The facilitating effects of mechanical forces on mineral deposition and crystal transition

Bone formation is an essential process in maintaining bone homeostasis during bone remodeling induced by mechanical force. As the product of bone formation, mineralized collagen is critical for bone strength and quality. However, the effects of mechanical forces on the formation of mineralized collagen remain obscure. Therefore, we applied mechanical force, either tensile force or compressive force, to the in vitro biomimetic mineralization system for 24, 48, and 72 hours. According to the morphological observation under scanning electron microscopy and high-resolution transmission electron microscopy, there was elevated production of minerals depositing along the collagen fibrils in the force-loading groups. We were able to detect the early transformation of crystals and the main components contained amorphous precursor and hydroxyapatite identified by X-ray diffraction. Besides, the changes in the binding energy of elements indicated that the mechanical force accelerated the surface chemical reaction. Furthermore, the comparison and semiquantitative analysis among the spectrum of corresponding groups showed that mechanical forces could affect the bond vibration as well as mechanical properties. Taken together, we confirmed the promoting effects of mechanical force on the formation of mineralized collagen, and this study has made a tentative exploration of the effects of orthodontic force on the formation of mineralized collagen, complementing the biological phenomena occurring in the process of bone remodeling. These findings are expected to provide a theoretical basis for further research into the underlying mechanisms.