The Study Of The Expression Of Inducible Nitric Oxide Synthase In Peri-implantitis In Rats

Objective:By detecting the expression of inducible nitric oxide synthase(i NOS)in peri-implantitis,and comparing with the expression of i NOS in periodontitis,exploring whether i NOS be a new target for the treatment of peri-implantitis.Methods:Twelve male Wistar rats aged 8-week-old were used in this study.The upper first molar on the right side were extracted,and pure titanium nails were implanted immediately.Four weeks later,an oral implant osseointegration model of Wistar rat was obtained.Then the rats were randomly divided into experimental group and control group with six rats in each group.In the experimental group,the peri-implantitis model was established by giving silk ligature around the neck of the implant on the right side of the maxilla,and the periodontitis model was established by giving silk ligature around the neck of the first molar on the right side of the maxilla.The rats in the control group were not ligated.All rats were sacrificed on the 28 th day after ligation,and maxillary specimens containing the right implants and the left first molars were intercepted for micro computed tomography(Micro-CT)analysis.After decalcification,the specimens were stained with the method of immunohistochemistry,and the expression of i NOS in each group was observed under light microscopy.The data were recorded and statistical analysis was concluded.Results:1.The results of morphological manifestation: the gingival tissue were edema and softened texture in the periodontitis group and the peri-implantitis group.2.The results of micro-CT scan:(1)Sagittal plane results of micro-CT scan showed that compared with the left maxillary natural teeth in the control group,obvious alveolar bone resorption occurred in the periodontitis group(P<0.001).Compared with healthy implants in the control group,significant alveolar bone resorption also occurred in the peri-implantitis group(P<0.001).The peri-implantitis group had more alveolar bone resorption than the periodontitis group,and the difference was statistically significant(P<0.001).(2)The results of micro-CT three-dimensional reconstruction showed that compared with the left maxillary natural teeth in the control group,the bone volume fraction(BV/TV)of the periodontitis group was significantly reduced(P<0.01).Compared with healthy implants in the control group,BV/TV reduction was more obvious in the peri-implantitis group(P<0.001).The BV/TV in the peri-implantitis group was lower than that in the periodontitis group,and the difference was statistically significant(P<0.05).There was no significant difference in BV/TV between natural teeth and implants in the control group(P>0.05).3.The results of immunohistochemical staining: compared with the left maxillary natural teeth in the control group,the expression of i NOS in the periodontitis group was significantly increased(P<0.001).Compared with the healthy implants in the control group,the expression of i NOS in the peri-implantitis group was also significantly increased(P<0.001).The expression of i NOS in the peri-implantitis group was significantly higher than that in the periodontitis group,and the difference was statistically significant(P<0.01).In the control group,the expression of i NOS in the implant group was higher than that in the natural tooth group,but the difference was not statistically significant(P>0.05).Conclusions:In this study,the results of micro-CT scan showed that the occurrence of inflammation leads to the destruction of the alveolar bone,and resulting in a decrease in bone mass.Peri-implantitis progressed faster than periodontitis,and more alveolar bone resorption occured in the peri-implantitis than in the periodontitis.The expression of i NOS was highly in peri-implantitis,and higher than that in periodontitis.It suggests us that i NOS has a promoting effect on the occurrence of peri-implantitis,especially the resorption of alveolar bone.