| Objective:To observe the situations of Osseointegration that porous hydroxyapatite with the structure of Micro-grooved Patterns repairing the mandibular defect in dogs and delay implantation in different times,to clarify whether and when the implants could combine with the new bone by induced materials,analyze and compare the difference and widen the thought of clinical case of implant restoration after repairing extensive bone defects of mandibular.Methods:Choose eight healthy adult male Beagle dogs,randomly divided into two groups of A and B.Respectively extracting dogs’ bilateral mandibular premolars,after three months open the buckle gums of double premolar,make two bone defect diameter of 8mm,height of 10mm.The experimental group A implanted porous hydroxyapatite with the structure of Micro-grooved Patterns that corresponding to the size of the material,control group B implantation of autologous bone as a positive control.After three months,on the center of the bone defect area to perpendicular implant 4.0 mm*10 mm Dentium implants.Four dogs were killed in four weeks and twelve weeks after surgery,take out the mandible bone with the implant and the surrounding material for CBCT testing,Micro CT testing,histological examination,implant resonance frequency analysis and mechanical testing.Evaluate and discuss the situation of new bone induced by the porous hydroxyapatite with the structure of Micro-grooved Patterns and dental implant’s bone union.Results:1.Observe the results of regular clinical examination and sample results.All the experimental dogs were healthy after the operation.The wound in the operative area recovered well.During the sampling,there was a good osteogenesis in each group at different periods,and the surface of group A was covered by bone tissue.In 4 weeks,there was a small amount of clearance around the implant,and the implant was closely related to the surrounding bone tissue in 12 weeks,without loosening and shedding,and the neck was not exposed.The implants neither of the two groups were no loose,and the neck was not exposed.2.CBCT detectionAt four weeks,it was seen that bone-grafting materials in group A.There was no obvious difference between high-density shadow and natural bone in the pores of the material,and some low-density shadows were found in the implant and osseous interface.A partial low-density image was also seen in group B implant and bone binding interface.At twelve weeks,the material images of the graft area of group A were still visible,and the space of the material was filled with the high density shadow consistent with the natural bone,and the area of the implant and bone combination increased.In group B bone tissue and implant were closely associated with no obvious shadow.3.Micro-CT detectionComparison of bone volume fraction(BV/TV):at four weeks,there was no significant difference between group A and group B(P>0.05).At twelve weeks,there was no significant difference between group A and group B(P>0.05).The comparison of two groups respectively at different time showed statistically significant difference(P<0.05),and the BV/TV value at twelve weeks was greater than four weeks.The thickness of bone trabecular(Tb.Th)was compared:at four weeks,there were significant differences between the two groups,group A was less than group B(P<0.05),and the difference between group A and group B was not statistically significant at twelve weeks(P>0.05).The comparison of two groups respectively at different time showed statistically significant difference(P<0.05),and the Tb.Th value at twelve weeks was greater than four weeks.Comparison of the separation degree of bone trabecular(Tb.Sp):at four weeks,there were significant differences between the two groups,group A was larger than group B(P<0.05),and there was no statistically significant difference between group A and group B at twelve weeks(P>0.05).The comparison of two groups respectively at different time showed statistically significant difference(P<0.05),and the Tb.Sp value at twelve weeks was less than four weeks.The number of bone trabecular(Tb.N)was compared:at four weeks,there were significant differences between the two groups,and group A was less than group B(P<0.05).At twelve weeks,the difference between group A and group B was not statistically significant(P>0.05).The comparison of two groups respectively at different time showed statistically significant difference(P<0.05),and the Tb.N value at twelve weeks was greater than four weeks.4.Histological observation.At four weeks,the new bone formation was seen in both two groups,with small and irregular bone trabecular,and visible osteoid and fibrous connective tissue.There were fewer new born bone in group A than group B.At twelve weeks,both groups showed reduced osteoblasts;thickening of bone trabecular,mature bone tissue,and wrapping of implant threads.The bone tissue in the visible material of group A is connected to the surrounding bone tissue of the implant.New blood vessels are embedded in bone tissue.BIC comparison:at four weeks,there was significant difference between the two groups,group A was less than group B(P<0.05),and the difference between group A and group B was not statistically significant(P>0.05).The groups were compared at different times.The difference of BIC was statistically significant(P<0.05),and the BIC of every groups at twelve weeks was greater than four weeks.5.Implant resonance frequency analysis(ISQ)and mechanical test.The results of the implant resonant frequency analysis showed that the ISQ values were less than group B(P<0.05)when the implant was first implanted,four weeks and twelve weeks.However,both groups had good stability during each period.The mechanical test(the implant experiment)showed that group A was smaller than group B at four weeks and twelve weeks,The maximum shear strength of the two groups was statistically significant(P<0.05).The groups were compared at different times.The difference of maximum shear strength of the implant was statistically significant(P<0.05),and the maximum shear strength of every groups at twelve weeks was greater than four weeks.Conclusion:Experiments show that the porous hydroxyapatite can induce new bone to repair wide range bone defect and combined with implant happen at the same time,the better effect can be achieved when especially in twelve weeks,provide reference for clinical and experimental research. |
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