Enhancement of Calcium Phosphate Crystal Formation and Bone-Bonding Function on Biological Bone Surfaces by Low-Intensity Pulsed Ultrasound (LIPUS) Irradiation

Abstract

The excellent osteoconductive properties of hydroxyapatite materials are well known, and hydroxyapatite-coated prostheses and dental implants for osseointegration are widely used in clinical practice. However, in clinical practice, there is a demand for even faster integration between implants and living bone from the perspective of rehabilitation and postoperative recovery of Activities of Daily Living, and research is progressing to achieve earlier osseointegration. Against these backgrounds, the author focused on Low-Intensity Pulsed Ultrasound (LIPUS), and has already reported that LIPUS stimulation promotes osseointegration through a physical crystallization mechanism of bone-like calcium phosphate-apatite deposited on the surface of hydroxyapatite material. This study examined whether Low-Intensity Pulsed Ultrasound (LIPUS) can promote the physical crystallization of bone-like calcium phosphate on natural bone surfaces. Natural bone specimens from porcine femurs were immersed in simulated body fluid and sonicated with LIPUS. The surface precipitate conditions were analyzed using scanning electron microscopy and X-ray diffraction. The results showed significantly more calcium phosphate precipitation on the surfaces of the samples irradiated by LIPUS than on the surfaces of the non-irradiated samples. These results suggest that ultrasound irradiation promotes the precipitation of bone-like hydroxyapatite on biological bone and realizes the excellent osseointegration of the hydroxyapatite material surface with the biological bone matrix.