewing was relatively common. A repeated pattern of cervical-root caries accompanying root exposure was found on the buccal surfaces of the posterior dentition, coinciding with the typical placement of coca quids during mastication. To further examine the association between caries patterning and coca chewing, caries site characteristics of molar teeth were utilized as indicators for estimating the likelihood of coca chewing for adults within each of the study samples. Likelihood estimates were then compared with results of a test for coca use derived from hair samples from the same individuals. The hair and dental studies exhibited an 85.7% agreement. Thus, we have demonstrated the validity of a hard-tissue technique for identifying the presence of habitual coca-leaf chewing in ancient human remains, which is useful in archaeological contexts where hair is not preserved. These data can be used to explore the distribution of coca chewing in prehistoric times. Simultaneously, we document the dental health associated with this traditional Andean cultural practice.

Coca↗
PubMed1979

Functional heterogeneity in a multipinnate muscle.

Many mammalian muscles have a complex internal architecture. This type of structure could allow a single muscle to produce a variety of force vectors through selective regional contractions. This hypothesis was tested electromyographically in the multipinnate pig masseter by recording simultaneously from several intramuscular sites. It was found that the activity in different portions of the masseter varied systematically during the various phases of mastication. anatomical correlates of the differential activity included fasciculus orientation and length, sarcomere length in specific jaw positions, and histochemical fiber type. The usual assumptions made about muscles for biomechanical analysis, such as uniform contraction and constant line of action, are inappropriate for complex muscles such as the pig masseter.

Animals↗
PubMed2003

Functional significance of cortical bone distribution in anthropoid mandibles: an in vitro assessment of bone strain under combined loads.

Local variation in cortical bone thickness in the postcanine mandibular corpus appears to be stereotypical among anthropoids. Specifically, at sections under the molars, lingually situated cortical bone is typically thinner than that along the lateral aspect. This pattern applies despite phylogenetic, dietary, and allometric differences among the anthropoids sampled to date. Demes et al. (Food Acquisition and Processing in Primates [1984] New York: Plenum Press, p. 369-390) employed a theoretical analysis of mastication in Gorilla and Homo to argue that this pattern could be explained with reference to biomechanical stresses. Specifically, they proposed that the combined effects of torsion and direct shear on the working-side corpus create a condition in which net stresses and strains are reduced along the lingual cortical plate. Demonstration of this effect would suggest a functional linkage between localized differences in bone mass and strain gradients in the facial skeleton. We conducted an empirical evaluation of the effects of the combined loads of torsion and direct shear in vitro on a sample of formalin-fixed human mandibles. Rosette strain gages were affixed to the lateral and medial aspects of the corpus in each specimen, and surface strains were recorded separately under controlled torsional and occlusal loads, and under simultaneous application of these loads. The hypothesis that lingual strains are reduced under combined twisting and occlusal loads was generally supported; however, we observed reduction in surface strains at some sites along the lateral aspect of the corpus under these combined loads as well. These unexpected findings are attributable to unanticipated loading conditions imposed by occlusal forces, which result from sources of stress in addition to direct shear. These experiments provide provisional support for the hypothesis that superposed sources of bone strain produce large strain gradients between buccal and lingual aspects of the mandibular corpus, and that local variation in bone mass may be associated with these gradients.

Animals↗
PubMed1976

Arch form, tooth size, and occlusomandibular kinesis in the Ceboidea.

Correlations between dental morphology, arch configuration, and jaw movement patterns were quantitatively investigated in 23 ceboid species to elucidate integrative aspects of occlusal functional anatomy in an adaptive and evolutionary context. Differential maxillary-mandibular arch widths are primary in guiding lateral jaw movements. These movements are characterized according to their associated condylar shifts as either predominantly translatory or rotational. Predominantly translatory movements result from peripheral contact relationships between maxillary arches which are considerably wider posteriorly than their opposing mandibular arches. The greatest degree of mandibular movement is in the molar region in functional association with wide "primitive" maxillary molars, narrow mandibular molars, constricted maxillary intercanine widths, and narrow maxillary incisors. In contrast, predominantly rotational masticatory jaw movements results from differential arch widths which are greatest in the maxillary canine and incisor regions. Here most jaw movement is in the anterior segment and this is reflected in small maxillary-mandibular molar widths differences, a high degree of premolarization, wide-set maxillary canine teeth, and wide maxillary incisors. Possible selectional factors in the putative evolution of rotational predominance in mastication from the more primitive translatory pattern are discussed.

Animals↗
PubMed1980

Experimental stress analysis of topographic diversity in early hominid gnathic morphology.

Reconstructing the biomechanics of early hominid mastication is a key element in most models of hominid differentiation. Traditionally, osteological features marking muscle attachment surfaces have served as a reference system from which the vector geometry of the masticatory force system and resultant force distributions could be predicted. To augment traditional morphological and computational approaches, we developed a simulation system capable of replicating human and non-human primate chewing motions. The forces of occlusion are recorded as photoelastic fringes in a urethane alveolar process. Simulation experiments evaluating the functional correlates of topographic diversity in zygomatic root position and mandibular ramus height in early hominids indicated that the mandibles and dentitions of robust australopithecines are well adapted to sustain high magnitude, low gradient load distributions.

Animals↗