ABSTRACT
This study assesses the effect of low intensity pulsed ultrasound (LIPUS) on new bone formation during mandibular distraction osteogenesis (DO) in rabbits. 24 rabbits underwent DO on the right side of the mandible. 12 rabbits received a daily 20-min LIPUS (1.5 MHz, 30 mW/cm2) treatment on the first day of the distraction until they were killed at week 0 (immediately after the distraction), week 2 and week 4 after the distraction. Four rabbits were killed at each time point. The other 12 rabbits followed the same protocol without the ultrasound treatment. A plain radiography, a micro-CT scan, a microhardness test and a histological examination were used to evaluate new bone formation in the distraction gap. At week 0 and week 2 after the distraction, the treatment groups showed higher radiopacity and microhardness (p<0.05), and more bone formation was detected by the histological examination. At week 4 after the distraction, there was no statistical difference between the two groups. In this study, LIPUS accelerated new bone formation during the distraction period and 2 weeks after the distraction, which implies that the effective time for using LIPUS is in the early stage of DO.
Subject(s)
Mandible/surgery , Osteogenesis, Distraction/methods , Osteogenesis/radiation effects , Sound , Animals , Bone Density/radiation effects , Bone Regeneration/radiation effects , Calcification, Physiologic/radiation effects , Hardness , Male , Mandible/pathology , Mandible/radiation effects , Rabbits , Radiographic Image Enhancement , Random Allocation , Time Factors , Transducers , Ultrasonics/instrumentation , X-Ray MicrotomographyABSTRACT
Bone morphogenetic proteins (BMPs) are growth and differentiation factors that have been purified and widely accepted to be the most important regulators in the processes of bone formation. The aim of this study was to identify the BMPs that are expressed in normal human bone, and to investigate the specific pattern of BMP2-BMP9 expression in normal human intramembranous and endochondral bone to maintain homeostasis, as well as in ex vivo primary cell culture of human osteoblasts from intramembranous and endochondral bone. Semi-quantitative RT-PCR indicated that 2 types of bone of different embryological origin have distinct patterns of BMP expression. BMP3, 4, 7 and 8 were strongly expressed in normal intramembranous bone compared to endochondral bone, whereas BMP2 and 5 were highly expressed in endochondral bone. The expression of BMP9 and BMP15 in human bone was identified for the first time. From the very similar expression patterns of BMPs in fresh normal bone and ex vivo osteoblastic cell culture, it can be proposed that the different proportions of BMPs in normal human intramembranous and endochondral bone needed to maintain normal homeostasis.
