| Objective: To establish an animal model for peri-implant infection. Detecting itwith radiographic and histologic methods to explore the effect of related risk factors inthe role of forming peri-implant infection. For the purpose of finding the earlypathological changes of peri-implant infection in clinic.Methods: Select six healthy adult dogs from12to24months old for experimentand number them from1st to6th randomly. Pulling off all of the mandibular bilateral2nd、3th and4th premolars after the anesthesia. After12weeks of healing period, theimplants were implanted. Another12weeks again, started to establish the Animal modelof peri-implant infection. According to different methods，all the implants wererandomly divided into6groups. Group A：orthodontic ligature wire；Group B：suturethread.；Group C：rubber band.；Group D：injecting bacteria；Group E：tie suture threadand inject bacteria at the same time.Group F：no additional operating, as controlgroup.The methods of six groups were assigned randomly to each dog’s six plantingpositions. After4weeks, Removed all the external stimuli. With common methods usedin clinic, we detected the implants. After another4weeks executed all the experimentaldogs, measure and record the test data again. Date of4weeks was respectively recordedasⅠ~Ⅵ group; Date of8weeks was respectively recorded as Ⅶ~Ⅻ group. Thesamples were evaluated and analyzed. Soft tissues were observed by histology; Scleroustissues were calculated by the IPP software for bone contact ratio. X-ray film imagingand CBCT were prepared to observe bone resorption status. Statistical softwareSPSS13.0was used to analysis the final data. Results:1.Gross observation: After the surgery one dog was died from cold，and wereplenished the samples. Mucosa packages around implants’ necks like “cuffs” afterhealing. In this study, we collected a total of36cases with no loss. A week later，hyperemia,swelling and burst reaction were found. After4weeks, X ray showed parts ofthe experimental groups with shallow bone resorption were like dishes. Theexperimental group auscultated low and dull while the control group of auscultation hadringing sound.2.Imaging observation: X-ray showed that the experimental group bone resorptionwas obvious around implants’ necks，prompted experimental implant had a certaindegree of absorption. Group A and group E had obvious bone resorption images. Bonetissue in Group B and group D had a certain degree of bone resorption, but they onlyhad a lesser degree. Bone resorption in Group C and group F were not visible.Conebeam CT constructed high-definition，high-resolution of bone images.3.Histological observationHE stain showed that there were a large number of inflammatory cells，such as Tlymphocytes, plasma cells. Morphology observation showed that implants inexperimental group have a certain degree of bone resorption. Analysis bone contact rateby IPP software, Group A:56.52%±1.15%；Group B61.28%±2.39%；Group C:76.13±1.90%；Group D:53.61%±1.58%；Group E:59.83%±2.64%；Group F:74.99%±1.66%.4.Statistical analysis results（1）At the same point of time，there was statistically significant difference inclinical observation indexes between group A and group D，group B and group E（p<0.05）（2）There was no statistically significant difference in clinical observation indexesbetween group C and group F（p>0.05）.(3) Using the same method, There was statistically significant difference betweengroupⅠand groupⅦ，groupⅡ and groupⅧ，group Ⅳ and group Ⅹ，groupⅤ and group X（Ip<0.05）；But group Ⅲ and group Ⅸ had no statistical difference（p>0.05）.There was statistically difference of bone contact ratio between the experimental groupand control group (P <0.05).Conclusion:1.Peri-implant infection can be caused by orthodontic ligature wire、suture threadand bacteria. There is certain feasibility based on animal model.2.After removing the stimulus, inflammation effect of soft tissue reduced, but boneabsorption continued.3.Tie sutures while inject bacteria can strengthen the infection process and effect.4.Suture thread caused more serious infections than bacteria injected around theimplant. |
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