| ObjectiveExperiment appling different formulations of gingival retraction,observed the degrees of injury and the expresstions of some inflammation factors'receptors via HE staining method,VG specific stain and immunohistochemistry stain. Providing comperhensive evaluation for different formulations of gingival retraction and their reference basis of clinical choices are our purposes of the research.MethodsExperiment selected 125 rats for the experiment .5 rats(group E) as controll group were chosed, others were random divided into gingival retraction cord (groupA), gingival retraction cord intervention(groupB), gingival retraction paste (groupC), gingival retraction paste intervention (groupD) and each group included 30 rats.Respectively simulated clinical operation for group A,B,C,D. Impressed gingival retraction cord into maxillary incisor gum of 60 rats(groupA and B),took them out after 5 min.Then rats,groupB, were droped intervenal drug—iodoglycerin in gingival sulcus .Crammed gingival retraction paste into maxillary incisor gum of 60 rats(group C and D),and also took gingival retraction paste out after 5 min .The rats ,group D,were also droped intervenal drug—iodoglycerin in the place as groupB.Rats in experimental groups were respectively collected living samples of maxillary central incisor ,around gum tissue and a part of alveolar bones after 30min,24h,48h,5d,7d,12d .Samples of maxillary tissue were fixed in 4% polyoxymethylene stationary liquid for 24h, were decaicification for 5 months in 13%demineralization liquid at atmospheric temperature, then were dehydrated in series of ethanol ,were displaced by dimethylbenzene and were embeded in paraffin.Conventionally made paraffin sections,which were3μm thick.We observed the inflammatory response of gum tissue using HE staining.VG staining was used to observe the apperance and the direction of arrangement of collagen fiber.The expresstions of Tumor necrosis factor-a (TNF-α) and epidermal growth factor receptor (EGFR) were observed after be used immunohis- tochemistry stain .Resultsgingival retraction cord and gingival retraction paste group gingival biopsy specimens of Inflammation score, Sulcular epithelium injury score, EGFR and TNF-αimmunohistochemical IOD showed that the results:1. gingival retraction cord group and gingival retraction paste group compared control group: There were significant differences (P<0.01).2. gingival retraction cord and gingival retraction paste group 12day,7day compared with control group: no significant difference (P>0.05).3. gingival retraction cord and gingival retraction paste group the peak of inflammation or injury compared: gingival retraction cord group HE staining 24hour and 48hour inflammation score 2.87±0.352, 2.60±0.507. gingival retraction paste group inflammation score 1.53±0.743,0.73±0.594,There were significant differences (P<0.01). TNF-αimmunohisto- chemical staining gingival retraction cord group 24 hour IOD 146.200±6.574, gingival retraction paste group 24 hour IOD 99.759±6.507, There were significant differences (P<0.01).4. Intervention and experimental group the peak of inflammation or injury compared: EGFR immunohistochemical staining gingival retraction cord group 48hour and 7 day IOD 75.357±5.740, 112.813±7.383,gingival retraction paste group IOD 93.472±6.082,27.349±3.515, There were significant differences (P<0.01).Conclusion1. After application of different gingival retraction formulations,On the gingival tissues are different degrees of damage.2. 12 days after the gums can return to normal morphology. Show that the retraction of two formulations are reliable and secure.3. Gingival retraction paste over the biological effects of gingival retraction cord better, on more minor damage gum tissue.4. Topical application of iodine glycerin gingival sulcus drugs can reduce the degree of gingival tissue injury.
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