The Osteoplastic Effect Of Y500R CHA And The CHA Composite Grafts With Fluoride On The Rabbit Skull

Background:The application of dental implant is most remarkable progress in the 20^th century's dental history.Because of various reasons,most of the patients have to accept the bone incremental surgery during the treatments,but the Osteogenic performance of the bone substitutes will affect the surgical results.Through continuous clinical treatment,people can fully understand the value of guided bone regeneration and bone substituting,so they try to improve the osteoinductive and osteoconductive efficacy in the scientific research.From the study of the structure and physical properties,the more reasonable ratio of calcium and phosphorus they contain,the more biocompatibility they have.Three-dimensional structure also plays an important role to the osteoconductive,so we need the ideal bone substitutes which are absorbable and can be reconstruction.Although,the bone substitutes which be commonly used today only provide the physical stents for new bone growing,cell stimulating factors are essential for the promotion of bone metabolism.They will also affect the whole process of bone remodeling by changing differentiation,proliferation, maturation and activation of the osteoblast and osteoclast.From the review of the bone substitutes in common used,we can see that they all have the good biocompatibility and a lot of detects simultaneously.For example,autogenous bone will be absorbed easily,so they can not maintain an adequate bone mass for the implant.On the contrary,demineralized ironganic bone can not be absorbed in the bone remodeling.These defects will reduce their value in the guided bone regeneration.At the same time,stimulating factors have certain defects such as major difficulty in preparation,high costs,unpredictable side effects and so on.They need to be improved in order to be applied in future.Recently,a new type of coral hydroxyapatite artificial bone has been successfully developed,arid fluorine also has been successfully used in implant surface treatment.These advances will make the preparation of the high-performance bone substitutes to be possible.They will be widely clinical used in future.This study will evaluate the guided bone regeneration capacity of CHA and the composite CHA which can release fluoride ion in low concentrations by the animals experiment.To explore the effect of Y500R CHA in Guided Bone Augmentation on rabbit skull and the impact of the F^- in bone osteogenic effect.Methods:1.Machined the titanium cylinder using theφ11.5mm medical titanium rod.After the polishing,,they would be cleaned by ultrasonography and chemical reagents., packaged.After the high temperature and high pressure disinfection,they would be dried for use.2.Prepared the Y500R CHA artificial bone.Their particle size were aboutφ0.25-1.0 mm.Compound the certain concentration of sodium fluoride solution,and the CHA would be soaked in sodium fluoride solution,so that fluoride ion could be adsorpted on the surface of bone.3.48 New Zealand white rabbits were randomly divided into A,B,C three groups.A group of 24 rabbits were prepared the annular craniofacial bone lacuna and fresh bone wound in surgery.After that one titanium cap cylinder with autogenous bone and another titanium cylinder with blood marrow would be fixed on the skull.B group of 12 rabbits were fixed two titanium cylinders with Y500R CHA on the skull. Similarly,C group of 12 rabbits were fixed two titanium cylinders with fluoride CHA composite on the skull.Bullosa the skin,and sutured wound closely.In three days after the surgery,20 million units of penicillin was injected intramuscularly to prevent infection.The all rabbits were held in separate cages.At the 10^th,11^th day after the surgery,the rabbits would have subcutaneous injection of tetracycline.They also had subcutaneous injection of calcein at the 3^rd,4th day before the executing.After 2,4 and 6 weeks,the animals were sacrificed.The soft tissues of the experimentalparietal bones comprising the 2 titanium cylinderswere taken en bloc and fixated by immersion in 4%buffered formaldehyde.The specimen were dechydrated in a graded series of alcohol and embedded in plastic resin.The sections were grounded to 30μm for histological evaluation and analysis.Results:1.The animals recovered well after the surgery,and the wound also grew well. The titanium cylinder were solid without loose.2.From observation of the specimens,soft tissue fibers can be seen to be closely wrapped around the titanium cylinders without dead space.Titanium cylinders were so solid that they could shield the growing of the connective tissue.They also provided an ideal space for the new bone growth.Take off the titanium cylinders;we could see that the cylindrical bone substitutes were regular.The new bones were dyed orange-red by calcein,so we can distinguish clearly.The osteogenic effect in fluoride CHA group was more significant than the CHA group,and there are much new bone in fluoride CHA group.3.The new bone were attached by fluorescent dye,so that they could issue a green and yellow fluorescence.The fluorescent height and area of each groups were clearly contrast,and the result also had good comparability.The measurement results of fluorescent area show the order of the new bone volume at 2 and 4weeks:fluoride CHA group＞CHA Group＞autogenous bone group＞blank control group,and when after 6 weeks,the order was that fluoride CHA group＞CHA Group≈autogenous bone group＞blank control group.4.By the toluidine blue and acid fuchsin dyeing,we could clearly see that the news bone had grown into the titanium cylinder.Mature bone was dyed garnet,and osteoid was stained blue.2 weeks later,there were less new bone.In blank group,almost no new bone formation could be found,while the new bone had grown above from the bone wound.The volume of neonatal bone in fluoride CHA group was the most,followed by the CHA group,and the new bone volume in autogenous bone group was obviously much less than all the groups which were filled in the bone substitutes.4 weeks later,there were more trabecular bone formation,and the osteogenic effect in fluoride CHA group was still more attractive than other groups.At the same time,there were a certain amount new bone in blank group.6 weeks later,the mature new bone was dense plate-like,and the osteoid had been fully occupied all the space in titanium cylinder.At this time,osteogenic effect of the fluoride CHA group was still the most significant.5.2 weeks later,the fluorescent area of the fluoride CHA group(7.38±0.57) mm², CHA group(4.46±0.38) mm²,autogenous bone group(2.86±0.43) mm²,and the blank group(1.09±0.2) mm²;the results were statistically significant in each group with each other(P＜0.01).4 weeks later,the fluorescent area of the fluoride CHA group(11.78±0.78) mm²,CHA group(9.22±0.52) mm², autogenous bone group(6.67±0.74) mm²,and the blank group(3.68±0.72) mm²;the results were also statistically significant in each group with each other.(P＜0.01).6 weeks later,the fluorescent area of the fluoride CHA group (13.91±0.60) mm²,CHA group(10.47±0.40) mm²,autogenous bone group (10.24±0.54) mm²,and the blank group(5.5±0.43) mm²;no statistically significant difference was found between CHA group and autogenous bone group,but they also have difference with the fluoride CHA group and the blank group.Conclusion:1.The operation method that used the titanium cylinders in the guided bone regeneration animal model is more simple,and the trauma is smaller.It can make the experimental result more reliable,objective and comparable.2.Although the blank group had been filled with the bone marrow blood which had a large number of osteoblasts and other cell components,osteogenic effect is also far lower than the other groups in the absence of scaffold circumstances.3.Compared with autogenous bone,the CHA had better guided bone regeneration capacity at the early stage of bone growth(2 weeks and 4 weeks),but the differences become smaller at 6 weeks obviously.4.Fluoride ion that in the status of low concentration can enhance the ability in guided bone regeneration of the substitutes and accelerate new bone formation.