Repair Effect Of NHA-Mg Porous Composite Materials Modified By PLGA On Jaw Bone Defect Of Rabbits

Many diseases can result in jaw bone defects,such as face deformity,tumor,trauma and chronic inflammation.Using bone tissue engineering scaffold materials to repair bone defects is one of the research focuses currently.nano-hydroxyapatite(nHA)has good structure and osteogenesis as the common implant materials of bone defects,but has a disadvantage of low mechanical strength and poor toughness.Mg has good mechanical properties,and can increase the activity of osteoblasts,but the metabolism velocity of Mg is very fast and there is no suitable space structure for new tissue growth.nHA-Mg composite materials can improve the osteogenesis and mechanical strength of materials,and surface modified by poly lactic acid/glycolic acid(PLGA)can slow the degradation rate of Mg.Previous experiments show that the composite materials have good spatial structure,suitable intensity and no cytotoxicity.This experiment will implant composite materials into animal model of mandibular defects,observe the effect of bone repair and provide experimental basis for the further research of the composite materials.The mandibular defect models of 10 mm×5 mm×1 mm in the rabbits were established,nine rabbits were selected and implanted with nHA–Mg composite materials modified by PLGA in the left as experimental group and the right as blank control group;the other nine were implanted with nHA–Mg in the left as positive control group and the right as blank control group.The rabbits were sacrificed at 4,8,12 weeks and the mandibular defect areas were intercepted and observed by imaging and histological examination;the sizes of the newborn trabecula area and residual materials in experimental group and control group were compared.Compared with positive control group and blank control group,the percentage of newborn trabecula area of the rabbits in experimental group was increased(P<0.05),and there was no statistic difference between positive control group and blank control group(P>0.05).The imaging results showed that the new bone formation can be observed in experimental group and better than positive control group and blank control group.The paraffin section results indicated that there were visible vascular tissue and newborn trabecula,osteoblasts gathered around the bone trabecula,a lot of pit were located in the bone trabecula and the pit contained osteocytes in experimental group.As time grew,thickened newborn trabecula,dense arrangement and trend of converting to lamellar bone were observed in experimental group.The hard tissue section results showed that the remaining amount of materials in experimental group was more than that in positive control group.In conclusion,nHA-Mg porous composite materials modified by PLGA can effectively reduce the rate of degradation in the body,promote osteogenesis and guide the bone regeneration.