Effect of Low-intensity Pulsed Ultrasound on Healing of Bone Defects in Rat Tibia as Measured by Reconstructed Three-dimensional Analysis of Micro CT Images.

BACKGROUND/AIM: The aim of this study was to evaluate the effect of low-intensity pulsed ultrasound (LIPUS) on bone metabolism during the healing period in rat tibiae bone defects using micro-computed tomography (micro CT) imaging for three-dimensional morphological evaluation. MATERIALS AND METHODS: The right tibia received ultrasound exposure (US group) every day, whereas the opposite side served as a control (Control group). At 1, 2, and 3 weeks after the operation, micro CT was performed, and the volume and surface area of new bone formation in the bone defects was evaluated three-dimensionally. RESULTS: Bone volume (BV) and bone surface (BS) in the tibiae of both the US and Control groups demonstrated the highest values 1 week after the operation, with no significant differences between the groups. At 2 weeks after the operation, the BV and BS values in both groups had decreased, but the decrease was smaller in the US group than the Control group. At 3 weeks after the operation, the BV and BS values in the Control group were significantly lower than those in the US group. CONCLUSION: LIPUS stimulation can prevent bone loss during the healing of bone defects.

Enamel Matrix Derivative in Diffusion Chamber Implanted Subcutaneously in Rat Induces Formation of Fibrous Connective Tissue Containing Abundant Blood Vessels.

BACKGROUND: Enamel matrix derivative (EMD) is widely used for regeneration therapy in dental clinical situations, but the mechanism of EMD bioactivity remains obscure. To clarify this mechanism, we focused on the formation of connective tissue and blood vessels. The aim of this study was to confirm whether EMD induces the formation of connective tissue and blood vessels by using the diffusion chamber (DC) technique. MATERIALS AND METHODS: Individual DCs containing EMD (DC-EMD) or propylene glycol alginate (PGA) were implanted subcutaneously in rat dorsum. At 4 weeks after the implantation, histological analysis of DCs was performed using azan staining. RESULTS: DC-EMD induced the formation of much larger amounts of connective tissue containing abundant blood vessels than did DC-PGA. CONCLUSION: The results indicated that EMD can induce the formation of both connective tissue and blood vessels. This bioactivity may contribute to the mechanism whereby EMD induces tissue regeneration.

Effects of surface microtopography of titanium disks on cell proliferation and differentiation of osteoblast-like cells isolated from rat calvariae.

The surface topography of implant fixture is an important factor affecting the osseointegration. We herein demonstrated the effects of surface microtopography of titanium disks on proliferation and differentiation of osteoblast-like cells isolated from rat calvariae. Titanium disks with machine surface (MS), rough surface (R1) and rough surface combined with small cavities (R2) were used in an in vitro culture system. Rough surfaces (R1 and R2 disks) induced stronger osteoblast proliferation and differentiation (BGP and sclerostin mRNA expressions and calcium content) than the smooth surface (MS disk). Furthermore, surface microtopography of R2 disk, which was rough with small cavities, more strongly induced cell proliferation and mineralized bone matrix production than R1 disk. Our results suggest that surface microtopography influences osteoblast proliferation and differentiation. R2 disk, which is rough with small cavities, may be used in implant fixtures to increase osseointegration.