| Objective:The aim of the present study is to implant the platelet rich fibrin (platelet rich fibrin, PRF) and nanometer-hydroxyapatite (nanometer-hydroxyapatite, nano-HA) alone or combined in the tooth extraction wound of rabbits, explore the mechanism of PRF to promote bone regeneration of the sockets and the restoration of the remaining alveolar bone, so as to hope to provide some guiding significance of PRF in the clinical application.Method:1. Experimental animal model:48rabbits were randomly divided into4groups(group A, group B, group C, group D), with one randomly mandibular central incisors extracted. We got the autologous blood of the rabbits through the ear marginal artery instantly and made it centrifuged to prepare the PRF membrane. We filled implantations into the sockets, A, B,C group respectively with PRF/nano-HA, PRF, nano-HA composite graft, D sockets without implantion as control. Gingiva were tightly sutured to closed the teeth sockets in four groups. The mandibular healing was evaluated by gross observation, X—ray film and histological dyeing at2,4,8and12weeks postoperatively.2. Observational method:to continuously observe bone healing in the wounds of the four groups in the2nd,4th,8th, and12th week after surgery. An assessment would be made to categorize bone healing in different groups, with excellent, good and poor three levels; and measure the density of the new bone based on panoramic radiographs, and calculate the ratio of the length between the extraction and non-extraction on the X-ray films. Then analyze the four kinds of statistics. Last, make histological slides from decalcified, dehydrated and paraffin-embedded specimen in order to observe angiogenesis and osteosis under microscope. Result:1. Radiological observation:The bone density measured through statistical analysis software in group A and C was significant higher than group B and D at the corresponding time points in the2nd,4th,8th week after surgery, P<0.05with statistical meaning, group B and group D had statistical differences(P<0.05), but group A and group C had no statistical differences(P>0.05). In the12th week after surgery bone density measured through statistical analysis software:group A> group B> group C>group D, P<0.05with statistical meaning. The relative length of the remaining alveolar ridge observed by X-ray resulted as follows:group A> group B> group C> group D, the difference was statistically significant (P<0.05) after2weeks and4weeks. After8weeks,12weeks, the group A was greater than group B and group C, the group B and group C are greater than group D (P<0.05).But there was no significant difference between group B and group C (P>0.05).Histological observation:in the2nd,4th week after surgery, the number of osteoblasts in group A was the biggest, group A> group B> group C>group D, and osteoblasts were most active. After8and12weeks the group A was greater than group B and group C.The three groups were greater than group D. There is no significant difference on the extent of calcification in the bone lamellar structure between the groupB and group C.Conclusion:1. PRF can remedy the inflammatory symptoms which can reduce post-traumatic inflammation and accelerate healing of the bone tissue.2. PRF/nano-HA can all preserve the alveolar ridge after teeth extraction and proves to be a favourable biological transplantation material on alveolarridge defect. |
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