Elastic properties of human supraorbital and mandibular bone

Dechow, Paul C.; Nail, G. A.; Schwartz-Dabney, Carina; Ashman, Richard

doi:10.1002/ajpa.1330900304

Cited by 151 publications

(152 citation statements)

References 46 publications

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“…This is important considering the role that the cranial vault plays in protection of the brain, and the finding that the cranial vault is denser than some postcranial bones. A comparison of our current findings to previous work on the human mandible in our laboratory (Dechow et al, 1993;Schwartz-Dabney and Dechow, in press) shows that parietal cortical bone is on average less dense than that of the mandible. However, density in the mandible varies by region and density in the parietal bone is greater than in the least-dense regions of the mandible, such as at the symphysis.…”

Section: Table 3 Elastic Moduli In Gpasupporting

confidence: 70%

“…The results demonstrate that determination of material orientation in cranial vault cortical bone is essential prior to measurement of elastic properties. A previous study in our laboratory (Dechow et al, 1993) showed a significant difference between the elastic properties of cortical bone taken from the superorbit compared to the buccal surface of the inferior border of the mandibular corpus. The mandibular cortical bone is stiffer and denser, and has a consistent anisotropy in the plane of the cortical plate.…”

Section: Materials Propertiesmentioning

confidence: 72%

“…Conversely, the aggregate moduli for the supraorbital cortex indicate isotropy in this plane. However, that study (Dechow et al, 1993) did not determine the principal directions of cortical stiffness prior to measurement of ultrasonic velocities. Rather, it was assumed that the principal direction of stiffness of the mandible is parallel to the inferior border, and that of the superorbit is parallel to the orientation of the browridges.…”

Section: Materials Propertiesmentioning

confidence: 95%

“…We computed 6 ϫ 6 matrices of elastic coefficients, or "C" matrices from the time delays, and widths and densities of the bone specimens, and then calculated elastic moduli from the "C" matrices. The elastic constants quantify the relationship between a load (stress) placed on a structure and the resulting deformation of that structure (strain), within its elastic range (Cowin, 1989;Dechow et al, 1993). Calculated technical constants included: 1) Young's modulus, a measure of the ability of a structure to resist deformation in a given direction; 2) the shear modulus, a measure of the ability of a structure to resist shear stresses; and 3) Poisson's ratio, a measure of the ability of a structure to resist deformation perpendicular to that of the applied load.…”

Section: Methodsmentioning

confidence: 99%

“…Preliminary studies of the cortical structure of human parietal and frontal bones Dechow, 1995, 1996;Peterson et al, 1997) were surprising because most specimens from both tables exhibited some anisotropy. An earlier investigation (Dechow et al, 1993) found little anisotropy in supraorbital bone, but did not use a technique designed to evaluate the principal directions of stiffness in the cortical specimens.…”

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confidence: 95%

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Material properties of the inner and outer cortical tables of the human parietal bone

Peterson¹,

Dechow²

2002

Anat. Rec.

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Even though the cranial vault functions as protection for the brain and as a support structure for facial and masticatory functions, little is known about its mechanical properties or their variations. The cranial vault bone is interesting because of its maintenance in spite of low functional strains, and because calvarial bone cells are often used in cell culture studies. We measured thickness, density, and ash weight, and ultrasonically determined elastic properties throughout the cortices of 10 human parietal bones. The results are unique for studies of the cranial vault because: 1) measurements focused specifically on the cortical components, 2) the orientations of the axes of maximum stiffness were determined before measurement of elastic properties, and 3) two related measurements (bone density and percent ash weight) were compared. Results showed that the periosteal cortical plate (outer table) and the endosteal cortical plate (inner table) had significant differences in material properties. The outer table was on average thicker, denser, and stiffer than the inner table, which had a higher ash weight percentage. Within each table there were significant differences in thicknesses, ash weight percentages, and E 2 /E 3 anisotropies among sites. Few sites on either table had significant orientations of the axes of maximum stiffness. Despite this apparent randomness in orientation, almost all sites exhibited anisotropies equivalent to other parts of the skeleton. Anat Rec 268:7-15, 2002.

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Section: Table 3 Elastic Moduli In Gpasupporting

confidence: 70%

Section: Materials Propertiesmentioning

confidence: 72%

Section: Materials Propertiesmentioning

confidence: 95%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 95%

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Material properties of the inner and outer cortical tables of the human parietal bone

Peterson¹,

Dechow²

2002

Anat. Rec.

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In vivo and in vitro bone strain in the owl monkey circumorbital region and the function of the postorbital septum

Ross

Hylander

1996

Am. J. Phys. Anthropol.

109

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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...

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In vivo bone strain patterns in the zygomatic arch of macaques and the significance of these patterns for functional interpretations of craniofacial form

Hylander

Johnson

1997

Am. J. Phys. Anthropol.

181

183

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It has been proposed that the mammalian facial skeleton is optimized for countering or dissipating masticatory stress. As optimized load-bearing structures by definition exhibit maximum strength with a minimum amount of material, this hypothesis predicts that during chewing and biting there should be relatively high and near uniform amounts of strain throughout the facial skeleton. If levels of strain in certain areas of the facial skeleton are relatively low during these behaviors, this indicates that the amount of bone mass in these areas could be significantly reduced without resulting in the danger of structural failure due to repeated masticatory loads. Furthermore, and by definition, this indicates that these areas are not optimized for countering masticatory stress, and instead their overall morphology and concentration of bone mass has most likely been selected or influenced mainly by factors unrelated to the dissipation or countering of chewing and biting forces. An analysis of in vivo bone strain along the lateral aspect of the zygomatic arch of macaques indicates the clear absence of a high and near uniform strain environment throughout its extent. Instead, there is a steep strain gradient along the zygomatic arch, with the highest strains along its anterior portion, intermediate strains along its middle portion, and the lowest strains along its posterior portion. These data, in combination with earlier published data (Hylander et al., 1991), indicate that levels of functional strains during chewing and biting are highly variable from one region of the face to the next, and therefore it is unlikely that all facial bones are especially designed so as to minimize bone tissue and maximize strength for countering masticatory loads. Thus, the functional significance of the morphology of certain facial bones need not necessarily bear any important or special relationship to routine and habitual cyclical mechanical loads associated with chewing or biting. Furthermore, the presence of these steep strain gradients within the facial skeleton suggests that the amount of bone mass in the low-strain areas may be largely determined by factors unrelated to processes frequently referred to as "functional adaptation," or conversely, that the "optimal strain environment" of bone varies enormously throughout the facial skeleton (cf., Rubin et al., 1994). Based solely on anatomical considerations, it is likely that the zygomatic arch is bent in both the parasagittal and transverse planes and twisted about its long axis. Due to constraints on rosette position, the strain data are incapable of determining if one or more of these loading conditions predominate. Instead, the strain data simply provide limited support for the possible presence of all of these loading regimes. Finally, as the masseter muscle is concentrated along the anterior portion of the zygomatic arch and as the arch has fixed ends, the largest shearing forces and the largest bending and twisting moments are located along its anterior portion. This in turn ...

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Elastic properties of human supraorbital and mandibular bone

Cited by 151 publications

References 46 publications

Material properties of the inner and outer cortical tables of the human parietal bone

Material properties of the inner and outer cortical tables of the human parietal bone

In vivo and in vitro bone strain in the owl monkey circumorbital region and the function of the postorbital septum

In vivo bone strain patterns in the zygomatic arch of macaques and the significance of these patterns for functional interpretations of craniofacial form

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