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Experimental Study of AZ31Magnesium Alloys on Repairing Jaw Bone Defects and Distraction Osteogenesis

Author: WangShuFeng
Tutor: WangChengYue
School: Liaoning Medical
Course: Clinical Stomatology
Keywords: Micro-arc oxidation AZ31magnesium alloy rBMSCs biocompatibility tissue engineeringAZ31magnesium alloy biodegradability micro-arc oxidation boneAZ31magnesium alloy distraction osteogenesis bone formation mongrel dogs
CLC: R318.08
Type: Master's thesis
Year: 2013
Downloads: 12
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Abstract

ObjectiveTo evaluate the biocompatibility of a micro-arc oxidation treated AZ31magnesium alloy, and to provide the experimental evidence for its applicationin tissue engineering.MethodsrBMSCs was expanded culturing in vitro. The third generation cells wereimplanted into the un-treated AZ31magnesium alloy (magnesium alloygroup+BMSCs) and micro-arc oxidation treated AZ31magnesium alloy(micro-arc oxidation treated magnesium alloy group+BMSCs), in addition of ablank control group (BMSCs group). Inverted microscope, HE dying, cell count,SEM were used at the pre-set time point to observe the ecology characters,cell growth and adhesion condition.ResultsAfter co-culturing, through optical microscopy observation, cells onmagnesium alloy group+BMSCs and micro-arc oxidation treated magnesiumalloy group+BMSCs were the same as the BMSCs group. In spindlemorphology and MTT analysis showed that the cells number and growthcondition of magnesium alloy group+BMSCs and micro-arc oxidation treatedmagnesium alloy group+BMSCs were consistent, however, the former was not equal to the later (p <0.05). Cells count analysis and SEM observationshowed that the surface of micro-arc oxidation treated magnesium alloy group+BMSCs had a large number of cells on it, which grew normally, and thesurface of magnesium alloy group+BMSCs had almost no cells and had somecracks (p <0.05).ConclusionMicro-arc oxidation treated AZ31magnesium alloy has a goodbiocompatibility, which can be helpful for cell adhesion and normal growth. ObjectiveTo investigate degradation, bonding of metals-bone interface and boneformation of AZ31magnesium alloy in bone defects repair.MethodsA7mm×5mm defect similar to the kind of bone fenestration defect wasmade in reach rabbit each mandibular buccal side. The detects were implantedwith untreated AZ31magnesium alloy group (group A), micro-arc oxidationtreated AZ31magnesium alloy group (group B), and blank control group (groupC, not repairing defects). The concentrations of magnesium ion in blood andurine were measured at pre-operatively1day, post-operatively1,2,4,8and12weeks. Rabbits were sacrificed at3months after postoperation. The defectswere evaluated by gross observation, SEM, and histology.ResultsMagnesium ion concentration detections in blood and urine showed thatmagnesium ion concentration in blood of group A and B had fluctuation in thenormal range (0.82-2.22mmol/l) and there was no significant difference before and after surgery.2weeks after operation, magnesium ion concentration inurine of group A was significantly increased compared with pre-operation,there was a significant differences. Magnesium ion concentration in urine ofgroup B had no significant difference between preoperation and postoperation.3months after surgery, the gross observation showed that the metals-bonetissue of group B was bounded more closely than group A, only thecartilage-like tissue was formed around material of group A, the new bone wasformed that covered around material of group B, no bone was formed andfibrous connective tissue filled the bone defect area of group C. SEMobservation indicated that the surface of group A had layered disintegration.While degradation is not obvious in group B. Histological observation showedthat the cartilage-like tissue was made around group A, there were a largenumber of new bone was around group B, but fibrous tissue was only repairedin group C.ConclusionMicro-arc oxidation reduces the degradation rate of magnesium alloy incertain extent. Bioactive ceramic layer formed on the surface of magnesiumalloy can effectively prevent the rejection. Micro-arc oxidation treated AZ31magnesium alloy has bone induction. untreated AZ31magnesium alloy andmicro-arc oxidation treated AZ31magnesium alloy have non-toxic to the bloodcirculation and urinary system。 ObjectiveThis study aimed to evaluate the bone formation using self-designedAZ31magnesium alloy tractor on vertical mandibular distraction osteogenesis(DO).MethodsTwelve mongrel dogs were used in this study. The last3star’s teeth of bilateral mandibular were pulled out3months before distraction osteogenesis.After3months, mandibular osteotomy was made in bilateral mandibles, themagnesium alloy tractors were implanted. The distraction ostoegenesis wascarried out5days after mandibuar osteotomy. Distraction proceeded at a rateof0.3mm/8hours and continued7days. The contralateral side of the mandibleserved as the control bone do not be traction. The animals were sacrificed4weeks after surgery. The evaluations were carrying out generalobservation,vertical height measurement of mandibular, scanning electronmicroscopy (SEM) observations, tetracycline fluorescence observation,histologic observations and liver-kidney pathological detection.ResultsThe height of mandibular was increased average (6.30±0.02) mm inexperimential group, it was significant difference compared to control (P<0.01).There were active osteoblasts and trabeculae formation manifestly inexperimential group. Mature bone was significantly less than in the controlmandible. SEM showed that there were obvious cracks on surface of themagnesium alloy. The liver and kidney pathological showed no exception inliver and kidney tissues.ConclusionAZ31biodegradable magnesium alloy could normally complete theprocess of traction and fixed period. It had potential ability to promote boneformation and increase width of the mandibular.AZ31magnesium alloy hascertain degradation speed in mandibular. AZ31magnesium alloy had not anynegative effect on the liver and kidney tissues.

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