Craniofacial growth under the influence of the blood supply. 12. Regulation of bone remodeling

: Growth is controlled by phylogenetic and ontogenetic factors. Regulation of bone growth can be regarded as taking place at 3 levels, a high, general level at which genetics and hormones represent the main regulators, a middle, regional level where the vascular influence predominates, and a low, local level dominated by mechanical factors. Stresses within the bone, which under physiological conditions are in a state of dynamic equilibrium, play a significant role in the shaping of bony structures. The apposition or resorption of bony material is accelerated if such stresses exceed or drop below certain limits. Biophysically, bone is comparable to technical materials consisting mainly of hydroxyl apatite and collagen. Deformation of the hydroxyl apatite is associated with piezoelectric effects which induce changes in bone structure.