Meeting Abstract
Processing mechanically challenging (e.g., tough or stiff) foods alters feeding behaviors in mammals, requiring larger bite forces or prolonged mastication. The bony response to high bite forces in the mammalian skull is well known, but osteogenesis due to protracted chewing (i.e., cyclical loading) is more poorly understood. Prior studies indicate greater bone formation in mandibles of rabbits raised on mechanically challenging foods, and a stronger link between bone remodeling and cyclical loading vs. high-magnitude strains. Here we assess the relationship between cyclical loading and remodeling, the repair of microdamage due to mechanical deformation and fatigue loading. Ten male white rabbits (Oryctolagus cuniculus) were obtained at weaning (4 weeks) and raised on one of two diets until mature (52 weeks). Five subjects ate pellets (E=29Mpa, R=1031Jm-2), and the other five processed pellets and hay (E=3336Mpa, R=2760Jm-2). Mastication of hay results in higher chewing investment (475 vs. 161 chews/g) and prolonged chewing duration (568 vs. 173 sec/g). Remodeling was measured as osteon population density (OPD) and percent Haversian bone (%HAV) in 100µm coronal sections of left maxillae between P2 and P3. An outlier was excluded from analysis due to sectioning error. Mean OPD and %HAV were greater in the hay group, but Mann-Whitney U tests revealed no significant difference between treatments (P=0.111, both). This finding suggests that elevated cyclical loading does not result in greater remodeling in rabbit maxillae. Future analyses will examine additional subjects as well as other cranial sites to more fully characterize mechanisms of adaptive plasticity in bone quantity and quality.
