The Experimental Research Of LIPUS Accelerate Earlier Bone Healing Of Mandile

The incidence of fracture is very high clinically,though mostof fractures can heal succeedly,there will be some delay to heal orcoundnot heal.So it will be a challenge to accelerate bone healing,avoid delayed healing and non-healing(maybe 5-10 in all ).Manybiotic and biophysical methods have been used to accelerate bonehealing and verified to be effective,one of which is low intensitypulsed ultrasound.It have been confirmed, low intensity pulsed ultrasound notonly can accelerate bone healing,decrease healing time by 40%,alsocan treat delayed healing or non-healing effectively,safely,none-invasively.FDA approve low intensity pulsed ultrasound can beused to treat fresh fractures in October 1994,then nonuions inFebruary2000, but most of the object is long bone,the report aboutmanibular healing is seldom seen. To explore whether lowintensity pulsed ultrasound can accelerate mandibuler defect to healin advance, 12 white rabbits were assigned randomly to experimentgroup and control group. After bone defect was performed inmandible. All of the left side defect received LIPU for 20 min/day(treatment group) and the right received sham LIPU (control group)from day 1 until sacrifice on day 7,14,28.After sacrifice, healingbone density and single-energy X-ray absorptiometry TGF-β andBMP immuno-histochemistry stain were performed in turn. Thenassay Bone density , grey value and the image. It have been foundall of the rabbits fed up to eat two days after surgery ,the the activityand eating is normal. One week after surgery the defect area isobvious, two and four weeks after it had obselete dividing linewith peripheral bone tissues. "V"bony callus can be seen at theinferior border of mandible. After surgery ,the treatment group isbetter the control group,mainly expressed in that bony callus area islarger, had obselete dividing line with peripheral bone tissues.One week after surgery,x-ray of experiment group indicatethat there is a little bony callus,while the control group is notobvious;two week after surgery,all of the experiment group sampleshave bony union, there is corniform dimple upto bony callus,but incontral group there are two have no bony union,obvious defectshadow is visible;four weeks after,all of the experiment group havecomplete bony callus,on the contex site bony callus is not smoothenough, but have dimple or ledging on the surface, in contral groupthere are one have no bony union, defect shadow is also visible,others are the some to experiment group.grey value measure-ementsindicated that bone defect of the treatment group were significantlyhigher than control group (p<0.05) at week 1and week 2, however,atweek 4 there were no significant differentce between the treatmentgroup and control group.In the mandibular model,after HE stain, fibrous tissue havefilled bone defect of the treatment group and part of control groupat week 1, a lot of fibroblast cells is visible, in the treatment groupsome bone trabecula is visible, and also neoplastic bone andosteoblast cells on the lateral border of the bony defect. In thecontrol group the osteoblast activity is not manifest.At week 2,newly formed bone trabecula extend to the middle of the defect,neoplastic bone and osteoblast cells is manifest, in control groupthere is newly formed bone trabecula and osteoblast cells on both ofthe lateral margin, but in the central part there are lots of fibroblastcells and tissues.At week 4,in experiment group bony callus havefilled the defect,but in the control group some fibrous callus is alsovisible.After immunohistochemistry strain the images analysisindicate that TGF-βand BMP of the treatment group were signific-antly higher than control group (p<0.05) at week 1and week 2,however,at week 4 there were no significant differentce between thetreatment group and control group.After all, LIPUS could accelerate proliferation and activity ofpreosteoblast, increase the amount of osteoblast cells, speed upcalcium salts to deposit in bony matrix, so that neoplastic bonemineralization and bone trabecula formation is accelerated. All ofthese indicate that earlier bone healing of mandible is possible. Butthere is no complete and unified cognition on the mechanism of howLIPUS accelerate bone healing. Maybe LIPUS accelerate bonehealing is not only through one mechanism,one stage,but throughaffect the whole stage of bone healing process.Therefor, advancedresearch is demandable.