Allometry of Masticatory Loading Parameters in Mammals

Abstract

Considerable research on the scaling of loading patterns in mammalian locomotor systems has not been accompanied by a similarly comprehensive analysis of the interspecific scaling of loading regimes in the mammalian masticatory complex. To address this deficiency, we analyzed mandibular corpus bone strain in 11 mammalian taxa varying in body size by over 2.5 orders of magnitude, including goats, horses, alpacas, pigs, and seven primate taxa. During alert chewing and biting of hard/ tough foods, bone-strain data were collected with rosette gauges placed along the lateral aspect of the mandibular corpus below the molars or premolars. Bone-strain data were used to characterize relevant masticatory loading parameters: peak loading magnitudes, chewing cycle duration, chewing frequency, occlusal duty factor, loading rate, and loading time. Interspecific analyses indicate that much as observed in limb elements, corpus peak-strain magnitudes are similar across mammals of disparate body sizes. Chewing frequency is inversely correlated with body size, much as with locomotor stride frequency. Some of this allometric variation in chewing frequency appears to be due to a negative correlation with loading time, which increases with body size. Similar to the locomotor apparatus, occlusal duty factor, or the duration of the chewing cycle during which the corpus is loaded, does not vary with body size. Peak principal-strain magnitudes are most strongly positively correlated with loading rate and only secondarily with loading, with this complex relationship best described by a multiple regression equation with an interaction term between loading rate and loading time. In addition to informing interpretations of craniomandibular growth, form, function, and allometry, these comparisons provide a skeleton-wide perspective on the patterning of osteogenic stimuli across body sizes. Anat Rec, 293:557-571,

Teaching an old jaw new tricks: Diet-induced plasticity in a model organism, from weaning to adulthood

“…In accord with our predictions derived from previous plasticity studies in rabbits (Ravosa et al, 2007;Ravosa et al, 2008;Ravosa et al, 2010a;Menegaz et al, 2009;Scott et al, 2014) and current understanding of bone functional adaptation (e.g. Bouvier and Hylander, 1981;Lanyon and Rubin, 1985;Biewener, 1993;Pearson and Lieberman, 2004;Ruff et al, 2006;Ravosa et al, 2010b), we found that our experimental groups responded to mechanically challenging foods -and the increase in loading such foods are expected to engender -by increasing the cross-sectional areas of various jaw structures, thereby presumably reducing bone strain. However, in contrast to our prediction that the magnitude of the plastic responses would decrease with age, we found remarkably similar effect sizes in juveniles (11 weeks of age) and young adults (29 weeks of age) at three out of the four sites we examined.…”

“…bone functional adaptation). The literature devoted to this subject is vast (for reviews, see Lanyon and Rubin, 1985;Bertram and Swartz, 1991;Biewener, 1993;Pearson and Lieberman, 2004;Ruff et al, 2006;Ravosa et al, 2010b). This intensive focus is related to skeletal plasticity's relevance to biomedical applications (e.g.…”

“…Menegaz et al, 2009;Holmes and Ruff, 2011;Scott et al, 2014;Standen et al, 2014). The way in which bone responds to loading over the course of an organism's lifetime is complex and multileveled (Bertram and Swartz, 1991;Hsieh et al, 2001;Pearson and Lieberman, 2004;Hamrick et al, 2006;Ruff et al, 2006;Ravosa et al, 2008;Ravosa et al, 2010b). Several studies have observed an age-related decrease in the ability of an organism to modify a bone's cross-sectional geometry adaptively (i.e.…”

Differential limb loading in miniature pigs (Sus scrofa domesticus): a test of chondral modeling theory

“…Clearly, there are extrinsic and intrinsic influences on regional and local variation in chondrogenic stimuli. Coupled with the fact that there are strain-mediated, site-specific osteogenic thresholds throughout the skeleton (Goodship et al, 1979;Rawlinson et al, 1995;Hylander and Johnson, 1997;Ravosa et al, 2010), this suggests it is highly likely that a similar scenario applies to both hard and soft connective tissues.…”

Bone up: craniomandibular development and hard-tissue biomineralization in neonate mice

“…This discovery contrasts with prior notions that bone throughout the skeleton generally has similar peak-strain magnitudes during forceful activities (Biewener, 1982, 1993; Rubin and Lanyon, 1984; Lanyon and Rubin, 1985). For instance, circumorbital and calvarial strains during biting and chewing are lower than along the mandible and other masticatory structures (Hylander et al, 1991; Hylander and Johnson, 1997; Herring and Teng, 2000; Ravosa et al, 2000, 2010). Also, while mammalian jaw and limb elements exhibit marked osteogenic responses in terms of initiating processes of resorption and formation of bone tissue under altered loading conditions, calvarial, circumorbital and basicranial hard tissues are minimally responsive to similar changes in loading stimuli (Bouvier and Hylander, 1981, 1996; Biewener et al, 1986; Rawlinson et al, 1995; Franks et al, 2017).…”