Expression of osseointegration-related genes around titanium implant: BMP2, BMP4

Expression of TGF-betaand IGF-I during osseointegration of titanium implant

Expression of BMP-2, -4 during distraction osteogenesis in the rabbit mandible

Distraction osteogenesis(DO) is defined as a gradual mechanical process of mechanical stretching two vascularized bone surface apart with a critical rate and rhythm such that new bone forms within the expanding gap, reliably bridges the gap, and ultimately remodels to normal structure. DO has become a mainstay in bone tissue engineering and has significantly improved our armamentarium for reconstructive craniomaxillofacial procedures. But the molecular and biological mechanisms that regulate the formation of new bone during distraction osteogenesis are not completely understood. BMPs are potent osteoinductive agents. Our hypothesis was that BMPs, especially BMP-2 and BMP-4, might play an importent role in the signaling pathways that link the mechanical forces created by distraction to biological responses and in promting new bone formation. Using a rabbit's mandible, we investigated the expression of BMP-2, -4 at different time points during distraction osteogenesis. The purpose of this study is to research the pattern of expression of BMP-2, -4 in new bone formation during distraction osteogenesis of the rabbit mandible. The experimental group was applied gradual distraction (0.7mm a day by twice a day, 4.9mm in total, for 7 days) and the control group was carried out osteotomy alone. They were examined clinically, histologically, and by RT-PCR analysis. On 3 days after osteotomy, the high level of expression of BMP-2, -4 was detected. But, the expression of BMP-4 was decreased during latency period. As distraction was started, its expression was increased and maintained till postoperative 28days. In control group, the expression of BMP-4was remarkably decreased till postoperative 14 days. On the other hand, the expression of BMP-2 was no difference between experimental group and control group. The expression of BMP-4 was maintanined at high level during the entire experimental period in both group. These findings suggested that excellent bone formation during distraction osteogenesis is associated with enhanced expression of BMP-4 genes by mechanical tension stress.

Expression of type I, type II collagen on distraction osteogenesis in the rabbit mandible

The purpose of this experiment was to examine the histological changes and the pattern of expression of type I, II collagen in the elongated area by distraction osteogenesis in the rabbit mandible. Sixteen rabbits weighing 2.5kg-3kg were used for this experiment. Experimental group was distracted at the rate of 0.7mm, twice/day for 7days, and control group was only osteotomized. After 5 days latency, osteotomic site is distracted for 7days. Consolidation period is 28days. The animal was sacrificed at the 3rd, 7th, 14th, 28th day after the operation. The distracted bone was examined by histological analysis and RT-PCR analysis. The results were summarized as follows: 1. Experimental group was observed that the gaps between the distracted bone edges were occupied by new bone. 2. Expression of Type I collagen were detected throughout the experiment in both groups and Expression of Type I collagen were markedly increased during distraction and consolidation period in experimental group than control group. 3. Expression of Type II collagen were detected throughout the experiment in both groups and expression of Type II collagen were maintained at high level during distraction and consolidation period in experimental group than control group. From these results, in contrast to type II collagen, type I collagen seemed to be more expressed by mechanical stimuli during distraction and consolidation period. The predominent mechanism of new bone formation in the distraction gap was intramembranous bone formation, but some of the regenerated bone was formed by endochondral ossification.

Expression of osteonectin on distraction osteogenesis in the rabbit mandible

Distraction osteogenesis has been thought to be promising technique for replacing bone graft in maxilla and mandible. The purpose of this study was to investigate the expression of osteonectin on distraction osteogenesis. Sixteen rabbits were used for this experiment. Osteotomy was performed between premolar and mental foramen. On the experimental group, distraction device was connected to the respective bone segments. On the control group, bone segments were fixed using plate and screws after osteotomy. Distraction was carried out at the rate of 0.7mm per day to obtain a 4.9mm elongation on the experimental group. After 3 days, 7 days, 14 days, and 28 days two rabbits of each group were sacrificed. The results obtained from this study were as follow : Experimental group was observed that the gaps between the distracted bone edges were occupied by new bone. Expression of Osteonectin were detected throughout the experiment in both groups and Expression of Osteonectin were markedly increased during distraction and consolidation period in experimental group than control group. From these results, it could be stated that distraction was shown to improve and accelerate bone formation and mechanical stress like distraction has considerable effects on osteonectin.

A Comparison Study On Distraction Osteogenesis In The Rat's Mandible According To Distraction Rhythm