| Objectives: Explore the effects of alveolar fossa implants on the healingof tooth extraction through implanting autologous platelet-rich fibrin (PRF),acellular dermal matrix (ADM), and the combination of the two, respectively,in the alveolar fossa immediate after tooth extraction.Methods: Thirty-six healthy female New Zeland rabbits, each of whichis five month old and weights between2to3kilograms, were selected for thestudy.5ml blood was drawn from the ear middle artery of each rabbit, andthen centrifuged at3000r min for10minutes to get the PRF for standby use.Then the maxillary first molars were extracted from each rabbit underanesthesia. The animals were divided into four groups, each group having9rabbits. Group I: the right side of teeth extraction socket implanted withplatelet-rich fibrin (PRF), and the left socket implanted with acellular dermalmatrix (ADM); Group II: the right side of teeth extraction socket implantedwith acellular dermal matrix patch (ADM), and the left tooth implanted withplatelet-rich fibrin (PRF); Group III: the right side of teeth extraction sockethaving no substance, and the left tooth implanted with platelet-rich fibrin(PRF) the surface of which was covered with acellular dermal matrix (ADM);Group IV: right side of teeth extraction socket implanted with platelet-richfibrin (PRF) the surface of which was covered with acellular dermal matrix(ADM), and the left socket having no substance. Rabbits were killed at2nd,4th, and8th weeks after extraction, respectively. Subsequently the maxillae ofeach rabbit were dissected from4mm away the tooth extraction on each side.The alveolar samples were divided into four groups. Group A: the extractionsockets implanted with platelet-rich fibrin the surface of which was coveredwith acellular dermal matrix (group PRF+ADM); Group B: socket implantedwith platelet-rich fibrin (group PRF); Group C: socket implanted withacellular dermal matrix (group ADM); Group D: extraction sockets without any treatment (control group). Then fixed them in the10%aldehyde formiquefor48hours after X-ray film was taken, decalcified in5%nitric acid aldehydeformique for3-5day, cleaned under running water for24hours, dehydrated inethanol, cleared in xylene, and finally infiltrated. Then4microns thick bonetissue was cut off the sagittal plane of the tooth extraction and stained withhematoxylin and eosin (HE) stain for histological observation andSimultaneous histomorphometry examination. The parameters measured inhistomorphometry included: the percent of trabercular area; trabercularcircumference; trabercular average width; trabercula maximum diameter;trabercular minimum diameter; osteoblasic number. Finally the acquired datawere analyzed for statistical significance using SPSS13.0software.Results:1X-ray observationTwo weeks after tooth extraction operation, groups A, B, and C showedgranular material of high density filled the entire alveolar fossa on theX-ray,where group D showed low density image of the socket.Four weeks after tooth extraction operation, in group A alveolar bonetrabecula structure and the surrounding bone structure were almost identical.And very little difference between alveolar bone trabecula structure and thesurrounding bone tissue in group B and group C was observed. Group D stillhad obvious alveolar fossa, and a part of the bone trabeculae showed visiblecalcification.Eight weeks after tooth extraction, the alveolar bone tissue in group Adisappeared, and the reconstructed fossa was almost identical to thesurrounding bone tissue structure. In groups B and C the socket disappeared,and the bone structure and the surrounding bone tissue fossa were almostidentical. In group D the socket disappeared, but the trabecular structure hadslightly lower density than that of the surrounding bone tissue.2Observation under the light microscope:Two weeks after surgery, in Group A extraction sockets of trabecularbone is rich and connected into a network, but the thickness is not uniform; osteoblasts are columnar or cuboidal; nucleus are round or oval, locatedaround the bone; trabecula is monolayer; bone cells are located in the centre oftrabecular bone lacuna in the shape of triangle or short bar. In Group B socketbone trabeculae is slender and less than that of group A, and in centralextraction sockets the fibroblast cells transform into osteoblasts and form newbone island. In Group C new bone is formed in fossa with a large amounts ofchildish trabecular bone, osteoblasts is arranged in a multilayer way, and thefibrous connective tissue is more than those in Group A and Group B. InGroup D plenty of collagen fibers are found extraction sockets, someimmature trabecular bone from fossa side wall grow toward central fossa, thesurrounding bone cells dense and are arranged in a multilayer way.Four weeks after tooth extraction, in Group A, the bone trabecula in thefossa become thicker and are connected to each other; the amount ofinterstitial components reduce; osteoblasts are around the bone trabecula andarranged in a single-layer way. In Group B the amount of trabecular bone isincreased, its width increases, but it is still slender compared with that inGroup A; the trabecular bone is connected to each other; the osteoblasts arearound the bone trabecula and arranged in a single-layer way. In Group C thetrabecular bone in the extraction sockets is less and slenderer than those inGroups A and B; the amount of stromal components is large; new bone islandis observed in central tooth fossa. In Group D pouch with fibrosis bone isformed, surrounded by a large amount of immature trabecular bone; theosteoblasts are dense and arranged around the bone trabecula in a multilayerway.Eight weeks after tooth extraction operation, in group A the fossa bone inthe extraction tends to be mature; the degree of calcification and bone platedensity are high; and the plate line is visible. In Group B the fossa bonetrabecula in the extraction is thicker and connected; the osteoblast showcuboidal or columnar shapes and are around the trabecular bone; the bonecells are in the shapes of triangle or short bars and located in central trabecularbone lacuna. In group C the bone trabeculae become thicker, and the amount of interstitial ingredient reduces. In Group D the trabecular bone in extractionsockets is less than those in the other three groups and sparse; the amount ofstromal components is large; the osteoblasts are dense and arranged around thebone trabecula.3Bone histomorphometry results:Two weeks after surgery, comparing the trabecular area ratio, trabecularperimeter, the bone trabecular average width, the longest diameter and theshortest diameter of trabecular bone of the four groups, the following resultwas obtained: group A> group B> group C> group D (P<0.01).The sameresults can be obtained four weeks after surgery. Again two weeks aftersurgery, comparing the osteoblast number in extraction of the four groups, thefollowing result was obtained: group A (group ADM+PRF)<group B <groupC <group D (P<0.01). And the some results can be obtained four week aftersurgery.Eight weeks after surgery, comparing the bone trabecular area ratio, trabecularperimeter, the bone trabecular average width, the longest diameter and theshortest diameter of trabecular bone,there is no significant difference betweengroup B and group C (P>0.05).However, there is significant statisticaldifference between group A and group B, group C (P<0.01);and betweengroup A and group B, group D (P<0.01). In terms of osteoblast number, on theother hand, there is significant statistical difference between group A andgroup B, group C (P<0.01); and between group A and group B, group D(P<0.01),but there is no statistical difference between group B and group C(P>0.05).Conclusions:1The platelet-rich fibrin, the acellular dermal matrix, and thecombination of the two, can promote early healing of tooth extraction wound.2When used individually, platelet-rich fibrin is more effective thanacellular dermal matrix to accelerate the healing process of tooth extractionwound. When used collectively, the healing-promoting effect is the mostobvious. 3The combination of PRF and ADM can effectively guide theregeneration of alveolar bone and shorten the restoration time of missing teeth,which makes it possible for them to be widely used as alveolar fossatransplantation materials in clinical applications. |
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