| Bone transplantation technology is an oral planting clinical method forrepairing bone defect. The technique, which affects the success rate of oralcavity planting and long-term effects, makes the oral planting technology morewidely indication. So that the patients who are lack of bone will be recover frombone grafting. At present, people use some materials to repair bone defect, forexample, autologous bone, allograft bone, artificial bone materials and so on.The ideal bone graft materials should do well in histocompatibility, boneinduction activity and osteogenic capability. Moreover porosity and intensity aretwo of the most important indicators to choose materials. The autologous bone isknown as the gold standard of bone grafting, because it has the above criteria.For the reasons that the source is limited and the need to open up a secondsurgery, autologous bone is limited in the clinical application. Otherwise, there are risks of immune rejection reaction and the spread of disease when do thesurgery of Allograft transplantation.In recent years, artificial bone material developed rapidly, which becomes aresearch hotspot. Application of the material in the present experiment-nano-hydroxyapatite, collagen／PLA，nHAC／PLA-is Nanoscale biomimeticbone graft material which researched and development by Tsinghua University.This material has good histocompatibility and osteoconductivity, while it can bedegraded in the body. Its porosity is about79.8%, the pore size is about150μm.The holes connected each other. The material can be processed into variousshapes, and with a certain degree of flexural strength. It has been used in clinical,and achieved good results in a small piece of bone graft.In order to shorten the healing of bone defects cycle and to improve thespeed and quality of bone development, a variety of physical stimulations areapplied to clinical, such as ultrasonic stimulation, electromagnetic stimulation, low intensity laser, treated with compressive etc.. Existing experimental datashows that as physical factors stimulate LIUS has promoting effect on culturedosteoblasts in vitro, a large number of animal experiments have proved thatLIUS can promote bone healing of animal model. Ultrasonic is a mechanicalwave, whose frequency above20000HZ. It’s directivity and penetrating power.Ultrasonic plays a big role in the diagnosis and treatment of medical.There are two kinds of ultrasound, the high intensity ultrasound and the lowintensity ultrasound (LIUS). The former used in lesions of cutting, lithotripsyetc.. The latter can be irradiated human tissue to promote tissue repair andfunctional recovery without organizational and cell damage.The LIUS can promote the early fracture healing, alleviate pain, the repairof muscle damage. Bone tissue is highly sensitive to de ultrasonic micropressure, so it causes the body’s biochemical reaction and accelerates the bonehealing. It can lead to physical and chemical effects, mechanical effects and thermal effects.In recent years, it is recognized that LIUS will accelerate the mineralizationand regeneration of bone tissue. But whether it can influence the repair ofArtificial bone is unknown.In spite of accelerating the mineralization and regeneration of bone tissue,there is still no report about use LIUS in the field of Oral Implantology. Thatmay shorten the cultivation cycle if use LIUS to do Oral Implantology bonegraft. And it may improve the success rate of cultivation. In brief, as anon-invasive treatment, the use of LIUS in clinical may promote healing ofartificial bone.This experiment will prove whether LIUS can speed up the healingbetween nHAC/PLA and rabbit skull, whether LIUS can improve the speed andthe quantity of new bone.Purpose of the experiment: Observe the stimulation of LIUS to experimental rabbit skull bone defects. Verify the effect of LIUS to promoterabbit skull and artificial bone healing. Evaluate the histological changes onbone defect after LIUS, such as Inflammation and new bone formation.Method:16New Zealand white rabbits were adopted. Random dividedinto four groups according to the time, each group of four. Put the materialwhich named nHAC/PLA,10mm diameter and2mm thickness into10mmdiameter on both sides of the skull layer of bone defects of the rabbits. The rightside for the experimental group was subjected to ultrasonic irradiation, the leftside of the control group did not irradiated. After surgery, respectively in twoweeks, four weeks, eight weeks, twelve weeks of partial killed the rabbit.Through direct observation, X-ray observation, histological staining to observeand compare the reparation of skull defect, formation of new bone anddegradation of the material. In this experiment, the strength of ultrasonic wavesis30mW/cm~2. Experimental results:1. The rabbits are healthy. There is no swelling, oozing, infection in theincisions of cranial. And no experimental animal died.2. General observation of samples: Around nHAC/PLA, there were boneformations in different degrees when eight weeks and twelve weeks later. Theamount and the hardness of bone tissue formation of experimental group is moreand harder than control group.3. X-ray observation: Compare to bone defect area X-ray resistance level indifferent time, resistance by X-ray radiation area of experimental group wassignificantly larger than the resistance of control group. The difference wassignificant (P<0.01).4. Histological observation: Skull experimental specimens in two weeks, four weeks, eight weeks, twelve weeks, the formations of new bone area ofexperimental group were larger than the formations of control group(P<0.05). Ineight weeks and twelve weeks, the rest formations of material of experimentalgroup were smaller than control group (P<0.05). Inflammation score of theexperimental group was significantly lower than the control group (P<0.05).Bone formation scores of the experimental group were significantly higher thanthose in the control group (P <0.05).Above all, appropriate amount LIUS can generate positive effect on newbone formation, and promote the healing between bone defects and artificialbone of animal model. It verified that LIUS is an ideal method to promoteartificial bone healing with autologous bone. LIUS used in Oral Implantologypostoperative healing period, may promote bone integration, shorten the healingtime, and thus achieve early weight bearing and early rehabilitation. This study provides a theoretical basis for LIUS used in the field of Oral ImplantologyClinical. |
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