Different Ways To Deal With Bone Defect Gap Around Immediate Implant:an Experimental Study In Dogs

Objective:The aim of this study was to determine the self-osteogenesis in an immediate implant wide-bound (3—4mm) bone-defect without bone-graft and the effect of PRF on osteogenesis in bone defects. To find out the accommodation of bone graft, to explore the excellent treatment for the wide-bound (3—4mm) bone-defect in immediate implant, raise the achievement ratio and security; lighten the economic burden of the patients.Method:Experiment1:Preparation of PRFUnder aseptic conditions,intravenous blood5ml, placed in sterile vacuum blood collection tubes which without additives,3000rpm speed centrifugation15min, you can see the blood sample is decided into three layers, the middle layer of pale yellow gel is the PRF gel.Discard the PPP supernatant,remove the PRF gel with tweezers, and cut off the bib layer in the bottom, collect the fibrin gel layer in the middle, gently squeeze out the inherent serum with sterile gauze,PRF membranes can be made.Experiment2:four different treatments in bone-defect following immediate implantFour healthy adult male Beagle dogs, adaptive feeding for2weeks, weighed and general anesthesia. After taking effect of anesthesia, disinfects the oral cavity and surgery area mucosa by0.5%iodophor, articaine hydrochloride and epinephrine tartrate injection of local infiltration anesthesia, spread the aseptic towel conventionally.Carefully pull out the bilateral mandible P1、P2、P3、P4tooth, at the distal root extraction socket,5-6mm away from the root interval small ball drill position and prepared the hole step by step, to a depth of8mm. Rinse the extraction sockets to remove the residual bone debris with normal saline, and immediately implant the diameter3.6mm length8mm Super Line implant. The implants implanted in the distal root extraction socket are all close to the distal bone wall, bucco wall and lingal wall, the torque is about35N.cm, the implants gain the initial stability, to keep wide-bound (3—4mm) bone-defect were made after place an implant. The approaches for the bone defect are as follows:A:graft bio-oss bone meal and cover collagen membrane; B:simply cover the collagen membrane without bone meal: simply cover the PRF membrane; D:simply fill in the PRF gel. Adopt the submergible implant; install the cover screw and layered-suture closely.Execute the animals after1month and3months respectively, prepare the specimen, and observe the following indicators:(1) Take X-ray and observe whether there is a gap between implant and the surrounding bone tissue, peri-implant bone density and bone resorption.(2) By HE slice, then observe the morphological changes of the peri-implant bone tissue under the light microscope, and count the number of bone cells.(3) Make hard tissue sections to observe the morphological changes of the peri-implant tissue, together with quantitative histological analysis to obtain the rate of bone ingrowth fraction(BIF) and contact length fraction(CLF),the data was analyzed with the statistics software SPSS13.0. The results were statistically significant based on P<0.05.Result1Visual study:soft tissue at the field of operation is healing well on4dogs, shape and color good, without swelling, ulceration and blennorrhea and some other inflammatory reaction, bone-implant area is healing well, no implant loose is found, bone-defects in each group all have been filled by the newly formed bone, part of the residual bone dust particles which was not depredated completely can be seen in group A.2X-ray observation:no significant gap can be seen between implant and bone tissue in all experimental time. No much obvious absorption images in the cervical bone, and no significant difference in bone density in each group.3Bone density analysis by CBCT:the newly formed bone and the primitive bone density were maintained in each group and distinct time section, with no statistically significant overall differences.(P>0.05)4Morphological and histological observation:(1) Group A after1month:trabecula of bone can be seen surrounding the not completely acsorbed bone meal particles.(2) Group B after1month:the upper half of the bone defect consist of connective tissue and the lower half of the scattered newly formed trabecular bone.(3) Group C after1month, compared to group B, connective tissue decreased significantly, a large number of newly formed bone trabeculae scattered, bulks of bone cells can be seen in the bone matrix.(4) Group D after1month, there is no significant difference between group C. osteoblast cells are active surrounding the bone trabeculae.(5) Group A after3months, no obvious bone meal particles can be observed in a microscopic observation, bone defect was completely filled with new bone, significant Harvard system can be seen.(6) Group B after3months, a clear boundary between different periods of bone modification is visible, each bone unit is obvious.(7) Group C after3months, defect area is completely filled with new bone. Fuse with the primitive bone, and the boundary is ambiguous.(8) Group D after3months, the newly formed bone and the primitive bone begin to mix together, bone remodeling process is obviously.5Quantitative histological analyses(1) Different approaches’effect on CLF and BIF have no significant difference in the same period (p<0.05), And the approach of the CLF and the BIF and bone defects, tooth extraction, no linear relationship between the time three factors.(2) Different treatment for the number of the bone cells has no statistically obvious difference in the same period (p<0.05), but there is a liner relationship between the number of bone cells and the time factor (p>0.05).Conclusion:(1) in a wide-bound (3—4mm) bone defect after immediate implantation, a method of simply cover collagen membrane without bone meal can get a good osseointegration.(2) A new generation of platelet concentrates products PRF plays a satisfactory part of guiding bone regeneration, promoting the osseointegration of the immediate implants. Jn a wide-bound (3—4mm) bone defect after immediate implantation, filling in the PRF may get a good osteogenic effect.(3) No much manifest distinction is performed whether the PRF is membrane form or gel status.